Effect of EPS Content on Activated Sludge Reduction in Process of Predation by T. tubifex

NASA Astrophysics Data System (ADS)

Lei, Yingjie; Ai, Cuiling; Zhang, Guochun

2017-12-01

A Sludge reduction in a conventional activated sludge process combined with a membrane biofilm inoculated with T. tubifex was investigated. The influence of microbial extracellular polymeric substances (EPS) extracted in forms of LB-EPS and TB-EPS respectively on the surface properties of biomass was studied. Results showed that variations of polysaccharides and protein along with the increasing of EPS feeding would affect the existence of T. tubifex. When the amount of EPS varied from 10 to 50μg/mg, the specific resistance of a sludge suspension was obtained from 3.5×107 to 1.4×107 S2/g. Meanwhile, polysaccharides content in EPS was to be positively correlated with the SSR of sludge suspension whereas protein content would be not. Anyway, it can be argued that an increase in LB-EPS not TB-EPS may affect the performance of activated sludge reduction with efficiency about 40.1% to 31.6%.

The Trickling Filter/Solids Contact Process: Application to Army Wastewater Plants

DTIC Science & Technology

1988-08-01

technology (activated sludge and rotating biological contactors [RBC]). 3 7 For the study, the plant was to be sized at 10 mgd. Electricity purchased from...Project Costs* Estimated Cost** ($K) Trickling Rotating Filter/Solids Activated Biological Item Contact Sludge Contactor Preliminary treatment 1100 1100...basins 4500 - Rotating biological contactor reactors - 4520 Flocculator clarifiers 2000 - - Conventional secondary clarifiers 1770 1500 Dual-media

Can activated sludge treatments and advanced oxidation processes remove organophosphorus flame retardants?

PubMed

Cristale, Joyce; Ramos, Dayana D; Dantas, Renato F; Machulek Junior, Amilcar; Lacorte, Silvia; Sans, Carme; Esplugas, Santiago

2016-01-01

This study aims to determine the occurrence of 10 OPFRs (including chlorinated, nonchlorinated alkyl and aryl compounds) in influent, effluent wastewaters and partitioning into sludge of 5 wastewater treatment plants (WWTP) in Catalonia (Spain). All target OPFRs were detected in the WWTPs influents, and the total concentration ranged from 3.67 µg L(-1) to 150 µg L(-1). During activated sludge treatment, most OPFRs were accumulated in the sludge at concentrations from 35.3 to 9980 ng g(-1) dw. Chlorinated compounds tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP) and tris(2,3-dichloropropyl) phosphate (TDCPP) were not removed by the conventional activated sludge treatment and they were released by the effluents at approximately the same inlet concentration. On the contrary, aryl compounds tris(methylphenyl) phosphate (TMPP) and 2-ethylhexyl diphenyl phosphate (EHDP) together with alkyl tris(2-ethylhexyl) phosphate (TEHP) were not detected in any of the effluents. Advanced oxidation processes (UV/H2O2 and O3) were applied to investigate the degradability of recalcitrant OPFRs in WWTP effluents. Those detected in the effluent sample (TCEP, TCIPP, TDCPP, tributyl phosphate (TNBP), tri-iso-butyl phosphate (TIBP) and tris(2-butoxyethyl) phosphate (TBOEP)) had very low direct UV-C photolysis rates. TBOEP, TNBP and TIBP were degraded by UV/H2O2 and O3. Chlorinated compounds TCEP, TDCPP and TCIPP were the most recalcitrant OPFR to the advanced oxidation processes applied. The study provides information on the partitioning and degradability pathways of OPFR within conventional activated sludge WWTPs. Copyright © 2015 Elsevier Inc. All rights reserved.

Review on innovative techniques in oil sludge bioremediation

NASA Astrophysics Data System (ADS)

Mahdi, Abdullah M. El; Aziz, Hamidi Abdul; Eqab, Eqab Sanoosi

2017-10-01

Petroleum hydrocarbon waste is produced in worldwide refineries in significant amount. In Libya, approximately 10,000 tons of oil sludge is generated in oil refineries (hydrocarbon waste mixtures) annually. Insufficient treatment of those wastes can threaten the human health and safety as well as our environment. One of the major challenges faced by petroleum refineries is the safe disposal of oil sludge generated during the cleaning and refining process stages of crude storage facilities. This paper reviews the hydrocarbon sludge characteristics and conventional methods for remediation of oil hydrocarbon from sludge. This study intensively focuses on earlier literature to describe the recently selected innovation technology in oily hydrocarbon sludge bioremediation process. Conventional characterization parameters or measurable factors can be gathered in chemical, physical, and biological parameters: (1) Chemical parameters are consequently necessary in the case of utilization of topsoil environment when they become relevant to the presence of nutrients and toxic compounds; (2) Physical parameters provide general data on sludge process and hand ability; (3) Biological parameters provide data on microbial activity and organic matter presence, which will be used to evaluate the safety of the facilities. The objective of this research is to promote the bioremediating oil sludge feasibility from Marsa El Hariga Terminal and Refinery (Tobruk).

Phyto-dewatering of sewage sludge using Panicum repens L.

PubMed

El-Gendy, A S; El-Kassas, H I; Razek, T M A; Abdel-Latif, H

2017-04-01

Experiments in the field environment have been conducted to study the growth of Panicum repens L., an aquatic plant, in the sewage sludge matrix. The experiments were also carried out to investigate the ability of this plant to dewater sewage sludge to increase the capacity of conventional drying beds. In addition, the ability of Panicum repens L. to reduce the sludge contents of certain elements (copper (Cu), Iron (Fe), Sodium (Na), lead (Pb), and Zinc (Zn)) was also investigated. All experiments were carried out in batch reactors. Different plant coverage densities were tested (0.00 to 27.3 kg/m 2 ). The liquid sewage sludge was collected from a wastewater treatment plant in Helwan city, Cairo Governorate, Egypt. The collected sludge represents a mixture of the primary sludge and waste activated sludge before discharging into drying beds.

Treatment of winery wastewater in a conventional municipal activated sludge process: five years of experience.

PubMed

Bolzonella, D; Zanette, M; Battistoni, P; Cecchi, F

2007-01-01

A full-scale wastewater treatment plant where municipal and winery wastewaters were co-treated was studied for five years. The experimental results showed that suspended solids, COD, nitrogen and phosphorous were effectively removed both during the treatment of municipal wastewater and the cotreatment of municipal and winery wastewater. The sludge production increase from 4 tons to 5.5 tons per day during the harvesting and wine making period. In any case the specific sludge production was 0.2 kgMLVSS per kgCOD(removed) despite the organic loading increasing. About 70% of the COD was removed through respiration. Also the energy demand increased from 6,000 to 7,000 kWh per day. The estimated costs for the treatment of the winery wastewater was 0.2-0.3 Euros per m3 of treated wastewater. With reference to the process efficiency, the nitrogen removal was just 20%. The co-treatment of municipal and winery wastewater in conventional activated sludge processes can be a feasible solution for the treatment of these streams at relatively low costs.

Production of biodegradable plastics from activated sludge generated from a food processing industrial wastewater treatment plant.

PubMed

Suresh Kumar, M; Mudliar, S N; Reddy, K M K; Chakrabarti, T

2004-12-01

Most of the excess sludge from a wastewater treatment plant (60%) is disposed by landfill. As a resource utilization of excess sludge, the production of biodegradable plastics using the sludge has been proposed. Storage polymers in bacterial cells can be extracted and used as biodegradable plastics. However, widespread applications have been limited by high production cost. In the present study, activated sludge bacteria in a conventional wastewater treatment system were induced, by controlling the carbon: nitrogen ratio to accumulate storage polymers. Polymer yield increased to a maximum 33% of biomass (w/w) when the C/N ratio was increased from 24 to 144, where as specific growth yield decreased with increasing C/N ratio. The conditions which are required for the maximum polymer accumulation were optimized and are discussed.

Settling properties of aerobic granular sludge (AGS) and aerobic granular sludge molasses (AGSM)

NASA Astrophysics Data System (ADS)

Mat Saad, Azlina; Aini Dahalan, Farrah; Ibrahim, Naimah; Yasina Yusuf, Sara; Aqlima Ahmad, Siti; Khalil, Khalilah Abdul

2018-03-01

Aerobic granulation technology is applied to treat domestic and industrial wastewater. The Aerobic granular sludge (AGS) cultivated has strong properties that appears to be denser and compact in physiological structure compared to the conventional activated sludge. It offers rapid settling for solid:liquid separation in wastewater treatment. Aerobic granules were developed using sequencing batch reactor (SBR) with intermittent aerobic - anaerobic mode with 8 cycles in 24 hr. This study examined the settling velocity performance of cultivated aerobic granular sludge (AGS) and aerobic granular sludge molasses (AGSM). The elemental composition in both AGS and AGSM were determined using X-ray fluorescence (XRF). The results showed that AGSM has higher settling velocity 30.5 m/h compared to AGS.

Hybrid activated sludge/biofilm process for the treatment of municipal wastewater in a cold climate region: a case study.

PubMed

Di Trapani, Daniele; Christensso, Magnus; Odegaard, Hallvard

2011-01-01

A hybrid activated sludge/biofilm process was investigated for wastewater treatment in a cold climate region. This process, which contains both suspended biomass and biofilm, usually referred as IFAS process, is created by introducing plastic elements as biofilm carrier media into a conventional activated sludge reactor. In the present study, a hybrid process, composed of an activated sludge and a moving bed biofilm reactor was used. The aim of this paper has been to investigate the performances of a hybrid process, and in particular to gain insight the nitrification process, when operated at relatively low MLSS SRT and low temperatures. The results of a pilot-scale study carried out at the Department of Hydraulic and Environmental Engineering at the Norwegian University of Science and Technology in Trondheim are presented. The experimental campaign was divided into two periods. The pilot plant was first operated with a constant HRT of 4.5 hours, while in the second period the influent flow was increased so that HRT was 3.5 hours. The average temperature was near 11.5°C in the overall experimental campaign. The average mixed liquor SRT was 5.7 days. Batch tests on both carriers and suspended biomass were performed in order to evaluate the nitrification rate of the two different biomasses. The results demonstrated that this kind of reactor can efficiently be used for the upgrading of conventional activated sludge plant for achieving year-round nitrification, also in presence of low temperatures, and without the need of additional volumes.

Detection and Molecular Characterization of Hepatitis A Virus from Tunisian Wastewater Treatment Plants with Different Secondary Treatments.

PubMed

Ouardani, Imen; Turki, Syrine; Aouni, Mahjoub; Romalde, Jesús L

2016-07-01

Hepatitis A virus (HAV) is the main causative agent of hepatitis infection associated with waterborne outbreaks worldwide. In Tunisia, there is no specific surveillance system for HAV and current secondary wastewater treatment processes are unable to remove viral particles, which present a potential public health problem. Qualitative and quantitative analysis of HAV in 271 raw and treated wastewater samples from five sewage treatment plants (STPs) during 13 months was performed. Moreover, the efficiency of three secondary wastewater treatment processes (conventional activated sludge, extended aeration, and oxidation ditch activated sludge) was evaluated. Data obtained demonstrated that HAV is endemic in Tunisia and circulates with high prevalence in both raw (66.9%) and treated (40.7%) wastewater. HAV circulates throughout the year in the coastal areas, with the highest rates found during summer and autumn, whereas in central Tunisia, high levels were shown in autumn and winter. Total virus removal was not achieved, since no difference in mean HAV loads was observed in effluents (6.0 × 10(3) genome copies [GC]/ml) and influents (2.7 × 10(3) GC/ml). The comparison of the HAV removal values of the three different wastewater treatment methods indicates that extended aeration and oxidation ditch activated sludge had better efficiency in removing viruses than conventional activated sludge did. Molecular characterization revealed that the vast majority of HAV strains belonged to subgenotype IA, with the cocirculation of subgenotype IB in wastewater treatment plants that collect tourism wastewater. This report provides important data on the incidence, behavior, seasonality, and genotype distribution of HAV in the environment in Tunisia, as well as the risk of infection derived from its occurrence in effluents due to inadequate wastewater treatment. In addition, these findings seem to confirm that the prevalence of HAV depends on socioeconomic level, sanitary conditions in the communities, sewage facilities, the locality, and the climate. The wide dispersion of HAV in effluents proves the inefficacity of the current wastewater treatment processes used in Tunisia to remove virus; therefore, establishment of tertiary treatment processes or replacement of the medium-charge activated sludge (conventional activated sludge) by the low-charge version (oxidation ditch activated sludge) is absolutely needed. Rapid detection of the HAV genome in wastewater may provide a timely warning sign to health authorities to implement population protection measures. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Improving volatile fatty acids production by exploiting the residual substrates in post-fermented sludge: Protease catalysis of refractory protein.

PubMed

Yin, Bo; Liu, Hongbo; Wang, Yuanyuan; Bai, Jie; Liu, He; Fu, Bo

2016-03-01

The real cause to the low yield of volatile fatty acids (VFAs), from inhibition or low biodegradation, is uncertain in sludge anaerobic fermentation. In this study, poor biodegradability of proteins and fast decrease of the indigenous hydrolase activity in the residual post-fermented sludge were found to be the major reasons. With the addition of trypsin or alkaline protease in residual post-fermented sludge after primary alkaline fermentation, degradation efficiency of refractory protein increased by 33.6% and 34.8%, respectively. Accordingly, the VFAs yields were improved by 69.7% and 106.1%, respectively. Furthermore, the activities of added trypsin and alkaline protease could maintain at 13.52 U/mL and 19.11 U/mL in the alkaline fermentation process. This study demonstrated that exploiting the refractory proteins in residual post-fermented sludge by protease addition seems to be a very promising way for improving VFAs yield of conventional alkaline fermentations with waste activated sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Stabilization of waste-activated sludge through the anoxic-aerobic digestion process.

PubMed

Hashimoto, S; Fujita, M; Terai, K

1982-08-01

During the aerobic digestion process, the nitrogen which had been embedded in the activated sludge is solubilized to form ammoniacal and nitric nitrogen which are in turn transferred to the liquor and cause the increase of nitrogen loading in the sewage treatment plant. In this study, the anoxic-aerobic sludge digestion system which is a modified form of the conventional aerobic sludge digestion is made up of aerobic and anoxic tanks and are designed to remove both the volatile suspended solids and the total nitrogen (TN) simultaneously. The removal efficiencies of both VSS and TN were investigated by feeding waste-activated sludge continuously and semicontinuously. The maximum percent reduction of both VSS and TN was achieved at a Q(r)/Q(s) ratio of 2 in the continuous process. The semicontinuous process was used to improve the nitrogen removal efficiency further. In the semicontinuous process, the VSS reduction efficiency as well as the nitrogen removal efficiency increased remarkably under a constant Q(r)/Q(s) ratio of 2. This process also achieved a VSS reduction efficiency higher than the aerobic digestion process (control). It was suggested that the additional anoxic tank enhanced the sludge digestion. Furthermore, the anoxic-aerobic digestion system can be applied to other treatment media like the primary sludge, industrial sludge, animal manure, etc.

Can activated sludge treatments and advanced oxidation processes remove organophosphorus flame retardants?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cristale, Joyce; Ramos, Dayana D.; Dantas, Renato F.

2016-01-15

This study aims to determine the occurrence of 10 OPFRs (including chlorinated, nonchlorinated alkyl and aryl compounds) in influent, effluent wastewaters and partitioning into sludge of 5 wastewater treatment plants (WWTP) in Catalonia (Spain). All target OPFRs were detected in the WWTPs influents, and the total concentration ranged from 3.67 µg L{sup −1} to 150 µg L{sup −1}. During activated sludge treatment, most OPFRs were accumulated in the sludge at concentrations from 35.3 to 9980 ng g{sup −1} dw. Chlorinated compounds tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP) and tris(2,3-dichloropropyl) phosphate (TDCPP) were not removed by the conventional activated sludge treatmentmore » and they were released by the effluents at approximately the same inlet concentration. On the contrary, aryl compounds tris(methylphenyl) phosphate (TMPP) and 2-ethylhexyl diphenyl phosphate (EHDP) together with alkyl tris(2-ethylhexyl) phosphate (TEHP) were not detected in any of the effluents. Advanced oxidation processes (UV/H{sub 2}O{sub 2} and O{sub 3}) were applied to investigate the degradability of recalcitrant OPFRs in WWTP effluents. Those detected in the effluent sample (TCEP, TCIPP, TDCPP, tributyl phosphate (TNBP), tri-iso-butyl phosphate (TIBP) and tris(2-butoxyethyl) phosphate (TBOEP)) had very low direct UV-C photolysis rates. TBOEP, TNBP and TIBP were degraded by UV/H{sub 2}O{sub 2} and O{sub 3}. Chlorinated compounds TCEP, TDCPP and TCIPP were the most recalcitrant OPFR to the advanced oxidation processes applied. The study provides information on the partitioning and degradability pathways of OPFR within conventional activated sludge WWTPs. - Highlights: • OPFRs were detected in wastewater and sludge of all studied WWTPs. • Alkyl and chloroalkyl phosphates were present in secondary treatment effluents. • TBOEP, TNBP and TIBP were degraded by UV/H{sub 2}O{sub 2} and O{sub 3} treatment. • TCEP, TCIPP and TDCPP were resistant to both secondary and tertiary treatment.« less

Startup of the Anammox Process in a Membrane Bioreactor (AnMBR) from Conventional Activated Sludge.

PubMed

Gutwiński, P; Cema, G; Ziembińska-Buczyńska, A; Surmacz-Górska, J; Osadnik, M

2016-12-01

  In this study, a laboratory-scale anammox process in a membrane bioreactor (AnMBR) was used to startup the anaerobic ammonium oxidation (anammox) process from conventional activated sludge. Stable operation was achieved after 125 days. From that time, nitrogen load was gradually increased. After six months, the average nitrogen removal efficiency exceeded 80%. The highest obtained special anammox activity (SAA) achieved was 0.17 g (-N + -N) (g VSS × d)-1. Fluorescent in situ hybridization also proved the presence of the anammox bacteria, typically a genus of Brocadia anammoxidans and Kuenenia stuttgartiensis.

Bioprocessing for elimination antibiotics and hormones from swine wastewater.

PubMed

Cheng, D L; Ngo, H H; Guo, W S; Liu, Y W; Zhou, J L; Chang, S W; Nguyen, D D; Bui, X T; Zhang, X B

2018-04-15

Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes' removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

Changes in hormone and stress-inducing activities of municipal wastewater in a conventional activated sludge wastewater treatment plant.

PubMed

Wojnarowicz, Pola; Yang, Wenbo; Zhou, Hongde; Parker, Wayne J; Helbing, Caren C

2014-12-01

Conventional municipal wastewater treatment plants do not efficiently remove contaminants of emerging concern, and so are primary sources for contaminant release into the aquatic environment. Although these contaminants are present in effluents at ng-μg/L concentrations (i.e. microcontaminants), many compounds can act as endocrine disrupting compounds or stress-inducing agents at these levels. Chemical fate analyses indicate that additional levels of wastewater treatment reduce but do not always completely remove all microcontaminants. The removal of microcontaminants from wastewater does not necessarily correspond to a reduction in biological activity, as contaminant metabolites or byproducts may still be biologically active. To evaluate the efficacy of conventional municipal wastewater treatment plants to remove biological activity, we examined the performance of a full scale conventional activated sludge municipal wastewater treatment plant located in Guelph, Ontario, Canada. We assessed reductions in levels of conventional wastewater parameters and thyroid hormone disrupting and stress-inducing activities in wastewater at three phases along the treatment train using a C-fin assay. Wastewater treatment was effective at reducing total suspended solids, chemical and biochemical oxygen demand, and stress-inducing bioactivity. However, only minimal reduction was observed in thyroid hormone disrupting activities. The present study underscores the importance of examining multiple chemical and biological endpoints in evaluating and monitoring the effectiveness of wastewater treatment for removal of microcontaminants. Copyright © 2014 Elsevier Ltd. All rights reserved.

Combined thermophilic aerobic process and conventional anaerobic digestion: effect on sludge biodegradation and methane production.

PubMed

Dumas, C; Perez, S; Paul, E; Lefebvre, X

2010-04-01

The efficiency of hyper-thermophilic (65 degrees Celsius) aerobic process coupled with a mesophilic (35 degrees Celsius) digester was evaluated for the activated sludge degradation and was compared to a conventional mesophilic digester. For two Sludge Retention Time (SRT), 21 and 42 days, the Chemical Oxygen Demand (COD) solubilisation and biodegradation processes, the methanisation yield and the aerobic oxidation were investigated during 180 days. The best results were obtained at SRT of 44 days; the COD removal yield was 30% higher with the Mesophilic Anaerobic Digestion/Thermophilic Aerobic Reactor (MAD-TAR) co-treatment. An increase of the sludge intrinsic biodegradability is also observed (20-40%), showing that the unbiodegradable COD in mesophilic conditions becomes bioavailable. However, the methanisation yield was quite similar for both processes at a same SRT. Finally, such a process enables to divide by two the volume of digester with an equivalent efficiency. Copyright 2009 Elsevier Ltd. All rights reserved.

Transesterification of Waste Activated Sludge for Biosolids Reduction and Biodiesel Production.

PubMed

Maeng, Min Ho; Cha, Daniel K

2018-02-01

  Transesterification of waste activated sludge (WAS) was evaluated as a cost-effective technique to reduce excess biosolids and recover biodiesel feedstock from activated sludge treatment processes. A laboratory-scale sequencing batch reactor (SBR) was operated with recycling transesterification-treated WAS back to the aeration basin. Seventy percent recycling of WAS resulted in a 48% reduction of excess biosolids in comparison with a conventional SBR, which was operated in parallel as the control SBR. Biodiesel recovery of 8.0% (dried weight basis) was achieved at an optimum transesterification condition using acidic methanol and xylene as cosolvent. Average effluent soluble chemical oxygen demand (COD) and total suspended solids (TSS) concentrations from the test SBR and control SBR were comparable, indicating that the recycling of transesterification-treated WAS did not have detrimental effect on the effluent quality. This study demonstrated that transesterification and recycling of WAS may be a feasible technique for reducing excess biosolids, while producing valuable biodiesel feedstock from the activated sludge process.

Effect of acetic acid on lipid accumulation by glucose-fed activated sludge cultures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mondala, Andro; Hernandez, Rafael; French, Todd

2012-01-01

The effect of acetic acid, a lignocellulose hydrolysis by-product, on lipid accumulation by activated sludge cultures grown on glucose was investigated. This was done to assess the possible application of lignocellulose as low-cost and renewable fermentation substrates for biofuel feedstock production. Results: Biomass yield was reduced by around 54% at a 2 g L -1 acetic acid dosage but was increased by around 18% at 10 g L -1 acetic acid dosage relative to the control run. The final gravimetric lipid contents at 2 and 10 g L -1 acetic acid levels were 12.5 + 0.7% and 8.8 + 3.2%more » w/w, respectively, which were lower than the control (17.8 + 2.8% w/w). However, biodiesel yields from activated sludge grown with acetic acid (5.6 + 0.6% w/w for 2 g L -1 acetic acid and 4.2 + 3.0% w/w for 10 g L -1 acetic acid) were higher than in raw activated sludge (1-2% w/w). The fatty acid profiles of the accumulated lipids were similar with conventional plant oil biodiesel feedstocks. Conclusions: Acetic acid enhanced biomass production by activated sludge at high levels but reduced lipid production. Further studies are needed to enhance acetic acid utilization by activated sludge microorganisms for lipid biosynthesis.« less

Micropollutant degradation via extracted native enzymes from activated sludge.

PubMed

Krah, Daniel; Ghattas, Ann-Kathrin; Wick, Arne; Bröder, Kathrin; Ternes, Thomas A

2016-05-15

A procedure was developed to assess the biodegradation of micropollutants in cell-free lysates produced from activated sludge of a municipal wastewater treatment plant (WWTP). This proof-of-principle provides the basis for further investigations of micropollutant biodegradation via native enzymes in a solution of reduced complexity, facilitating downstream protein analysis. Differently produced lysates, containing a variety of native enzymes, showed significant enzymatic activities of acid phosphatase, β-galactosidase and β-glucuronidase in conventional colorimetric enzyme assays, whereas heat-deactivated controls did not. To determine the enzymatic activity towards micropollutants, 20 compounds were spiked to the cell-free lysates under aerobic conditions and were monitored via LC-ESI-MS/MS. The micropollutants were selected to span a wide range of different biodegradabilities in conventional activated sludge treatment via distinct primary degradation reactions. Of the 20 spiked micropollutants, 18 could be degraded by intact sludge under assay conditions, while six showed reproducible degradation in the lysates compared to the heat-deactivated negative controls: acetaminophen, N-acetyl-sulfamethoxazole (acetyl-SMX), atenolol, bezafibrate, erythromycin and 10,11-dihydro-10-hydroxycarbamazepine (10-OH-CBZ). The primary biotransformation of the first four compounds can be attributed to amide hydrolysis. However, the observed biotransformations in the lysates were differently influenced by experimental parameters such as sludge pre-treatment and the addition of ammonium sulfate or peptidase inhibitors, suggesting that different hydrolase enzymes were involved in the primary degradation, among them possibly peptidases. Furthermore, the transformation of 10-OH-CBZ to 9-CA-ADIN was caused by a biologically-mediated oxidation, which indicates that in addition to hydrolases further enzyme classes (probably oxidoreductases) are present in the native lysates. Although the full variety of indigenous enzymatic activity of the activated sludge source material could not be restored, experimental modifications, e.g. different lysate filtration, significantly enhanced specific enzyme activities (e.g. >96% removal of the antibiotic erythromycin). Therefore, the approach presented in this study provides the experimental basis for a further elucidation of the enzymatic processes underlying wastewater treatment on the level of native proteins. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Characterization and biodegradability of sludge from a high rate A-stage contact tank and B-stage membrane bioreactor of a pilot-scale AB system treating municipal wastewaters.

PubMed

Trzcinski, Antoine Prandota; Ganda, Lily; Kunacheva, Chinagarn; Zhang, Dong Qing; Lin, Li Leonard; Tao, Guihe; Lee, Yingjie; Ng, Wun Jern

2016-10-01

In light of global warming mitigation efforts, increasing sludge disposal costs, and need for reduction in the carbon footprint of wastewater treatment plants, innovation in treatment technology has been tailored towards energy self-sufficiency. The AB process is a promising technology for achieving maximal energy recovery from wastewaters with minimum energy expenditure and therefore inherently reducing excess sludge production. Characterization of this novel sludge and its comparison with the more conventional B-stage sludge are necessary for a deeper understanding of AB treatment process design. This paper presents a case study of a pilot-scale AB system treating municipal wastewaters as well as a bio- (biochemical methane potential and adenosine tri-phosphate analysis) and physico-chemical properties (chemical oxygen demand, sludge volume index, dewaterability, calorific value, zeta potential and particle size distribution) comparison of the organic-rich A-stage against the B-stage activated sludge. Compared to the B-sludge, the A-sludge yielded 1.4 to 4.9 times more methane throughout the 62-week operation.

Excess sludge reduction using pilot-scale lysis-cryptic growth system integrated ultrasonic/alkaline disintegration and hydrolysis/acidogenesis pretreatment.

PubMed

Ma, Huaji; Zhang, Shuting; Lu, Xuebin; Xi, Bo; Guo, Xingli; Wang, Han; Duan, Jingxiao

2012-07-01

A pilot-scale lysis-cryptic growth system was built and operated continuously for excess sludge reduction. Combined ultrasonic/alkaline disintegration and hydrolysis/acidogenesis were integrated into its sludge pretreatment system. Continuous operation showed that the observed biomass yield and the sludge reduction efficiency of the lysis-cryptic growth system were 0.27 kg VSS/kg COD consumed and 56.5%, respectively. The water quality of its effluent was satisfactory. The sludge pretreatment system performed well and its TCOD removal efficiency was 7.9% which contributed a sludge reduction efficiency of 2.1%. The SCOD, VFA, TN, NH(4)(+)-N, TP and pH in the supernatant of pretreated sludge were 1790 mg/L, 1530 mg COD/L, 261.1mg/L, 114.0mg/L, 93.1mg/L and 8.69, respectively. The total operation cost of the lysis-cryptic growth system was $ 0.186/m(3) wastewater, which was 11.4% less than that of conventional activated sludge (CAS) system without excess sludge pretreatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Determination of main components in the extracellular polymeric substances extracted from activated sludge using a spectral probing method.

PubMed

Shen, Rong; Sheng, Guo-Ping; Yu, Han-Qing

2012-06-01

In this study, a spectral probing method was applied to determine the content of the main components, i.e., proteins, polysaccharides and humic substances, in the extracellular polymeric substances (EPS) extracted from activated sludge. The measurement results were consistent with those obtained from the conventional methods, such as the anthrone for polysaccharide determination, the modified Lowry method for protein and humic substance determination. The recoveries for the determination of proteins, humic substances and polysaccharides in the EPS extracted from six sludge samples using standard additional method were between 92.4 and 108.9%, 84.8 and 108.9%, 75.1 and 117.2%, respectively. These results indicate that the propose method has a good accuracy and precision, and can be used as an effective approach to determine the main components in sludge EPS. Copyright © 2012 Elsevier B.V. All rights reserved.

Carbon, nitrogen and phosphorus removal mechanisms of aerobic granules.

PubMed

Sarma, Saurabh Jyoti; Tay, Joo-Hwa

2018-04-10

Aerobic granules are the potential tools to develop modern wastewater treatment technologies with improved nutrient removal efficiency. These granules have several promising advantages over conventional activated sludge-based wastewater treatment processes. This technology has the potential of reducing the infrastructure and operation costs of wastewater treatment by 25%, energy requirement by 30%, and space requirement by 75%. The nutrient removal mechanisms of aerobic granules are slightly different from that of the activated sludge. For instance, unlike activated sludge process, according to some reports, as high as 70% of the total phosphorus removed by aerobic granules were attributed to precipitation within the granules. Similarly, aerobic granule-based technology reduces the total amount of sludge produced during wastewater treatment. However, the reason behind this observation is unknown and it needs further explanations based on carbon and nitrogen removal mechanisms. Thus, as a part of the present review, a set of new hypotheses have been proposed to explain the peculiar nutrient removal mechanisms of the aerobic granules.

Stabilization of waste-activated sludge through the anoxic-aerobic digestion process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashimoto, S.; Fujita, M.; Terai, K.

1982-08-01

During the aerobic digestion process, the nitrogen which had been embedded in the activated sludge is solubilized to form ammoniacal and nitric nitrogen which are in turn transferred to the liquor and cause the increase of nitrogen loading in the sewage treatment plant. In this study, the anoxic-aerobic sludge digestion system which is a modified form of the conventional aerobic sludge digestion is made up of aerobic and anoxic tanks and are designed to remove both the volatile suspended solids and the total nitrogen (TN) simultaneously. The removal efficiencies of both VSS and TN were investigated by feeding waste-activated sludgemore » continuously and semicontinuously. The maximum percent reduction of both VSS and TN was achieved at a Q /SUB r/ /Q /SUB s/ ratio of 2 in the continuous process. The semicontinuous process was used to improve the nitrogen removal efficiency further. In the semicontinuous process, the VSS reduction efficiency as well as the nitrogen removal efficiency increased remarkably under a constant Q /SUB r/ /Q /SUB s/ ratio of 2. This process also achieved a VSS reduction efficiency higher than the aerobic digestion process (control). It was suggested that the additional anoxic tank enhanced the sludge digestion. Furthermore, the anoxic-aerobic digestion system can be applied to other treatment media like the primary sludge, industrial sludge, animal manure, etc.« less

Economic feasibility of irradiation-composting plant of sewage sludge

NASA Astrophysics Data System (ADS)

Hashimoto, S.; Nishimura, K.; Machi, S.

Design and cost analysis were made for a sewage sludge treatment plant (capacity 25 - 200 ton sludge/day) with an electron accelerator. Dewatered sludge is spreaded on a rolling drum through a flat nozzle and disinfected by electron irradiation with a dose of 5 kGy. Composting of the irradiated sludge is also made at the optimum temperature for 3 days. The accelerating voltage of electron and capacity of the accelerator are 1.5 MV and 15 kW, respectively. Total volume of the fermentor is about one third of that of conventional composting process because the irradiation makes the time of composting shorter. The cost of sludge treatment is almost the same as that of conventional method.

Persistence of pathogenic prion protein during simulated wastewater treatment processes

USGS Publications Warehouse

Hinckley, G.T.; Johnson, C.J.; Jacobson, K.H.; Bartholomay, C.; Mcmahon, K.D.; McKenzie, D.; Aiken, Judd M.; Pedersen, J.A.

2008-01-01

Transmissible spongiform encephalopathies (TSEs, prion diseases) are a class of fatal neurodegenerative diseases affecting a variety of mammalian species including humans. A misfolded form of the prion protein (PrP TSE) is the major, if not sole, component of the infectious agent. Prions are highly resistant to degradation and to many disinfection procedures suggesting that, if prions enter wastewater treatment systems through sewers and/or septic systems (e.g., from slaughterhouses, necropsy laboratories, rural meat processors, private game dressing) or through leachate from landfills that have received TSE-contaminated material, prions could survive conventional wastewater treatment Here, we report the results of experiments examining the partitioning and persistence of PrPTSE during simulated wastewater treatment processes including activated and mesophilic anaerobic sludge digestion. Incubation with activated sludge did not result in significant PrPTSE degradation. PrPTSE and prion infectivity partitioned strongly to activated sludge solids and are expected to enter biosolids treatment processes. A large fraction of PrPTSE survived simulated mesophilic anaerobic sludge digestion. The small reduction in recoverable PrPTSE after 20-d anaerobic sludge digestion appeared attributable to a combination of declining extractability with time and microbial degradation. Our results suggest that if prions were to enter municipal wastewater treatment systems, most would partition to activated sludge solids, survive mesophilic anaerobic digestion, and be present in treated biosolids. ?? 2008 American Chemical Society.

Fluorochemical Mass Flows in a Municipal Wastewater Treatment Facility

PubMed Central

Schultz, Melissa M.; Higgins, Christopher P.; Huset, Carin A.; Luthy, Richard G.; Barofsky, Douglas F.; Field, Jennifer A.

2008-01-01

Fluorochemicals have widespread applications and are released into municipal wastewater treatment plants via domestic wastewater. A field study was conducted at a full-scale municipal wastewater treatment plant to determine the mass flows of selected fluorochemicals. Flow-proportional, 24-h samples of raw influent, primary effluent, trickling filter effluent, secondary effluent, and final effluent and grab samples of primary, thickened, activated, and anaerobically-digested sludge were collected over ten days and analyzed by liquid chromatography electrospray-ionization tandem mass spectrometry. Significant decreases in the mass flows of perfluorohexane sulfonate and perfluorodecanoate occurred during trickling filtration and primary clarification, while activated sludge treatment decreased the mass flow of perfluorohexanoate. Mass flows of the 6:2 fluorotelomer sulfonate and perfluorooctanoate were unchanged as a result of wastewater treatment, which indicates that conventional wastewater treatment is not effective for removal of these compounds. A net increase in the mass flows for perfluorooctane and perfluorodecane sulfonates occurred from trickling filtration and activated sludge treatment. Mass flows for perfluoroalkylsulfonamides and perfluorononanoate also increased during activated sludge treatment and are attributed to degradation of precursor molecules. PMID:17180988

Comparison of natural estrogen removal efficiency in the conventional activated sludge process and the oxidation ditch process.

PubMed

Hashimoto, T; Onda, K; Nakamura, Y; Tada, K; Miya, A; Murakami, T

2007-05-01

The presence of natural estrogens, 17beta-estradiol (E2), estrone (E1) and estriol (E3), as well as estrogenic activity in wastewater influents and secondary effluents were investigated in 20 full-scale wastewater treatment plants in Japan. In all of the influent samples, natural estrogens were detected at concentrations above the minimum limits of detection (0.5ng/L). The concentrations of natural estrogens detected in the effluent of oxidation ditch plants were generally lower than previously reported values. On the other hand, in the conventional activated sludge plants, increments of E1 during biological treatment were frequently observed although E2 and E3 were removed effectively in the process. The removal rates of natural estrogens or estrogenic activity show no observed statistical relationship with the solids retention time (SRT) and the hydraulic retention time (HRT). However, the plants with high SRT or HRT generally showed high and stable removal of both natural estrogens and estrogenic activity.

Removal of native coliphages and coliform bacteria from municipal wastewater by various wastewater treatment processes: implications to water reuse.

PubMed

Zhang, K; Farahbakhsh, K

2007-06-01

The efficacy of a conventional activated sludge wastewater treatment process and the membrane bioreactor technology in removing microbial pathogens was investigated. Total and fecal coliforms and somatic and F-specific coliphages were used as indicators of pathogenic bacteria and viruses. Up to 5.7 logs removal of coliforms and 5.5 logs of coliphages were observed in the conventional treatment process with advanced tertiary treatment. Addition of chemical coagulants seemed to improve the efficacy of primary and secondary treatment for microorganism removal. Complete removal of fecal coliforms and up to 5.8 logs removal of coliphages was observed in the MBR system. It was shown that the MBR system was capable of high removal of coliphages despite the variation in feed coliphage concentrations. The results of this study indicated that the MBR system can achieve better microbial removal in far fewer steps than the conventional activated sludge process with advanced tertiary treatment. The final effluent from either treatment processes can be potentially reused.

Effects of microwave and alkali induced pretreatment on sludge solubilization and subsequent aerobic digestion.

PubMed

Chang, Chia-Jung; Tyagi, Vinay Kumar; Lo, Shang-Lien

2011-09-01

Individual and combined effects of microwave (MW) and alkali pretreatments on sludge disintegration and subsequent aerobic digestion of waste activated sludge (WAS) were studied. Pretreatments with MW (600W-85°C-2 min), conventional heating (520 W-80°C-12 min) and alkali (1.5 g NaOH/L - pH 12-30 min) achieved 8.5%, 7% and 18% COD solubilization, respectively. However, combined MW-alkali pretreatment synergistically enhanced sludge solubilization and achieved 46% COD solubilization, 20% greater than the additive value of MW alone and alkali alone (8.5+18%=26.5%). Moreover, the results of the batch aerobic digestion study on MW-alkali pretreated sludge showed 93% and 63% reductions in SCOD and VSS concentrations, respectively, at 16 days of SRT. The VSS reduction was 20% higher than that of WAS without pretreatment. Copyright © 2011 Elsevier Ltd. All rights reserved.

Fate and distribution of pharmaceuticals in wastewater and sewage sludge of the conventional activated sludge (CAS) and advanced membrane bioreactor (MBR) treatment.

PubMed

Radjenović, Jelena; Petrović, Mira; Barceló, Damià

2009-02-01

In this paper we report on the performances of full-scale conventional activated sludge (CAS) treatment and two pilot-scale membrane bioreactors (MBRs) in eliminating various pharmaceutically active compounds (PhACs) belonging to different therapeutic groups and with diverse physico-chemical properties. Both aqueous and solid phases were analysed for the presence of 31 pharmaceuticals included in the analytical method. The most ubiquitous contaminants in the sewage water were analgesics and anti-inflammatory drugs ibuprofen (14.6-31.3 microg/L) and acetaminophen (7.1-11.4 microg/L), antibiotic ofloxacin (0.89-31.7 microg/L), lipid regulators gemfibrozil (2.0-5.9 microg/L) and bezafibrate (1.9-29.8 microg/L), beta-blocker atenolol (0.84-2.8 microg/L), hypoglycaemic agent glibenclamide (0.12-15.9 microg/L) and a diuretic hydrochlorothiazide (2.3-4.8 microg/L). Also, several pharmaceuticals such as ibuprofen, ketoprofen, diclofenac, ofloxacin and azithromycin were detected in sewage sludge at concentrations up to 741.1, 336.3, 380.7, 454.7 and 299.6 ng/g dry weight. Two pilot-scale MBRs exhibited enhanced elimination of several pharmaceutical residues poorly removed by the CAS treatment (e.g., mefenamic acid, indomethacin, diclofenac, propyphenazone, pravastatin, gemfibrozil), whereas in some cases more stable operation of one of the MBR reactors at prolonged SRT proved to be detrimental for the elimination of some compounds (e.g., beta-blockers, ranitidine, famotidine, erythromycin). Moreover, the anti-epileptic drug carbamazepine and diuretic hydrochlorothiazide by-passed all three treatments investigated. Furthermore, sorption to sewage sludge in the MBRs as well as in the entire treatment line of a full-scale WWTP is discussed for the encountered analytes. Among the pharmaceuticals encountered in sewage sludge, sorption to sludge could be a relevant removal pathway only for several compounds (i.e., mefenamic acid, propranolol, and loratidine). Especially in the case of loratidine the experimentally determined sorption coefficients (Kds) were in the range 2214-3321 L/kg (mean). The results obtained for the solid phase indicated that MBR wastewater treatment yielding higher biodegradation rate could reduce the load of pollutants in the sludge. Also, the overall output load in the aqueous and solid phase of the investigated WWTP was calculated, indicating that none of the residual pharmaceuticals initially detected in the sewage sludge were degraded during the anaerobic digestion. Out of the 26 pharmaceutical residues passing through the WWTP, 20 were ultimately detected in the treated sludge that is further applied on farmland.

Evaluation of acute ecotoxicity removal from industrial wastewater using a battery of rapid bioassays.

PubMed

Dries, Jan; Daens, Dominique; Geuens, Luc; Blust, Ronny

2014-01-01

The present study compares conventional wastewater treatment technologies (coagulation-flocculation and activated sludge) and powdered activated carbon (PAC) treatment for the removal of acute ecotoxicity from wastewater generated by tank truck cleaning (TTC) processes. Ecotoxicity was assessed with a battery of four commercially available rapid biological toxicity testing systems, verified by the US Environmental Protection Agency. Chemical coagulation-flocculation of raw TTC wastewater had no impact on the inhibition of the bioluminescence by Vibrio fischeri (BioTox assay). Subsequent biological treatment with activated sludge without PAC resulted in BioTox inhibition-free effluent (<10% inhibition). In contrast, activated sludge treatment without PAC produced an effluent that significantly inhibited (>50%) (i) the bioluminescence by Photobacterium leiognathi (ToxScreen³ test kit), (ii) the photosynthesis by the green algae Chlorella vulgaris (LuminoTox SAPS test kit), and (iii) the particle ingestion by the crustacean Thamnocephalus platyurus (Rapidtoxkit test kit). The lowest inhibition was measured after activated sludge treatment with the highest PAC dose (400 mg/L), demonstrating the effectiveness of PAC treatment for ecotoxicity removal from TTC wastewater. In conclusion, the combination of bioassays applied in the present study represents a promising test battery for rapid ecotoxicty assessment in wastewater treatment.

Rapid startup and high rate nitrogen removal from anaerobic sludge digester liquor using a SNAP process.

PubMed

Qiao, Sen; Nishiyama, Takashi; Fujii, Tatsuo; Bhatti, Zafar; Furukawa, Kenji

2012-02-01

In this study, a single-stage autotrophic nitrogen removal reactor, packed with a novel acrylic fiber biomass carrier material (Biofix), was applied for nitrogen removal from sludge digester liquor. For rapid start-up, conventional activated sludge was added to the reactor soon after the attachment of anammox biomass on the Biofix carriers, which allowed conventional activated sludge to form a protective layer of biofilm around the anammox biomass. The Nitrogen removal efficiency reached 75% within 1 week at a nitrogen loading rate of 0.46 kg-N/m(3)/day for synthetic wastewater treatment. By the end of the synthetic wastewater treatment period, the maximum nitrogen removal rate had increased to 0.92 kg-N/m(3)/day at a nitrogen loading rate of 1.0 kg-N/m(3)/day. High nitrogen removal rate was also achieved during the actual raw digester liquor treatment with the highest nitrogen removal rate being 0.83 kg-N/m(3)/day at a nitrogen loading rate of 0.93 kg-N/m(3)/day. The thick biofilm on Biofix carriers allowed anammox bacteria to survive under high DO concentration of 5-6 mg/l resulting in stable and high nitrogen removal performance. FISH and CLSM analysis demonstrated that anammox bacteria coexisted and surrounded by ammonium oxidizing bacteria.

Occurrence, distribution, and potential influencing factors of sewage sludge components derived from nine full-scale wastewater treatment plants of Beijing, China.

PubMed

Wang, Xu; Li, Meiyan; Liu, Junxin; Qu, Jiuhui

2016-07-01

Millions of tons of waste activated sludge (WAS) produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants (WWTPs) of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples (up to 9478mg/L), followed by endogenous residues (6736mg/L), extracellular polymeric substances (2088mg/L), and intracellular storage products (464mg/L) among others. Moreover, significant differences (p<0.05) were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge. Copyright © 2016. Published by Elsevier B.V.

Important operational parameters of membrane bioreactor-sludge disintegration (MBR-SD) system for zero excess sludge production.

PubMed

Yoon, Seong-Hoon

2003-04-01

In order to prevent excess sludge production during wastewater treatment, a membrane bioreactor-sludge disintegration (MBR-SD) system has been introduced, where the disintegrated sludge is recycled to the bioreactor as a feed solution. In this study, a mathematical model was developed by incorporating a sludge disintegration term into the conventional activated sludge model and the relationships among the operational parameters were investigated. A new definition of F/M ratio for the MBR-SD system was suggested to evaluate the actual organic loading rate. The actual F/M ratio was expected to be much higher than the apparent F/M ratio in MBR-SD. The kinetic parameters concerning the biodegradability of organics hardly affect the system performance. Instead, sludge solubilization ratio (alpha) in the SD process and particulate hydrolysis rate constant (k(h)) in biological reaction determine the sludge disintegration number (SDN), which is related with the overall economics of the MBR-SD system. Under reasonable alpha and k(h) values, SDN would range between 3 and 5 which means the amount of sludge required to be disintegrated would be 3-5 times higher for preventing a particular amount of sludge production. Finally, normalized sludge disintegration rate (q/V) which is needed to maintain a certain level of MLSS in the MBR-SD system was calculated as a function of F/V ratio.

Modeling energy consumption in membrane bioreactors for wastewater treatment in north Africa.

PubMed

Skouterisl, George; Arnot, Tom C; Jraou, Mouna; Feki, Firas; Sayadi, Sami

2014-03-01

Two pilot-scale membrane bioreactors were operated alongside a full-sized activated sludge plant in Tunisia in order to compare specific energy demand and treated water quality. Energy consumption rates were measured for the complete membrane bioreactor systems and for their different components. Specific energy demand was measured for the systems and compared with the activated sludge plant, which operated at around 3 kWh m(-3). A model was developed for each membrane bioreactor based on both dynamic and steady-state mass balances, microbial kinetics and stoichiometry, and energy balance. Energy consumption was evaluated as a function of mixed-liquor suspended solids concentration, net permeate fluxes, and the resultant treated water quality. This work demonstrates the potential for using membrane bioreactors in decentralised domestic water treatment in North Africa, at energy consumption levels similar or lower than conventional activated sludge systems, with the added benefit of producing treated water suitable for unrestricted crop irrigation.

Changes at an activated sludge sewage treatment plant alter the numbers of airborne aerobic microorganisms.

PubMed

Fernando, Nadeesha L; Fedorak, Phillip M

2005-11-01

In 1976, the activated sludge sewage treatment plant in Edmonton, Canada, was surveyed to determine the numbers of culturable airborne microorganisms. Many changes have been made at the plant to reduce odors and improve treatment efficiency, so in 2004 another survey was done to determine if these changes had reduced the bioaerosols. Covering the grit tanks and primary settling tanks greatly reduced the numbers of airborne microbes. Changing the design and operation of indoor automated sampling taps and sinks also reduced bioaerosols. The secondary was expanded and converted from a conventional activated sludge process using coarse bubble aeration to a biological nutrient removal system using fine bubble aeration. Although the surface area of the secondary more than doubled, the average number of airborne microorganisms in this part of the plant in 2004 was about 1% of that in 1976.

Practical experience with full-scale structured sheet media (SSM) integrated fixed-film activated sludge (IFAS) systems for nitrification.

PubMed

Li, Hua; Zhu, Jia; Flamming, James J; O'Connell, Jack; Shrader, Michael

2015-01-01

Many wastewater treatment plants in the USA, which were originally designed as secondary treatment systems with no or partial nitrification requirements, are facing increased flows, loads, and more stringent ammonia discharge limits. Plant expansion is often not cost-effective due to either high construction costs or lack of land. Under these circumstances, integrated fixed-film activated sludge (IFAS) systems using both suspended growth and biofilms that grow attached to a fixed plastic structured sheet media are found to be a viable solution for solving the challenges. Multiple plants have been retrofitted with such IFAS systems in the past few years. The system has proven to be efficient and reliable in achieving not only consistent nitrification, but also enhanced bio-chemical oxygen demand removal and sludge settling characteristics. This paper presents long-term practical experiences with the IFAS system design, operation and maintenance, and performance for three full-scale plants with distinct processes; that is, a trickling filter/solids contact process, a conventional plug flow activated sludge process and an extended aeration process.

Characteristics of aerobic granules grown on glucose a sequential batch shaking reactor.

PubMed

Cai, Chun-guang; Zhu, Nan-wen; Liu, Jun-shen; Wang, Zhen-peng; Cai, Wei-min

2004-01-01

Aerobic heterotrophic granular sludge was cultivated in a sequencing batch shaking reactor (SBSR) in which a synthetic wastewater containing glucose as carbon source was fed. The characteristics of the aerobic granules were investigated. Compared with the conventional activated sludge flocs, the aerobic granules exhibit excellent physical characteristics in terms of settleability, size, shape, biomass density, and physical strength. Scanning electron micrographs revealed that in mature granules little filamentous bacteria could be found, rod-shaped and coccoid bacteria were the dominant microorganisms.

Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation

PubMed Central

Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

2016-01-01

To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application. PMID:27739486

Characterizing shallow secondary clarifier performance where conventional flux theory over-estimates allowable solids loading rate.

PubMed

Daigger, Glen T; Siczka, John S; Smith, Thomas F; Frank, David A; McCorquodale, J A

The performance characteristics of relatively shallow (3.3 and 3.7 m sidewater depth in 30.5 m diameter) activated sludge secondary clarifiers were extensively evaluated during a 2-year testing program at the City of Akron Water Reclamation Facility (WRF), Ohio, USA. Testing included hydraulic and solids loading stress tests, and measurement of sludge characteristics (zone settling velocity (ZSV), dispersed and flocculated total suspended solids), and the results were used to calibrate computational fluid dynamic (CFD) models of the various clarifiers tested. The results demonstrated that good performance could be sustained at surface overflow rates in excess of 3 m/h, as long as the clarifier influent mixed liquor suspended solids (MLSS) concentration was controlled to below critical values. The limiting solids loading rate (SLR) was significantly lower than the value predicted by conventional solids flux analysis based on the measured ZSV/MLSS relationship. CFD analysis suggested that this resulted because mixed liquor entering the clarifier was being directed into the settled sludge blanket, diluting it and also creating a 'thin' concentration sludge blanket that overlays the thicker concentration sludge blanket typically expected. These results indicate the need to determine the allowable SLR for shallow clarifiers using approaches other than traditional solids flux analysis. A combination of actual testing and CFD analyses are demonstrated here to be effective in doing so.

Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation.

PubMed

Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

2016-10-14

To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application.

Characterization, modeling and application of aerobic granular sludge for wastewater treatment.

PubMed

Liu, Xian-Wei; Yu, Han-Qing; Ni, Bing-Jie; Sheng, Guo-Ping

2009-01-01

Recently extensive studies have been carried out to cultivate aerobic granular sludge worldwide, including in China. Aerobic granules, compared with conventional activated sludge flocs, are well known for their regular, dense, and strong microbial structure, good settling ability, high biomass retention, and great ability to withstand shock loadings. Studies have shown that the aerobic granules could be applied for the treatment of low- or high-strength wastewaters, simultaneous removal of organic carbon, nitrogen and phosphorus, and decomposition of toxic wastewaters. Thus, this new form of activate sludge, like anaerobic granular sludge, could be employed for the treatment of municipal and industrial wastewaters in near future. This chapter attempts to provide an up-to-date review on the definition, cultivation, characterization, modeling and application of aerobic granular sludge for biological wastewater treatment. This review outlines some important discoveries with regard to the factors affecting the formation of aerobic granular sludge, their physicochemical characteristics, as well as their microbial structure and diversity. It also summarizes the modeling of aerobic granule formation. Finally, this chapter highlights the applications of aerobic granulation technology in the biological wastewater treatment. It is concluded that the knowledge regarding aerobic granular sludge is far from complete. Although previous studies in this field have undoubtedly improved our understanding on aerobic granular sludge, it is clear that much remains to be learned about the process and that many unanswered questions still remain. One of the challenges appears to be the integration of the existing and growing scientific knowledge base with the observations and applications in practice, which this paper hopes to partially achieve.

Characterization, Modeling and Application of Aerobic Granular Sludge for Wastewater Treatment

NASA Astrophysics Data System (ADS)

Liu, Xian-Wei; Yu, Han-Qing; Ni, Bing-Jie; Sheng, Guo-Ping

Recently extensive studies have been carried out to cultivate aerobic granular sludge worldwide, including in China. Aerobic granules, compared with conventional activated sludge flocs, are well known for their regular, dense, and strong microbial structure, good settling ability, high biomass retention, and great ability to withstand shock loadings. Studies have shown that the aerobic granules could be applied for the treatment of low- or high-strength wastewaters, simultaneous removal of organic carbon, nitrogen and phosphorus, and decomposition of toxic wastewaters. Thus, this new form of activate sludge, like anaerobic granular sludge, could be employed for the treatment of municipal and industrial wastewaters in near future. This chapter attempts to provide an up-to-date review on the definition, cultivation, characterization, modeling and application of aerobic granular sludge for biological wastewater treatment. This review outlines some important discoveries with regard to the factors affecting the formation of aerobic granular sludge, their physicochemical characteristics, as well as their microbial structure and diversity. It also summarizes the modeling of aerobic granule formation. Finally, this chapter highlights the applications of aerobic granulation technology in the biological wastewater treatment. It is concluded that the knowledge regarding aerobic granular sludge is far from complete. Although previous studies in this field have undoubtedly improved our understanding on aerobic granular sludge, it is clear that much remains to be learned about the process and that many unanswered questions still remain. One of the challenges appears to be the integration of the existing and growing scientific knowledge base with the observations and applications in practice, which this paper hopes to partially achieve.

Bacterial communities and enzymatic activities in the vegetation-activated sludge process (V-ASP) and related advantages by comparison with conventional constructed wetland.

PubMed

Yuan, Jiajia; Dong, Wenyi; Sun, Feiyun; Zhao, Ke; Du, Changhang; Shao, Yunxian

2016-11-01

A new-developed vegetation-activated sludge process (V-ASP) was implemented for decentralized domestic wastewater treatment, and studied in lab-scale and full-scale. The main purpose of this work was the investigation of biomass activities and microbial communities in V-ASP by comparison with conventional constructed wetland (CW), to unveil the causations of its consistently higher pollutants removal efficiencies. Compared with CWs, V-ASP has greater vegetation nitrogen and phosphorus uptake rates, higher biomass and enzymatic activities, and more bacteria community diversity. The microbial community structure was comprehensively analyzed by using high-throughput sequencing. It was observed that Proteobacteria was dominated in both CWs and V-ASPs, while their subdivisions distribution was rather different. V-ASPs contained a higher nitrite-oxidizing bacteria (Nitrospira) abundances that resulted in a consistently better nitrogen removal efficiency. Hence, a long-term experiment of full-scale V-ASP displayed stably excellent capability in resistance of influent loading shocks and seasonal temperature effect. Copyright © 2016 Elsevier Ltd. All rights reserved.

Treatment of old landfill leachate with high ammonium content using aerobic granular sludge.

PubMed

Ren, Yanan; Ferraz, Fernanda; Kang, Abbass Jafari; Yuan, Qiuyan

2017-01-01

Aerobic granular sludge has become an attractive alternative to the conventional activated sludge due to its high settling velocity, compact structure, and higher tolerance to toxic substances and adverse conditions. Aerobic granular sludge process has been studied intensively in the treatment of municipal and industrial wastewater. However, information on leachate treatment using aerobic granular sludge is very limited. This study investigated the treatment performance of old landfill leachate with different levels of ammonium using two aerobic sequencing batch reactors (SBR): an activated sludge SBR (ASBR) and a granular sludge SBR (GSBR). Aerobic granules were successfully developed using old leachate with low ammonium concentration (136 mg L -1  NH 4 + -N). The GSBR obtained a stable chemical oxygen demand (COD) removal of 70% after 15 days of operation; while the ASBR required a start-up of at least 30 days and obtained unstable COD removal varying from 38 to 70%. Ammonium concentration was gradually increased in both reactors. Increasing influent ammonium concentration to 225 mg L -1  N, the GSBR removed 73 ± 8% of COD; while COD removal of the ASBR was 59 ± 9%. The GSBR was also more efficient than the ASBR for nitrogen removal. The granular sludge could adapt to the increasing concentrations of ammonium, achieving 95 ± 7% removal efficiency at a maximum influent concentration of 465 mg L -1  N. Ammonium removal of 96 ± 5% was obtained by the ASBR when it was fed with a maximum of 217 mg L -1  NH 4 + -N. However, the ASBR was partially inhibited by free-ammonia and nitrite accumulation rate increased up to 85%. Free-nitrous acid and the low biodegradability of organic carbon were likely the main factors affecting phosphorus removal. The results from this research suggested that aerobic granular sludge have advantage over activated sludge in leachate treatment.

Distribution and characterization of anammox in a swine wastewater activated sludge facility.

PubMed

Yamagishi, Takao; Takeuchi, Mio; Wakiya, Yuichiro; Waki, Miyoko

2013-01-01

Anaerobic ammonium oxidation (anammox) is a novel biological nitrogen removal process that oxidizes NH4(+) to N2 with NO2(-) as an electron acceptor. The purpose of this study was to examine the potential activity and characteristics of anammox in a conventional swine wastewater treatment facility, which uses an activated sludge system consisting of three cascade aeration tanks equipped with ceramic support material. Anammox activity was estimated by a (15)N tracer assay method and was detected in all the sludge and biofilm samples in each aeration tank. Biofilm taken from the third aeration tank, in which the dissolved oxygen concentration was 7.5 mg/L and the wastewater included a high concentration of NO3(-), showed by far the highest anammox activity. A clone library analysis showed the existence of anammox bacteria closely related to 'Candidatus Jettenia asiatica' and 'Ca. Brocadia caroliniensis'. The optimum conditions for anammox activity were a pH of 6.7-7.2, a temperature of 35 °C, a NO2(-) concentration of 10 mmol/L or less, and an NH4(+) concentration of 32 mmol/L or less.

Reuse of industrial sludge as construction aggregates.

PubMed

Tay, J H; Show, K Y; Hong, S Y

2001-01-01

Industrial wastewater sludge and dredged marine clay are high volume wastes that needed enormous space at landfill disposal sites. Due to the limitation of land space, there is an urgent need for alternative disposal methods for these two wastes. This study investigates the possibility of using the industrial sludge in combination with marine clay as construction aggregates. Different proportions of sludge and clay were made into round and angular aggregates. It was found that certain mix proportions could provide aggregates of adequate strength, comparable to that of conventional aggregates. Concrete samples cast from the sludge-clay aggregates yield compressive strengths in the range of 31.0 to 39.0 N/mm2. The results showed that the round aggregates of 100% sludge and the crush aggregates of sludge with up to 20% clay produced concrete of compressive strengths which are superior to that of 38.0 N/mm2 for conventional aggregate. The study indicates that the conversion of high volume wastes into construction materials is a potential option for waste management.

Technology Assessment Report: Aqueous Sludge Gasification Technologies

EPA Science Inventory

The study reveals that sludge gasification is a potentially suitable alternative to conventional sludge handling and disposal methods. However, very few commercial operations are in existence. The limited pilot, demonstration or commercial application of gasification technology t...

Cost minimization in a full-scale conventional wastewater treatment plant: associated costs of biological energy consumption versus sludge production.

PubMed

Sid, S; Volant, A; Lesage, G; Heran, M

2017-11-01

Energy consumption and sludge production minimization represent rising challenges for wastewater treatment plants (WWTPs). The goal of this study is to investigate how energy is consumed throughout the whole plant and how operating conditions affect this energy demand. A WWTP based on the activated sludge process was selected as a case study. Simulations were performed using a pre-compiled model implemented in GPS-X simulation software. Model validation was carried out by comparing experimental and modeling data of the dynamic behavior of the mixed liquor suspended solids (MLSS) concentration and nitrogen compounds concentration, energy consumption for aeration, mixing and sludge treatment and annual sludge production over a three year exercise. In this plant, the energy required for bioreactor aeration was calculated at approximately 44% of the total energy demand. A cost optimization strategy was applied by varying the MLSS concentrations (from 1 to 8 gTSS/L) while recording energy consumption, sludge production and effluent quality. An increase of MLSS led to an increase of the oxygen requirement for biomass aeration, but it also reduced total sludge production. Results permit identification of a key MLSS concentration allowing identification of the best compromise between levels of treatment required, biological energy demand and sludge production while minimizing the overall costs.

[Characteristics of novel wastewater treatment technology by swimming bed combined with aerobic granular sludge].

PubMed

Zhang, Yan; Wang, Yong-sheng; Bai, Yu-hua; Chen, Chen; Lü, Jian; Zhang, Jie

2007-10-01

Swimming bed combined with aerobic granular sludge as a novel technology for wastewater treatment was developed, which was on the basis of the biofilm process and activated sludge process, and results demonstrated notable performance of high-efficiency treatment capability and sludge reduction. Even when hydraulic retention time (HRT) was only at 3.2 h with average COD volumetric loading of 2.03 kg/(m3 x d) and NH4(+)-N of 0.52 kg/(m3 X d), 90.9% of average COD removal rate and 98.3% of NH4(+)-N removal rate were achieved. Aerobic granular sludge appeared with spherical or rod shape after 16 days operation. Mixed liquor suspended solid (MLSS) concentrations in the reactor reached 5,640 mg/L at the highest during operation period, and the average ratio of mixed liquor volatile suspended solid (MLVSS) to MLSS reached 0.87. Furthermore, microscopic observation of biofilm and aerobic granules revealed much presence of protozoa and metazoa on the biofilm and suspended sludge, and this long food chain can contribute to the sludge reduction. Only 0. 175 5 of sludge yields (MLSS/ CODremoved) was obtained in the experiment, which was only about 50% of the conventional aerobic processes.

Environmental and resource implications of phosphorus recovery from waste activated sludge.

PubMed

Sørensen, Birgitte Lilholt; Dall, Ole Leinikka; Habib, Komal

2015-11-01

Phosphorus is an essential mineral resource for the growth of crops and thus necessary to feed the ever increasing global population. The essentiality and irreplaceability of phosphorus in food production has raised the concerns regarding the long-term phosphorus availability and the resulting food supply issues in the future. Hence, the recovery of phosphorus from waste activated sludge and other waste streams is getting huge attention as a viable solution to tackle the potential availability issues of phosphorus in the future. This study explores the environmental implications of phosphorus recovery from waste activated sludge in Denmark and further elaborates on the potential availability or scarcity issue of phosphorus today and 2050. Life cycle assessment is used to assess the possibility of phosphorus recovery with little or no environmental impacts compared to the conventional mining. The phosphorus recovery method assessed in this study consists of drying process, and thermal gasification of the waste activated sludge followed by extraction of phosphorus from the ashes. Our results indicate that the environmental impacts of phosphorus recovery in an energy efficient process are comparable to the environmental effects from the re-use of waste activated sludge applied directly on farmland. Moreover, our findings conclude that the general recommendation according to the waste hierarchy, where re-use of the waste sludge on farmland is preferable to material and energy recovery, is wrong in this case. Especially when phosphorus is a critical resource due to its life threatening necessity, lack of substitution options and potential future supply risk originating due to the high level of global supply concentration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characteristics of aerobic granules grown on glucose and acetate in sequential aerobic sludge blanket reactors.

PubMed

Tay, J H; Liu, Q S; Liu, Y

2002-08-01

Aerobic granules were cultivated in two column-type sequential aerobic sludge blanket reactors fed with glucose and acetate, respectively. The characteristics of aerobic granules were investigated. Results indicated that the glucose- and acetate-fed granules have comparable characteristics in terms of settling velocity, size, shape, biomass density, hydrophobicity, physical strength, microbial activity and storage stability. Substrate component does not seem to be a key factor on the formation of aerobic granules. However, microbial diversity of the granules is closely associated with the carbon sources supplied to the reactors. Compared with the conventional activated sludge flocs, aerobic granules exhibit excellent physical characteristics that would be essential for industrial application. This research provides a complete set of characteristics data of aerobic granules grown on glucose and acetate, which would be useful for further development of aerobic granules-based compact bioreactor for handling high strength organic wastewater.

Microbial-based evaluation of foaming events in full-scale wastewater treatment plants by microscopy survey and quantitative image analysis.

PubMed

Leal, Cristiano; Amaral, António Luís; Costa, Maria de Lourdes

2016-08-01

Activated sludge systems are prone to be affected by foaming occurrences causing the sludge to rise in the reactor and affecting the wastewater treatment plant (WWTP) performance. Nonetheless, there is currently a knowledge gap hindering the development of foaming events prediction tools that may be fulfilled by the quantitative monitoring of AS systems biota and sludge characteristics. As such, the present study focuses on the assessment of foaming events in full-scale WWTPs, by quantitative protozoa, metazoa, filamentous bacteria, and sludge characteristics analysis, further used to enlighten the inner relationships between these parameters. In the current study, a conventional activated sludge system (CAS) and an oxidation ditch (OD) were surveyed throughout a period of 2 and 3 months, respectively, regarding their biota and sludge characteristics. The biota community was monitored by microscopic observation, and a new filamentous bacteria index was developed to quantify their occurrence. Sludge characteristics (aggregated and filamentous biomass contents and aggregate size) were determined by quantitative image analysis (QIA). The obtained data was then processed by principal components analysis (PCA), cross-correlation analysis, and decision trees to assess the foaming occurrences, and enlighten the inner relationships. It was found that such events were best assessed by the combined use of the relative abundance of testate amoeba and nocardioform filamentous index, presenting a 92.9 % success rate for overall foaming events, and 87.5 and 100 %, respectively, for persistent and mild events.

Removal of pharmaceuticals in conventionally treated wastewater by a polishing moving bed biofilm reactor (MBBR) with intermittent feeding.

PubMed

Tang, Kai; Ooi, Gordon T H; Litty, Klaus; Sundmark, Kim; Kaarsholm, Kamilla M S; Sund, Christina; Kragelund, Caroline; Christensson, Magnus; Bester, Kai; Andersen, Henrik R

2017-07-01

Previous studies have demonstrated that aerobic moving bed biofilm reactors (MBBRs) remove pharmaceuticals better than activated sludge. Thus we used a MBBR system to polish the effluent of an activated sludge wastewater treatment plant. To overcome that effluent contains insufficient organic matter to sustain enough biomass, the biofilm was intermittently fed with raw wastewater. The capacity of pharmaceutical degradation was investigated by spiking pharmaceuticals. Actual removal during treatment was assessed by sampling the inlets and outlets of reactors. The removal of the majority of pharmaceuticals was enhanced through the intermittent feeding of the MBBR. First-order rate constants for pharmaceutical removal, normalised to biomass, were significantly higher compared to other studies on activated sludge and suspended biofilms, especially for diclofenac, metoprolol and atenolol. Due to the intermittently feeding, degradation of diclofenac occurred with a half-life of only 2.1h and was thus much faster than any hitherto described wastewater bioreactor treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhancing total nitrogen removal from wastewater of a science and industrial park using entrapped biomass.

PubMed

Chao, Yeong-Nan; Ng, Kok-Kwang; Wu, Chung-Hsin; Hong, Pui-Kwan Andy; Lin, Cheng-Fang

2014-01-01

This study employed entrapped biomass technology to augment the conventional activated sludge process with anoxic-oxic (AO)/anaerobic-anoxic-oxic (A20) functions for the removal of total nitrogen (TN) from wastewater of a science and industrial park in Taiwan. The entrapped biomass unit was fabricated in the format of carrier plates on which microbial cells were entrapped. Due to mass transport limitations, anoxic and anaerobic conditions were created within the bioplates that enabled denitrification to occur. The treatment basin incorporated an equivalent amount of 1300-2400mg MLSS/L of activated sludge on the bioplates at packing ratios of 10-30% (volume ratio ofbioplates to basin) operating with the addition of sodium carbonate for alkalinity and methanol for the electron donor. The results showed nearly 90% of ammonia nitrogen being converted to nitrate and 63% of TN removal, in comparison with typically 10% of TN removal in traditional activated sludge process of domestic wastewater plants.

Performance evaluation of the sulfur-redox-reaction-activated up-flow anaerobic sludge blanket and down-flow hanging sponge anaerobic/anoxic sequencing batch reactor system for municipal sewage treatment.

PubMed

Hatamoto, Masashi; Ohtsuki, Kota; Maharjan, Namita; Ono, Shinya; Dehama, Kazuya; Sakamoto, Kenichi; Takahashi, Masanobu; Yamaguchi, Takashi

2016-03-01

A sulfur-redox-reaction-activated up-flow anaerobic sludge blanket (UASB) and down-flow hanging sponge (DHS) system, combined with an anaerobic/anoxic sequencing batch reactor (A2SBR), has been used for municipal sewage treatment for over 2 years. The present system achieved a removal rate of 95±14% for BOD, 74±22% for total nitrogen, and 78±25% for total phosphorus, including low water temperature conditions. Sludge conversion rates during the operational period were 0.016 and 0.218 g-VSS g-COD-removed(-1) for the UASB, and DHS, respectively, which are similar to a conventional UASB-DHS system, which is not used of sulfur-redox-reaction, for sewage treatment. Using the sulfur-redox reaction made advanced treatment of municipal wastewater with minimal sludge generation possible, even in winter. Furthermore, the occurrence of a unique phenomenon, known as the anaerobic sulfur oxidation reaction, was confirmed in the UASB reactor under the winter season. Copyright © 2016. Published by Elsevier Ltd.

Impact of Coagulant and Flocculant Addition to an Anaerobic Dynamic Membrane Bioreactor (AnDMBR) Treating Waste-Activated Sludge.

PubMed

Kooijman, Guido; Lopes, Wilton; Zhou, Zhongbo; Guo, Hongxiao; de Kreuk, Merle; Spanjers, Henri; van Lier, Jules

2017-03-23

In this work, we investigated the effects of flocculation aid (FA) addition to an anaerobic dynamic membrane bioreactor (AnDMBR) (7 L, 35 °C) treating waste-activated sludge (WAS). The experiment consisted of three distinct periods. In period 1 (day 1-86), the reactor was operated as a conventional anaerobic digester with a solids retention time (SRT) and hydraulic retention time (HRT) of 24 days. In period 2 (day 86-303), the HRT was lowered to 18 days with the application of a dynamic membrane while the SRT was kept the same. In period 3 (day 303-386), a cationic FA in combination with FeCl₃ was added. The additions led to a lower viscosity, which was expected to lead to an increased digestion performance. However, the FAs caused irreversible binding of the substrate, lowering the volatile solids destruction from 32% in period 2 to 24% in period 3. An accumulation of small particulates was observed in the sludge, lowering the average particle size by 50%. These particulates likely caused pore blocking in the cake layer, doubling the trans-membrane pressure. The methanogenic consortia were unaffected. Dosing coagulants and flocculants into an AnDMBR treating sludge leads to a decreased cake layer permeability and decreased sludge degradation.

Evaluation of advanced wastewater treatment systems for water reuse in the era of advanced wastewater treatment

NASA Astrophysics Data System (ADS)

Kon, Hisao; Watanabe, Masahiro

This study focuses on effluent COD concentration from wastewater treatment in regards to the reduction of pathogenic bacteria and trace substances in public waters. The main types of secondary wastewater treatment were conventional activated sludge processes. Recently, however, advance wastewater treatment processes have been developed aimed at the removal of nitrogen and phosphorus, and the effluent quality of these processes was analyzed in this study. Treatment processes for water reclamation that make effluent to meet the target water quality for reuse purposes were selected and also optimum design parameters for these processes were proposed. It was found that the treatment cost to water reclamation was greatly affected by the effluent COD of the secondary treatment. It is important to maintain low COD concentration in the secondary treated effluent. Therefore, it is considered that adequate cost benefits would be obtained by achieving target COD quality through shifting from a conventional activated sludge process to an advanced treatment process.

Removal Efficiency of COD, Total P and Total N Components from Municipal Wastewater using Hollow-fibre MBR.

PubMed

Petrinić, Irena; Curlin, Mirjana; Korenak, Jasmina; Simonič, Marjana

2011-06-01

The membrane bioreactor (MBR) integrates well within the conventionally activated sludge system regarding advanced membrane separation for wastewater treatment. Over the last decade, a number of MBR systems have been constructed worldwide and this system is now accepted as a technology of choice for wastewater treatment especially for municipal wastewater. The aim of this work was to investigate and compare submerged MBR with conventionally-activated sludge system for the treatment of municipal wastewater in Maribor, Slovenia. It can be concluded from the results, that the efficiencies being determined by the parameters were satisfied, such as, chemical oxygen demand, total phosphorous, and total nitrogen, which were 97%, 75%, and 90%, respectively. The efficiencies of ultrafiltration membrane for the same parameters were also determined, and compared with biological treatment. The results of this analysis show an additional effect regarding an improvement in the quality of the permeate but primary treatment is also very important. For successfully application of MBR system smaller grid for primary treatment is needed.

Start-up of the ananmmox process from the conventional activated sludge in a hybrid bioreactor.

PubMed

Duan, Xiumei; Zhou, Jiti; Qiao, Sen; Yin, Xin; Tian, Tian; Xu, Fangdi

2012-01-01

The anaerobic ammonium oxidation (anammox) process was successfully started up from conventional activated sludge using a hybrid bioreactor within 2 months. The average removal efficiencies of ammonia and nitrite were both over 80%, and the maximum total nitrogen removal rate of 1.85 kg N/(m3 x day) was obtained on day 362 with the initial sludge concentration of 0.7 g mixed liquor suspended solids (MLSS)/L. Scanning electron microscope (SEM) observation of the granular sludge in the hybrid reactor clearly showed a high degree of compactness and cell sphericity, and the cell size was quite uniform. Transmission electron microscope photos showed that cells were round or oval, the cellular diameter was 0.6-1.0 microm, and the percentage of the anammoxosome compartment was 51%-85% of the whole cell volume. Fluorescence in situ hybridization analysis (FISH) indicated that anammox bacteria became the dominant population in the community (accounting for more than 51% of total bacteria on day 250). Seven planctomycete 16S rRNA gene sequences were present in the 16S rRNA gene clone library generated from the biomass and affiliated to Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia sp., a new anammox species. In addition, the average effluent suspended solid (MLSS) concentrations of outlets I (above the non-woven carrier) and II (below the non-woven carrier) were 0.0009 and 0.0035 g/L, respectively. This showed that the non-woven carrier could catch the biomass effectively, which increased biomass and improved the nitrogen removal rate in the reactor.

Real-time PCR for rapidly detecting aniline-degrading bacteria in activated sludge.

PubMed

Kayashima, Takakazu; Suzuki, Hisako; Maeda, Toshinari; Ogawa, Hiroaki I

2013-05-01

We developed a detection method that uses quantitative real-time PCR (qPCR) and the TaqMan system to easily and rapidly assess the population of aniline-degrading bacteria in activated sludge prior to conducting a biodegradability test on a chemical compound. A primer and probe set for qPCR was designed by a multiple alignment of conserved amino acid sequences encoding the large (α) subunit of aniline dioxygenase. PCR amplification tests showed that the designed primer and probe set targeted aniline-degrading strains such as Acidovorax sp., Gordonia sp., Rhodococcus sp., and Pseudomonas putida, thereby suggesting that the developed method can detect a wide variety of aniline-degrading bacteria. There was a strong correlation between the relative copy number of the α-aniline dioxygenase gene in activated sludge obtained with the developed qPCR method and the number of aniline-degrading bacteria measured by the Most Probable Number method, which is the conventional method, and a good correlation with the lag time of the BOD curve for aniline degradation produced by the biodegradability test in activated sludge samples collected from eight different wastewater treatment plants in Japan. The developed method will be valuable for the rapid and accurate evaluation of the activity of inocula prior to conducting a ready biodegradability test. Copyright © 2013 Elsevier Ltd. All rights reserved.

Specific aerobic granules can be developed in a completely mixed tank reactor by bioaugmentation using micro-mycelial pellets of Phanerochaete chrysosporium.

PubMed

Hailei, Wang; Ping, Li; Qianlong, Jin; Ge, Qin

2014-03-01

Aerobic granules were firstly developed in a completely mixed tank reactor (CMTR) by seeding micro-mycelial pellets (MMPs) of Phanerochaete chrysosporium. During phenol wastewater treatment, sludge granulation rate reached 67 % after 15-day operation. The granules in CMTR are different from aerobic granules described in literature in morphology, and a majority of them are rod-shaped or rodlike sludge besides spherical granules. The polymorphic granules, having no essential difference with aerobic granules previously reported, achieve advantages over conventional activated sludge in settling ability, biomass concentration, density, integrity coefficient and removal ability to phenol wastewater. The optimized parameters for sludge granulation in CMTR including temperature, inoculum quantity, rotary speed and superficial air upflow velocity are 30 °C, 5–7 g/l, 150 rpm, and 0.5 cm/s, respectively. Analysis on sludge granulation mechanism indicates that MMPs not only result in the formation of aerobic granules containing MMPs as nuclei, but also induce the formation of biogranules which do not have MMP at their cores. The work challenges the general belief that the homogenous circular flow pattern of microbial aggregates is necessary for aerobic sludge granulation.

Energy saving system with high effluent quality for municipal sewage treatment by UASB-DHS.

PubMed

Tanaka, H; Takahashi, M; Yoneyama, Y; Syutsubo, K; Kato, K; Nagano, A; Yamaguchi, T; Harada, H

2012-01-01

An up-flow anaerobic sludge blanket (UASB) - down-flow hanging sponge (DHS) was applied to Japanese municipal sewage treatment, and its treatability, energy consumption, and sludge production were evaluated. The designed sewage load was 50 m(3)/d. The sewage typically had a chemical oxygen demand (COD) of 402 mg/L, a suspended solids (SS) content of 167 mg/L, and a temperature of 17-29 °C. The UASB and DHS exhibited theoretical hydraulic retention times of 9.7 and 2.5 h, respectively. The entire system was operated without temperature control. Operation was started with mesophilic anaerobic digested sludge for the UASB and various sponge media for the DHS. Continuous operational data suggest that although the cellulose decomposition and methanogenic process in the UASB are temperature sensitive, stable operation can be obtained by maintaining a satisfactory sludge volume index and sludge concentration. For the DHS, the cube-type medium G3-2 offers superior filling rates, biological preservation and operational execution. The SS derived from the DHS contaminated the effluent but could be removed by optional sand filtration. A comparison with conventional activated sludge (CAS) treatment confirmed that this system is adequate for municipal sewage treatment, with an estimated energy requirement and excess sludge production approximately 75 and 85% less than those of CAS, respectively.

Effects of sludge concentrations and different sponge configurations on the performance of a sponge-submerged membrane bioreactor.

PubMed

Nguyen, Tien Thanh; Ngo, Huu Hao; Guo, Wenshan; Li, Jianxin; Listowski, Andrzej

2012-07-01

The performance of a novel sponge-submerged membrane bioreactor (SSMBR) was evaluated to treat primary treated sewage effluent at three different activated sludge concentrations. Polyurethane sponge cubes with size of 1 × 1 × 1 cm were used as attached growth media in the bioreactor. The results indicated the successful removal of organic carbon and phosphorous with the efficiency higher than 98% at all conditions. Acclimatised sponge MBR showed about 5% better ammonia nitrogen removal at 5 and 10 g/L sludge concentration as compared to the new sponge system. The respiration test revealed that the specific oxygen uptake rate was around 1.0-3.5 mgO(2)/gVSS.h and likely more stable at 10 g/L sludge concentration. The sludge volume index of less than 100 mL/g during the operation indicated the good settling property of the sludge. The low mixed liquor suspended solid increase indicated that SSMBR could control the sludge production. This SSMBR was also successful in reducing membrane fouling with significant lower transmembrane pressure (e.g. only 0.5 kPa/day) compared to the conventional MBR system. Further study will be conducted to optimise other operating conditions.

[Characteristic of the removal of 2,4-dichlorophenol by biological activated carbon].

PubMed

Liu, Hong; Li, An-jie; Quan, Xiang-chun; Kong, Xiang-hui; Yun, Ying

2004-11-01

The adsorption characteristics and kinetics of 2,4-Dichlorophenol (2,4-DCP) by biological activated carbon (BAC) was studied through contrast experiments with conventional activated sludge alone or quartz as the carrier. The advantage and disadvantage of removing 2,4-DCP using BAC and the mechanism of this process were investigated. The results show that the method of removing 2,4-DCP by BAC is applicable in practices, and the process of BAC demonstrates high removal rate than the process of suspended activated sludge and biofilm with quartz as the carrier. In addition, the BAC process showed high resistance to shock loadings, therefore, it is suitable to be utilized at high organic loading and under long-term operation. In BAC-system, activated carbon could not only adsorb 2,4-DCP but also oxidized 2,4-DCP.

Dynamic modelling of solids in a full-scale activated sludge plant preceded by CEPT as a preliminary step for micropollutant removal modelling.

PubMed

Baalbaki, Zeina; Torfs, Elena; Maere, Thomas; Yargeau, Viviane; Vanrolleghem, Peter A

2017-04-01

The presence of micropollutants in the environment has triggered research on quantifying and predicting their fate in wastewater treatment plants (WWTPs). Since the removal of micropollutants is highly related to conventional pollutant removal and affected by hydraulics, aeration, biomass composition and solids concentration, the fate of these conventional pollutants and characteristics must be well predicted before tackling models to predict the fate of micropollutants. In light of this, the current paper presents the dynamic modelling of conventional pollutants undergoing activated sludge treatment using a limited set of additional daily composite data besides the routine data collected at a WWTP over one year. Results showed that as a basis for modelling, the removal of micropollutants, the Bürger-Diehl settler model was found to capture the actual effluent total suspended solids (TSS) concentrations more efficiently than the Takács model by explicitly modelling the overflow boundary. Results also demonstrated that particular attention must be given to characterizing incoming TSS to obtain a representative solids balance in the presence of a chemically enhanced primary treatment, which is key to predict the fate of micropollutants.

Enhanced waste activated sludge digestion using a submerged anaerobic dynamic membrane bioreactor: performance, sludge characteristics and microbial community

NASA Astrophysics Data System (ADS)

Yu, Hongguang; Wang, Zhiwei; Wu, Zhichao; Zhu, Chaowei

2016-02-01

Anaerobic digestion (AD) plays an important role in waste activated sludge (WAS) treatment; however, conventional AD (CAD) process needs substantial improvements, especially for the treatment of WAS with low solids content and poor anaerobic biodegradability. Herein, we propose a submerged anaerobic dynamic membrane bioreactor (AnDMBR) for simultaneous WAS thickening and digestion without any pretreatment. During the long-term operation, the AnDMBR exhibited an enhanced sludge reduction and improved methane production over CAD process. Moreover, the biogas generated in the AnDMBR contained higher methane content than CAD process. Stable carbon isotopic signatures elucidated the occurrence of combined methanogenic pathways in the AnDMBR process, in which hydrogenotrophic methanogenic pathway made a larger contribution to the total methane production. It was also found that organic matter degradation was enhanced in the AnDMBR, thus providing more favorable substrates for microorganisms. Pyrosequencing revealed that Proteobacteria and Bacteroidetes were abundant in bacterial communities and Methanosarcina and Methanosaeta in archaeal communities, which played an important role in the AnDMBR system. This study shed light on the enhanced digestion of WAS using AnDMBR technology.

Enhanced waste activated sludge digestion using a submerged anaerobic dynamic membrane bioreactor: performance, sludge characteristics and microbial community

PubMed Central

Yu, Hongguang; Wang, Zhiwei; Wu, Zhichao; Zhu, Chaowei

2016-01-01

Anaerobic digestion (AD) plays an important role in waste activated sludge (WAS) treatment; however, conventional AD (CAD) process needs substantial improvements, especially for the treatment of WAS with low solids content and poor anaerobic biodegradability. Herein, we propose a submerged anaerobic dynamic membrane bioreactor (AnDMBR) for simultaneous WAS thickening and digestion without any pretreatment. During the long-term operation, the AnDMBR exhibited an enhanced sludge reduction and improved methane production over CAD process. Moreover, the biogas generated in the AnDMBR contained higher methane content than CAD process. Stable carbon isotopic signatures elucidated the occurrence of combined methanogenic pathways in the AnDMBR process, in which hydrogenotrophic methanogenic pathway made a larger contribution to the total methane production. It was also found that organic matter degradation was enhanced in the AnDMBR, thus providing more favorable substrates for microorganisms. Pyrosequencing revealed that Proteobacteria and Bacteroidetes were abundant in bacterial communities and Methanosarcina and Methanosaeta in archaeal communities, which played an important role in the AnDMBR system. This study shed light on the enhanced digestion of WAS using AnDMBR technology. PMID:26830464

The effects of waste-activated sludge pretreatment using hydrodynamic cavitation for methane production.

PubMed

Lee, Ilgyu; Han, Jong-In

2013-11-01

Disintegration of waste-activated sludge (WAS) is regarded as a prerequisite of the anaerobic digestion (AD) process to reduce sludge volume and increase methane yield. Hydrodynamic cavitation (HC), which shares a similar underlying principle with ultrasonication but is energy-efficient, was employed as a physical means to break up WAS. Compared with ultrasonic (180-3600 kJ/kg TS) and thermal methods (72,000 kJ/kg TS), HC (60-1200 kJ/kg TS) found to consume significantly low power. A synergetic effect was observed when HC was combined with alkaline treatment in which NaOH, KOH, and Ca(OH)2 were used as alkaline catalysts at pH ranging from 8 to 13. As expected, the production yield of CH4 gas increased proportionally as WAS disintegration proceeded. HC, when combined with alkaline pretreatment, was found to be a cost-effective substitute to conventional methods for WAS pretreatment. Copyright © 2013 Elsevier B.V. All rights reserved.

Upgrading of an activated sludge wastewater treatment plant by adding a moving bed biofilm reactor as pre-treatment and ozonation followed by biofiltration for enhanced COD reduction: design and operation experience.

PubMed

Kaindl, Nikolaus

2010-01-01

A paper mill producing 500,000 ton of graphic paper annually has an on-site wastewater treatment plant that treats 7,240,000 m³ of wastewater per year, mechanically first, then biologically and at last by ozonation. Increased paper production capacity led to higher COD load in the mill effluent while production of higher proportions of brighter products gave worse biodegradability. Therefore the biological capacity of the WWTP needed to be increased and extra measures were necessary to enhance the efficiency of COD reduction. The full scale implementation of one MBBR with a volume of 1,230 m³ was accomplished in 2000 followed by another MBBR of 2,475 m³ in 2002. An ozonation step with a capacity of 75 kg O₃/h was added in 2004 to meet higher COD reduction demands during the production of brighter products and thus keeping the given outflow limits. Adding a moving bed biofilm reactor prior to the existing activated sludge step gives: (i) cost advantages when increasing biological capacity as higher COD volume loads of MBBRs allow smaller reactors than usual for activated sludge plants; (ii) a relief of strain from the activated sludge step by biological degradation in the MBBR; (iii) equalizing of peaks in the COD load and toxic effects before affecting the activated sludge step; (iv) a stable volume sludge index below 100 ml/g in combination with an optimization of the activated sludge step allows good sludge separation--an important condition for further treatment with ozone. Ozonation and subsequent bio-filtration pre-treated waste water provide: (i) reduction of hard COD unobtainable by conventional treatment; (ii) controllable COD reduction in a very wide range and therefore elimination of COD-peaks; (iii) reduction of treatment costs by combination of ozonation and subsequent bio-filtration; (iv) decrease of the color in the ozonated wastewater. The MBBR step proved very simple to operate as part of the biological treatment. Excellent control of the COD-removal rate in the ozone step allowed for economical usage and therefore acceptable operation costs in relation to the paper production.

Integrated aerobic biological-chemical treatment of winery wastewater diluted with urban wastewater. LED-based photocatalysis in the presence of monoperoxysulfate.

PubMed

Solís, Rafael R; Rivas, Francisco Javier; Ferreira, Leonor C; Pirra, Antonio; Peres, José A

2018-01-28

The oxidation of Winery Wastewater (WW) by conventional aerobic biological treatment usually leads to inefficient results due to the presence of organic substances, which are recalcitrant or toxic in conventional procedures. This study explores the combination of biological and chemical processes in order to complete the oxidation of biodegradable and non-biodegradable compounds in two sequential steps. Thus, a biological oxidation of a diluted WW is carried out by using the activated sludge process. Activated sludge was gradually acclimated to the Diluted Winery Wastewater (DWW). Some aspects concerning the biological process were evaluated (kinetics of the oxidation and sedimentation of the sludge produced). The biological treatment of the DWW led to a 40-50% of Chemical Oxygen Demand (COD) removal in 8 h, being necessary the application of an additional process. Different chemical processes combining UVA-LEDs radiation, monoperoxysulfate (MPS) and photocatalysts were applied in order to complete the COD depletion and efficient removal of polyphenols content, poorly oxidized in the previous biological step. From the options tested, the combination of UVA, MPS and a novel LaCoO 3 -TiO 2 composite, with double route of MPS decomposition through heterogeneous catalysis and photocatalysis, led to the best results (95% of polyphenol degradation, and additional 60% of COD removal). Initial MPS concentration and pH effect in this process were assessed.

Xenobiotic benzotriazoles--biodegradation under meso- and oligotrophic conditions as well as denitrifying, sulfate-reducing, and anaerobic conditions.

PubMed

Herzog, Bastian; Lemmer, Hilde; Huber, Bettina; Horn, Harald; Müller, Elisabeth

2014-02-01

The intensive use of benzotriazoles as corrosion inhibitors for various applications and their application in dishwasher detergents result in an almost omnipresence of benzotriazole (BTri), 4-methyl- and 5-methyl-benzotriazole (4-TTri and 5-TTri, respectively) in aquatic systems. This study aims on the evaluation of the biodegradation potential of activated sludge communities (ASCs) toward the three benzotriazoles regarding aerobic, anoxic, and anaerobic conditions and different nutrients. ASCs were taken from three wastewater treatment plants with different technologies, namely, a membrane bioreactor (MBR-MH), a conventional activated sludge plant CAS-E (intermittent nitrification/denitrification), and CAS-M (two-stage activated sludge treatment) and used for inoculation of biodegradation setups. All ASCs eliminated up to 30 mg L(-1) 5-TTri and BTri under aerobic conditions within 2-7 and 21-49 days, respectively, but not under anoxic or anaerobic conditions. 4-TTri was refractory at all conditions tested. Significant differences were observed for BTri biodegradation with non-acclimated ASCs from MBR-MH with 21 days, CAS-E with 41 days, and CAS-M with 49 days. Acclimated ASCs removed BTri within 7 days. Furthermore, different carbon and nitrogen concentrations revealed that nitrogen was implicitly required for biodegradation while carbon showed no such effect. The fastest biodegradation occurred for 5-TTri with no need for acclimatization, followed by BTri. BTri showed sludge-specific biodegradation patterns, but, after sludge acclimation, was removed with the same pattern, regardless of the sludge used. Under anaerobic conditions in the presence of different electron acceptors, none of the three compounds showed biological removal. Thus, presumably, aerobic biodegradation is the major removal mechanism in aquatic systems.

[Formation Mechanism of Aerobic Granular Sludge and Removal Efficiencies in Integrated ABR-CSTR Reactor].

PubMed

Wu, Kai-cheng; Wu, Peng; Xu, Yue-zhong; Li, Yue-han; Shen, Yao-liang

2015-08-01

Anaerobic Baffled Reactor (ABR) was altered to make an integrated anaerobic-aerobic reactor. The research investigated the mechanism of aerobic sludge granulation, under the condition of continuous-flow. The last two compartments of the ABR were altered into aeration tank and sedimentation tank respectively with seeded sludge of anaerobic granular sludge in anaerobic zone and conventional activated sludge in aerobic zone. The HRT was gradually decreased in sedimentation tank from 2.0 h to 0.75 h and organic loading rate was increased from 1.5 kg x (M3 x d)(-1) to 2.0 kg x (M3 x d)(-1) while the C/N of 2 was controlled in aerobic zone. When the system operated for 110 days, the mature granular sludge in aerobic zone were characterized by compact structure, excellent sedimentation performance (average sedimentation rate was 20.8 m x h(-1)) and slight yellow color. The system performed well in nitrogen and phosphorus removal under the conditions of setting time of 0.75 h and organic loading rate of 2.0 kg (m3 x d)(-1) in aerobic zone, the removal efficiencies of COD, NH4+ -N, TP and TN were 90%, 80%, 65% and 45%, respectively. The results showed that the increasing selection pressure and the high organic loading rate were the main propulsions of the aerobic sludge granulation.

Evaluation of a biological wastewater treatment system combining an OSA process with ultrasound for sludge reduction.

PubMed

Romero-Pareja, P M; Aragon, C A; Quiroga, J M; Coello, M D

2017-05-01

Sludge production is an undesirable by-product of biological wastewater treatment. The oxic-settling-anaerobic (OSA) process constitutes one of the most promising techniques for reducing the sludge produced at the treatment plant without negative consequences for its overall performance. In the present study, the OSA process is applied in combination with ultrasound treatment, a lysis technique, in a lab-scale wastewater treatment plant to assess whether sludge reduction is enhanced as a result of mechanical treatment. Reported sludge reductions of 45.72% and 78.56% were obtained for the two regimes of combined treatment tested in this study during two respective stages: UO1 and UO2. During the UO1 stage, the general performance and nutrient removal improved, obtaining 47.28% TN removal versus 21.95% in the conventional stage. However, the performance of the system was seriously damaged during the UO2 stage. Increases in dehydrogenase and protease activities were observed during both stages. The advantages of the combined process are not necessarily economic, but operational, as US treatment acts as contributing factor in the OSA process, inducing mechanisms that lead to sludge reduction in the OSA process and improving performance parameters. Copyright © 2016 Elsevier B.V. All rights reserved.

Energy recovery from wastewater treatment plants through sludge anaerobic digestion: effect of low-organic-content sludge.

PubMed

Zhang, Yuyao; Li, Huan

2017-09-18

During anaerobic digestion, low-organic-content sludge sometimes is used as feedstock, resulting in deteriorated digestion performance. The operational experience of conventional anaerobic digestion cannot be applied to this situation. To investigate the feature of low-organic-content sludge digestion and explain its intrinsic mechanism, batch experiments were conducted using designed feedstock having volatile solids (VS) contents that were 30-64% of total solids (TS). The results showed that the accumulative biogas yield declined proportionally from 173.7 to 64.8 ml/g VS added and organic removal rate decreased from 34.8 to 11.8% with decreasing VS/TS in the substrate. The oligotrophic environment resulting from low-organic-content substrates led to decreased microbial activity and a switch from butyric fermentation to propionic fermentation. A first-order model described the biogas production from the batch experiments very well, and the degradation coefficient decreased from 0.159 to 0.069 day -1 , exhibiting a positive relation with organic content in substrate. The results observed here corroborated with data from published literature on anaerobic digestion of low-organic-content sludge and showed that it may not be feasible to recover energy from sludge with an organic content lower than 50% through mono digestion.

CHARACTERIZATION OF ACTINIDES IN SIMULATED ALKALINE TANK WASTE SLUDGES AND LEACHATES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, Kenneth L.

In this project, both the fundamental chemistry of actinides in alkaline solutions (relevant to those present in Hanford-style waste storage tanks), and their dissolution from sludge simulants (and interactions with supernatants) have been investigated under representative sludge leaching procedures. The leaching protocols were designed to go beyond conventional alkaline sludge leaching limits, including the application of acidic leachants, oxidants and complexing agents. The simulant leaching studies confirm in most cases the basic premise that actinides will remain in the sludge during leaching with 2-3 M NaOH caustic leach solutions. However, they also confirm significant chances for increased mobility of actinidesmore » under oxidative leaching conditions. Thermodynamic data generated improves the general level of experiemental information available to predict actinide speciation in leach solutions. Additional information indicates that improved Al removal can be achieved with even dilute acid leaching and that acidic Al(NO3)3 solutions can be decontaminated of co-mobilized actinides using conventional separations methods. Both complexing agents and acidic leaching solutions have significant potential to improve the effectiveness of conventional alkaline leaching protocols. The prime objective of this program was to provide adequate insight into actinide behavior under these conditions to enable prudent decision making as tank waste treatment protocols develop.« less

Application of electro acoustics for dewatering pharmaceutical sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golla, P.S.; Johnson, H.W.

1992-02-01

Application of electro acoustic principles for dewatering has been developed by Battelle Institute. The Department of Energy, Battelle Institute, and Ashbrook-Simon-Hartley, have jointly developed an Electro Acoustic Dewatering press (EAD press). The EAD press applies a combination of mechanical pressure, electrical current and ultrasonics. This press is utilized after conventional dewatering devices and can remove up to 50% water from filtered sludge cake at a fraction of the cost incurred in existing thermal drying devices. The dominant mechanism of sludge dewatering by EAD press is electro-osmosis due to the application of a direct current field. Electro-osmosis is caused by anmore » electrical double layer of oppositely charged ions formed at the solid liquid interface, which is characterized by zeta potential. The ultrasonic fields help electro-osmosis by consolidation of the filter cake and by release of inaccessible liquid. The EAD press has been tested successfully on a variety of materials including apple pomace, corn gluten, sewage sludge, and coal fines. A three week long full scale trial was conducted successfully at a pharmaceutical industry to determine the application of this technology for dewatering waste activated sludge.« less

Systematic comparison of mechanical and thermal sludge disintegration technologies.

PubMed

Wett, B; Phothilangka, P; Eladawy, A

2010-06-01

This study presents a systematic comparison and evaluation of sewage sludge pre-treatment by mechanical and thermal techniques. Waste activated sludge (WAS) was pre-treated by separate full scale Thermo-Pressure-Hydrolysis (TDH) and ball milling facilities. Then the sludge was processed in pilot-scale digestion experiments. The results indicated that a significant increase in soluble organic matter could be achieved. TDH and ball milling pre-treatment could offer a feasible treatment method to efficiently disintegrate sludge and enhance biogas yield of digestion. The TDH increased biogas production by ca. 75% whereas ball milling allowed for an approximately 41% increase. The mechanisms of pre-treatment were investigated by numerical modeling based on Anaerobic Digestion Model No. 1 (ADM1) in the MatLab/SIMBA environment. TDH process induced advanced COD-solubilisation (COD(soluble)/COD(total)=43%) and specifically complete destruction of cell mass which is hardly degradable in conventional digestion. While the ball mill technique achieved a lower solubilisation rate (COD(soluble)/COD(total)=28%) and only a partial destruction of microbial decay products. From a whole-plant prospective relevant release of ammonia and formation of soluble inerts have been observed especially from thermal hydrolysis. Copyright 2009 Elsevier Ltd. All rights reserved.

Enhanced Versus Conventional Sludge Anaerobic Processes: Performances and Techno-Economic Assessment.

PubMed

Gianico, Andrea; Bertanza, Giorgio; Braguglia, Camilla M; Canato, Matteo; Gallipoli, Agata; Laera, Giuseppe; Levantesi, Caterina; Mininni, Giuseppe

2016-05-01

Sewage sludge processing is a key issue in water resource recovery facilities due to the inefficacy of conventional treatments to produce high quality biosolids to be safely used in agriculture. Under this framework, the performances of several enhanced stabilization processes, namely ultrasound-pretreated Mesophilic Anaerobic Digestion (US+MAD), thermophilic anaerobic digestion (TAD), thermal-pretreated TAD (TH+TAD) and ultrasound-pretreated inverse Temperature Phased Anaerobic Digestion (US+iTPAD) have been investigated. Such enhanced processes resulted in higher biogas yields and higher destruction of pathogens with respect to conventional MAD process, thus suggesting their feasibility in full-scale implementation perspectives. A procedure for technical-economic comparison of new sludge processing lines against conventional ones (benchmarking) was developed, based on the definition of technical issues (e.g. reliability, complexity, etc.) which are rated for each situation. Moreover, capital and operating costs were estimated. The enhanced processes analyzed in this work showed some potentially critical items, mainly related to energy balance and reagent consumption.

Trade-off between carbon emission and effluent quality of activated sludge processes under seasonal variations of wastewater temperature and mean cell retention time.

PubMed

Guo, Jingbo; Fu, Xin; Andrés Baquero, G; Sobhani, Reza; Nolasco, Daniel A; Rosso, Diego

2016-03-15

Over the seasonal cycles, the mean cell retention time (MCRT) of the activated sludge process is varied to compensate the wastewater temperature variations. The effects of these variations on the carbon footprint (CFP) and effluent quality index (EQI) of a conventional activated sludge (CAS) process and a nitrification/denitrification (NDN) process were quantified. The carbon emission included both biogenic and non-biogenic carbon. Carbon emissions of wasted biosolids management were also addressed. Our results confirmed that the effluent quality indicated by EQI was not necessarily improved by increasing MCRT. Higher MCRT increased the carbon emission and reduced excess sludge production, which decreased the potential for biogas energy recovery. The NDN process was preferable to the CAS process from the perspective of effluent quality. This consideration extended to the whole plant CFP if the N2O emitted during NDN was limited ([N2O]<1% [NH4(+)]removed) as the carbon emission per unit effluent quality achieved by NDN process is less than that of the CAS process. By putting forward carbon emission intensity (γ) derived from CFP and EQI, our work provides a quantitative tool for decision makers evaluating process alternatives when there is a trade-off between carbon emission and effluent quality. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of microbubbles on gas-liquid mass transfer coefficient and degradation rate of COD in wastewater treatment.

PubMed

Yao, Kangning; Chi, Yong; Wang, Fei; Yan, Jianhua; Ni, Mingjiang; Cen, Kefa

2016-01-01

A commonly used aeration device at present has the disadvantages of low mass transfer rate because the generated bubbles are several millimeters in diameter which are much bigger than microbubbles. Therefore, the effect of a microbubble on gas-liquid mass transfer and wastewater treatment process was investigated. To evaluate the effect of each bubble type, the volumetric mass transfer coefficients for microbubbles and conventional bubbles were determined. The volumetric mass transfer coefficient was 0.02905 s(-1) and 0.02191 s(-1) at a gas flow rate of 0.67 L min(-1) in tap water for microbubbles and conventional bubbles, respectively. The degradation rate of simulated municipal wastewater was also investigated, using aerobic activated sludge and ozone. Compared with the conventional bubble generator, the chemical oxygen demand (COD) removal rate was 2.04, 5.9, 3.26 times higher than those of the conventional bubble contactor at the same initial COD concentration of COD 200 mg L(-1), 400 mg L(-1), and 600 mg L(-1), while aerobic activated sludge was used. For the ozonation process, the rate of COD removal using microbubble generator was 2.38, 2.51, 2.89 times of those of the conventional bubble generator. Based on the results, the effect of initial COD concentration on the specific COD degradation rate were discussed in different systems. Thus, the results revealed that microbubbles could enhance mass transfer in wastewater treatment and be an effective method to improve the degradation of wastewater.

Sorption of Perfluorinated Compounds onto different types of sewage sludge and assessment of its importance during wastewater treatment.

PubMed

Arvaniti, Olga S; Andersen, Henrik R; Thomaidis, Nikolaos S; Stasinakis, Athanasios S

2014-09-01

The distribution coefficient (Kd) and the organic carbon distribution coefficient (KOC) were determined for four Perfluorinated Compounds (PFCs) to three different types of sludge taken from a conventional Sewage Treatment Plant (STP). Batch experiments were performed in six different environmental relevant concentrations (200ngL(-1)to 5μgL(-1)) containing 1gL(-1) sludge. Kd values ranged from 330 to 6015, 329 to 17432 and 162 to 11770Lkg(-1) for primary, secondary and digested sludge, respectively. The effects of solution's pH, ionic strength and cation types on PFCs sorption were also evaluated. Sorption capacities of PFCs significantly decreased with increased pH values from 6 to 8. Furthermore, the divalent cation (Ca(2+)) enhanced PFCs sorption to a higher degree in comparison with the monovalent cation (Na(+)) at the same ionic strength. The obtained Kd values were applied to estimate the sorbed fractions of each PFC in different stages of a typical STP and to calculate their removal through treated wastewater and sludge. In primary settling tank, the predicted sorbed fractions ranged from 3% for Perfluorooctanoic Acid (PFOA) to 55% for Perfluoroundecanoic acid (PFUdA), while in activated sludge tank and anaerobic digester sorption was more than 50% for all target compounds. Almost 86% of initial PFOA load is expected to be detected in treated wastewater; while Perfluorodecanoic acid (PFDA), PFUdA and Perfluorooctanesulfonate (PFOS) can be significantly removed (>49%) via sorption to primary and excess secondary sludge. In anaerobic digester, the major part (>76%) of target PFCs is expected to be sorbed to sludge, while almost 3% of initial PFOA load will be detected in sludge leachates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biochar Production from Domestic Sludge: A Cost-effective, Recycled Product for Removal of Amoxicillin in Wastewater

NASA Astrophysics Data System (ADS)

Arun, Sija; Kothari, Kaushal; Mazumdar, Debayan; Mukhopadhyay, Moitraiyee; Chakraborty, Paromita

2017-08-01

Due to the broad spectrum, antimicrobial activity, Amoxicillin is one of the extensively used antibiotics. Amoxicillin ends up in the wastewater stream by direct or indirect disposal pathways which ultimately affect the aquatic ecosystem. Conventional wastewater treatment plant cannot remove it completely. Hence our objective was to produce sludge derived biochar and use it as an adsorbent for removal of amoxicillin. Effective biochar was obtained at 300°C produced from the sludge of the domestic wastewater treatment plant. 100 ppm amoxicillin solution spiked in biochar was kept for 180 mins in an orbital shaker and every 30 minutes the filtrate was checked in UV spectrophotometer. A steady decreasing gradient was obtained for absorbance of amoxicillin after 30 minutes. Further scanning electron microscopy showed significant morphological change in biochar obtained before and after spiking amoxicillin. Our preliminary assessment suggests that biochar can be exploited as an effective treatment technique to remove amoxicillin from wastewater. Moreover, we suggest that utilization of domestic sludge for commercial application in treatment plants can reduce the load of domestic waste in the open dumpsites.

Anaerobic digestion of municipal wastewater sludges using anaerobic fluidized bed bioreactor.

PubMed

Mustafa, Nizar; Elbeshbishy, Elsayed; Nakhla, George; Zhu, Jesse

2014-11-01

The anaerobic digestion of primary sludge (PS) and thickened waste activated sludge (TWAS) using an anaerobic fluidized bed bioreactor (AnFBR) employing zeolite particles as the carrier media was investigated at different organic loading rates (OLRs). PS was tested at OLRs from 4.2 to 39kgCOD/m(3)-d corresponding to hydraulic retention times (HRTs) from 1.0 to 8.9days. The highest COD removal and VSS destruction efficiencies for primary sludge of 85% and 88%, respectively, were achieved at an HRT of 8.9days and OLR of 4.2kgCOD/m(3)-d. For TWAS, VSS destruction efficiencies varied from 42% at an HRT of 2.6days and OLR of 13.1kgCOD/m(3)-d to 69% at an HRT of 8.8days and an OLR of 4.2kgCOD/m(3)-d. The first-order COD biodegradation rates in the AnFBR for PS and TWAS were 0.4d(-1) and 0.1d(-1), respectively, almost double the rates in conventional high-rate digesters. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microbial and nutritional regulation of high-solids anaerobic mono-digestion of fruit and vegetable wastes.

PubMed

Mu, Hui; Li, Yan; Zhao, Yuxiao; Zhang, Xiaodong; Hua, Dongliang; Xu, Haipeng; Jin, Fuqiang

2018-02-01

The anaerobic digestion of single fruit and vegetable wastes (FVW) can be easily interrupted by rapid acidogenesis and inhibition of methanogen, and the digestion system tends to be particularly unstable at high solid content. In this study, the anaerobic digestion of FVW in batch experiments under mesophilic condition at a high solid concentration of 10% was successfully conducted to overcome the acidogenesis problem through several modifications. Firstly, compared with the conventional anaerobic sludge (CAS), the acclimated anaerobic granular sludge (AGS) was found to be a better inoculum due to its higher Archaea abundance. Secondly, waste activated sludge (WAS) was chosen to co-digest with FVW, because WAS had abundant proteins that could generate intermediate ammonium. The ammonium could neutralize the accumulated volatile fatty acids (VFAs) and prevent the pH value of the digestion system from rapidly decreasing. Co-digestion of FVW and WAS with TS ratio of 60:40 gave the highest biogas yield of 562 mL/g-VS and the highest methane yield of 362 mL/g-VS. Key parameters in the digestion process, including VFAs concentration, pH, enzyme activity, and microbial activity, were also examined.

Fatty acid methyl ester (FAME) technology for monitoring biological foaming in activated sludge: full scale plant verification.

PubMed

Lee, J W; Cha, D K; Kim, I; Son, A; Ahn, K H

2008-02-01

Fatty acid methyl ester (FAME) technology was evaluated as a monitoring tool for quantification of Gordonia amarae in activated sludge systems. The fatty acid, 19:1 alcohol, which was identified as a unique fatty acid in G. amarae was not only confirmed to be present in foaming plant samples, but the quantity of the signature peak correlated closely with the degree of foaming. Foaming potential experiment provided a range of critical foaming levels that corresponded to G. amarae population. This range of critical Gordonia levels was correlated to the threshold signature FAME amount. Six full-scale wastewater treatment plants were selected based on a survey to participate in our full-scale study to evaluate the potential application of the FAME technique as the Gordonia monitoring tool. Greater amounts of signature FAME were extracted from the mixed liquor samples obtained from treatment plants experiencing Gordonia foaming problems. The amounts of signature FAME correlated well with the conventional filamentous counting technique. These results demonstrated that the relative abundance of the signature FAMEs can be used to quantitatively monitor the abundance of foam-causing microorganism in activated sludge.

Co-conditioning and dewatering of chemical sludge and waste activated sludge.

PubMed

Chang, G R; Liu, J C; Lee, D J

2001-03-01

The conditioning and dewatering behaviors of chemical and waste activated sludges from a tannery were studied. Capillary suction time (CST), specific resistance to filtration (SRF), and bound water content were used to evaluate the sludge dewatering behaviors. Zeta potentials were also measured. Experiments were conducted on each sludge conditioned and dewatered separately, and on the sludge mixed at various ratios. Results indicate that the chemical sludge was relatively difficult to be dewatered, even in the presence of polyelectrolyte. When the waste activated sludge was mixed with the chemical sludge at ratios of 1:1 and 2:1, respectively, the dewaterability of chemical sludge improved remarkably while the relatively better dewaterability of the waste activated sludge deteriorated only to a limited extent. As the mixing ratios became 4:1 and 8:1, the dewaterability of the mixed sludge was equal to that of the waste activated sludge. The optimal polyelectrolyte dosage for the mixed sludge was equal to or less than that of the waste activated sludge. It is proposed that the chemical sludges act as skeleton builders that reduce the compressibility of the mixed sludge whose dewaterability is enhanced. Bound water contents of sludge decreased at low polyelectrolyte dosage and were not significantly affected as polyelectrolyte dosage increased. Advantages and disadvantages of co-conditioning and dewatering chemical sludge and waste activated sludge were discussed.

Use of silicon carbide sludge to form porous alkali-activated materials for insulating application

NASA Astrophysics Data System (ADS)

Prud'homme, E.; Joussein, E.; Rossignol, S.

2015-07-01

One of the objectives in the field of alkali-activated materials is the development of materials having greater thermal performances than conventional construction materials such as aerated concrete. The aim of this paper is to present the possibility to obtain controlled porosity and controlled thermal properties with geopolymer materials including a waste like silicon carbide sludge. The porosity is created by the reaction of free silicon contains in silicon carbide sludge leading to the formation of hydrogen. Two possible ways are investigated to control the porosity: modification of mixture formulation and additives introduction. The first way is the most promising and allowed the formation of materials presenting the same density but various porosities, which shows that the material is adaptable to the application. The insulation properties are logically linked to the porosity and density of materials. A lower value of thermal conductivity of 0.075 W.m-1.K-1 can be reached for a material with a low density of 0.27 g.cm-3. These characteristics are really good for a mineral-based material which always displays non-negligible resistance to manipulation.

Activated sludge is a potential source for production of biodegradable plastics from wastewater.

PubMed

Khardenavis, A; Guha, P K; Kumar, M S; Mudliar, S N; Chakrabarti, T

2005-05-01

Increased utilization of synthetic plastics caused severe environmental pollution due to their non-biodegradable nature. In the search for environmentally friendly materials to substitute for conventional plastics, different biodegradable plastics have been developed by microbial fermentations. However, limitations of these materials still exist due to high cost. This study aims at minimization of cost for the production of biodegradable plastics P(3HB) and minimization of environmental pollution. The waste biological sludge generated at wastewater treatment plants is used for the production of P(3HB) and wastewater is used as carbon source. Activated sludge was induced by controlling the carbon: nitrogen ratio to accumulate storage polymer. Initially polymer accumulation was studied by using different carbon and nitrogen sources. Maximum accumulation of polymer was observed with carbon source acetic acid and diammonium hydrogen phosphate (DAHP) as nitrogen source. Further studies were carried out to optimize the carbon: nitrogen ratios using acetic acid and DAHP. A maximum of 65.84% (w/w) P(3HB) production was obtained at C/N ratio of 50 within 96 hours of incubation.

Sequencing batch reactor biofilm system for treatment of milk industry wastewater.

PubMed

Sirianuntapiboon, Suntud; Jeeyachok, Narumon; Larplai, Rarintorn

2005-07-01

A sequencing batch reactor biofilm (MSBR) system was modified from the conventional sequencing batch reactor (SBR) system by installing 2.7 m2 surface area of plastic media on the bottom of the reactor to increase the system efficiency and bio-sludge quality by increasing the bio-sludge in the system. The COD, BOD5, total kjeldahl nitrogen (TKN) and oil & grease removal efficiencies of the MSBR system, under a high organic loading of 1340 g BOD5/m3 d, were 89.3+/-0.1, 83.0+/-0.2, 59.4+/-0.8, and 82.4+/-0.4%, respectively, while they were only 87.0+/-0.2, 79.9+/-0.3, 48.7+/-1.7 and 79.3+/-10%, respectively, in the conventional SBR system. The amount of excess bio-sludge in the MSBR system was about 3 times lower than that in the conventional SBR system. The sludge volume index (SVI) of the MSBR system was lower than 100 ml/g under an organic loading of up to 1340 g BOD5/m3 d. However, the MSBR under an organic loading of 680 g BOD5/m3 d gave the highest COD, BOD5, TKN and oil & grease removal efficiencies of 97.9+/-0.0, 97.9+/-0.1, 79.3+/-1.0 and 94.8+/-0.5%, respectively, without any excess bio-sludge waste. The SVI of suspended bio-sludge in the MSBR system was only 44+/-3.4 ml/g under an organic loading of 680 g BOD5/m3 d.

[Adsorption of a dye by sludges and the roles of extracellular polymeric substances].

PubMed

Kong, Wang-sheng; Liu, Yan

2007-12-01

This paper investigated the adsorption of a dye, acid turquoise blue A, by four kinds of sludges including activated sludge, anaerobic sludge, dried activated sludge, and dried anaerobic sludge, respectively. The roles of extracellular polymeric substances (EPS) including the soluble EPS (SEPS) and bound EPS (BEPS) for the biosorption of activated sludge and anaerobic sludge were further studied. Results show that the relation between four kinds of sludge adsorption amount and remained concentration of the dye fitted well both Freundlich model (R2: 0.921-0.995) and Langmuir model (R2: 0.958-0.993), but not quite fitted BET model (R2: 0.07-0.863). The adsorption capability of dried anaerobic sludge ranked the highest, and dried activated sludge was the lowest. According to Langmuir isotherm, the maximum adsorption amount of dried anaerobic, anaerobic, activated, and dried activated sludge was 104 mg/g, 86 mg/g, 65 mg/g, 20 mg/g, respectively. The amount of the dye found in EPS for both activated sludge and anaerobic sludge were over 50%, illustrating that EPS adsorption was predominant in adsorption of the dye by sludge. The amount of adsorbed dye by BEPS was greater than that by SEPS for anaerobic sludge, but for activated sludge the result was quite opposite. The amount of adsorbed dye by unit mass SEPS was much higher than the corresponding values of BEPS for both sludges. The average amount of adsorbed dye by unit mass SEPS was 52 times of the corresponding value of BEPS for activated sludge, and 10 times for anaerobic sludge. The relation between adsorption amount of dye by BEPS from anaerobic sludge and remained concentration of the dye in mixed liquor was best fitted to Langmuir model (R2: 0.9986).

Thermal decomposition of sewage sludge under N2, CO2 and air: Gas characterization and kinetic analysis.

PubMed

Hernández, Ana Belén; Okonta, Felix; Freeman, Ntuli

2017-07-01

Thermochemical valorisation processes that allow energy to be recovered from sewage sludge, such as pyrolysis and gasification, have demonstrated great potential as convenient alternatives to conventional sewage sludge disposal technologies. Moreover, these processes may benefit from CO 2 recycling. Today, the scaling up of these technologies requires an advanced knowledge of the reactivity of sewage sludge and the characteristics of the products, specific to the thermochemical process. In this study the behaviour of sewage sludge during thermochemical conversion, under different atmospheres (N 2 , CO 2 and air), was studied, using TGA-FTIR, in order to understand the effects of different atmospheric gases on the kinetics of degradation and on the gaseous products. The different steps observed during the solid degradation were related with the production of different gaseous compounds. A higher oxidative degree of the atmosphere surrounding the sample resulted in higher reaction rates and a shift of the degradation mechanisms to lower temperatures, especially for the mechanisms taking place at temperatures above 400 °C. Finally, a multiple first-order reaction model was proposed to compare the kinetic parameters obtained under different atmospheres. Overall, the highest activation energies were obtained for combustion. This work proves that CO 2 , an intermediate oxidative atmosphere between N 2 and air, results in an intermediate behaviour (intermediate peaks in the derivative thermogravimetric curves and intermediate activation energies) during the thermochemical decomposition of sewage sludge. Overall, it can be concluded that the kinetics of these different processes require a different approach for their scaling up and specific consideration of their characteristic reaction temperatures and rates should be evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of biological and chemical oxidation on the removal of estrogenic compounds (NP and BPA) from wastewater: an integrated assessment procedure.

PubMed

Bertanza, Giorgio; Pedrazzani, Roberta; Dal Grande, Mario; Papa, Matteo; Zambarda, Valerio; Montani, Claudia; Steimberg, Nathalie; Mazzoleni, Giovanna; Di Lorenzo, Diego

2011-04-01

A major source of the wide presence of EDCs (Endocrine Disrupting Compounds) in water bodies is represented by direct/indirect discharge of sewage. Recent scientific literature reports data about their trace concentration in water, sediments and aquatic organisms, as well as removal efficiencies of different wastewater treatment schemes. Despite the availability of a huge amount of data, some doubts still persist due to the difficulty in evaluating synergistic effects of trace pollutants in complex matrices. In this paper, an integrated assessment procedure was used, based on chemical and biological analyses, in order to compare the performance of two full scale biological wastewater treatment plants (either equipped with conventional settling tanks or with an ultrafiltration membrane unit) and tertiary ozonation (pilot scale). Nonylphenol and bisphenol A were chosen as model EDCs, together with the parent compounds mono- and di-ethoxylated nonylphenol (quantified by means of GC-MS). Water estrogenic activity was evaluated by applying the human breast cancer MCF-7 based reporter gene assay. Process parameters (e.g., sludge age, temperature) and conventional pollutants (e.g., COD, suspended solids) were also measured during monitoring campaigns. Conventional activated sludge achieved satisfactory removal of both analytes and estrogenicity. A further reduction of biological activity was exerted by MBR (Membrane Biological Reactor) as well as ozonation; the latter contributed also to decrease EDC concentrations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Physicochemical changes of microbe and solid surface properties during biofilm formation

NASA Astrophysics Data System (ADS)

Sfaelou, Stavroula; Vakros, John; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.

2013-04-01

Cell immobilization is a promising biotechnology process. For example, entrapment of bacteria cells on synthetic polymeric matrices such as biocarriers is widely used for wastewater treatment because they have strong mechanical strength and durability in contrast to natural polymers. This method is based on the formation of biofilm on the surface of the used carriers and combines two different processes; attached and suspended biomass in a hybrid system. Previous studies have shown that immobilized cell systems have the potential to degrade toxic chemicals faster than conventional wastewater treatment systems because high densities of specialized microorganisms are used in immobilized cell systems. The present study elucidates the surface charge and properties of activated sludge and their role in the formation of biofilm. This information can be used for the optimization of the formation of biofilms as well as for the study of the transport of microorganisms in different environments. The two types of biocarriers that were used in this study are polyvinyl alcohol (PVA)-gel beads and Moving Bed Biofilm Reactor (MBBR) carriers. The sludge samples that were investigated were taken from the aeration tank of the wastewater treatment plant of University of Patras (Greece). Measurements of the surface charge of the sludge, the biocarriers and the formed biofilm, were performed using potentiometric mass titrations with different kinds of electrolytes (e.g. NaCl, NaNO3) and at pH ranging from 3 to 11. The determination of pzc and surface charge of activated sludge and biocarriers is significant, because it can provide new valuable informations about the interaction mechanisms and the formation of biofilms. In each case, the point of zero charge (pzc) was identified as the common intersection point of the potentiometric curve of the blank solution of the electrolyte with the corresponding curves of each material. The pzc value for the biofilm was 6.1 to 6.7 and 6.6 to 6.9 for PVA gel and MBBR, respectively. These values differ both from the pzc values found for PVA biocarriers (pzc = 9.4; no pzc value was obtained for MBBR as expected based on its hydrophobic nature and the absence of surface groups with acid-base behavior) and the pzc value of activated sludge (activated sludge mixed liquor: pzc = 8.0 to 8.2, solid activated sludge: pzc = 7.2 to 7.3). These results lead us to the conclusion that the formed biofilms have different acid-base behavior and properties in relation to the activated sludge and the biocarriers. This fact is in accordance to previous studies, where biofilm-associated cells can be differentiated from their suspended counterparts due to the generation of an extracellular polymeric substance (EPS) matrix. One other possible explanation is that the complicated processes of the biofilm formation can alter the distribution of different cells in the sludge compared with the cell distribution in the suspended unsupported sludge.

Application of electrochemical peroxidation (ECP) process for waste-activated sludge stabilization and system optimization using response surface methodology (RSM).

PubMed

Gholikandi, Gagik Badalians; Kazemirad, Khashayar

2018-03-01

In this study, the performance of the electrochemical peroxidation (ECP) process for removing the volatile suspended solids (VSS) content of waste-activated sludge was evaluated. The Fe 2+ ions required by the process were obtained directly from iron electrodes in the system. The performance of the ECP process was investigated in various operational conditions employing a laboratory-scale pilot setup and optimized by response surface methodology (RSM). According to the results, the ECP process showed its best performance when the pH value, current density, H 2 O 2 concentration and the retention time were 3, 3.2 mA/cm 2 , 1,535 mg/L and 240 min, respectively. In these conditions, the introduced Fe 2+ concentration was approximately 500 (mg/L) and the VSS removal efficiency about 74%. Moreover, the results of the microbial characteristics of the raw and the stabilized sludge demonstrated that the ECP process is able to remove close to 99.9% of the coliforms in the raw sludge during the stabilization process. The energy consumption evaluation showed that the required energy of the ECP reactor (about 1.8-2.5 kWh (kg VSS removed) -1 ) is considerably lower than for aerobic digestion, the conventional waste-activated sludge stabilization method (about 2-3 kWh (kg VSS removed) -1 ). The RSM optimization process showed that the best operational conditions of the ECP process comply with the experimental results, and the actual and the predicted results are in good conformity with each other. This feature makes it possible to predict the introduced Fe 2+ concentrations into the system and the VSS removal efficiency of the process precisely.

Recycled and virgin plastic carriers in hybrid reactors for wastewater treatment.

PubMed

Paul, Etienne; Wolff, Delmira Beatriz; Ochoa, Juan Carlos; da Costa, Rejane Helena Ribeiro

2007-07-01

The reduction of organic and nitrogen pollution of wastewater was investigated in two hybrid reactors and compared with the reduction obtained by using a conventional activated sludge reactor (ASR) run as a control. Both HR-1 and HR-2 were activated sludge systems where a low-density carrier, P1 (polyethylene) for HR-1 and P2 (recycled plastics) for HR-2, was added. Firstly, the three reactors were operated at 10 days Suspended Solid Retention Time (SRT(SS)), leading to a complete nitrification. Secondly, the SRT(SS) for each reactor was lowered to 3 days. Nitrification was lost for the ASR but remained complete for HR's. Respirometric techniques were used to measure fixed or suspended biomass activities for heterotrophic and autotrophic biomass. More than 90% of the autotrophic activity was found on the supports whatever the SRT(SS) used. The results may underline the role of the carrier geometry or surface characteristics on the autotrophic/heterotrophic microorganism distribution.

Integrated fixed-biofilm activated sludge reactor as a powerful tool to enrich anammox biofilm and granular sludge.

PubMed

Zhang, Liang; Liu, Miaomiao; Zhang, Shujun; Yang, Yandong; Peng, Yongzhen

2015-12-01

A pilot-scale activated sludge bioreactor was filled with immobile carrier to treat high ammonium wastewater. Autotrophic nitrogen elimination occurred rapidly by inoculating nitrifying activated sludge and anammox biofilm. As the ammonium loading rate increased, nitrogen removal rate of 1.2kgNm(-3)d(-1) was obtained with the removal efficiency of 80%. Activated sludge diameter distribution profiles presented two peak values, indicating simultaneous existence of flocculent and granular sludge. Red granular sludge was observed in the reactor. Furthermore, the results of morphological and molecular analysis showed that the characteristics of granular sludge were similar to that of biofilm, while much different from the flocculent sludge. It was assumed granular sludge was formed through the continuous growth and detachment of anammox biofilm. The mechanism of granular sludge formation was discussed and the procedure model was proposed. According to the experimental results, the integrated fixed-biofilm activated sludge reactor provided an alternative to nitrogen removal based on anammox. Copyright © 2015 Elsevier Ltd. All rights reserved.

Activated Sludge. Student Manual. Biological Treatment Process Control.

ERIC Educational Resources Information Center

Boe, Owen K.; Klopping, Paul H.

This student manual contains the textual material for a seven-lesson unit on activated sludge. Topic areas addressed in the lessons include: (1) activated sludge concepts and components (including aeration tanks, aeration systems, clarifiers, and sludge pumping systems); (2) activated sludge variations and modes; (3) biological nature of activated…

Bacterial community assembly in activated sludge: mapping beta diversity across environmental variables.

PubMed

Isazadeh, Siavash; Jauffur, Shameem; Frigon, Dominic

2016-12-01

Effect of ecological variables on community assembly of heterotrophic bacteria at eight full-scale and two pilot-scale activated sludge wastewater treatment plants (AS-WWTPs) were explored by pyrosequencing of 16S rRNA gene amplicons. In total, 39 samples covering a range of abiotic factors spread over space and time were analyzed. A core bacterial community of 24 families detected in at least six of the eight AS-WWTPs was defined. In addition to the core families, plant-specific families (observed at <50% AS-WWTPs) were found to be also important in the community structure. Observed beta diversity was partitioned with respect to ecological variables. Specifically, the following variables were considered: influent wastewater characteristics, season (winter vs. summer), process operations (conventional, oxidation ditch, and sequence batch reactor), reactor sizes (pilot-scale vs. full-scale reactors), chemical stresses defined by ozonation of return activated sludge, interannual variation, and geographical locations. Among the assessed variables, influent wastewater characteristics and geographical locations contributed more in explaining the differences between AS-WWTP bacterial communities with a maximum of approximately 26% of the observed variations. Partitioning of beta diversity is necessary to interpret the inherent variability in microbial community assembly and identify the driving forces at play in engineered microbial ecosystem. © 2016 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Improvement of primary settling performance with activated sludge.

PubMed

Yetis, U; Tarlan, E

2002-04-01

In biological treatment plants employing activated sludge processes, it is possible to recirculate some portion of the waste activated sludge that is not sent to the aeration basin, to the inlet of the primary sedimentation tanks. But in the literature there is no detailed information about the conditions, ratios and the characteristics of the waste sludge that can be recirculated back. However, depending on its settling characteristics, the addition of waste activated sludge to raw wastewater may improve primary settling. Settling tests have shown that the effect of waste activated sludge on primary settling is strongly dependent on the mean cell residence time (or sludge age), theta(c), of the waste activated sludge and also on the suspended solids concentration. Different sludge ages of 4, 6, 8, 10, 14, 20 and 26 days, and for each sludge age at least five different initial suspended solids concentrations were studied. A sludge age of 8-10 days achieved the optimum efficiency in terms of the remaining suspended solids concentration as well as percent-suspended solids removal. Also, the settled sludge volumes were measured throughout the experiments; so, the comparison was made between settled sludge volumes, initial suspended solids (SS) concentrations and theta(c).

[Dynamics of quickly absorption of the carbon source in wastewater by activated sludge].

PubMed

Liu, Hong-Bo; Wen, Xiang-Hua; Zhao, Fang

2011-09-01

In this paper, absorption characteristics of organic matter in municipal wastewater by three kinds of activated sludge (carbon-enriching, nitrification and denitrification sludge) were studied, and the absorption kinetic data was checked using three kinds of absorption kinetic equations based on Ritchie rate equation. The objectives of this study were to investigate the absorption mechanism of activated sludge to organic matter in municipal wastewater, and to identify the possibility of reclaiming organic matter by activated sludge. Results indicated that in the early 30 min, absorption process of organic matter by activated sludge was found to be mainly physical adsorption, which could be expressed by the Lagergren single-layer adsorption model. The carbon-enriching sludge had the highest adsorption capacity (COD/SS) which was 60 mg/g but the adsorption rate was lower than that of denitrification sludge. While nitrification sludge had the lowest adsorption rate and higher adsorption capacity compared with denitrification sludge, which was about 35 mg/g. The rates of the fitting index theta(0) of carbon-enriching, nitrification and denitrification sludge were 0.284, 0.777 and 0.923, respectively, which indicated that the sorbed organic matter on the surface of carbon-enriching sludge was the easiest fraction to be washed away. That is, the combination intensity of carbon-enriching sludge and organic matter was the feeblest, which was convenient for carbon-enriching sludge to release sorbed carbon. Furthermore, by fitting with Langmuir model, concentration of organic matter was found to be the key parameter influencing the adsorption capacity of activated sludge, while the influence of temperature was not obvious. The kinetic law of organic matter absorption by activated sludge was developed, which introduces a way to kinetically analyze the removing mechanism of pollutant by activated sludge and provides theoretical base for the reclaiming of nutriments in wastewater by the absorption of activated sludge.

Life cycle assessment of an intensive sewage treatment plant in Barcelona (Spain) with focus on energy aspects.

PubMed

Bravo, L; Ferrer, I

2011-01-01

Life Cycle Assessment was used to evaluate environmental impacts associated to a full-scale wastewater treatment plant (WWTP) in Barcelona Metropolitan Area, with a treatment capacity of 2 million population equivalent, focussing on energy aspects and resources consumption. The wastewater line includes conventional pre-treatment, primary settler, activated sludge with nitrogen removal, and tertiary treatment; and the sludge line consists of thickening, anaerobic digestion, cogeneration, dewatering and thermal drying. Real site data were preferably included in the inventory. Environmental impacts of the resulting impact categories were determined by the CLM 2 baseline method. According to the results, the combustion of natural gas in the cogeneration engine is responsible for the main impact on Climate Change and Depletion of Abiotic Resources, while the combustion of biogas in the cogeneration unit accounts for a minor part. The results suggest that the environmental performance of the WWTP would be enhanced by increasing biogas production through improved anaerobic digestion of sewage sludge.

Effects of conventional and no-tillage soil management and compost and sludge amendment on soil CO2 fluxes and microbial activities

NASA Astrophysics Data System (ADS)

Garcia-Gil, Juan Carlos; Haller, Isabel; Soler-Rovira, Pedro; Polo, Alfredo

2010-05-01

Soil management exerts a significant influence on the dynamic of soil organic matter, which is a key issue to enhance soil quality and its ecological functions, but also affects to greenhouse gas emissions and C sequestration processes. The objective of the present research was to determine the influence of soil management (conventional deep-tillage and no-tillage) and the application of two different organic amendment -thermally-dry sewage sludge (TSL) and municipal waste compost (MWC)- on soil CO2 fluxes and microbial activities in a long-term field experiment under semi-arid conditions. Both organic amendments were applied at a rate of 30 t ha-1 prior to sowing a barley crop. The experiment was conducted on an agricultural soil (Calcic Luvisol) from the experimental farm "La Higueruela" (Santa Olalla, Toledo). Unamended soils were used as control in both conventional and no-tillage management. During the course of the experiment, soil CO2 fluxes, microbial biomass C (MBC) and enzyme activities involved in the biogeochemical cycles of C, N and P were monitored during 12 months. The results obtained during the experiment for soil CO2 fluxes showed a great seasonal fluctuation due to semi-arid climate conditions. Overall, conventional deep-tillage soils exhibited higher CO2 fluxes, which was particularly larger during the first hours after deep-tillage was performed, and smaller MBC content and significantly lower dehydrogenase, beta-glucosidase, phosphatase, urease and BAA protease activities than no-tillage soils. Both MWC and TSL amendments provoked a significant increase of CO2 fluxes in both conventional and no-tillage soils, which was larger in TSL amended soils and particularly in no-tillage soils. The application of these organic amendments also enhanced MBC content and the overall enzyme activities in amended soils, which indicate a global revitalization of soil microbial metabolism in response to the fresh input of organic compounds that are energy sources for microbial growing, especially with TSL that is a raw organic material with no stabilization treatment.

Analysis of Combustion Process of Sewage Sludge in Reference to Coals and Biomass

NASA Astrophysics Data System (ADS)

Środa, Katarzyna; Kijo-Kleczkowska, Agnieszka

2016-06-01

Production of sewage sludge is an inseparable part of the treatment process. The chemical and sanitary composition of sewage sludge flowing into the treatment plant is a very important factor determining the further use of the final product obtained in these plants. The sewage sludge is characterized by heterogeneity and multi-components properties, because they have characteristics of the classical and fertilizer wastes and energetic fuels. The thermal utilization of sewage sludge is necessary due to the unfavorable sanitary characteristics and the addition of the industrial sewage. This method ensures use of sewage sludge energy and return of expenditure incurred for the treatment of these wastes and their disposal. Sewage sludge should be analyzed in relation to conventional fuels (coals and biomass). They must comply with the applicable requirements, for example by an appropriate degree of dehydration, which guarantee the stable and efficient combustion. This paper takes the issue of the combustion process of the different sewage sludge and their comparison of the coal and biomass fuels.

The significance of denitrifying polyphosphate accumulating organisms in biological nutrient removal activated sludge systems.

PubMed

Hu, Z R; Wentzel, M C; Ekama, G A

2002-01-01

In this paper the advantages and disadvantages of denitrifying PAOs (polyphosphate accumulating organisms) in conventional BNRAS (biological nutrient removal activated sludge) and external nitrification BNRAS (ENBNRAS) systems are evaluated, with experimental data exhibiting a range of anoxic P uptake from low (<10%) to very high (>60%). The results indicate that the specific denitrification rate of the PAOs on internally stored PHB COD is about 1/5th of that of the "ordinary" heterotrophic organisms on SBCOD, and the PAOs contribute little (maximum 20%) to the denitrification in BNRAS systems even when the anoxic P uptake is high (60% of the total P uptake). Considering the unpredictable nature of anoxic P uptake and the reduction in BEPR it causes compared with aerobic P uptake BEPR, it is concluded that anoxic P uptake does not add a significant advantage to the BNR system.

Fate of antibiotics in activated sludge followed by ultrafiltration (CAS-UF) and in a membrane bioreactor (MBR).

PubMed

Sahar, Eyal; Messalem, Rami; Cikurel, Haim; Aharoni, Avi; Brenner, Asher; Godehardt, Manuel; Jekel, Martin; Ernst, Mathias

2011-10-15

The fates of several macrolide, sulphonamide, and trimethoprim antibiotics contained in the raw sewage of the Tel-Aviv wastewater treatment plant (WWTP) were investigated after the sewage was treated using either a full-scale conventional activated sludge (CAS) system coupled with a subsequent ultrafiltration (UF) step or a pilot membrane bioreactor (MBR) system. Antibiotics removal in the MBR system, once it achieved stable operation, was 15-42% higher than that of the CAS system. This advantage was reduced to a maximum of 20% when a UF was added to the CAS. It was hypothesized that the contribution of membrane separation (in both systems) to antibiotics removal was due either to sorption to biomass (rather than improvement in biodegradation) or to enmeshment in the membrane biofilm (since UF membrane pores are significantly larger than the contaminant molecules). Batch experiments with MBR biomass showed a markedly high potential for sorption of the tested antibiotics onto the biomass. Moreover, methanol extraction of MBR biomass released significant amounts of sorbed antibiotics. This finding implies that more attention must be devoted to the management of excess sludge. Copyright © 2011 Elsevier Ltd. All rights reserved.

The sludge loading rate regulates the growth and release of heterotrophic bacteria resistant to six types of antibiotics in wastewater activated sludge.

PubMed

Yuan, Qing-Bin; Guo, Mei-Ting; Yang, Jian

2015-01-01

Wastewater treatment plants are considered as hot reservoirs of antimicrobial resistance. However, the fates of antibiotic-resistant bacteria during biological treatment processes and relevant influencing factors have not been fully understood. This study evaluated the effects of the sludge loading rate on the growth and release of six kinds of antibiotic-resistant bacteria in an activated sludge system. The results indicated that higher sludge loading rates amplified the growth of all six types of antibiotic resistant bacteria. The release of most antibiotic-resistant bacteria through both the effluent and biosolids was amplified with increased sludge loading rate. Biosolids were the main pattern for all antibiotic-resistant bacteria release in an activated sludge system, which was determined primarily by their growth in the activated sludge. A higher sludge loading rate reactor tended to retain more antibiotic resistance. An activated sludge system with lower sludge loading rates was considered more conducive to the control of antibiotic resistance.

Rheological characterisation of municipal sludge: a review.

PubMed

Eshtiaghi, Nicky; Markis, Flora; Yap, Shao Dong; Baudez, Jean-Christophe; Slatter, Paul

2013-10-01

Sustainable sludge management is becoming a major issue for wastewater treatment plants due to increasing urban populations and tightening environmental regulations for conventional sludge disposal methods. To address this problem, a good understanding of sludge behaviour is vital to improve and optimize the current state of wastewater treatment operations. This paper provides a review of the recent experimental works in order for researchers to be able to develop a reliable characterization technique for measuring the important properties of sludge such as viscosity, yield stress, thixotropy, and viscoelasticity and to better understand the impact of solids concentrations, temperature, and water content on these properties. In this context, choosing the appropriate rheological model and rheometer is also important. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stepwise hydrolysis to improve carbon releasing efficiency from sludge.

PubMed

Liu, Hongbo; Wang, Yuanyuan; Wang, Ling; Yu, Tiantian; Fu, Bo; Liu, He

2017-08-01

Based on thermal alkaline hydrolysis (TAH), a novel strategy of stepwise hydrolysis was developed to improve carbon releasing efficiency from waste activated sludge (WAS). By stepwise increasing hydrolysis intensity, conventional sludge hydrolysis (the control) was divided into four stages for separately recovering sludge carbon sources with different bonding strengths, namely stage 1 (60 °C, pH 6.0-8.0), stage 2 (80 °C, pH 6.0-8.0), stage 3 (80 °C, pH 10.0) and stage 4 (90 °C, pH 12.0). Results indicate stepwise hydrolysis could enhance the amount of released soluble chemical oxygen demand (SCOD) for almost 2 times, from 7200 to 14,693 mg/L, and the released carbon presented better biodegradability, with BOD/COD of 0.47 and volatile fatty acids (VFAs) yield of 0.37 g VFAs/g SCOD via anaerobic fermentation. Moreover, stepwise hydrolysis also improved the dewaterability of hydrolyzed sludge, capillary suction time (CST) reducing from 2500 to 1600 s. Economic assessment indicates stepwise hydrolysis shows less alkali demand and lower thermal energy consumption than those of the control. Furthermore, results of this study help support the concepts of improving carbon recovery in wastewater by manipulating WAS composition and the idea of classifiably recovering the nutrients in WAS. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Detection of anaerobic processes and microorganisms in immobilized activated sludge of a wastewater treatment plant with intense aeration].

PubMed

Litti, Iu V; Nekrasova, V K; Kulikov, N I; Siman'kova, M V; Nozhevnikova, A N

2013-01-01

Attached activated sludge from the Krasnaya Polyana (Sochi) wastewater treatment plant was studied after the reconstruction by increased aeration and water recycle, as well as by the installation of a bristle carrier for activated sludge immobilization. The activated sludge biofilms developing under conditions of intense aeration were shown to contain both aerobic and anaerobic microorganisms. Activity of a strictly anaerobic methanogenic community was revealed, which degraded organic compounds to methane, further oxidized by aerobic methanotrophs. Volatile fatty acids, the intermediates of anaerobic degradation of complex organic compounds, were used by both aerobic and anaerobic microorganisms. Anaerobic oxidation of ammonium with nitrite (anammox) and the presence of obligate anammox bacteria were revealed in attached activated sludge biofilms. Simultaneous aerobic and anaerobic degradation of organic contaminants by attached activated sludge provides for high rates of water treatment, stability of the activated sludge under variable environmental conditions, and decreased excess sludge formation.

Enhanced phenol removal in an innovative lignite activated coke-assisted biological process.

PubMed

Zhang, Chen; Li, Jianfeng; Cheng, Fangqin; Liu, Yu

2018-07-01

In this study, a lignite activated coke (LAC)-assisted activated sludge (AS) process was developed for enhancing biodegradation of phenol, while the effects of LAC on sludge properties and microbial community structure were investigated. It was found that more than 90% of phenol was removed within 1 h in the LAC/AS, which was 3 times higher than the conventional AS process. Moreover, the floc size and settleability were also significantly improved in the LAC/AS. These results suggested that LAC could serve as the nucleating agent to promote the formation of compact floc, which was beneficial for toxicity mitigation and system stability. The microbial community analysis by 16S high-throughput pyrosequencing technology further revealed a more abundant bacterial richness and diversity in the LAC/AS process loaded with phenol, while some phenol degraders, such as Propionibacteriaceae were enriched. Engineering implications further suggests the LAC-assisted AS process is technically sound and economically viable. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of glucose on the performance of enhanced biological phosphorus removal activated sludge enriched with acetate.

PubMed

Gebremariam, Seyoum Yami; Beutel, Marc W; Christian, David; Hess, Thomas F

2012-10-01

The effects of glucose on enhanced biological phosphorus removal (EBPR) activated sludge enriched with acetate was investigated using sequencing batch reactors. A glucose/acetate mixture was serially added to the test reactor in ratios of 25/75%, 50/50%, and 75/25% and the EBPR activity was compared to the control reactor fed with 100% acetate. P removal increased at a statistically significant level to a near-complete in the test reactor when the mixture increased to 50/50%. However, EBPR deteriorated when the glucose/acetate mixture increased to 75/25% in the test reactor and when the control reactor abruptly switched to 100% glucose. These results, in contrast to the EBPR conventional wisdom, suggest that the addition of glucose at moderate levels in wastewaters does not impede and may enhance EBPR, and that glucose waste products should be explored as an economical sustainable alternative when COD enhancement of EBPR is needed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of mechanical disintegration on the microbial growth of aerobic sludge biomass: A comparative study of ultrasonic and shear gap homogenizers by oxygen uptake measurements.

PubMed

Divyalakshmi, P; Murugan, D; Sivarajan, M; Saravanan, P; Lajapathi Rai, C

2015-11-01

Wastewater treatment plant incorporates physical, chemical and biological processes to treat and remove the contaminants. The main drawback of conventional activated sludge process is the huge production of excess sludge, which is an unavoidable byproduct. The treatment and disposal of excess sludge costs about 60% of the total operating cost. The ideal way to reduce excess sludge production during wastewater treatment is by preventing biomass formation within the aerobic treatment train rather than post treatment of the generated sludge. In the present investigation two different mechanical devices namely, Ultrasonic and Shear Gap homogenizers have been employed to disintegrate the aerobic biomass. This study is intended to restrict the multiplication of microbial biomass and at the same time degrade the organics present in wastewater by increasing the oxidative capacity of microorganisms. The disintegrability on biomass was determined by biochemical methods. Degree of inactivation provides the information on inability of microorganisms to consume oxygen upon disruption. The soluble COD quantifies the extent of release of intra cellular compounds. The participation of disintegrated microorganism in wastewater treatment process was carried out in two identical respirometeric reactors. The results show that Ultrasonic homogenizer is very effective in the disruption of microorganisms leading to a maximum microbial growth reduction of 27%. On the other hand, Shear gap homogenizer does not favor the sludge growth reduction rather it facilitates the growth. This study also shows that for better microbial growth reduction, floc size reduction alone is not sufficient but also microbial disruption is essential. Copyright © 2015 Elsevier Inc. All rights reserved.

Operating aerobic wastewater treatment at very short sludge ages enables treatment and energy recovery through anaerobic sludge digestion.

PubMed

Ge, Huoqing; Batstone, Damien J; Keller, Jurg

2013-11-01

Conventional abattoir wastewater treatment processes for carbon and nutrient removal are typically designed and operated with a long sludge retention time (SRT) of 10-20 days, with a relatively high energy demand and physical footprint. The process also generates a considerable amount of waste activated sludge that is not easily degradable due to the long SRT. In this study, an innovative high-rate sequencing batch reactor (SBR) based wastewater treatment process with short SRT and hydraulic retention time (HRT) is developed and characterised. The high-rate SBR process was shown to be most effective with SRT of 2-3 days and HRT of 0.5-1 day, achieving >80% reduction in chemical oxygen demand (COD) and phosphorus and approximately 55% nitrogen removal. A majority of carbon removal (70-80%) was achieved by biomass assimilation and/or accumulation, rather than oxidation. Anaerobic degradability of the sludge generated in the high-rate SBR process was strongly linked to SRT, with measured degradability extent being 85% (2 days SRT), 73% (3 days), and 63% (4 days), but it was not influenced by digestion temperature. However, the rate of degradation for 3 and 4 days SRT sludge was increased by 45% at thermophilic conditions compared to mesophilic conditions. Overall, the treatment process provides a very compact and energy efficient treatment option for highly degradable wastewaters such as meat and food processing, with a substantial space reduction by using smaller reactors and a considerable net energy output through the reduced aerobic oxidation and concurrent increased methane production potential through the efficient sludge digestion. Copyright © 2013 Elsevier Ltd. All rights reserved.

The presence and role of bacterial quorum sensing in activated sludge

PubMed Central

Chong, Grace; Kimyon, Onder; Rice, Scott A.; Kjelleberg, Staffan; Manefield, Mike

2012-01-01

Summary Activated sludge used for wastewater treatment globally is composed of a high‐density microbial community of great biotechnological significance. In this study the presence and purpose of quorum sensing via N‐acylated‐l‐homoserine lactones (AHLs) in activated sludge was explored. The presence of N‐heptanoyl‐l‐homoserine lactone in organic extracts of sludge was demonstrated along with activation of a LuxR‐based AHL monitor strain deployed in sludge, indicating AHL‐mediated gene expression is active in sludge flocculates but not in the bulk aqueous phase. Bacterial isolates from activated sludge were screened for AHL production and expression of phenotypes commonly but not exclusively regulated by AHL‐mediated gene transcription. N‐acylated‐l‐homoserine lactone and exoenzyme production were frequently observed among the isolates. N‐acylated‐l‐homoserine lactone addition to sludge upregulated chitinase activity and an AHL‐ and chitinase‐producing isolate closely related to Aeromonas hydrophila was shown to respond to AHL addition with upregulation of chitinase activity. N‐acylated‐l‐homoserine lactones produced by this strain were identified and genes ahyI/R and chiA, encoding AHL production and response and chitinase activity respectively, were sequenced. These experiments provide insight into the relationship between AHL‐mediated gene expression and exoenzyme activity in activated sludge and may ultimately create opportunities to improve sludge performance. PMID:22583685

A novel method for harmless disposal and resource reutilization of steel wire rope sludges.

PubMed

Zhang, Li; Liu, Yang-Sheng

2016-10-01

Rapid development of steel wire rope industry has led to the generation of large quantities of pickling sludge, which causes significant ecological problems and considerable negative environmental effects. In this study, a novel method was proposed for harmless disposal and resource reutilization of the steel wire rope sludge. Based on the method, two steel wire rope sludges (the Pb sludge and the Zn sludge) were firstly extracted by hydrochloric or sulfuric acid and then mixed with the hydrochloride acid extracting solution of aluminum skimmings to produce composite polyaluminum ferric flocculants. The optimum conditions (acid concentration, w/v ratio, reaction time, and reaction temperature) for acid extraction of the sludges were studied. Results showed that 97.03 % of Pb sludge and 96.20 % of Zn sludge were extracted. Leaching potential of the residues after acid extraction was evaluated, and a proposed treatment for the residues had been instructed. The obtained flocculant products were used to purify the real domestic wastewater and showed an equivalent or better performance than the commercial ones. This method is environmental-friendly and cost-effective when compared with the conventional sludge treatments.

Spectroscopic study of the humification process during sewage sludge treatment

NASA Astrophysics Data System (ADS)

Pajączkowska, J.; Sułkowska, A.; Sułkowski, W. W.; Jędrzejczyk, M.

2003-06-01

The aim of this work was to study the free radical transition of organic materials during the sewage treatment process. Investigations of sludge from biologic-mechanical sewage treatment plant in Sosnowiec Zagórze were carried out. The course of the humification processes during sewage treatment was studied by electron paramagnetic resonance (EPR) technique. The concentration of free radicals at each process stage and the value g were determined. Sludge samples and extracted fractions of humic acids were examined. Humic acids were extracted from sludge by means of conventional methods elaborated by Stevenson. For study of humic acids structures, besides EPR, the UV-Vis and IR spectroscopy were used.

Effect of semi-permeable cover system on the bacterial diversity during sewage sludge composting.

PubMed

Robledo-Mahón, Tatiana; Aranda, Elisabet; Pesciaroli, Chiara; Rodríguez-Calvo, Alfonso; Silva-Castro, Gloria Andrea; González-López, Jesús; Calvo, Concepción

2018-06-01

Sewage sludge composting is a profitable process economically viable and environmentally friendly. In despite of there are several kind of composting types, the use of combined system of semipermeable cover film and aeration air-floor is widely developed at industrial scale. However, the knowledge of the linkages between microbial communities structure, enzyme activities and physico-chemical factors under these conditions it has been poorly explored. Thus, the aim of this study was to investigate the bacterial dynamic and community structure using next generation sequencing coupled to analyses of microbial enzymatic activity and culturable dependent techniques in a full-scale real composting plant. Sewage sludge composting process was conducted using a semi-permeable Gore-tex cover, in combination with an air-insufflation system. The highest values of enzymatic activities such as dehydrogenase, protease and arylsulphatase were detected in the first 5 days of composting; suggesting that during this period of time a greater degrading activity of organic matter took place. Culturable bacteria identified were in agreement with the bacteria found by massive sequencing technologies. The greatest bacterial diversity was detected between days 15 and 30, with Actinomycetales and Bacillales being the predominant orders at the beginning and end of the process. Bacillus was the most representative genus during all the process. A strong correlation between abiotic factors as total organic content and organic matter and enzymatic activities such as dehydrogenase, alkaline phosphatase, and ß-glucosidase activity was found. Bacterial diversity was strongly influenced by the stage of the process, community-structure change was concomitant with a temperature rise, rendering favorable conditions to stimulate microbial activity and facilitate the change in the microbial community linked to the degradation process. Moreover, results obtained confirmed that the use of semipermeable cover in the composting of sewage sludge allow a noticeable reduction in the process-time comparing to conventional open windrows. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparative study on kinetic adsorption of Cu(II), Cd(II) and Ni(II) ions from aqueous solutions using activated sludge and dried sludge

NASA Astrophysics Data System (ADS)

Ong, Soon-An; Toorisaka, Eiichi; Hirata, Makoto; Hano, Tadashi

2013-03-01

The adsorption of Cu(II), Cd(II) and Ni(II) ions from aqueous solutions by activated sludge and dried sludge was investigated under laboratory conditions to assess its potential in removing metal ions. The adsorption behavior of metal ions onto activated sludge and dried sludge was analyzed with Weber-Morris intra-particle diffusion model, Lagergren first-order model and pseudo second-order model. The rate constant of intra-particle diffusion on activated sludge and dried sludge increased in the sequence of Cu(II) > Ni(II) > Cd(II). According to the regression coefficients, it was observed that the kinetic adsorption data can fit better by the pseudo second-order model compared to the first-order Lagergren model with R 2 > 0.997. The adsorption capacities of metal ions onto activated sludge and dried sludge followed the sequence Ni(II) ≈ Cu(II) > Cd(II) and Cu(II) > Ni(II) > Cd(II).

Sulfur Transformation during Microwave and Conventional Pyrolysis of Sewage Sludge.

PubMed

Zhang, Jun; Zuo, Wei; Tian, Yu; Chen, Lin; Yin, Linlin; Zhang, Jie

2017-01-03

The sulfur distributions and evolution of sulfur-containing compounds in the char, tar and gas fractions were investigated during the microwave and conventional pyrolysis of sewage sludge. Increased accumulation of sulfur in the char and less production of H 2 S were obtained from microwave pyrolysis at higher temperatures (500-800 °C). Three similar conversion pathways were identified for the formation of H 2 S during microwave and conventional pyrolysis. The cracking of unstable mercaptan structure in the sludge contributed to the release of H 2 S below 300 °C. The decomposition of aliphatic-S compounds in the tars led to the formation of H 2 S (300-500 °C). The thermal decomposition of aromatic-S compounds in the tars generated H 2 S from 500 to 800 °C. However, the secondary decomposition of thiophene-S compounds took place only in conventional pyrolysis above 700 °C. Comparing the H 2 S contributions from microwave and conventional pyrolysis, the significant increase of H 2 S yields in conventional pyrolysis was mainly attributed to the decomposition of aromatic-S (increasing by 10.4%) and thiophene-S compounds (11.3%). Further investigation on the inhibition mechanism of H 2 S formation during microwave pyrolysis confirmed that, with the special heating characteristics and relative shorter residence time, microwave pyrolysis promoted the retention of H 2 S on CaO and inhibited the secondary cracking of thiophene-S compounds at higher temperatures.

Aerobic granular sludge: a promising technology for decentralised wastewater treatment.

PubMed

Li, Z H; Kuba, T; Kusuda, T

2006-01-01

In order to evaluate the characteristics of aerobic granular sludge, a sequencing batch reactor, feeding with synthetic wastewater at the organic loading rate of 8 kg COD/m3 d, was employed on the laboratory scale. Granules occurred in the reactor within 1 week after the inoculation from conventional flocculent sludge. Aerobic granular sludge was characterised by the outstanding settling properties and considerable contaminates removal efficiencies. The SVI30 values were in the range of 20 to 40 ml g(-1). However, the sludge volume index of short settling time (e.g. SVI10--10 min) is suggested to describe the fast settling properties of aerobic granular sludge. The potential application in the decentralised system is evaluated from the point view of footprint and high bioactivity. The occurrence of sloughing, resulting from the outgrowth of filamentous organisms, would be responsible for the instability of aerobic granules. The starvation phase should therefore be carefully controlled for the maintenance and stability of aerobic granular sludge system.

Decontamination of sludge by the METIX-AC process. Part II: effects on maize growth and bioaccumulation of metals.

PubMed

Barraoui, Driss; Labrecque, Michel; Blais, Jean-François

2008-03-01

Given the fact that, according to our knowledge, no study has compared the agro-environmental use of decontaminated with non-decontaminated sludge, a greenhouse experiment was carried out to test the growth of maize (Zea mays L., G-4011 Hybrid) and bioaccumulation of metals in the presence of four different sludges (MUC, QUC, BEC and DAI), before and after their decontamination by a novel process (METIX-AC). Data showed that decontaminated sludge ameliorated plant growth and biomass production, and decreased bioaccumulation of metals, more than control soil, inorganic chemical fertilization, or conventional non-decontaminated sludge. Since chemicals used by the METIX-AC process contained S and Fe, decontaminated sludge introduced large amounts of these elements, while the overall presence of metals was reduced. Often, sludge dose also affected maize growth and bioaccumulation of metals. Overall, no toxicity to plants was noticed and bioaccumulation and transfer of many metals remained below the limits reported in the literature.

An integrated AMBBR and IFAS-SBR process for municipal wastewater treatment towards enhanced energy recovery, reduced energy consumption and sludge production.

PubMed

Gu, Jun; Xu, Guangjing; Liu, Yu

2017-03-01

The conventional activated sludge (CAS) process has been widely employed for wastewater treatment for more than one hundred years. Recently, more and more concerns have been raised on the CAS process due to its high energy consumption and production of huge amount of waste activated sludge, which are inevitably linked to the issue of environmental sustainability and global climate change. Facing to such emerging and challenging situation, this study reported a novel A-B process in which an anaerobic moving bed biofilm reactor (AMBBR) served a lead A-stage for COD capture towards biogas production and an integrated fixed-biofilm and activated sludge sequencing batch reactor (IFAS-SBR) was employed as B-stage for biological nitrogen removal. Results showed that about 85% of wastewater COD was removed in the steady-state AMBBR with a total energy production rate of 0.28 kWh/m 3 wastewater treated, while 85% of N-removal was achieved when the stable nitrite shunt was established in the IFAS-SBR. Moreover, 90% of dissolved methane in the AMBBR effluent could be removed by the proposed flash chamber at the lower energy demand of 0.12 kWh/m 3 which could be offset by the potential energy harvested from produced methane. Compared to the CAS process, the production of waste sludge was reduced by about 75% in the proposed A-B process due to the efficient COD capture at the A-stage, leading to significant energy savings from aeration for COD oxidation and post-treatment of waste sludge at the B-stage. Consequently, this study offers in-depth insights into A-B process which should be considered as an ideal candidate for achieving the energy-neutral or even energy positive operation of a municipal wastewater treatment. Given the complex situation in A-B process, future study is needed to look into the system optimization towards the operational synergy between A- and B-stage in terms of energy recovery and nitrogen removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carbon mass balance and microbial ecology in a laboratory scale reactor achieving simultaneous sludge reduction and nutrient removal.

PubMed

Huang, Pei; Li, Liang; Kotay, Shireen Meher; Goel, Ramesh

2014-04-15

Solids reduction in activated sludge processes (ASP) at source using process manipulation has been researched widely over the last two-decades. However, the absence of nutrient removal component, lack of understanding on the organic carbon, and limited information on key microbial community in solids minimizing ASP preclude the widespread acceptance of sludge minimizing processes. In this manuscript, we report simultaneous solids reduction through anaerobiosis along with nitrogen and phosphorus removals. The manuscript also reports carbon mass balance using stable isotope of carbon, microbial ecology of nitrifiers and polyphosphate accumulating organisms (PAOs). Two laboratory scale reactors were operated in anaerobic-aerobic-anoxic (A(2)O) mode. One reactor was run in the standard mode (hereafter called the control-SBR) simulating conventional A(2)O type of activated sludge process and the second reactor was run in the sludge minimizing mode (called the modified-SBR). Unlike other research efforts where the sludge minimizing reactor was maintained at nearly infinite solids retention time (SRT). To sustain the efficient nutrient removal, the modified-SBR in this research was operated at a very small solids yield rather than at infinite SRT. Both reactors showed consistent NH3-N, phosphorus and COD removals over a period of 263 days. Both reactors also showed active denitrification during the anoxic phase even if there was no organic carbon source available during this phase, suggesting the presence of denitrifying PAOs (DNPAOs). The observed solids yield in the modified-SBR was 60% less than the observed solids yield in the control-SBR. Specific oxygen uptake rate (SOUR) for the modified-SBR was almost 44% more than the control-SBR under identical feeding conditions, but was nearly the same for both reactors under fasting conditions. The modified-SBR showed greater diversity of ammonia oxidizing bacteria and PAOs compared to the control-SBR. The diversity of PAOs in the modified-SBR was even more interesting in which case novel clades of Candidatus Accumulibacter phosphatis (CAP), an uncultured but widely found PAOs, were found. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biodegradation of sulfamethoxazole by individual and mixed bacteria.

PubMed

Larcher, Simone; Yargeau, Viviane

2011-07-01

Antibiotic compounds, like sulfamethoxazole (SMX), have become a concern in the aquatic environment due to the potential development of antibacterial resistances. Due to excretion and disposal, SMX has been frequently detected in wastewaters and surface waters. SMX removal in conventional wastewater treatment plants (WWTPs) ranges from 0% to 90%, and there are opposing results regarding its biodegradability at lab scale. The objective of this research was to determine the ability of pure cultures of individual and mixed consortia of bacteria (Bacillus subtilis, Pseudomonas aeruginosa, Pseudomonas putida, Rhodococcus equi, Rhodococcus erythropolis, Rhodococcus rhodocrous, and Rhodococcus zopfii) known to exist in WWTP activated sludge to remove SMX. Results showed that R. equi alone had the greatest ability to remove SMX leading to 29% removal (with glucose) and the formation of a metabolite. Degradation pathways and metabolite structures have been proposed based on the potential enzymes produced by R. equi. When R. equi was mixed with other microorganisms, a positive synergistic effect was not observed and the maximum SMX removal achieved was 5%. This indicates that pure culture results cannot be extrapolated to mixed culture conditions, and the methodology developed here to study the biodegradability of compounds under controlled mixed culture conditions offers an alternative to conventional studies using pure bacterial cultures or inocula from activated sludge sources consisting of unknown and variable microbial populations.

Comparison of bacterial communities of conventional and A-stage activated sludge systems

PubMed Central

Gonzalez-Martinez, Alejandro; Rodriguez-Sanchez, Alejandro; Lotti, Tommaso; Garcia-Ruiz, Maria-Jesus; Osorio, Francisco; Gonzalez-Lopez, Jesus; van Loosdrecht, Mark C. M.

2016-01-01

The bacterial community structure of 10 different wastewater treatment systems and their influents has been investigated through pyrosequencing, yielding a total of 283486 reads. These bioreactors had different technological configurations: conventional activated sludge (CAS) systems and very highly loaded A-stage systems. A-stage processes are proposed as the first step in an energy producing municipal wastewater treatment process. Pyrosequencing analysis indicated that bacterial community structure of all influents was similar. Also the bacterial community of all CAS bioreactors was similar. Bacterial community structure of A-stage bioreactors showed a more case-specific pattern. A core of genera was consistently found for all influents, all CAS bioreactors and all A-stage bioreactors, respectively, showing that different geographical locations in The Netherlands and Spain did not affect the functional bacterial communities in these technologies. The ecological roles of these bacteria were discussed. Influents and A-stage bioreactors shared several core genera, while none of these were shared with CAS bioreactors communities. This difference is thought to reside in the different operational conditions of the two technologies. This study shows that bacterial community structure of CAS and A-stage bioreactors are mostly driven by solids retention time (SRT) and hydraulic retention time (HRT), as suggested by multivariate redundancy analysis. PMID:26728449

Molecular and conventional analyses of microbial diversity in mesophilic and thermophilic upflow anaerobic sludge blanket granular sludges.

PubMed

Sekiguchi, Y; Kamagata, Y; Ohashi, A; Harada, H

2002-01-01

The microbial community structure of mesophilic (35 degrees C) and thermophilic (55 degrees C) methanogenic granular sludges was surveyed by using both cultivation-independent molecular approach and conventional cultivation technique in order to address the fundamental questions on the microbial populations, i.e. who are present, where they are located, and what they are doing there. To elucidate the microbial constituents within both sludges, we first constructed 16S ribosomal DNA clone libraries, and partial sequencing of the clones was conducted for phylogenetic analysis. In this experiment, we found a number of unidentifiable clones within the domain Bacteria as well as clones that were closely related with 16S rDNAs of cultured microbes. The unidentifiable clones accounted for approximately 60-70% of the total clones in both mesophilic and thermophilic libraries. 16S rRNA-targeted in situ hybridization combined with confocal laser scanning microscopy was subsequently employed to examine where the uncultured populations were located within sludge granules. Spatial organization of uncultured microbes was visualized in thin-sections of both types of granules using fluorescent oligonucleotide probes, which were designed based on the clone sequences of certain novel clusters. This resulted in the detection of two types of uncultured cells in specific locations inside the granules. Finally, the goal-directed conventional cultivation technique was employed to recover such uncultured anaerobes and uncover their physiology and functions. In this approach, a total of five new species of thermophilic microorganisms were isolated, including several types of syntrophs and a novel sugar-fermenting bacterium. In the previous molecular approaches, all of these isolates were suggested to be significant populations within thermophilic granular sludge, hence obtaining these isolates in pure culture decreased the fraction of unknown clones in the previous thermophilic clone library from 70% to 40%. In conclusion, these approaches successfully revealed biodiversity and spatial organization of microbes of interest in sludge granules, and enlarged the fundamental knowledge of microbial constituents functioning as significant populations in the UASB processes.

Aerobic Heterotrophic Bacterial Populations of Sewage and Activated Sludge

PubMed Central

Prakasam, T. B. S.; Dondero, N. C.

1970-01-01

An activated sludge from a sewage treatment plant and a laboratory activated sludge developed on an artificial waste were compared for their ability to utilize 11 aromatic compounds. There were several significant differences between them. The laboratory sludge contained higher numbers of organisms and metabolized the aromatics to a greater extent. Laboratory activated sludges acclimated to utilization of the aromatics differed from each other in population structure and the pattern of oxygen consumption with aromatic substrates. The oxidative patterns of uncontrolled mixed populations were unreliable for investigating metabolic pathways. Extracts of the various sludges elevated the plate counts of the sludges. PMID:5418946

Application of a membrane bioreactor for winery wastewater treatment.

PubMed

Bolzonella, D; Fatone, F; Pavan, P; Cecchi, F

2010-01-01

Winery wastewaters are variable in nature and are hard to treat by means of the conventional activated sludge process because of the high organic loading associated with their production, especially during vintage. To face this situation, recently, membrane bioreactors have been widely applied to treat winery wastewaters. In this study, a full-scale membrane bioreactor treated some 110 m(3)/d of wastewater and organic loadings up to 1,600 kg COD per day. The average removal efficiency was 95% while the corresponding sludge yield was only 0.1 kg MLVSS per kg COD removed, as usual for these wastewaters. A detailed analysis of energy consumption showed specific energy demands of 2.0-3.6 kWh/m(3) of treated wastewater or 1 kWh per kg of COD removed.

Highly efficient secondary dewatering of dewatered sewage sludge using low boiling point solvents.

PubMed

He, Chao; Chena, Chia-Lung; Xu, Zhirong; Wang, Jing-Yuan

2014-01-01

Secondary dewatering of dewatered sludge is imperative to make conventional drying and incineration of sludge more economically feasible. In this study, a secondary dewatering of dewatered sludge with selected solvents (i.e. acetone and ethanol) followed by vacuum filtration and nature drying was investigated to achieve in-depth dewatering. After the entire secondary dewatering process, the sludge was shown to be odourless and the organic matter content was greatly retained. Increased mean particle size of sludge after solvent contact improved solid-liquid separation. With an acetone/sludge ratio of 3:1 (mL:g) in solvent contact and subsequent nature drying at ambient temperature after 24 h, the moisture content of sludge can be reduced to a level less than 20%. It is found that the polysaccharides were mainly precipitated by acetone, whereas the release ratios of protein and DNA were increased significantly as the added acetone volumes were elevated. During nature drying, accumulated evaporation rates of the sludge after solvent contact were 5-6 times higher than original dewatered sludge. Furthermore, sludge after acetone contact had better nature drying performance than ethanol. The two-stage dewatering involves solvent contact dewatering and solvent enhanced evaporation dewatering. Through selecting an appropriate solvent/sludge ratio as well as economical solvents and minimizing the solvent loss in a closed-pilot system, this dewatering process can be competitive in industrial applications. Therefore, this solvent-aided secondary dewatering is an energy-saving technology for effective in-depth dewatering of dewatered sludge and subsequent sludge utilization.

Evaluating the effects of activated carbon on methane generation and the fate of antibiotic resistant genes and class I integrons during anaerobic digestion of solid organic wastes.

PubMed

Zhang, Jingxin; Mao, Feijian; Loh, Kai-Chee; Gin, Karina Yew-Hoong; Dai, Yanjun; Tong, Yen Wah

2018-02-01

The effects of activated carbon (AC) on methane production and the fate of antibiotic resistance genes (ARGs) were evaluated through comparing the anaerobic digestion performance and transformation of ARGs among anaerobic mono-digestion of food waste, co-digestion of food waste and chicken manure, and co-digestion of food waste and waste activated sludge. Results showed that adding AC in anaerobic digesters improved methane yield by at least double through the enrichment of bacteria and archaea. Conventional digestion process showed ability in removing certain types of ARGs, such as tetA, tetX, sul1, sul2, cmlA, floR, and intl1. Supplementing AC in anaerobic digester enhanced the removal of most of the ARGs in mono-digestion of food waste. The effects tended to be minimal in co-digestion of co-substrates such as chicken manure and waste activated sludge, both of which contain a certain amount of antibiotics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced deodorization and sludge reduction in situ by a humus soil cooperated anaerobic/anoxic/oxic (A2O) wastewater treatment system.

PubMed

Yan, Xing; Li, Biqing; Lei, Fang; Feng, Xin; Pang, Bo

2016-08-01

Simultaneous sludge reduction and malodor abatement in humus soil cooperated an anaerobic/anoxic/oxic (A2O) wastewater treatment were investigated in this study. The HSR-A2O was composed of a humus soil reactor (HSR) and a conventional A2O (designated as C-A2O).The results showed that adding HSR did not deteriorate the chemical oxygen demand (COD) removal, while total phosphorus (TP) removal efficiency in HSR-A2O was improved by 18 % in comparison with that in the C-A2O. Both processes had good performance on total nitrogen (TN) removal, and there was no significant difference between them (76.8 and 77.1 %, respectively). However, NH4 (+)-N and NO3 (-)-N were reduced to 0.3 and 6.7 mg/L in HSR-A2O compared to 1.5 and 4.5 mg/L. Moreover, adding HSR induced the sludge reduction, and the sludge production rate was lower than that in the C-A2O. The observed sludge yield was estimated to be 0.32 kg MLSS/day in HSR-A2O, which represent a 33.5 % reduction compared to a C-A2O process. Activated sludge underwent humification and produced more humic acid in HSR-A2O, which is beneficial to sludge reduction. Odor abatement was achieved in HSR-A2O, ammonium (NH3), and sulfuretted hydrogen (H2S) emission decreased from 1.34 and 1.33 to 0.06 mg/m(3), 0.025 mg/m(3) in anaerobic area, with the corresponding reduction efficiency of 95.5 and 98.1 %. Microbial community analysis revealed that the relevant microorganism enrichment explained the reduction effect of humus soil on NH3 and H2S emission. The whole study demonstrated that humus soil enhanced odor abatement and sludge reduction in situ.

Extracellular protein analysis of activated sludge and their functions in wastewater treatment plant by shotgun proteomics.

PubMed

Zhang, Peng; Shen, Yu; Guo, Jin-Song; Li, Chun; Wang, Han; Chen, You-Peng; Yan, Peng; Yang, Ji-Xiang; Fang, Fang

2015-07-10

In this work, proteins in extracellular polymeric substances extracted from anaerobic, anoxic and aerobic sludges of wastewater treatment plant (WWTP) were analyzed to probe their origins and functions. Extracellular proteins in WWTP sludges were identified using shotgun proteomics, and 130, 108 and 114 proteins in anaerobic, anoxic and aerobic samples were classified, respectively. Most proteins originated from cell and cell part, and their most major molecular functions were catalytic activity and binding activity. The results exhibited that the main roles of extracellular proteins in activated sludges were multivalence cations and organic molecules binding, as well as in catalysis and degradation. The catalytic activity proteins were more widespread in anaerobic sludge compared with those in anoxic and aerobic sludges. The structure difference between anaerobic and aerobic sludges could be associated with their catalytic activities proteins. The results also put forward a relation between the macro characteristics of activated sludges and micro functions of extracellular proteins in biological wastewater treatment process.

Effect of potassium ferrate on disintegration of waste activated sludge (WAS).

PubMed

Ye, Fenxia; Ji, Haizhuang; Ye, Yangfang

2012-06-15

The activated sludge process of wastewater treatment results in the generation of a considerable amount of excess activated sludge. Increased attention has been given to minimization of waste activated sludge recently. This paper investigated the effect of potassium ferrate oxidation pretreatment on the disintegration of the waste activated sludge at various dosages of potassium ferrate. The results show that potassium ferrate pretreatment disintegrated the sludge particle, resulting in the reduction of total solid content by 31%. The solubility (SCOD/TCOD) of the sludge increased with the increase of potassium ferrate dosage. Under 0.81 g/g SS dosage of potassium ferrate, SCOD/TCOD reached 0.32. Total nitrogen (TN) and total phosphorous (TP) concentrations in the solution all increased significantly after potassium ferrate pretreatment. The sludge particles reduced from 116 to 87 μm. The settleability of the sludge (SVI) was enhanced by 17%, which was due to the re-flocculation by the by-product, Fe(III), during potassium ferrate oxidation and the decrease of the viscosity. From the result of the present investigations, it can be concluded that potassium ferrate oxidation is a feasible method for disintegration of excess activated sludge. Copyright © 2012 Elsevier B.V. All rights reserved.

Economic evaluation of alternative wastewater treatment plant options for pulp and paper industry.

PubMed

Buyukkamaci, Nurdan; Koken, Emre

2010-11-15

Excessive water consumption in pulp and paper industry results in high amount of wastewater. Pollutant characteristics of the wastewater vary depending on the processes used in production and the quality of paper produced. However, in general, high organic material and suspended solid contents are considered as major pollutants of pulp and paper industry effluents. The major pollutant characteristics of pulp and paper industry effluents in Turkey were surveyed and means of major pollutant concentrations, which were grouped in three different pollution grades (low, moderate and high strength effluents), and flow rates within 3000 to 10,000m(3)/day range with 1000m(3)/day steps were used as design parameters. Ninety-six treatment plants were designed using twelve flow schemes which were combinations of physical treatment, chemical treatment, aerobic and anaerobic biological processes. Detailed comparative cost analysis which includes investment, operation, maintenance and rehabilitation costs was prepared to determine optimum treatment processes for each pollution grade. The most economic and technically optimal treatment processes were found as extended aeration activated sludge process for low strength effluents, extended aeration activated sludge process or UASB followed by an aeration basin for medium strength effluents, and UASB followed by an aeration basin or UASB followed by the conventional activated sludge process for high strength effluents. Copyright © 2010 Elsevier B.V. All rights reserved.

Evaluation of the simultaneous removal of recalcitrant drugs (bezafibrate, gemfibrozil, indomethacin and sulfamethoxazole) and biodegradable organic matter from synthetic wastewater by electro-oxidation coupled with a biological system.

PubMed

Rodríguez-Nava, Odín; Ramírez-Saad, Hugo; Loera, Octavio; González, Ignacio

2016-12-01

Pharmaceutical degradation in conventional wastewater treatment plants (WWTP) represents a challenge since municipal wastewater and hospital effluents contain pharmaceuticals in low concentrations (recalcitrant and persistent in WWTP) and biodegradable organic matter (BOM) is the main pollutant. This work shows the feasibility of coupling electro-oxidation with a biological system for the simultaneous removal of recalcitrant drugs (bezafibrate, gemfibrozil, indomethacin and sulfamethoxazole (BGIS)) and BOM from wastewater. High removal efficiencies were attained without affecting the performance of activated sludge. BGIS degradation was performed by advanced electrochemical oxidation and the activated sludge process for BOM degradation in a continuous reactor. The selected electrochemical parameters from microelectrolysis tests (1.2 L s(-1) and 1.56 mA cm(-2)) were maintained to operate a filter press laboratory reactor FM01-LC using boron-doped diamond as the anode. The low current density was chosen in order to remove drugs without decreasing BOM and chlorine concentration control, so as to avoid bulking formation in the biological process. The wastewater previously treated by FM01-LC was fed directly (without chemical modification) to the activated sludge reactor to remove 100% of BGIS and 83% of BOM; conversely, the BGIS contained in wastewater without electrochemical pre-treatment were persistent in the biological process and promoted bulking formation.

Valuation of OSA process and folic acid addition as excess sludge minimization alternatives applied in the activated sludge process.

PubMed

Martins, C L; Velho, V F; Ramos, S R A; Pires, A S C D; Duarte, E C N F A; Costa, R H R

2016-01-01

The aim of this study was to investigate the ability of the oxic-settling-anaerobic (OSA)-process and the folic acid addition applied in the activated sludge process to reduce the excess sludge production. The study was monitored during two distinct periods: activated sludge system with OSA-process, and activated sludge system with folic acid addition. The observed sludge yields (Yobs) were 0.30 and 0.08 kgTSS kg(-1) chemical oxygen demand (COD), control phase and OSA-process (period 1); 0.33 and 0.18 kgTSS kg(-1) COD, control phase and folic acid addition (period 2). The Yobs decreased by 73 and 45% in phases with the OSA-process and folic acid addition, respectively, compared with the control phases. The sludge minimization alternatives result in a decrease in excess sludge production, without negatively affecting the performance of the effluent treatment.

Start-up period investigation of pilot-scale submerged membrane electro-bioreactor (SMEBR) treating raw municipal wastewater.

PubMed

Hasan, Shadi W; Elektorowicz, Maria; Oleszkiewicz, Jan A

2014-02-01

Submerged membrane electro-bioreactor (SMEBR) is a new hybrid technology for wastewater treatment employing electrical field and microfiltration in a nutrient-removing activated sludge process. A pilot SMEBR system was located at the wastewater treatment plant in the City of l'Assomption (Quebec, Canada) with the objective of investigating the start-up period performance under variable organic loadings and environmental conditions with respect to effluent quality, membrane fouling, and sludge properties. The pilot SMEBR facility was fed with the raw de-gritted municipal wastewater. At steady state operation, the removal efficiencies of ammonia (as NH3(+)-N), phosphorus (as PO4(3-)-P), and COD were 99%, 99%, and 92%, respectively. No substantial increase in the monitored transmembrane pressure as 0.02kPad(-1) was reported. The time necessary to filter 100mL of the sludge sample has decreased by 78% after treatment whilst the sludge volume index averaged 119mLg(-1). Energy requirements were in the range of 1.1-1.6kWhm(-3) of wastewater. It was concluded that the SMEBR is a very competitive technology when compared to conventional membrane systems as it can enhance treatment performance to an appreciable extent, remove phosphorus and reduce fouling. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Distribution, partition and removal of polycyclic aromatic hydrocarbons (PAHs) during coking wastewater treatment processes.

PubMed

Zhang, Wanhui; Wei, Chaohai; An, Guanfeng

2015-05-01

In this study, we report the performance of a full-scale conventional activated sludge (A-O1-O2) treatment in eliminating polycyclic aromatic hydrocarbons (PAHs). Both aqueous and solid phases along with the coking wastewater treatment processes were analyzed for the presence of 18 PAHs. It was found that the target compounds occurred widely in raw coking wastewater, treated effluent and sludge samples. In the coking wastewater treatment system, 4-5 ring PAHs were the dominant compounds, while 4 rings PAHs predominated in the sludge samples. Over 98% of the PAH removal was achieved in the coking wastewater treatment plant (WWTP), with the total concentration of PAHs being 21.3 ± 1.9 μg L(-1) in the final effluent. During the coking wastewater treatment processes, the association of the lower molecular weight PAH with suspended solids was generally less than 60%, while the association of higher molecular weight PAHs was greater than 90%. High distribution efficiencies (Kdp and Kds) were found, suggesting that adsorption was the potential removal pathway of PAHs. Finally, the mass balances of PAHs in various stages of the coking WWTP were obtained, and the results indicated that adsorption to sludge was the main removal pathway for PAHs in the coking wastewater treatment processes.

Denitrifying capability and community dynamics of glycogen accumulating organisms during sludge granulation in an anaerobic-aerobic sequencing batch reactor

PubMed Central

Bin, Zhang; Bin, Xue; Zhigang, Qiu; Zhiqiang, Chen; Junwen, Li; Taishi, Gong; Wenci, Zou; Jingfeng, Wang

2015-01-01

Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3−-N could be removed or reduced, some amount of NO2−-N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy. PMID:26257096

Denitrifying capability and community dynamics of glycogen accumulating organisms during sludge granulation in an anaerobic-aerobic sequencing batch reactor.

PubMed

Bin, Zhang; Bin, Xue; Zhigang, Qiu; Zhiqiang, Chen; Junwen, Li; Taishi, Gong; Wenci, Zou; Jingfeng, Wang

2015-08-10

Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3(-)-N could be removed or reduced, some amount of NO2(-)-N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy.

Denitrifying capability and community dynamics of glycogen accumulating organisms during sludge granulation in an anaerobic-aerobic sequencing batch reactor

NASA Astrophysics Data System (ADS)

Bin, Zhang; Bin, Xue; Zhigang, Qiu; Zhiqiang, Chen; Junwen, Li; Taishi, Gong; Wenci, Zou; Jingfeng, Wang

2015-08-01

Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3--N could be removed or reduced, some amount of NO2--N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy.

Electro-dewatering of wastewater sludge: An investigation of the relationship between filtrate flow rate and electric current.

PubMed

Olivier, Jérémy; Conrardy, Jean-Baptiste; Mahmoud, Akrama; Vaxelaire, Jean

2015-10-01

Compared to conventional dewatering techniques, electrical assisted mechanical dewatering, also called electro-dewatering (EDW) is an alternative and an effective technology for the dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading). Copyright © 2015 Elsevier Ltd. All rights reserved.

Environmental & economic life cycle assessment of current & future sewage sludge to energy technologies.

PubMed

Mills, N; Pearce, P; Farrow, J; Thorpe, R B; Kirkby, N F

2014-01-01

The UK Water Industry currently generates approximately 800GWh pa of electrical energy from sewage sludge. Traditionally energy recovery from sewage sludge features Anaerobic Digestion (AD) with biogas utilisation in combined heat and power (CHP) systems. However, the industry is evolving and a number of developments that extract more energy from sludge are either being implemented or are nearing full scale demonstration. This study compared five technology configurations: 1 - conventional AD with CHP, 2 - Thermal Hydrolysis Process (THP) AD with CHP, 3 - THP AD with bio-methane grid injection, 4 - THP AD with CHP followed by drying of digested sludge for solid fuel production, 5 - THP AD followed by drying, pyrolysis of the digested sludge and use of the both the biogas and the pyrolysis gas in a CHP. The economic and environmental Life Cycle Assessment (LCA) found that both the post AD drying options performed well but the option used to create a solid fuel to displace coal (configuration 4) was the most sustainable solution economically and environmentally, closely followed by the pyrolysis configuration (5). Application of THP improves the financial and environmental performance compared with conventional AD. Producing bio-methane for grid injection (configuration 3) is attractive financially but has the worst environmental impact of all the scenarios, suggesting that the current UK financial incentive policy for bio-methane is not driving best environmental practice. It is clear that new and improving processes and technologies are enabling significant opportunities for further energy recovery from sludge; LCA provides tools for determining the best overall options for particular situations and allows innovation resources and investment to be focused accordingly. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

The role and control of sludge age in biological nutrient removal activated sludge systems.

PubMed

Ekama, G A

2010-01-01

The sludge age is the most fundamental and important parameter in the design, operation and control of biological nutrient removal (BNR) activated sludge (AS) systems. Generally, the better the effluent and waste sludge quality required from the system, the longer the sludge age, the larger the biological reactor and the more wastewater characteristics need to be known. Controlling the reactor concentration does not control sludge age, only the mass of sludge in the system. When nitrification is a requirement, sludge age control becomes a requirement and the secondary settling tanks can no longer serve the dual purpose of clarifier and waste activated sludge thickeners. The easiest and most practical way to control sludge age is with hydraulic control by wasting a defined proportion of the reactor volume daily. In AS plants with reactor concentration control, nitrification fails first. With hydraulic control of sludge age, nitrification will not fail, rather the plant fails by shedding solids over the secondary settling tank effluent weirs.

Studies on the toxic effects of pentachlorophenol on the biological activity of anaerobic granular sludge.

PubMed

Liu, Xin-Wen; He, Ruo; Shen, Dong-Sheng

2008-09-01

In order to explore the pathway of the anaerobic biotreatment of the wastewater containing pentachlorophenol (PCP) and ensure the normal operation of Upflow Anaerobic Sludge Blanket (UASB) reactor, the anaerobic sludge under different acclimation conditions were selected to seed and start up UASB reactors. Anaerobic toxicity assays were employed to study the biological activity, the tolerance and the capacity to degrade PCP of different anaerobic granular sludge from UASB reactors. Results showed that the anaerobic granular sludge acclimated to chlorophenols (CPs) could degrade PCP more quickly (up to 9.50mg-PCP g(-1)TVS d(-1)). And the anaerobic granular sludge without acclimation to CPs had only a little activity of degrading PCP (less than 0.07 mg-PCP g(-1)TVS d(-1)). Different PCP concentrations (2, 4, 6, 8 mg L(-1)) had different inhibition effects on glucose utilization, volatile fatted acidity (VFA)-degrading and methanogens activity of PCP degradation anaerobic granular sludge, and the biological activity declined with the increase in PCP concentration. The methanogens activity suffered inhibition from PCP more easily. The different acclimation patterns of seeded sludge had distinctly different effects on biological activity of the degradation of PCP of anaerobic granular sludge from UASB reactors. The biological activity of the anaerobic granular sludge acclimated to PCP only was also inhibited. This inhibition was weak compared to that of anaerobic granular sludge acclimated to CPs, further, the activity could recover more quickly in this case. In the same reactor, the anaerobic granular sludge from the mid and base layers showed higher tolerance to PCP than that from super layer or if the sludge is unacclimated to CPs, and the corresponding recovery time of the biological activity in the mid and base layers were short. Acetate-utilizing methanogens and syntrophic propinate degraders were sensitive to PCP, compared to syntrophic butyrate degraders.

Fate of cyanobacteria in drinking water treatment plant lagoon supernatant and sludge.

PubMed

Pestana, Carlos J; Reeve, Petra J; Sawade, Emma; Voldoire, Camille F; Newton, Kelly; Praptiwi, Radisti; Collingnon, Lea; Dreyfus, Jennifer; Hobson, Peter; Gaget, Virginie; Newcombe, Gayle

2016-09-15

In conventional water treatment processes, where the coagulation and flocculation steps are designed to remove particles from drinking water, cyanobacteria are also concentrated into the resultant sludge. As a consequence, cyanobacteria-laden sludge can act as a reservoir for metabolites such as taste and odour compounds and cyanotoxins. This can pose a significant risk to water quality where supernatant from the sludge treatment facility is returned to the inlet to the plant. In this study the complex processes that can take place in a sludge treatment lagoon were investigated. It was shown that cyanobacteria can proliferate in the conditions manifest in a sludge treatment lagoon, and that cyanobacteria can survive and produce metabolites for at least 10days in sludge. The major processes of metabolite release and degradation are very dependent on the physical, chemical and biological environment in the sludge treatment facility and it was not possible to accurately model the net effect. For the first time evidence is provided to suggest that there is a greater risk associated with recycling sludge supernatant than can be estimated from the raw water quality, as metabolite concentrations increased by up to 500% over several days after coagulation, attributed to increased metabolite production and/or cell proliferation in the sludge. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluating the efficiency of carbon utilisation via bioenergetics between biological aerobic and denitrifying phosphorus removal systems

PubMed Central

Jin, Zhan; He, Yin; Xu, Xuan; Zheng, Xiang-yong

2017-01-01

There are two biological systems available for removing phosphorus from waste water, conventional phosphorus removal (CPR) and denitrifying phosphorus removal (DPR) systems, and each is characterized by the type of sludge used in the process. In this study, we compared the characteristics associated with the efficiency of carbon utilization between CPR and DPR sludge using acetate as a carbon source. For DPR sludge, the heat emitted during the phosphorus release and phosphorus uptake processes were 45.79 kJ/mol e- and 84.09 kJ/mol e-, respectively. These values were about 2 fold higher than the corresponding values obtained for CPR sludge, suggesting that much of the energy obtained from the carbon source was emitted as heat. Further study revealed a smaller microbial mass within the DPR sludge compared to CPR sludge, as shown by a lower sludge yield coefficient (0.05 gVSS/g COD versus 0.36 gVSS/g COD), a result that was due to the lower energy capturing efficiency of DPR sludge according to bioenergetic analysis. Although the efficiency of anoxic phosphorus removal was only 39% the efficiency of aerobic phosphorus removal, the consumption of carbon by DPR sludge was reduced by 27.8% compared to CPR sludge through the coupling of denitrification with dephosphatation. PMID:29065157

Predicting the apparent viscosity and yield stress of digested and secondary sludge mixtures.

PubMed

Eshtiaghi, Nicky; Markis, Flora; Zain, Dwen; Mai, Kiet Hung

2016-05-15

The legal banning of conventional sludge disposal methods such as landfill has led to a global movement towards achieving a sustainable sludge management strategy. Reusing sludge for energy production (biogas production) through the anaerobic digestion of sludge can provide a sustainable solution. However, for the optimum performance of digesters with minimal use of energy input, operating conditions must be regulated in accordance with the rheological characteristics of the sludge. If it is assumed that only secondary sludge enters the anaerobic digesters, an impact of variations to the solids concentration and volume fraction of each sludge type must be investigated to understand how the apparent viscosity and yield stress of the secondary and digested sludge mixture inside the digesters changes. In this study, five different total solids concentration of secondary and digested sludge were mixed at different digested sludge volume fractions ranging from 0 to 1. It was found that if secondary sludge was mixed with digested sludge at the same total solids concentration, the apparent viscosity and the yield stress of the mixture increased exponentially by increasing the volume fraction of digested sludge. However, if secondary sludge was added to digested sludge with a different solids concentration, the apparent viscosity and yield stress of the resulting mixed sludge was controlled by the concentrated sludge regardless of its type. Semi - empirical correlations were proposed to predict the apparent viscosity and yield stress of the mixed digested and secondary sludge. A master curve was also developed to predict the flow behaviour of sludge mixtures regardless of the total solid concentration and volume fraction of each sludge type within the studied solids concentration range of 1.4 and 7%TS. This model can be used for digesters optimization and design by predicting the rheology of sludge mixture inside digester. Copyright © 2016 Elsevier Ltd. All rights reserved.

Activated sludge model (ASM) based modelling of membrane bioreactor (MBR) processes: a critical review with special regard to MBR specificities.

PubMed

Fenu, A; Guglielmi, G; Jimenez, J; Spèrandio, M; Saroj, D; Lesjean, B; Brepols, C; Thoeye, C; Nopens, I

2010-08-01

Membrane bioreactors (MBRs) have been increasingly employed for municipal and industrial wastewater treatment in the last decade. The efforts for modelling of such wastewater treatment systems have always targeted either the biological processes (treatment quality target) as well as the various aspects of engineering (cost effective design and operation). The development of Activated Sludge Models (ASM) was an important evolution in the modelling of Conventional Activated Sludge (CAS) processes and their use is now very well established. However, although they were initially developed to describe CAS processes, they have simply been transferred and applied to MBR processes. Recent studies on MBR biological processes have reported several crucial specificities: medium to very high sludge retention times, high mixed liquor concentration, accumulation of soluble microbial products (SMP) rejected by the membrane filtration step, and high aeration rates for scouring purposes. These aspects raise the question as to what extent the ASM framework is applicable to MBR processes. Several studies highlighting some of the aforementioned issues are scattered through the literature. Hence, through a concise and structured overview of the past developments and current state-of-the-art in biological modelling of MBR, this review explores ASM-based modelling applied to MBR processes. The work aims to synthesize previous studies and differentiates between unmodified and modified applications of ASM to MBR. Particular emphasis is placed on influent fractionation, biokinetics, and soluble microbial products (SMPs)/exo-polymeric substances (EPS) modelling, and suggestions are put forward as to good modelling practice with regard to MBR modelling both for end-users and academia. A last section highlights shortcomings and future needs for improved biological modelling of MBR processes. (c) 2010 Elsevier Ltd. All rights reserved.

Model assisted startup of anaerobic digesters fed with thermally hydrolysed activated sludge.

PubMed

Batstone, D J; Balthes, C; Barr, K

2010-01-01

This paper presents the use of the IWA ADM1 to predict and interpret results from two full-scale anaerobic digesters fed with thermal hyrolysate (waste activated sludge with a long upstream sludge age) from a Cambi hydrolysis process operating at 165°C and 6 bar-g. The first digester was fed conventionally-though intermittently, while the second was heavily diluted through a substantial component of the evaluation period (110 days). There were a number of important outcomes-related to both model application, and model predictions. Input and inert COD: mass ratio was very important, and was considerably higher than the 1.42 g g⁻¹ used for biomass throughout the IWA activated sludge and anaerobic digestion models. Input COD: VS ratio was 1.6 g g⁻¹, and inert COD: VS ratio was 1.7 g g⁻¹. The model succeeded on a number of levels, including effective prediction of important outputs (degradability, gas flow and composition, and final solids), clarification of the substantial data scatter, prediction of recovery times during operationally poor periods, and cross-validation of the results between digester 1 and digester 2. Key failures in model performance were related to an early incorrect assumption of the COD: VS ratio of 1.42 g g⁻¹, and intermittent high acetate levels, most likely caused by inhibition, and rapid acclimatisation to ammonia. The acute free ammonia limit was found to be 0.008 M NH(3)-N, while the chronic inhibition constant (K(I,NH₃,ac)) was 0.007 ± 0.001 M NH₃-N. Overall, this is a complex system, and application of the model added significant confidence to the initial operational decisions during an aggressive startup on an atypical feed.

Somatic coliphages as surrogates for enteroviruses in sludge hygienization treatments.

PubMed

Martín-Díaz, Julia; Casas-Mangas, Raquel; García-Aljaro, Cristina; Blanch, Anicet R; Lucena, Francisco

2016-01-01

Conventional bacterial indicators present serious drawbacks giving information about viral pathogens persistence during sludge hygienization treatments. This calls for the search of alternative viral indicators. Somatic coliphages' (SOMCPH) ability for acting as surrogates for enteroviruses was assessed in 47 sludge samples subjected to novel treatment processes. SOMCPH, infectious enteroviruses and genome copies of enteroviruses were monitored. Only one of these groups, the bacteriophages, was present in the sludge at concentrations that allowed the evaluation of treatment's performance. An indicator/pathogen relationship of 4 log10 (PFU/g dw) was found between SOMCPH and infective enteroviruses and their detection accuracy was assessed. The obtained results and the existence of rapid and standardized methods encourage the inclusion of SOMCPH quantification in future sludge directives. In addition, an existing real-time quantitative polymerase chain reaction (RT-qPCR) for enteroviruses was adapted and applied.

Tracing the evolution of degraders in activated sludge during the sludge’s acclimation to a xenobiotic organic

NASA Astrophysics Data System (ADS)

Chong, N. M.; Fan, C. H.; Yang, Y. C.

2017-01-01

The molecular biology method of high-throughput pyrosequencing was employed to examine the change of activated sludge community structures during the process in which activated sludge was acclimated to and degraded a target xenobiotic. The sample xenobiotic organic compound used as the activated sludge acclimation target was the herbicide 2,4-dichlorphenoxyacetic acid (2,4-D). Indigenous activated sludge microorganisms were acclimated to 2,4-D as the sole carbon source in both the batch and the continuous-flow reaction modes. Sludge masses at multiple time points during the course of acclimation were subjected to pyrosequencing targeting the microorganisms’ 16S rRNA genes. With the bacterial 16S rRNA sequencing results the genera that increased in abundance were checked with degradative pathway databases or literature to confirm that they are commonly seen as potent degraders of 2,4-D. From this systematic examination of degrader changes at time points during activated sludge acclimation and degradation of the target xenobiotic, the trend of degrader evolution in activated sludge over the sludge’s acclimation process to a xenobiotic was traced.

Toxic influence of silver and uranium salts on activated sludge of wastewater treatment plants and synthetic activated sludge associates modeled on its pure cultures.

PubMed

Tyupa, Dmitry V; Kalenov, Sergei V; Skladnev, Dmitry A; Khokhlachev, Nikolay S; Baurina, Marina M; Kuznetsov, Alexander Ye

2015-01-01

Toxic impact of silver and uranium salts on activated sludge of wastewater treatment facilities has been studied. Some dominating cultures (an active nitrogen fixer Agrobacterium tumifaciens (A.t) and micromyces such as Fusarium nivale, Fusarium oxysporum, and Penicillium glabrum) have been isolated and identified as a result of selection of the activated sludge microorganisms being steadiest under stressful conditions. For these cultures, the lethal doses of silver amounted 1, 600, 50, and 300 µg/l and the lethal doses of uranium were 120, 1,500, 1,000, and 1,000 mg/l, respectively. A.tumifaciens is shown to be more sensitive to heavy metals than micromyces. Synthetic granular activated sludge was formed on the basis of three cultures of the isolated micromyces steadiest against stress. Its granules were much more resistant to silver than the whole native activated sludge was. The concentration of silver causing 50 % inhibition of synthetic granular activated sludge growth reached 160-170 μg/l as far as for the native activated sludge it came only to 100-110 μg/l.

Oxygen transfer dynamics and activated sludge floc structure under different sludge retention times at low dissolved oxygen concentrations.

PubMed

Fan, Haitao; Liu, Xiuhong; Wang, Hao; Han, Yunping; Qi, Lu; Wang, Hongchen

2017-02-01

In activated sludge systems, the aeration process consumes the most energy. The energy cost can be dramatically reduced by decreasing the operating dissolved oxygen (DO) concentration. However, low DO may lead to incomplete nitrification and poor settling performance of activated sludge flocs (ASFs). This study investigates oxygen transfer dynamics and settling performances of activated sludge under different sludge retention times (SRTs) and DO conditions using microelectrodes and microscopic techniques. Our experimental results showed that with longer SRTs, treatment capacity and settling performances of activated sludge improved due to smaller floc size and less extracellular polymeric substances (EPS). Long-term low DO conditions produced larger flocs and more EPS per unit sludge, which produced a more extensive anoxic area and led to low oxygen diffusion performance in flocs. Long SRTs mitigated the adverse effects of low DO. According to the microelectrode analysis and fractal dimension determination, smaller floc size and less EPS in the long SRT system led to high oxygen diffusion property and more compact floc structure that caused a drop in the sludge volume index (SVI). In summary, our results suggested that long SRTs of activated sludge can improve the operating performance under low DO conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Acclimation of aerobic-activated sludge degrading benzene derivatives and co-metabolic degradation activities of trichloroethylene by benzene derivative-grown aerobic sludge.

PubMed

Wang, Shizong; Yang, Qi; Bai, Zhiyong; Wang, Shidong; Wang, Yeyao; Nowak, Karolina M

2015-01-01

The acclimation of aerobic-activated sludge for degradation of benzene derivatives was investigated in batch experiments. Phenol, benzoic acid, toluene, aniline and chlorobenzene were concurrently added to five different bioreactors which contained the aerobic-activated sludge. After the acclimation process ended, the acclimated phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic-activated sludge were used to explore the co-metabolic degradation activities of trichloroethylene (TCE). Monod equation was employed to simulate the kinetics of co-metabolic degradation of TCE by benzene derivative-grown sludge. At the end of experiments, the mixed microbial communities grown under different conditions were identified. The results showed that the acclimation periods of microorganisms for different benzene derivatives varied. The maximum degradation rates of TCE for phenol-, benzoic acid-, toluene-, aniline- and chlorobenzene-grown aerobic sludge were 0.020, 0.017, 0.016, 0.0089 and 0.0047 mg g SS(-1) h(-1), respectively. The kinetic of TCE degradation in the absence of benzene derivative followed Monod equation well. Also, eight phyla were observed in the acclimated benzene derivative-grown aerobic sludge. Each of benzene derivative-grown aerobic sludge had different microbial community composition. This study can hopefully add new knowledge to the area of TCE co-metabolic by mixed microbial communities, and further the understanding on the function and applicability of aerobic-activated sludge.

EMMC process for combined removal of organics, nitrogen and an odor producing substance.

PubMed

Yang, P Y; Su, R; Kim, S J

2003-12-01

In order to improve the process performance regarding the removal of organics, nitrogen, and an odor-causing compound (sulfide) contained in domestic wastewater, an entrapped-mixed-microbial cell (EMMC) with and without humic substances for both fixed and moving carrier reactors and conventional suspended growth culture (i.e. conventional activated sludge process) were investigated simultaneously. Both synthetic (simulated to the organics concentration of general domestic sewage) and actual domestic wastewater were investigated under operational conditions of 12 h of hydraulic retention time (HRT) with 1 h of aeration and 1 h of non-aeration, and 6 h of HRT with continuous aeration, at a room temperature of 25 +/- 2 degrees C. It was found that entrapping humic substances in the EMMC carriers had no impact on the removal of organics, nitrogen, and the odor-producing compound. Additionally, the performance of the EMMC moving carrier system for the removal of these pollutants is similar to that of the EMMC fixed carrier system. In general, the EMMC associated systems which provide high solids retention time achieve a better removal of chemical oxygen demand (COD), nitrogen, and the odor-producing substance than the suspended growth system for both HRTs of 6 h (continuous aeration) and 12 h (1 h of aeration and 1 h of non-aeration). Both the fixed and moving carrier EMMC processes, therefore, have the potential for improvement or replacement of the existing conventional activated sludge process with regard to improving the effluent qualities (such as COD, nitrogen and odor-producing compound) for reuse/disposal.

Evaluating sedimentation problems in activated sludge treatment plants operating at complete sludge retention time.

PubMed

Amanatidou, Elisavet; Samiotis, Georgios; Trikoilidou, Eleni; Pekridis, George; Taousanidis, Nikolaos

2015-02-01

Zero net sludge growth can be achieved by complete retention of solids in activated sludge wastewater treatment, especially in high strength and biodegradable wastewaters. When increasing the solids retention time, MLSS and MLVSS concentrations reach a plateau phase and observed growth yields values tend to zero (Yobs ≈ 0). In this work, in order to evaluate sedimentation problems arised due to high MLSS concentrations and complete sludge retention operational conditions, two identical innovative slaughterhouse wastewater treatment plants were studied. Measurements of wastewaters' quality characteristics, treatment plant's operational conditions, sludge microscopic analysis and state point analysis were conducted. Results have shown that low COD/Nitrogen ratios increase sludge bulking and flotation phenomena due to accidental denitrification in clarifiers. High return activated sludge rate is essential in complete retention systems as it reduces sludge condensation and hydraulic retention time in the clarifiers. Under certain operational conditions sludge loading rates can greatly exceed literature limit values. The presented methodology is a useful tool for estimation of sedimentation problems encountered in activated sludge wastewater treatment plants with complete retention time. Copyright © 2014 Elsevier Ltd. All rights reserved.

Co-management of domestic wastewater and food waste: A life cycle comparison of alternative food waste diversion strategies.

PubMed

Becker, Adilson M; Yu, Kevin; Stadler, Lauren B; Smith, Adam L

2017-01-01

Food waste is increasingly viewed as a resource that should be diverted from landfills. This study used life cycle assessment to compare co-management of food waste and domestic wastewater using anaerobic membrane bioreactor (AnMBR) against conventional activated sludge (CAS) and high rate activated sludge (HRAS) with three disposal options for food waste: landfilling (LF), anaerobic digestion (AD), and composting (CP). Based on the net energy balance (NEB), AnMBR and HRAS/AD were the most attractive scenarios due to cogeneration of produced biogas. However, cogeneration negatively impacted carcinogenics, non-carcinogenics, and ozone depletion, illustrating unavoidable tradeoffs between energy recovery from biogas and environmental impacts. Fugitive emissions of methane severely increased global warming impacts of all scenarios except HRAS/AD with AnMBR particularly affected by effluent dissolved methane emissions. AnMBR was also most sensitive to food waste diversion participation, with 40% diversion necessary to achieve a positive NEB at the current state of development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Helminth ova control in wastewater and sludge for advanced and conventional sanitation.

PubMed

Jiménez, B; Maya, C; Galván, M

2007-01-01

Worldwide, the most important reuse of wastewater, in volume, is agricultural irrigation. Therefore, there is a need to properly treat wastewater for such purpose, considering the removal of pathogens while leaving suitable amounts of nutrients and other compounds to increase productivity. Helminth ova are one of the main targeted pathogens in the new guidelines for water reuse in agriculture and aquaculture issued in 2006 by the World Health Organization. However, relatively little research has been done recently on how to remove and inactivate helminth ova from wastewater and sludge and recommendations given several decades ago are still used, but when put into practice, particularly in developing countries, produce unsatisfactory results. One problem is that these criteria were developed using inaccurate analytical techniques and the other is the large number and variety of helminth ova species found in wastewater and sludge from the developing world. In fact, the few technological options to remove and inactivate helminth ova come from research performed using wastewater and sludge with low helminth ova content, and refer almost only to Ascaris (one type of helminth). This paper summarises recent research work and results from practical experience concerning helminth ova control for advanced and conventional sanitation.

Calculation of energy recovery and greenhouse gas emission reduction from palm oil mill effluent treatment by an anaerobic granular-sludge process.

PubMed

Show, K Y; Ng, C A; Faiza, A R; Wong, L P; Wong, L Y

2011-01-01

Conventional aerobic and low-rate anaerobic processes such as pond and open-tank systems have been widely used in wastewater treatment. In order to improve treatment efficacy and to avoid greenhouse gas emissions, conventional treatment can be upgraded to a high performance anaerobic granular-sludge system. The anaerobic granular-sludge systems are designed to capture the biogas produced, rendering a potential for claims of carbon credits under the Kyoto Protocol for reducing emissions of greenhouse gases. Certified Emission Reductions (CERs) would be issued, which can be exchanged between businesses or bought and sold in international markets at the prevailing market prices. As the advanced anaerobic granular systems are capable of handling high organic loadings concomitant with high strength wastewater and short hydraulic retention time, they render more carbon credits than other conventional anaerobic systems. In addition to efficient waste degradation, the carbon credits can be used to generate revenue and to finance the project. This paper presents a scenario on emission avoidance based on a methane recovery and utilization project. An example analysis on emission reduction and an overview of the global emission market are also outlined.

Removal of Triclocarban and Triclosan during Municipal Biosolid Production

PubMed Central

Ogunyoku, Temitope A.; Young, Thomas M.

2014-01-01

The antimicrobial compounds triclosan (TCS) and triclocarban (TCC) accumulate in sludges produced during municipal wastewater treatment and persist through sludge treatment processes into finished biosolids. The objective of this research was to determine the extent to which conventional sludge processing systems such as aerobic digestion, anaerobic digestion, and lime stabilization were able to remove TCC and TCS. Sludge and biosolid samples were collected from 10 municipal wastewater treatment plants in the United States. The concentrations of TCC and TCS in sludge and biosolid samples were determined via heated solvent extraction and analysis with liquid chromatography electrospray ionization mass spectrometry. Dry weight concentrations of TCC and TCS frequently were higher in finished biosolids than in the source sludges because of sludge mass reduction during digestion. The removal of TCC and TCS in municipal biosolid processing systems was determined from the measured concentration change after correcting for reductions in solid mass during sludge treatment. Removal in the digester systems ranged from 15 – 68 % for TCC and 20 – 75 % for TCS. Increased solid retention times during sludge treatment operations were correlated with higher removals of TCC and TCS. Apparent first order degradation rates for TCC ranged from 0.015–0.08 1/d and for TCS were between 0.003–0.15 1/d. PMID:24734467

Valorization of pellets from municipal WWTP sludge in lightweight clay ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cusido, Joan A., E-mail: joan.antoni.cusido@upc.edu; Soriano, Cecilia

2011-06-15

A direct result of the growing number of municipal wastewater-treatment plants (WWTPs) has been an increase in the generation of large amounts of sewage sludge that requires environmentally acceptable final destination. To decrease the volume of sludge, a common technique is drying the sludge at a low temperature in rotary kilns. The result of this process is a granulated material consisting of dehydrated sludge pellets. After this treatment, this pelletized material becomes easier to manipulate, but it also becomes a more toxic waste, containing dangerous substances, mostly of the lipid type. At its final stage, this material is usually incinerated,more » used as a comburent material, used as an agricultural fertilizer, or used in the cement industry. Each application has its own problems and requires remediation measures from the safety and environmental viewpoints. In this study, we looked beyond these possible applications and analyzed the transformation of sewage sludge through a ceramization process into a material similar to expanded clays; we subsequently explored its uses in the building industry or in the agriculture industry, among others. Both the properties of the product material and the production method were characterized, and an environmental analysis was conducted. The new, lightweight material had a microstructure with open porosity and low thermal conductivity. Environmental characterization such as the leaching test revealed that undetectable amounts of hazardous metals from the sludge were present in the leachate after the sludge went through a thermal treatment, despite their initial presence (with the exception of vanadium, which could pose some restrictions on some of the proposed uses for the final product). Toxicity tests also showed negative results. The study of gaseous emissions during production revealed emissions factors similar to those during the production of conventional clay ceramics, although with higher organic emissions. As for conventional clay ceramics, industrial production would require the implementation of some type of air-depuration system. The results showed that the ceramization of sludge pellets is a promising valorization technique worth considering from both the economic and technological perspectives.« less

Valorization of pellets from municipal WWTP sludge in lightweight clay ceramics.

PubMed

Cusidó, Joan A; Soriano, Cecilia

2011-06-01

A direct result of the growing number of municipal wastewater-treatment plants (WWTPs) has been an increase in the generation of large amounts of sewage sludge that requires environmentally acceptable final destination. To decrease the volume of sludge, a common technique is drying the sludge at a low temperature in rotary kilns. The result of this process is a granulated material consisting of dehydrated sludge pellets. After this treatment, this pelletized material becomes easier to manipulate, but it also becomes a more toxic waste, containing dangerous substances, mostly of the lipid type. At its final stage, this material is usually incinerated, used as a comburent material, used as an agricultural fertilizer, or used in the cement industry. Each application has its own problems and requires remediation measures from the safety and environmental viewpoints. In this study, we looked beyond these possible applications and analyzed the transformation of sewage sludge through a ceramization process into a material similar to expanded clays; we subsequently explored its uses in the building industry or in the agriculture industry, among others. Both the properties of the product material and the production method were characterized, and an environmental analysis was conducted. The new, lightweight material had a microstructure with open porosity and low thermal conductivity. Environmental characterization such as the leaching test revealed that undetectable amounts of hazardous metals from the sludge were present in the leachate after the sludge went through a thermal treatment, despite their initial presence (with the exception of vanadium, which could pose some restrictions on some of the proposed uses for the final product). Toxicity tests also showed negative results. The study of gaseous emissions during production revealed emissions factors similar to those during the production of conventional clay ceramics, although with higher organic emissions. As for conventional clay ceramics, industrial production would require the implementation of some type of air-depuration system. The results showed that the ceramization of sludge pellets is a promising valorization technique worth considering from both the economic and technological perspectives. Copyright © 2011 Elsevier Ltd. All rights reserved.

Adsorption/desorption of linear alkylbenzenesulfonate (LAS) and azoproteins by/from activated sludge flocs.

PubMed

Conrad, A; Cadoret, A; Corteel, P; Leroy, P; Block, J-C

2006-01-01

Our study investigated the adsorption/desorption by/from activated sludge flocs, dispersed in river water or in diluted wastewater, of organic compounds (C(11)-LAS, azoalbumin and azocasein) at concentrations relevant to environmental conditions. Activated sludge flocs, used as a model of biological aggregates, are characterized by a very heterogeneous matrix able to sorb the three organic compounds tested at 4 degrees C. The adsorbed amount of C(11)-LAS by activated sludge flocs was higher than that of azocasein or azoalbumin, as shown by the Freundlich parameters (K(ads)=8.6+/-1.7, 1.6+/-0.3 and 0.3+/-0.1 micromol(1-1/n)g(-1)l(1/n) for C(11)-LAS, azocasein and azoalbumin, respectively; n=3 sludges). C(11)-LAS sorption from activated sludge appeared to be partially reversible in river water, while a marked hysteresis phenomenon was observed for azocasein and azoalbumin, implying a low degree of reversibility in their exchange between activated sludge and river water. It has also been displayed that the conductivity variation of bulk water (comprised between 214 and 838 microS cm(-1)) exerted no dramatic effect on the C(11)-LAS desorption from activated sludge flocs, while a little effect of it on azocasein desorption was observed. Thus, biological aggregates as activated sludge flocs can serve as an intermediate carrier for C(11)-LAS, while it represents a sink for proteins.

Utilizing waste activated sludge for animal feeding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beszedits, S.

1981-01-01

Activated sludge has a high protein content and is a good source of B-group vitamins and generally also of minerals (Ca, Mg, Fe and K). Propionibacterium freudenreichii can be readily incorporated into the activated sludge to synthesize vitamin B12, particularly high vitamin yields being obtained with sewage mixed with dairy waste. Numerous examples of successful use of activated sludge in animal feeding are given.

High-rate anaerobic co-digestion of kraft mill fibre sludge and activated sludge by CSTRs with sludge recirculation.

PubMed

Ekstrand, Eva-Maria; Karlsson, Marielle; Truong, Xu-Bin; Björn, Annika; Karlsson, Anna; Svensson, Bo H; Ejlertsson, Jörgen

2016-10-01

Kraft fibre sludge from the pulp and paper industry constitutes a new, widely available substrate for the biogas production industry, with high methane potential. In this study, anaerobic digestion of kraft fibre sludge was examined by applying continuously stirred tank reactors (CSTR) with sludge recirculation. Two lab-scale reactors (4L) were run for 800days, one on fibre sludge (R1), and the other on fibre sludge and activated sludge (R2). Additions of Mg, K and S stabilized reactor performance. Furthermore, the Ca:Mg ratio was important, and a stable process was achieved at a ratio below 16:1. Foaming was abated by short but frequent mixing. Co-digestion of fibre sludge and activated sludge resulted in more robust conditions, and high-rate operation at stable conditions was achieved at an organic loading rate of 4g volatile solids (VS)L(-1)day(-1), a hydraulic retention time of 4days and a methane production of 230±10NmL per g VS. Copyright © 2016. Published by Elsevier Ltd.

Multiple syntrophic interactions drive biohythane production from waste sludge in microbial electrolysis cells.

PubMed

Liu, Qian; Ren, Zhiyong Jason; Huang, Cong; Liu, Bingfeng; Ren, Nanqi; Xing, Defeng

2016-01-01

Biohythane is a new and high-value transportation fuel present as a mixture of biomethane and biohydrogen. It has been produced from different organic matters using anaerobic digestion. Bioenergy can be recovered from waste activated sludge through methane production during anaerobic digestion, but energy yield is often insufficient to sludge disposal. Microbial electrolysis cell (MEC) is also a promising approach for bioenergy recovery and waste sludge disposal as higher energy efficiency and biogas production. The systematic understanding of microbial interactions and biohythane production in MEC is still limited. Here, we report biohythane production from waste sludge in biocathode microbial electrolysis cells and reveal syntrophic interactions in microbial communities based on high-throughput sequencing and quantitative PCR targeting 16S rRNA gene. The alkali-pretreated sludge fed MECs (AS-MEC) showed the highest biohythane production rate of 0.148 L·L(-1)-reactor·day(-1), which is 40 and 80 % higher than raw sludge fed MECs (RS-MEC) and anaerobic digestion (open circuit MEC, RS-OCMEC). Current density, metabolite profiles, and hydrogen-methane ratio results all confirm that alkali-pretreatment and microbial electrolysis greatly enhanced sludge hydrolysis and biohythane production. Illumina Miseq sequencing of 16S rRNA gene amplicons indicates that anode biofilm was dominated by exoelectrogenic Geobacter, fermentative bacteria and hydrogen-producing bacteria in the AS-MEC. The cathode biofilm was dominated by fermentative Clostridium. The dominant archaeal populations on the cathodes of AS-MEC and RS-MEC were affiliated with hydrogenotrophic Methanobacterium (98 %, relative abundance) and Methanocorpusculum (77 %), respectively. Multiple pathways of gas production were observed in the same MEC reactor, including fermentative and electrolytic H2 production, as well as hydrogenotrophic methanogenesis and electromethanogenesis. Real-time quantitative PCR analyses showed that higher amount of methanogens were enriched in AS-MEC than that in RS-MEC and RS-OCMEC, suggesting that alkali-pretreated sludge and MEC facilitated hydrogenotrophic methanogen enrichment. This study proves for the first time that biohythane could be produced directly in biocathode MECs using waste sludge. MEC and alkali-pretreatment accelerated enrichment of hydrogenotrophic methanogen and hydrolysis of waste sludge. The results indicate syntrophic interactions among fermentative bacteria, exoelectrogenic bacteria and methanogenic archaea in MECs are critical for highly efficient conversion of complex organics into biohythane, demonstrating that MECs can be more competitive than conventional anaerobic digestion for biohythane production using carbohydrate-deficient substrates. Biohythane production from waste sludge by MEC provides a promising new way for practical application of microbial electrochemical technology.

Strategies to improve energy efficiency in sewage treatment plants

NASA Astrophysics Data System (ADS)

Au, Mau Teng; Pasupuleti, Jagadeesh; Chua, Kok Hua

2013-06-01

This paper discusses on strategies to improve energy efficiency in Sewage Treatment Plant (STP). Four types of STP; conventional activated sludge, extended aeration, oxidation ditch, and sequence batch reactor are presented and strategized to reduce energy consumption based on their influent flow. Strategies to reduce energy consumption include the use of energy saving devices, energy efficient motors, automation/control and modification of processes. It is envisaged that 20-30% of energy could be saved from these initiatives.

Gravitational sedimentation of flocculated waste activated sludge.

PubMed

Chu, C P; Lee, D J; Tay, J H

2003-01-01

The sedimentation characteristics of flocculated wastewater sludge have not been satisfactorily explored using the non-destructive techniques, partially owing to the rather low solid content (ca. 1-2%) commonly noted in the biological sediments. This paper investigated, for the first time, the spatial-temporal gravitational settling characteristics of original and polyelectrolyte flocculated waste activated sludge using Computerized Axial Tomography Scanner. The waste activated sludge possessed a distinct settling characteristic from the kaolin slurries. The waste activated sludges settled more slowly and reached a lower solid fraction in the final sediment than the latter. Flocculation markedly enhanced the settleability of both sludges. Although the maximum achievable solid contents for the kaolin slurries were reduced, flocculation had little effects on the activated sludge. The purely plastic rheological model by Buscall and White (J Chem Soc Faraday Trans 1(83) (1987) 873) interpreted the consolidating sediment data, while the purely elastic model by Tiller and Leu (J. Chin. Inst. Chem. Eng. 11 (1980) 61) described the final equilibrated sediment. Flocculation produced lower yield stress during transient settling, thereby resulting in the more easily consolidated sludge than the original sample. Meanwhile, the flocculated activated sludge was stiffer in the final sediment than in the original sample. The data reported herein are valuable to the theories development for clarifier design and operation.

Hybrid life-cycle environmental and cost inventory of sewage sludge treatment and end-use scenarios: a case study from China.

PubMed

Murray, Ashley; Horvath, Arpad; Nelson, Kara L

2008-05-01

Sewage sludge management poses environmental, economic, and political challenges for wastewater treatment plants and municipalities around the globe. To facilitate more informed and sustainable decision making, this study used life-cycle inventory (LCI) to expand upon previous process-based LCIs of sewage sludge treatmenttechnologies. Additionally, the study evaluated an array of productive end-use options for treated sewage sludge, such as fertilizer and as an input into construction materials, to determine how the sustainability of traditional manufacturing processes changes with sludge as a replacement for other raw inputs. The inclusion of the life-cycle of necessary inputs (such as lime) used in sludge treatment significantly impacts the sustainability profiles of different treatment and end-use schemes. Overall, anaerobic digestion is generally the optimal treatment technology whereas incineration, particularly if coal-fired, is the most environmentally and economically costly. With respect to sludge end use, offsets are greatest for the use of sludge as fertilizer, but all of the productive uses of sludge can improve the sustainability of conventional manufacturing practices. The results are intended to help inform and guide decisions about sludge handling for existing wastewater treatment plants and those that are still in the planning phase in cities around the world. Although additional factors must be considered when selecting a sludge treatment and end-use scheme, this study highlights how a systems approach to planning can contribute significantly to improving overall environmental sustainability.

Ozonation of return activated sludge for disintegration and solubilisation with synthesized titanium oxide as catalyst

NASA Astrophysics Data System (ADS)

Sarif, S. F. Z. Mohd; Alias, S. S.; Ridwan, F. Muhammad; Salim, K. S. Ku; Abidin, C. Z. A.; Ali, U. F. Md.

2018-03-01

Ozonation of activated sludge in the present of titanium dioxide (TiO2) as catalyst to enhance the production of hydroxyl radical was evaluated in comparison to the sole ozonation process. In this process, the catalytic ozontion showed improvement in increasing ozone consumption and improving activated sludge disintegration and solubilisation. The reduction of total suspended solid (TSS), volatile suspended solid (VSS) and soluble chemical oxygen demand (SCOD) solubilisation was better in the catalytic ozonation system. Initial pH 7 of activated sludge was found best to disintegrate and solubilise the sludge flocs. However upon additional of sodium hydroxide (NaOH) in pH adjustment enhanced the solubilisation of organic matter from the flocs and cells, making the initial pH 9 is the best condition for activated sludge solubilisation. Yet the initial pH 7 of activated sludge supernatant was the best condition to achieve SCOD solubilisation due to sludge floc disintegration, when it had stronger correlation between TSS reduction and SCOD solubilisation (R2=0.961). Lower amount of catalyst of 100 mgTiO2/gTSS was found to disintegrate and solubilise the activated sludge better with 30.4% TSS reduction and 25.2% SCOD solubilisation efficiency, compared to 200 mgTiO2/gTSS with 21.9% and 17.1% TSS reduction and SCOD solubilisation, respectively.

Sludge Retention Time as a Suitable Operational Parameter to Remove Both Estrogen and Nutrients in an Anaerobic–Anoxic–Aerobic Activated Sludge System

PubMed Central

Zeng, Qingling; Li, Yongmei; Yang, Shijia

2013-01-01

Abstract Estrogen in wastewater are responsible for a significant part of the endocrine-disrupting effects observed in the aquatic environment. The effect of sludge retention time (SRT) on the removal and fate of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in an anaerobic–anoxic–oxic activated sludge system designed for nutrient removal was investigated by laboratory-scale experiments using synthetic wastewater. With a hydraulic retention time of 8 h, when SRT ranged 10–25 days, E2 was almost completely removed from water, and EE2 removal efficiency was 65%–81%. Both estrogens were easily sorbed onto activated sludge. Distribution coefficients (Kd) of estrogens on anaerobic sludge were greater than those on anoxic and aerobic sludges. Mass balance calculation indicated that 99% of influent E2 was degraded by the activated sludge process, and 1% remained in excess sludge; of influent EE2, 62.0%–80.1% was biodegraded; 18.9%–34.7% was released in effluent; and 0.88%–3.31% remained in excess sludge. Optimal SRT was 20 days for both estrogen and nutrient removal. E2 was almost completely degraded, and EE2 was only partly degraded in the activated sludge process. Residual estrogen on excess sludge must be considered in the sludge treatment and disposal processes. The originality of the work is that removal of nutrients and estrogens were linked, and optimal SRT for both estrogen and nutrient removal in an enhanced biological phosphorus removal system was determined. This has an important implication for the design and operation of full-scale wastewater treatment plants. PMID:23633892

State of the art on granular sludge by using bibliometric analysis.

PubMed

Zheng, Tianlong; Li, Pengyu; Wu, Wenjun; Liu, Jianguo; Shi, Zhining; Guo, Xuesong; Liu, Junxin

2018-04-01

With rapid industrialization and urbanization in the nineteenth century, the activated sludge process (ASP) has experienced significant steps forward in the face of greater awareness of and sensitivity toward water-related environmental problems. Compared with conventional flocculent ASP, the major advantages of granular sludge are characterized by space saving and resource recovery, where the methane and hydrogen recovery in anaerobic granular and 50% more space saving, 30-50% of energy consumption reduction, 75% of footprint cutting, and even alginate recovery in aerobic granular. Numerous engineers and scientists have made great efforts to explore the superiority over the last 40 years. Therefore, a bibliometric analysis was desired to trace the global trends of granular sludge research from 1992 to 2016 indexed in the SCI-EXPANDED. Articles were published in 276 journals across 44 subject categories spanning 1420 institutes across 68 countries. Bioresource Technology (293, 11.9%), Water Research (235, 9.6%), and Applied Microbiology and Biotechnology (127, 5.2%) dominated in top three journals. The Engineering (991, 40.3%), China (906, 36.9%), and Harbin Inst Technol, China (114, 4.6%) were the most productive subject category, country, and institution, respectively. The hotspot is the emerging techniques depended on granular reactors in response to the desired removal requirements and bio-energy production (primarily in anaerobic granular sludge). In view of advanced and novel bio-analytical methods, the characteristics, functions, and mechanisms for microbial granular were further revealed in improving and innovating the granulation techniques. Therefore, a promising technique armed with strengthened treatment efficiency and efficient resource and bio-energy recovery can be achieved.

Sequential Anaerobic/Aerobic Digestion for Enhanced Carbon/Nitrogen Removal and Cake Odor Reduction.

PubMed

Ahmad, Muneer; Denee, Marco Abel; Jiang, Hao; Eskicioglu, Cigdem; Kadota, Paul; Gregonia, Theresa

2016-12-01

  Anaerobic digestion (AD) has been proven to be an effective process for the treatment of wastewater sludge. However, it produces high levels of ammonia in the digester effluent, which may jeopardize meeting stringent nutrient discharge limits. In this study, the effect of a sequential anaerobic/aerobic (AN/AERO) digestion and a single-stage conventional AN digestion (as control) was investigated on mixed (primary + secondary) sludge generated by the Annacis Island wastewater treatment plant (WWTP) (BC, Canada). An overall sludge retention time (SRT) of 22.5 days under three different scenarios was chosen based on the current operational SRT of the digesters at the Annacis Island WWTP. The steady state results have shown that sequential AN/AERO digestion configurations achieved up to 11% higher volatile solids (VS) removal and 72% lower ammonia generation over single-stage conventional AN digestion. Furthermore, sequential AN/AERO system also showed enhanced dewaterability, improved fecal coliform destruction and reduced digested cake odors over control digesters.

Pharmaceutically active compounds in sludge stabilization treatments: anaerobic and aerobic digestion, wastewater stabilization ponds and composting.

PubMed

Martín, Julia; Santos, Juan Luis; Aparicio, Irene; Alonso, Esteban

2015-01-15

Sewage sludge disposal onto lands has been stabilized previously but still many pollutants are not efficiently removed. Special interest has been focused on pharmaceutical compounds due to their potential ecotoxicological effects. Nowadays, there is scarce information about their occurrence in different sludge stabilization treatments. In this work, the occurrence of twenty-two pharmaceutically active compounds has been studied in sludge from four sludge stabilization treatments: anaerobic digestion, aerobic digestion, composting and lagooning. The types of sludge evaluated were primary, secondary, anaerobically-digested and dehydrated, composted, mixed, aerobically-digested and dehydrated and lagoon sludge. Nineteen of the twenty-two pharmaceutically active compounds monitored were detected in sewage sludge. The most contaminated samples were primary sludge, secondary sludge and mixed sludge (the average concentrations of studied compounds in these sludges were 179, 310 and 142 μg/kg dm, respectively) while the mean concentrations found in the other types of sewage sludge were 70 μg/kg dm (aerobically-digested sludge), 63 μg/kg dm (lagoon sludge), 12 μg/kg dm (composted sludge) and 8 μg/kg dm (anaerobically-digested sludge). The antibiotics ciprofloxacin and norfloxacin were found at the highest concentration levels in most of the analyzed sludge samples (up to 2660 and 4328 μg/kg dm, respectively). Anaerobic-digestion treatment reduced more considerably the concentration of most of the studied compounds than aerobic-digestion (especially in the case of bezafibrate and fluoroquinolones) and more than anaerobic stabilization ponds (in the case of acetaminophen, atenolol, bezafibrate, carbamazepine, 17α-ethinylestradiol, naproxen and salicylic acid). Ecotoxicological risk assessment, of sludge application onto soils, has also been evaluated. Risk quotients, expressed as the ratio between the predicted environmental concentration and the predicted non-effect concentration, were lower than 1 for all the pharmaceutically active compounds so no significant risks are expected to occur due to the application of sewage sludge onto soils, except for 17α-ethinylestradiol when chronic toxicity was considered. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhanced Lipid and Biodiesel Production from Glucose-Fed Activated Sludge: Kinetics an Microbial Community Analysis

EPA Science Inventory

An innovative approach to increase biofuel feedstock lipid yields from municipal sewage sludge via manipulation of carbon:nitrogen (C:N) ratio and glucose loading in activated sludge bioreactors was investigated. Sludge lipid and fatty acid methyl ester (biodiesel) yields (% cel...

Cultivation of activated sludge using sea mud as seed to treat industrial phenolic wastewater with high salinity.

PubMed

Tan, Songwen; Cui, Chunzhi; Hou, Yang; Chen, Xuncai; Xu, Aiqin; Li, Weiguo; You, Hong

2017-01-30

A technique is proposed to treat saline hazardous wastewater by using marine activated sludge, cultivated with sea mud as seed. Since the developed marine activated sludge had phenol-tolerant microorganisms (MAS-1, MAS-2 and MAS-3) which originated from the ocean, it was envisaged that these bacteria could survive and breakdown phenol in saline environments. In this work, typical phenol-tolerant microorganisms were isolated from the marine activated sludge and identified. After a hierarchical acclimation process, the marine activated sludge was used to treat the industrial phenolic wastewater with high salinity. The marine activated sludge was able to break down phenol and other organic components effectively and efficiently in treating the wastewater with salinity of 5.7% w/v. The results showed a high removal of phenol (99%), COD (80%) and NH 3 -N (68%). Copyright © 2016 Elsevier Ltd. All rights reserved.

Metal fractionation in olive oil and urban sewage sludges using the three-stage BCR sequential extraction method and microwave single extractions.

PubMed

Pérez Cid, B; Fernández Alborés, A; Fernández Gómez, E; Faliqé López, E

2001-08-01

The conventional three-stage BCR sequential extraction method was employed for the fractionation of heavy metals in sewage sludge samples from an urban wastewater treatment plant and from an olive oil factory. The results obtained for Cu, Cr, Ni, Pb and Zn in these samples were compared with those attained by a simplified extraction procedure based on microwave single extractions and using the same reagents as employed in each individual BCR fraction. The microwave operating conditions in the single extractions (heating time and power) were optimized for all the metals studied in order to achieve an extraction efficiency similar to that of the conventional BCR procedure. The measurement of metals in the extracts was carried out by flame atomic absorption spectrometry. The results obtained in the first and third fractions by the proposed procedure were, for all metals, in good agreement with those obtained using the BCR sequential method. Although in the reducible fraction the extraction efficiency of the accelerated procedure was inferior to that of the conventional method, the overall metals leached by both microwave single and sequential extractions were basically the same (recoveries between 90.09 and 103.7%), except for Zn in urban sewage sludges where an extraction efficiency of 87% was achieved. Chemometric analysis showed a good correlation between the results given by the two extraction methodologies compared. The application of the proposed approach to a certified reference material (CRM-601) also provided satisfactory results in the first and third fractions, as it was observed for the sludge samples analysed.

Comparative Analysis of Performance and Microbial Characteristics Between High-Solid and Low-Solid Anaerobic Digestion of Sewage Sludge Under Mesophilic Conditions.

PubMed

Lu, Qin; Yi, Jing; Yang, Dianhai

2016-01-01

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 high-throughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

Sludge reduction and microbial community structure in an anaerobic/anoxic/oxic process coupled with potassium ferrate disintegration.

PubMed

An, Ying; Zhou, Zhen; Yao, Jie; Niu, Tianhao; Qiu, Zhan; Ruan, Danian; Wei, Haijuan

2017-12-01

An anaerobic/anoxic/oxic (AAO) wastewater treatment system combining with a potassium ferrate (K 2 FeO 4 ) oxidation side-stream reactor (SSR) was proposed for sludge reduction. Batch experiments showed that optimal K 2 FeO 4 dosage and reaction time for sludge disintegration was 100mg/g suspended solids (SS) and 24h, respectively. Subsequently, an AAO-SSR and a conventional AAO were operated in parallel to investigate effects of K 2 FeO 4 oxidation on process performance, sludge characteristics and microbial community structures. The AAO-SSR process operated under the optimized condition achieved efficient COD and NH 4 + -N removal, and reduced sludge by 47.5% with observed yield coefficient of 0.21gSS/g COD. K 2 FeO 4 addition broke sludge particles, increased dissolved organic matters in the mixed liquor, and improved sludge dewaterability. Illumina-MiSeq sequencing results showed that K 2 FeO 4 oxidation in the AAO-SSR decreased microbial richness and diversity, enriched slow growers (Dechloromonas), anaerobic fermentative bacteria (Azospira) and Fe(III)-reducing bacteria (Ferribacterium), but limited the growth of phosphate-accumulating organisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical field: a historical review of its application and contributions in wastewater sludge dewatering.

PubMed

Mahmoud, Akrama; Olivier, Jérémy; Vaxelaire, Jean; Hoadley, Andrew F A

2010-04-01

Electric field-assisted dewatering, also called electro-dewatering, is a technology in which a conventional dewatering mechanism such a pressure dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the dewatering process with low energy consumption compared to thermal drying. Electro-dewatering is not a new idea, but the practical industrial applications have been limited to niche areas in soil mechanics, civil engineering, and the ceramics industry. Recently, it has received great attention, specially, in the fields of fine-particle sludge, gelatinous sludge, sewage sludge, pharmaceutical industries, food waste and bull kelp, which could not be successfully dewatered with conventional mechanical methods. This review focuses on the scientific and practical aspects of the application of an electrical field in laboratory/industrial dewatering, and discusses this in relation to conventional dewatering techniques. A comprehensive bibliography of research in the electro-dewatering of wastewater sludges is included. As the fine-particle suspensions possess a surface charge, usually negative, they are surrounded by a layer with a higher density of positive charges, the electric double layer. When an electric field is applied, the usually negative charged particles move towards the electrode of the opposite charge. The water, commonly with cations, is driven towards the negative electrode. Electro-dewatering thus involves the well-known phenomena of electrophoresis, electro-osmosis, and electromigration. Following a detailed outline of the role of the electric double layer and electrokinetic phenomena, an analysis of the components of applied voltage and their significance is presented from an electrochemical viewpoint. The aim of this elementary analysis is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements. Also discussed herein is the investigation of the electrical behaviour of a porous medium, with particular emphasis on porous medium conductivity determination. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Sequential anaerobic/aerobic digestion of waste activated sludge: analysis of the process performance and kinetic study.

PubMed

Tomei, M Concetta; Rita, Sara; Mininni, Giuseppe

2011-12-15

Sequential anaerobic-aerobic digestion was applied to waste activated sludge (WAS) of a full scale wastewater treatment plant. The study was performed with the objective of testing the sequential digestion process on WAS, which is characterized by worse digestibility in comparison with the mixed sludge. Process performance was evaluated in terms of biogas production, volatile solids (VS) and COD reduction, and patterns of biopolymers (proteins and polysaccharides) in the subsequent digestion stages. VS removal efficiency of 40%, in the anaerobic phase, and an additional removal of 26%, in the aerobic one, were observed. For total COD removal efficiencies of 35% and 25% for anaerobic and aerobic stage respectively, were obtained. Kinetics of VS degradation process was analyzed by assuming a first order equation with respect to VS concentration. Evaluated kinetic parameters were 0.44 ± 0.20 d(-1) and 0.25 ± 0.15 d(-1) for the anaerobic stage and aerobic stage, respectively. With regard to biopolymers, in the anaerobic phase the content of proteins and polysaccharides increased to 50% and 69%, respectively, whereas in the subsequent aerobic phase, a decrease of 71% for proteins and 67% for polysaccharides was observed. The average specific biogas production 0.74 m(3)/(kg VS destroyed), was in the range of values reported in the specialized literature for conventional anaerobic mesophilic WAS digestion. Copyright © 2011 Elsevier B.V. All rights reserved.

Impact of wastewater treatment configuration and seasonal conditions on thyroid hormone disruption and stress effects in Rana catesbeiana tailfin.

PubMed

Wojnarowicz, Pola; Ogunlaja, Olumuyiwa O; Xia, Chen; Parker, Wayne J; Helbing, Caren C

2013-12-03

Improved endocrine disrupting compound (EDC) removal is desirable in municipal wastewater treatment plants (MWWTPs) although increased removal does not always translate into reduced biological activity. Suitable methods for determining reduction in biological activity of effluents are needed. In order to determine which MWWTPs are the most effective at removing EDC activities, we operated three configurations of pilot sized biological reactors (conventional activated sludge, CAS; nitrifying activated sludge, NAS; and biological nutrient removal, BNR) receiving the same influent under simulated winter and summer conditions. As frogs are model organisms for the study of thyroid hormone (TH) action, we used the North American species Rana catesbeiana in a cultured tadpole tailfin (C-fin) assay to compare the effluents. TH-responsive (thyroid hormone receptors alpha (thra) and beta (thrb)) and stress-responsive (superoxide dismutase, catalase, and heat shock protein 30) mRNA transcript levels were examined. Effluents infrequently perturbed stress-responsive transcript abundance but thra/thrb levels were significantly altered. In winter conditions, CAS caused frequent TH perturbations while BNR caused none. In summer conditions, however, BNR caused substantial TH perturbations while CAS caused few. Our findings contrast other studies of seasonal variations of EDC removal and accentuate the importance of utilizing appropriate biological readouts for assessing EDC activities.

Biodiesel from dewatered wastewater sludge: a two-step process for a more advantageous production.

PubMed

Pastore, Carlo; Lopez, Antonio; Lotito, Vincenzo; Mascolo, Giuseppe

2013-07-01

Alternative approaches for obtaining biodiesel from municipal sludge have been successfully investigated. In order to avoid the expensive conventional preliminary step of sludge drying, dewatered sludge (TSS: 15wt%) was used as starting material. The best performance in terms of yield of fatty acid methyl esters (18wt%) with the lowest energy demand (17MJkgFAME(-1)) was obtained by a new two-step approach based on hexane extraction carried out directly on dewatered acidified (H2SO4) sludge followed by methanolysis of extracted lipids. It was found that sulphuric acid plays a key role in the whole process not only for the transesterification of glycerides but also for the production of new free fatty acids from soaps and their esterification with methanol. In addition to biodiesel production, the investigated process allows valorization of primary sludge as it turns it into a valuable source of chemicals, namely sterols (2.5wt%), aliphatic alcohols (0.8wt%) and waxes (2.3wt%). Copyright © 2013 Elsevier Ltd. All rights reserved.

Levels and distribution patterns of short chain chlorinated paraffins in sewage sludge of wastewater treatment plants in China.

PubMed

Zeng, Lixi; Wang, Thanh; Ruan, Ting; Liu, Qian; Wang, Yawei; Jiang, Guibin

2012-01-01

Short chain chlorinated paraffins (SCCPs) are listed as persistent organic pollutant candidates in the Stockholm Convention and are receiving more and more attentions worldwide. In general, concentrations of contaminants in sewage sludge can give an important indication on their pollution levels at a local/regional basis. In this study, SCCPs were investigated in sewage sludge samples collected from 52 wastewater treatment plants in China. Concentrations of total SCCPs (ΣSCCPs) in sludge were in the range of 0.80-52.7 μg/g dry weight (dw), with a mean value of 10.7 μg/g dw. Most of SCCPs in the sludge samples showed a similar congener distribution patterns, and C(11) and Cl(7,8) were identified as the dominant carbon and chlorine congener groups. Significant linear relationships were found among different SCCP congener groups (r(2) ≥ 0.9). High concentrations of SCCPs in sewage sludge imply that SCCPs are widely present in China. Copyright © 2011 Elsevier Ltd. All rights reserved.

Sludge dewatering and stabilization in drying reed beds: characterization of three full-scale systems in Catalonia, Spain.

PubMed

Uggetti, Enrica; Llorens, Esther; Pedescoll, Anna; Ferrer, Ivet; Castellnou, Roger; García, Joan

2009-09-01

Optimization of sludge management can help reducing sludge handling costs in wastewater treatment plants. Sludge drying reed beds appear as a new and alternative technology which has low energy requirements, reduced operating and maintenance costs, and causes little environmental impact. The objective of this work was to evaluate the efficiency of three full-scale drying reed beds in terms of sludge dewatering, stabilization and hygienisation. Samples of influent sludge and sludge accumulated in the reed beds were analysed for pH, Electrical Conductivity, Total Solids (TS), Volatile Solids (VS), Chemical Oxygen Demand, Biochemical Oxygen Demand, nutrients (Total Kjeldahl Nitrogen (TKN) and Total Phosphorus (TP)), heavy metals and faecal bacteria indicators (Escherichiacoli and Salmonella spp.). Lixiviate samples were also collected. There was a systematic increase in the TS concentration from 1-3% in the influent to 20-30% in the beds, which fits in the range obtained with conventional dewatering technologies. Progressive organic matter removal and sludge stabilization in the beds was also observed (VS concentration decreased from 52-67% TS in the influent to 31-49% TS in the beds). Concentration of nutrients of the sludge accumulated in the beds was quite low (TKN 2-7% TS and TP 0.04-0.7% TS), and heavy metals remained below law threshold concentrations. Salmonella spp. was not detected in any of the samples, while E. coli concentration was generally lower than 460MPN/g in the sludge accumulated in the beds. The studied systems demonstrated a good efficiency for sludge dewatering and stabilization in the context of small remote wastewater treatment plants.

A comparison of the physical, chemical, and biological properties of sludges from a complete-mix activated sludge reactor and a submerged membrane bioreactor.

PubMed

Merlo, Rion P; Trussell, R Shane; Hermanowicz, Slawomir W; Jenkins, David

2007-03-01

The properties of sludges from a pilot-scale submerged membrane bioreactor (SMBR) and two bench-scale complete-mix, activated sludge (CMAS) reactors treating municipal primary effluent were determined. Compared with the CMAS sludges, the SMBR sludge contained a higher amount of soluble microbial products (SMP) and colloidal material attributed to the use of a membrane for solid-liquid separation; a higher amount nocardioform bacteria, resulting from efficient foam trapping; and a lower amount of extracellular polymeric substances (EPS), possibly because there was no selective pressure for the sludge to settle. High aeration rates in both the CMAS and SMBR reactors produced sludges with higher numbers of smaller particles. Normalized capillary suction time values for the SMBR sludge were lower than for the CMAS sludges, possibly because of its lower EPS content.

Biodegradation of Organophosphate Chemical Warfare Agents by Activated Sludge

DTIC Science & Technology

2012-03-01

Holmstedt, B. (1963). Structure- activity relationships of the organophosphorus anticholinesterase agents. In: Koelle, G.B. (ed.), Handbuch...BIODEGRADATION OF ORGANOPHOSPHATE CHEMICAL WARFARE AGENTS BY ACTIVATED SLUDGE Steven J. Schuldt...AFIT/GES/ENV/12-M04 BIODEGRADATION OF ORGANOPHOSPHATE CHEMICAL WARFARE AGENTS BY ACTIVATED SLUDGE THESIS Presented to the

Biotransformation and adsorption of pharmaceutical and personal care products by activated sludge after correcting matrix effects.

PubMed

Deng, Yu; Li, Bing; Yu, Ke; Zhang, Tong

2016-02-15

This study reported significant suppressive matrix effects in analyses of six pharmaceutical and personal care products (PPCPs) in activated sludge, sterilized activated sludge and untreated sewage by ultra-performance liquid chromatography-tandem mass spectrometry. Quantitative matrix evaluation on selected PPCPs supplemented the limited quantification data of matrix effects on mass spectrometric determination of PPCPs in complex environment samples. The observed matrix effects were chemical-specific and matrix-dependent, with the most pronounced average effect (-55%) was found on sulfadiazine in sterilized activated sludge. After correcting the matrix effects by post-spiking known amount of PPCPs, the removal mechanisms and biotransformation kinetics of selected PPCPs in activated sludge system were revealed by batch experiment. Experimental data elucidated that the removal of target PPCPs in the activated sludge process was mainly by biotransformation while contributions of adsorption, hydrolysis and volatilization could be neglected. High biotransformation efficiency (52%) was observed on diclofenac while other three compounds (sulfadiazine, sulfamethoxazole and roxithromycin) were partially biotransformed by ~40%. The other two compounds, trimethoprim and carbamazepine, showed recalcitrant to biotransformation of the activated sludge. Copyright © 2015 Elsevier B.V. All rights reserved.

The influence of SRT on phosphorus removal and sludge characteristics in the HA-A/A-MCO sludge reduction process

NASA Astrophysics Data System (ADS)

Zuo, N.; Ji, F. Y.

2013-02-01

By researching the influence of sludge age (SRT) on phosphorous removal and sludge characteristics in the HA-A/A-MCO (hydrolysis-acidification-anaerobic/anoxic-multistep continuous oxic tank) process, which has the effect of simultaneous phosphorous and nitrogen removal and sludge reduction, it is found that extended SRT is helpful for improving the ability of anaerobic phosphorous release and chemical recovery of phosphate, but the hosphorous removal efficiency is not affected. Extended SRT causes the system to have even more active sludge; it can also lead to the system having a powerful ability of biochemical reaction by using superiority of concentration. Meanwhile, extended SRT can still reduce sludge yield. Extended SRT cannot make soluble metabolic product (SMP) accumulate in the reactor, so that the pollutant removal power is reduced; it also cannot affect the activity of the sludge. However, extended SRT is able to make the coagulation of the sludge hard, and cause the sludge volume index value increase, but cannot cause sludge bulking.

The Different Physiological and Antioxidative Responses of Zucchini and Cucumber to Sewage Sludge Application.

PubMed

Wyrwicka, Anna; Urbaniak, Magdalena

2016-01-01

The present study investigates the effect of soil amended with sewage sludge on oxidative changes in zucchini and cucumber plants (Cucurbitaceae) and the consequent activation of their antioxidative systems and detoxification mechanisms. The plants were grown in pots containing soil amended with three concentrations of sewage sludge (1.8 g, 5.4 g and 10.8 g per pot), while controls were potted with vegetable soil. The activities of three antioxidative enzymes, ascorbate peroxidase (APx), catalase (CAT) and guaiacol peroxidase (POx), were assessed, as well as of the detoxifying enzyme S-glutathione transferase (GST). Lipid peroxidation was evaluated by measuring the extent of oxidative damage; α-tocopherol content, the main lipophilic antioxidant, was also measured. Visible symptoms of leaf blade damage after sewage sludge application occurred only on the zucchini plants. The zucchini and cucumber plants showed a range of enzymatic antioxidant responses to sewage sludge application. While APx and POx activities increased significantly with increasing sludge concentration in the zucchini plants, they decreased in the cucumber plants. Moreover, although the activity of these enzymes increased gradually with increasing doses of sewage sludge, these levels fell at the highest dose. An inverse relationship between peroxidases activity and CAT activity was observed in both investigated plant species. In contrast, although GST activity increased progressively with sludge concentration in both the zucchini and cucumber leaves, the increase in GST activity was greater in the zucchini plants, being visible at the lowest dose used. The results indicate that signs of sewage sludge toxicity were greater in zucchini than cucumber, and its defense reactions were mainly associated with increases in APx, POx and GST activity.

The Different Physiological and Antioxidative Responses of Zucchini and Cucumber to Sewage Sludge Application

PubMed Central

Wyrwicka, Anna; Urbaniak, Magdalena

2016-01-01

The present study investigates the effect of soil amended with sewage sludge on oxidative changes in zucchini and cucumber plants (Cucurbitaceae) and the consequent activation of their antioxidative systems and detoxification mechanisms. The plants were grown in pots containing soil amended with three concentrations of sewage sludge (1.8 g, 5.4 g and 10.8 g per pot), while controls were potted with vegetable soil. The activities of three antioxidative enzymes, ascorbate peroxidase (APx), catalase (CAT) and guaiacol peroxidase (POx), were assessed, as well as of the detoxifying enzyme S-glutathione transferase (GST). Lipid peroxidation was evaluated by measuring the extent of oxidative damage; α-tocopherol content, the main lipophilic antioxidant, was also measured. Visible symptoms of leaf blade damage after sewage sludge application occurred only on the zucchini plants. The zucchini and cucumber plants showed a range of enzymatic antioxidant responses to sewage sludge application. While APx and POx activities increased significantly with increasing sludge concentration in the zucchini plants, they decreased in the cucumber plants. Moreover, although the activity of these enzymes increased gradually with increasing doses of sewage sludge, these levels fell at the highest dose. An inverse relationship between peroxidases activity and CAT activity was observed in both investigated plant species. In contrast, although GST activity increased progressively with sludge concentration in both the zucchini and cucumber leaves, the increase in GST activity was greater in the zucchini plants, being visible at the lowest dose used. The results indicate that signs of sewage sludge toxicity were greater in zucchini than cucumber, and its defense reactions were mainly associated with increases in APx, POx and GST activity. PMID:27327659

Improvement of sedimentation and dewatering of municipal sludge by radiation

NASA Astrophysics Data System (ADS)

Sawai, Teruko; Yamazaki, Masao; Shimokawa, Toshinari; Sekiguchi, Masayuki; Sawai, Takeshi

As the promotion of sewerage system, the volume of municipal sludge in Tokyo has increased rapidly. Due to recent changes in the properties of the sludge, moreover, it has become difficult to thicken the liquid sewage sludge by sedimentation and to dewater the thickening sludge mechanically. The development of a new effective method for sludge treatment is necessary. Therefore, a study on the improvement of sedimentation and dewatering of sewage sludge by irradiation with 60Co gamma rays and electron beams was undertaken. Sedimentation tests and various dewatering tests were carried out for the waste activated sludge and anaerobically digested sludge. From the changes in the settling rate, capillary suction time, water content of the sludge cake, and the quality of separated water by irradiation, the optimum irradiation conditions for improving the sedimentation and dewatering of 2 types sludge were determined. The necessary dose for improving the sedimentation and dewatering was observed to be 1-3 kGy for the activated sludge and 5-10 kGy for the digested sludge. To confirm the cause of those changes by irradiation, the zeta potential and viscosity of the sludge were measured.

Ultrasonic waste activated sludge disintegration for improving anaerobic stabilization.

PubMed

Tiehm, A; Nickel, K; Zellhorn, M; Neis, U

2001-06-01

The pretreatment of waste activated sludge by ultrasonic disintegration was studied in order to improve the anaerobic sludge stabilization. The ultrasound frequency was varied within a range from 41 to 3217 kHz. The impact of different ultrasound intensities and treatment times was examined. Sludge disintegration was most significant at low frequencies. Low-frequency ultrasound creates large cavitation bubbles which upon collapse initiate powerful jet streams exerting strong shear forces in the liquid. The decreasing sludge disintegration efficiency observed at higher frequencies was attributed to smaller cavitation bubbles which do not allow the initiation of such strong shear forces. Short sonication times resulted in sludge floc deagglomeration without the destruction of bacteria cells. Longer sonication brought about the break-up of cell walls, the sludge solids were distintegrated and dissolved organic compounds were released. The anaerobic digestion of waste activated sludge following ultrasonic pretreatment causing microbial cell lysis was significantly improved. There was an increase in the volatile solids degradation as well as an increase in the biogas production. The increase in digestion efficiency was proportional to the degree of sludge disintegration. To a lesser degree the deagglomeration of sludge flocs also augmented the anaerobic volatile solids degradation.

Tetrazolium Reduction-Malachite Green Method for Assessing the Viability of Filamentous Bacteria in Activated Sludge

PubMed Central

Bitton, Gabriel; Koopman, Ben

1982-01-01

A method was developed to assess the activity of filamentous bacteria in activated sludge. It involves the incubation of activated sludge with 2(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride followed by staining with malachite green. Both cells and 2(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride-formazan crystals can be observed in prepared specimens by using bright-field microscopy. This procedure allowed us to distinguish between inactive and actively metabolizing filaments after chlorine application to control the bulking of activated sludge. Images PMID:16345999

Comparison between a moving bed membrane bioreactor and a conventional membrane bioreactor on organic carbon and nitrogen removal.

PubMed

Yang, Shuai; Yang, Fenglin; Fu, Zhimin; Lei, Ruibo

2009-04-01

A membrane bioreactor filled with carriers instead of activated sludge named a moving bed membrane bioreactor (MBMBR) was investigated for simultaneously removing organic carbon and nitrogen in wastewater. Its performance was compared with a conventional membrane bioreactor (CMBR) at various influent COD/TN ratios of 8.9-22.1. The operational parameters were optimized to increase the treatment efficiency. COD removal efficiency averaged at 95.6% and 96.2%, respectively, for MBMBR and CMBR during the 4 months experimental period. The MBMBR system demonstrated good performance on nitrogen removal at different COD/TN ratios. When COD/TN was 8.9 and the total nitrogen (TN) load was 7.58 mg/l h, the TN and ammonium nitrogen removal efficiencies of the MBMBR were maintained over 70.0% and 80.0%, respectively, and the removed total nitrogen (TN) load reached to 5.31 mg/l h. Multifunctional microbial reactions in the carrier, such as simultaneous nitrification and denitrification (SND), play important roles in nitrogen removal. In comparison, the CMBR did not perform so well. Its TN removal was not stable, and the removed total nitrogen (TN) load was only 1.02 mg/l h at COD/TN ratio 8.9. The specific oxygen utilization rate (SOUR) showed that the biofilm has a better microbial activity than an activated sludge. Nevertheless, the membrane fouling behavior was more severe in the MBMBR than in the CMBR due to a thick and dense cake layer formed on the membrane surface, which was speculated to be caused by the filamentous bacteria in the MBMBR.

Human Enteropathogen Load in Activated Sewage Sludge and Corresponding Sewage Sludge End Products▿

PubMed Central

Graczyk, Thaddeus K.; Lucy, Frances E.; Tamang, Leena; Miraflor, Allen

2007-01-01

This study demonstrated a significant reduction in the concentrations of Cryptosporidium parvum and Cryptosporidium hominis oocysts, Giardia lamblia cysts, and spores of human-virulent microsporidia in dewatered and biologically stabilized sewage sludge cake end products compared to those of the respective pathogens in the corresponding samples collected during the sludge activation process. PMID:17277215

40 CFR Appendix G to Part 403 - Pollutants Eligible for a Removal Credit

Code of Federal Regulations, 2012 CFR

2012-07-01

... and leachate collection system. I—firing of sewage sludge in a sewage sludge incinerator. 1 The... Trichloroethylene 3 10 9500 3 10 Zinc 4500 4500 4500 1 Active sewage sludge unit without a liner and leachate collection system. 2 Active sewage sludge unit with a liner and leachate collection system. 3 Value expressed...

40 CFR Appendix G to Part 403 - Pollutants Eligible for a Removal Credit

Code of Federal Regulations, 2011 CFR

2011-07-01

... and leachate collection system. I—firing of sewage sludge in a sewage sludge incinerator. 1 The... Trichloroethylene 3 10 9500 3 10 Zinc 4500 4500 4500 1 Active sewage sludge unit without a liner and leachate collection system. 2 Active sewage sludge unit with a liner and leachate collection system. 3 Value expressed...

40 CFR Appendix G to Part 403 - Pollutants Eligible for a Removal Credit

Code of Federal Regulations, 2014 CFR

2014-07-01

... and leachate collection system. I—firing of sewage sludge in a sewage sludge incinerator. 1 The... Trichloroethylene 3 10 9500 3 10 Zinc 4500 4500 4500 1 Active sewage sludge unit without a liner and leachate collection system. 2 Active sewage sludge unit with a liner and leachate collection system. 3 Value expressed...

Enhancement of sludge reduction and methane production by removing extracellular polymeric substances from waste activated sludge.

PubMed

Nguyen, Minh Tuan; Mohd Yasin, Nazlina Haiza; Miyazaki, Toshiki; Maeda, Toshinari

2014-12-01

The management of waste activated sludge (WAS) recycling is a concern that affects the development of the future low-carbon society, particularly sludge reduction and biomass utilization. In this study, we investigated the effect of removing extracellular polymeric substances (EPS), which play important roles in the adhesion and flocculation of WAS, on increased sludge disintegration, thereby enhancing sludge reduction and methane production by anaerobic digestion. EPS removal from WAS by ethylenediaminetetraacetic acid (EDTA) significantly enhanced sludge reduction, i.e., 49 ± 5% compared with 27 ± 1% of the control at the end the digestion process. Methane production was also improved in WAS without EPS by 8881 ± 109 CH4 μmol g(-1) dry-weight of sludge. Microbial activity was determined by denaturing gradient gel electrophoresis and real-time polymerase chain reaction, which showed that the hydrolysis and acetogenesis stages were enhanced by pretreatment with 2% EDTA, with a larger methanogenic community and better methane production. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparative effectiveness of membrane bioreactors, conventional secondary treatment, and chlorine and UV disinfection to remove microorganisms from municipal wastewaters.

PubMed

Francy, Donna S; Stelzer, Erin A; Bushon, Rebecca N; Brady, Amie M G; Williston, Ashley G; Riddell, Kimberly R; Borchardt, Mark A; Spencer, Susan K; Gellner, Terry M

2012-09-01

Log removals of bacterial indicators, coliphage, and enteric viruses were studied in three membrane bioreactor (MBR) activated-sludge and two conventional secondary activated-sludge municipal wastewater treatment plants during three recreational seasons (May-Oct.) when disinfection of effluents is required. In total, 73 regular samples were collected from key locations throughout treatment processes: post-preliminary, post-MBR, post-secondary, post-tertiary, and post-disinfection (UV or chlorine). Out of 19 post-preliminary samples, adenovirus by quantitative polymerase chain reaction (qPCR) was detected in all 19, enterovirus by quantitative reverse transcription polymerase chain reaction (qRT-PCR) was detected in 15, and norovirus GI by qRT-PCR was detected in 11. Norovirus GII and Hepatitis A virus were not detected in any samples, and rotavirus was detected in one sample but could not be quantified. Although culturable viruses were found in 12 out of 19 post-preliminary samples, they were not detected in any post-secondary, post-MBR, post-ultraviolet, or post-chlorine samples. Median log removals for all organisms were higher for MBR secondary treatment (3.02 to >6.73) than for conventional secondary (1.53-4.19) treatment. Ultraviolet disinfection after MBR treatment provided little additional log removal of any organism except for somatic coliphage (>2.18), whereas ultraviolet or chlorine disinfection after conventional secondary treatment provided significant log removals (above the analytical variability) of all bacterial indicators (1.18-3.89) and somatic and F-specific coliphage (0.71 and >2.98). Median log removals of adenovirus across disinfection were low in both MBR and conventional secondary plants (no removal detected and 0.24), and few removals of individual samples were near or above the analytical variability of 1.2 log genomic copies per liter. Based on qualitative examinations of plots showing reductions of organisms throughout treatment processes, somatic coliphage may best represent the removal of viruses across secondary treatment in both MBR and conventional secondary plants. F-specific coliphage and Escherichia coli may best represent the removal of viruses across the disinfection process in MBR facilities, but none of the indicators represented the removal of viruses across disinfection in conventional secondary plants. Published by Elsevier Ltd.

Comparative effectiveness of membrane bioreactors, conventional secondary treatment, and chlorine and UV disinfection to remove microorganisms from municipal wastewaters

USGS Publications Warehouse

Francy, Donna S.; Erin, A. Stelzer; Bushon, Rebecca N.; Brady, Amie M.G.; Williston, Ashley G.; Riddell, Kimberly R.; Borchardt, Mark A.; Spencer, Susan K.; Gellner, Terry M.

2012-01-01

Log removals of bacterial indicators, coliphage, and enteric viruses were studied in three membrane bioreactor (MBR) activated-sludge and two conventional secondary activated-sludge municipal wastewater treatment plants during three recreational seasons (May-Oct.) when disinfection of effluents is required. In total, 73 regular samples were collected from key locations throughout treatment processes: post-preliminary, post-MBR, post-secondary, post-tertiary, and post-disinfection (UV or chlorine). Out of 19 post-preliminary samples, adenovirus by quantitative polymerase chain reaction (qPCR) was detected in all 19, enterovirus by quantitative reverse transcription polymerase chain reaction (qRT-PCR) was detected in 15, and norovirus GI by qRT-PCR was detected in 11. Norovirus GII and Hepatitis A virus were not detected in any samples, and rotavirus was detected in one sample but could not be quantified. Although culturable viruses were found in 12 out of 19 post-preliminary samples, they were not detected in any post-secondary, post-MBR, post-ultraviolet, or post-chlorine samples. Median log removals for all organisms were higher for MBR secondary treatment (3.02 to >6.73) than for conventional secondary (1.53-4.19) treatment. Ultraviolet disinfection after MBR treatment provided little additional log removal of any organism except for somatic coliphage (>2.18), whereas ultraviolet or chlorine disinfection after conventional secondary treatment provided significant log removals (above the analytical variability) of all bacterial indicators (1.18-3.89) and somatic and F-specific coliphage (0.71 and >2.98). Median log removals of adenovirus across disinfection were low in both MBR and conventional secondary plants (no removal detected and 0.24), and few removals of individual samples were near or above the analytical variability of 1.2 log genomic copies per liter. Based on qualitative examinations of plots showing reductions of organisms throughout treatment processes, somatic coliphage may best represent the removal of viruses across secondary treatment in both MBR and conventional secondary plants. F-specific coliphage and Escherichia coli may best represent the removal of viruses across the disinfection process in MBR facilities, but none of the indicators represented the removal of viruses across disinfection in conventional secondary plants.

Polyhydroxyalkanoate (PHA) accumulation potential and PHA-accumulating microbial communities in various activated sludge processes of municipal wastewater treatment plants.

PubMed

Sakai, K; Miyake, S; Iwama, K; Inoue, D; Soda, S; Ike, M

2015-01-01

To clarify the polyhydroxyalkanoate (PHA) accumulation potential and the PHA-accumulating microbial community structure in activated sludge in municipal wastewater treatment plants (WWTPs) and to identify their influential factors. Nine activated sludge samples were collected from municipal WWTPs employing various biological treatment processes. In acetate-fed 24-h batch experiments under aerobic and nitrogen- and phosphorus-limited conditions, polyhydroxybutyrate (PHB) content of activated sludge increased from 0-1·3 wt% to 7·9-24 wt%, with PHB yields of 0·22-0·50 C-mol 3-hydroxybutyrate (C-mol acetate)(-1). Microbial community analyses found that activated sludge samples that accumulated >20 wt% of PHB after 24-h PHA accumulation experiments had >5·0 × 10(8) copies g(-1)-mixed liquor-suspended solid of phaC genes. Results indicated that (i) activated sludge in municipal WWTPs can accumulate up to approx. 20 wt% of PHA without enrichment processes, (ii) PHA accumulation potential of activated sludge varied depending on the operational conditions (treatment processes) of WWTPs, and (iii) phaC gene number can provide a simple indication of PHA accumulation potential. This is the first study to compare the PHA accumulation potential and PHA-accumulating microbial communities in activated sludge of various treatment processes. Our findings may be useful for enhancing the resource recovery potential of wastewater treatment systems. © 2014 The Society for Applied Microbiology.

Effect of gamma-ray irradiation on the dewaterability of waste activated sludge

NASA Astrophysics Data System (ADS)

Wu, Yuqi; Jiang, Yinghe; Ke, Guojun; Liu, Yingjiu

2017-01-01

The effect of gamma-ray irradiation on waste activated sludge (WAS) dewaterability was investigated with irradiation doses of 0-15 kGy. Time to filter (TTF50), specific resistance of filtration (SRF) and water content of sludge cake were measured to evaluate sludge dewaterability. Soluble chemical oxygen demand (SCOD), soluble extracellular polymeric substances (EPS) concentration and sludge particle size were determined to explain changes in sludge dewaterability. The optimal irradiation dose to obtain the maximum dewaterability characteristics was 1-4 kGy, which generated sludge with optimal disintegration (1.5-4.0%), soluble EPS concentration (590-750 mg/L) and particle size distribution (100-115 μm diameter). The combination of irradiation and cationic polyacrylamide (CPAM) addition exhibited minimal synergistic effect on increasing sludge dewatering rate compared with CPAM conditioning alone.

Removal of pharmaceuticals from wastewater by biological processes, hydrodynamic cavitation and UV treatment.

PubMed

Zupanc, Mojca; Kosjek, Tina; Petkovšek, Martin; Dular, Matevž; Kompare, Boris; Širok, Brane; Blažeka, Željko; Heath, Ester

2013-07-01

To augment the removal of pharmaceuticals different conventional and alternative wastewater treatment processes and their combinations were investigated. We tested the efficiency of (1) two distinct laboratory scale biological processes: suspended activated sludge and attached-growth biomass, (2) a combined hydrodynamic cavitation-hydrogen peroxide process and (3) UV treatment. Five pharmaceuticals were chosen including ibuprofen, naproxen, ketoprofen, carbamazepine and diclofenac, and an active metabolite of the lipid regulating agent clofibric acid. Biological treatment efficiency was evaluated using lab-scale suspended activated sludge and moving bed biofilm flow-through reactors, which were operated under identical conditions in respect to hydraulic retention time, working volume, concentration of added pharmaceuticals and synthetic wastewater composition. The suspended activated sludge process showed poor and inconsistent removal of clofibric acid, carbamazepine and diclofenac, while ibuprofen, naproxen and ketoprofen yielded over 74% removal. Moving bed biofilm reactors were filled with two different types of carriers i.e. Kaldnes K1 and Mutag BioChip™ and resulted in higher removal efficiencies for ibuprofen and diclofenac. Augmentation and consistency in the removal of diclofenac were observed in reactors using Mutag BioChip™ carriers (85%±10%) compared to reactors using Kaldnes carriers and suspended activated sludge (74%±22% and 48%±19%, respectively). To enhance the removal of pharmaceuticals hydrodynamic cavitation with hydrogen peroxide process was evaluated and optimal conditions for removal were established regarding the duration of cavitation, amount of added hydrogen peroxide and initial pressure, all of which influence the efficiency of the process. Optimal parameters resulted in removal efficiencies between 3-70%. Coupling the attached-growth biomass biological treatment, hydrodynamic cavitation/hydrogen peroxide process and UV treatment resulted in removal efficiencies of >90% for clofibric acid and >98% for carbamazepine and diclofenac, while the remaining compounds were reduced to levels below the LOD. For ibuprofen, naproxen, ketoprofen and diclofenac the highest contribution to overall removal was attributed to biological treatment, for clofibric acid UV treatment was the most efficient, while for carbamazepine hydrodynamic cavitation/hydrogen peroxide process and UV treatment were equally efficient. Copyright © 2012 Elsevier B.V. All rights reserved.

Combining high-rate aerobic wastewater treatment with anaerobic digestion of waste activated sludge at a pulp and paper mill.

PubMed

Magnusson, Björn; Ekstrand, Eva-Maria; Karlsson, Anna; Ejlertsson, Jörgen

2018-05-01

The activated sludge process within the pulp and paper industry is generally run to minimize the production of waste activated sludge (WAS), leading to high electricity costs from aeration and relatively large basin volumes. In this study, a pilot-scale activated sludge process was run to evaluate the concept of treating the wastewater at high rate with a low sludge age. Two 150 L containers were used, one for aeration and one for sedimentation and sludge return. The hydraulic retention time was decreased from 24 hours to 7 hours, and the sludge age was lowered from 12 days to 2-4 days. The methane potential of the WAS was evaluated using batch tests, as well as continuous anaerobic digestion (AD) in 4 L reactors in mesophilic and thermophilic conditions. Wastewater treatment capacity was increased almost four-fold at maintained degradation efficiency. The lower sludge age greatly improved the methane potential of the WAS in batch tests, reaching 170 NmL CH 4 /g VS at a sludge age of 2 days. In addition, the continuous AD showed a higher methane production at thermophilic conditions. Thus, the combination of high-rate wastewater treatment and AD of WAS is a promising option for the pulp and paper industry.

Biofiltration vs conventional activated sludge plants: what about priority and emerging pollutants removal?

PubMed

Mailler, R; Gasperi, J; Rocher, V; Gilbert-Pawlik, S; Geara-Matta, D; Moilleron, R; Chebbo, G

2014-04-01

This paper compares the removal performances of two complete wastewater treatment plants (WWTPs) for all priority substances listed in the Water Framework Directive and additional compounds of interest including flame retardants, surfactants, pesticides, and personal care products (PCPs) (n = 104). First, primary treatments such as physicochemical lamellar settling (PCLS) and primary settling (PS) are compared. Similarly, biofiltration (BF) and conventional activated sludge (CAS) are then examined. Finally, the removal efficiency per unit of nitrogen removed of both WWTPs for micropollutants is discussed, as nitrogenous pollution treatment results in a special design of processes and operational conditions. For primary treatments, hydrophobic pollutants (log K ow > 4) are well removed (>70 %) for both systems despite high variations of removal. PCLS allows an obvious gain of about 20 % regarding pollutant removals, as a result of better suspended solids elimination and possible coagulant impact on soluble compounds. For biological treatments, variations of removal are much weaker, and the majority of pollutants are comparably removed within both systems. Hydrophobic and volatile compounds are well (>60 %) or very well removed (>80 %) by sorption and volatilization. Some readily biodegradable molecules are better removed by CAS, indicating a better biodegradation. A better sorption of pollutants on activated sludge could be also expected considering the differences of characteristics between a biofilm and flocs. Finally, comparison of global processes efficiency using removals of micropollutants load normalized to nitrogen shows that PCLS + BF is as efficient as PS + CAS despite a higher compactness and a shorter hydraulic retention time (HRT). Only some groups of pollutants seem better removed by PS + CAS like alkylphenols, flame retardants, or di-2-ethylhexyl phthalate (DEHP), thanks to better biodegradation and sorption resulting from HRT and biomass characteristics. For both processes, and out of the 68 molecules found in raw water, only half of them are still detected in the water discharged, most of the time close to their detection limit. However, some of them are detected at higher concentrations (>1 μg/L and/or lower than environmental quality standards), which is problematic as they represent a threat for aquatic environment.

Metagenomes reveal microbial structures, functional potentials, and biofouling-related genes in a membrane bioreactor.

PubMed

Ma, Jinxing; Wang, Zhiwei; Li, Huan; Park, Hee-Deung; Wu, Zhichao

2016-06-01

Metagenomic sequencing was used to investigate the microbial structures, functional potentials, and biofouling-related genes in a membrane bioreactor (MBR). The results showed that the microbial community in the MBR was highly diverse. Notably, function analysis of the dominant genera indicated that common genes from different phylotypes were identified for important functional potentials with the observation of variation of abundances of genes in a certain taxon (e.g., Dechloromonas). Despite maintaining similar metabolic functional potentials with a parallel full-scale conventional activated sludge (CAS) system due to treating the identical wastewater, the MBR had more abundant nitrification-related bacteria and coding genes of ammonia monooxygenase, which could well explain its excellent ammonia removal in the low-temperature period. Furthermore, according to quantification of the genes involved in exopolysaccharide and extracellular polymeric substance (EPS) protein metabolism, the MBR did not show a much different potential in producing EPS compared to the CAS system, and bacteria from the membrane biofilm had lower abundances of genes associated with EPS biosynthesis and transport compared to the activated sludge in the MBR.

Review on the fate of organic micropollutants in wastewater treatment and water reuse with membranes.

PubMed

Siegrist, H; Joss, A

2012-01-01

A brief review of the fate of micropollutants in membrane-based wastewater treatment due to sorption, stripping, biological degradation/transformation and membrane separation is discussed, to give an overview of these technologies due to the growing importance for water reuse purposes. Compared with conventional activated sludge treatment (CAS) micropollutant removal in membrane bioreactor (MBR) is slightly improved due to complete suspended solids removal and increased sludge age. For discharge to sensitive receiving waters advanced treatment, such as post-ozonation or activated carbon adsorption, is recommended. In water reuse plants nanofiltration (NF) and reverse osmosis (RO) efficiently reject micropollutants due to size exclusions as well as electrostatic and hydrophobic effects reaching potable quality. To remove micropollutants fully, additionally post-ozone or the addition of powdered activated carbon (PAC) have to be applied, which in parallel also reduce NDMA precursors. The concentrate has to be treated if disposed to sensitive receiving waters due to its high micropollutant concentration and ecotoxicity potential. The present review summarizes principles and capabilities for the most important membrane-based applications for wastewater treatment, i.e. porous membranes in MBRs (micro- or ultrafiltration) and dense membrane applications (NF and RO) for water reuse.

Study of Methanogenesis while Bioutilisation of Plant Residuals

NASA Astrophysics Data System (ADS)

Ilyin, V. K.; Korniushenkova, I. N.; Starkova, L. V.; Lauriniavichius, K. S.

respect principals of planet ecology, and compatibility with other habitability systems. For these purpose the waste management technologies, relevant to application of the biodegradation properties of bacteria are of great value. Biological treatment method is based upon the biodegradation of organic substances by various microorganisms. vegetable non-edible residual, using artificial inoculum; to study peculiarities of biogas, possibilities to optimize or to reduce the share of methane. fermentation. The biogas production achieved 46 l per 1 kg of substrate. The microbial studies of biodegradation process revealed following peculiarities: (i)gradual quantitative increasing of Lactobacillus sp. (from 103 to 105 colony forming units (CFU) per ml); (ii)activation of Clostridia sp. (from 102 to 104 CFU/ml); (iii) elimination of aerobic conventional pathogens (Enterobacteriaceae sp., Protea sp., staphylococci). methane content measures revealed traces 0.1-0.4%. granules, the amount of methane in biogas reached 80-90%. biodegradation of vegetable wastes. This inoculum consists of active sludge adapted to wastes mixed with excretes of insects which consume plant wastes. Using this inoculum the biodegradation process takes less time, then that using active sludge. Regulation of methane concentration from traces to 90% may be achieved by adding of methane reactor to the plant digester.

Utilization of AMD sludges from the anthracite region of Pennsylvania for removal of phosphorus from wastewater

USGS Publications Warehouse

Sibrell, P.L.; Cravotta, C.A.; Lehman, W.G.; Reichert, W.

2010-01-01

Excess phosphorus (P) inputs from human sewage, animal feeding operations, and nonpoint source discharges to the environment have resulted in the eutrophication of sensitive receiving bodies of water such as the Great Lakes and Chesapeake Bay. Phosphorus loads in wastewater discharged from such sources can be decreased by conventional treatment with iron and aluminum salts but these chemical reagents are expensive or impractical for many applications. Acid mine drainage (AMD) sludges are an inexpensive source of iron and aluminum hydrous oxides that could offer an attractive alternative to chemical reagent dosing for the removal of P from local wastewater. Previous investigations have focused on AMD sludges generated in the bituminous coal region of western Pennsylvania, and confirmed that some of those sludges are good sorbents for P over a wide range of operating conditions. In this study, we sampled sludges produced by AMD treatment at six different sites in the anthracite region of Pennsylvania for potential use as P sequestration sorbents. Sludge samples were dried, characterized, and then tested for P removal from water. In addition, the concentrations of acid-extractable metals and other impurities were investigated. Test results revealed that sludges from four of the sites showed good P sorption and were unlikely to add contaminants to treated water. These results indicate that AMD sludges could be beneficially used to sequester P from the environment, while at the same time decreasing the expense of sludge disposal.

Distribution, mass load and environmental impact of multiple-class pharmaceuticals in conventional and upgraded municipal wastewater treatment plants in East China.

PubMed

Yuan, Xiangjuan; Qiang, Zhimin; Ben, Weiwei; Zhu, Bing; Qu, Jiuhui

2015-03-01

The occurrence, fate and environmental impact of 30 pharmaceuticals including sulfonamides, fluoroquinolones, tetracyclines, macrolides, dihydrofolate reductase inhibitors, β-blockers, antiepileptics, lipid regulators, and stimulants were studied in two municipal wastewater treatment plants (WWTPs) located in Wuxi City, East China. A total of 23 pharmaceuticals were detected in wastewater samples, with a maximum concentration of 16.1 μg L(-1) (caffeine) in the influent and 615.5 ng L(-1) (azithromycin) in the effluent; 19 pharmaceuticals were detected in sludge samples at concentrations up to 12.13 mg kg(-1), with ofloxacin, azithromycin and norfloxacin being the predominant species. Mass balance analysis showed that biodegradation primarily accounted for the removal of sulfonamides, most of the macrolides, and other miscellaneous pharmaceuticals, while adsorption onto the sludge was the primary removal pathway for fluoroquinolones, tetracylines, and azithromycin during biological treatment. The total mass loads of target pharmaceuticals per capita in the two WWTPs were in the ranges of 2681.8-4333.3, 248.0-416.6 and 214.6-374.5 μg per day per inhabitant in the influent, effluent and dewatered sludge, respectively. The upgraded Plant A adopting the combined anaerobic/anoxic/oxic and moving bed biofilm process exhibited a much higher removal of target pharmaceuticals than the conventional Plant B adopting the C-Orbal oxidation ditch process. The concentration levels of sulfamethoxazole, ofloxacin, ciprofloxacin and clarithromycin in the effluent, ofloxacin in the sludge, and the mixture of all target pharmaceuticals in both effluent and sludge posed a high risk to algae in aquatic environments.

A novel approach to realize SANI process in freshwater sewage treatment--Use of wet flue gas desulfurization waste streams as sulfur source.

PubMed

Jiang, Feng; Zhang, Liang; Peng, Guo-Liang; Liang, Si-Yun; Qian, Jin; Wei, Li; Chen, Guang-Hao

2013-10-01

SANI (Sulfate reduction, Autotrophic denitrification and Nitrification Integrated) process has been approved to be a sludge-minimized sewage treatment process in warm and coastal cities with seawater supply. In order to apply this sulfur-based process in inland cold areas, wet flue gas desulfurization (FGD) can be simplified and integrated with SANI process, to provide sulfite as electron carrier for sulfur cycle in sewage treatment. In this study, a lab-scale system of the proposed novel process was developed and run for over 200 days while temperature varied between 30 and 5 °C, fed with synthetic FGD wastewaters and sewage. The sulfite-reducing upflow anaerobic sludge bed (SrUASB) reactor, as the major bioreactor of the system, removed 86.9% of organics while the whole system removed 94% of organics even when water temperature decreased to around 10 °C. The bactericidal effect of sulfite was not observed in the SrUASB reactor, while thiosulfate was found accumulated under psychrophilic conditions. The sludge yield of the SrUASB reactor was determined to be 0.095 kg VSS/kg COD, higher than of sulfate reduction process but still much lower than of conventional activated sludge processes. The dominant microbes in the SrUASB reactor were determined as Lactococcus spp. rather than sulfate-reducing bacteria, but sulfite reduction still contributed 85.5% to the organic carbon mineralization in this reactor. Ammonia and nitrate were effectively removed in the aerobic and anoxic filters, respectively. This study confirms the proposed process was promising to achieve sludge-minimized sewage treatment integrating with flue gas desulfurization in inland and cold areas. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of an ATP measurement method suitable for xenobiotic treatment activated sludge biomass.

PubMed

Nguyen, Lan Huong; Chong, Nyuk-Min

2015-09-01

Activated sludge consumes a large amount of energy to degrade a xenobiotic organic compound. By tracking the energy inventory of activated sludge biomass during the sludge's degradation of a xenobiotic, any disadvantageous effect on the sludge's performance caused by energy deficiency can be observed. The purpose of this study was to develop a reliable and accurate method for measuring the ATP contents of activated sludge cells that were to degrade a xenobiotic organic. Cell disruption and cellular ATP extraction were performed by a protocol with which xenobiotic degrading activated sludge biomass was washed with SDS, treated by Tris and TCA, and followed by bead blasting. The suspension of disrupted cells was filtered before the filtrate was injected into HPLC that was set at optimal conditions to measure the ATP concentration therein. This extraction protocol and HPLC measurement of ATP was evaluated for its linearity, limits of detection, and reproducibility. Evaluation test results reported a R(2) of 0.999 of linear fit of ATP concentration versus activated sludge concentration, a LOD=0.00045mg/L, a LOQ=0.0015mg/L for HPLC measurement of ATP, a MDL=0.46mg/g SS for ATP extraction protocol, and a recovery efficiency of 96.4±2%. This method of ATP measurement was simple, rapid, reliable, and was unburdened of some limitations other methods may have. Copyright © 2015 Elsevier B.V. All rights reserved.

Suspended biofilm carrier and activated sludge removal of acidic pharmaceuticals.

PubMed

Falås, P; Baillon-Dhumez, A; Andersen, H R; Ledin, A; la Cour Jansen, J

2012-03-15

Removal of seven active pharmaceutical substances (ibuprofen, ketoprofen, naproxen, diclofenac, clofibric acid, mefenamic acid, and gemfibrozil) was assessed by batch experiments, with suspended biofilm carriers and activated sludge from several full-scale wastewater treatment plants. A distinct difference between nitrifying activated sludge and suspended biofilm carrier removal of several pharmaceuticals was demonstrated. Biofilm carriers from full-scale nitrifying wastewater treatment plants, demonstrated considerably higher removal rates per unit biomass (i.e. suspended solids for the sludges and attached solids for the carriers) of diclofenac, ketoprofen, gemfibrozil, clofibric acid and mefenamic acid compared to the sludges. Among the target pharmaceuticals, only ibuprofen and naproxen showed similar removal rates per unit biomass for the sludges and biofilm carriers. In contrast to the pharmaceutical removal, the nitrification capacity per unit biomass was lower for the carriers than the sludges, which suggests that neither the nitrite nor the ammonia oxidizing bacteria are primarily responsible for the observed differences in pharmaceutical removal. The low ability of ammonia oxidizing bacteria to degrade or transform the target pharmaceuticals was further demonstrated by the limited pharmaceutical removal in an experiment with continuous nitritation and biofilm carriers from a partial nitritation/anammox sludge liquor treatment process. Copyright © 2011 Elsevier Ltd. All rights reserved.

Full scale implementation of the nutrient limited BAS process at Södra Cell Värö.

PubMed

Malmqvist, A; Berggren, B; Sjölin, C; Welander, T; Heuts, L; Fransén, A; Ling, D

2004-01-01

A combination of the suspended carrier biofilm process and the activated sludge process (biofilm-activated sludge--BAS) has been shown to be very successful for the treatment of different types of pulp and paper mill effluents. The robust biofilm pre-treatment in combination with activated sludge results in a stable, compact and highly efficient process. Recent findings have shown that nutrient limited operation of the biofilm process greatly improves the sludge characteristics in the following activated sludge stage, while minimising sludge production and effluent discharge of nutrients. The nutrient limited BAS process was implemented at full scale at the Södra Cell Värö kraft mill and taken into operation in July 2002. After start-up and optimisation over about 5 months, the process meets all effluent discharge limits. The removal of COD is close to 70% and the removal of EDTA greater than 90%. Typical effluent concentrations of suspended solids and nutrients during stable operations have been 20-30 mg/L TSS, 0.3-0.5 mg/L phosphorus and 3-5 mg/L nitrogen. The sludge production was 0.09 kgSS/kg COD removed and the sludge volume index was 50-100 mL/g.

Comparison of two treatments for the removal of selected organic micropollutants and bulk organic matter: conventional activated sludge followed by ultrafiltration versus membrane bioreactor.

PubMed

Sahar, E; Ernst, M; Godehardt, M; Hein, A; Herr, J; Kazner, C; Melin, T; Cikurel, H; Aharoni, A; Messalem, R; Brenner, A; Jekel, M

2011-01-01

The potential of membrane bioreactor (MBR) systems to remove organic micropollutants was investigated at different scales, operational conditions, and locations. The effluent quality of the MBR system was compared with that of a plant combining conventional activated sludge (CAS) followed by ultrafiltration (UF). The MBR and CAS-UF systems were operated and tested in parallel. An MBR pilot plant in Israel was operated for over a year at a mixed liquor suspended solids (MLSS) range of 2.8-10.6 g/L. The MBR achieved removal rates comparable to those of a CAS-UF plant at the Tel-Aviv wastewater treatment plant (WWTP) for macrolide antibiotics such as roxythromycin, clarithromycin, and erythromycin and slightly higher removal rates than the CAS-UF for sulfonamides. A laboratory scale MBR unit in Berlin - at an MLSS of 6-9 g/L - showed better removal rates for macrolide antibiotics, trimethoprim, and 5-tolyltriazole compared to the CAS process of the Ruhleben sewage treatment plant (STP) in Berlin when both were fed with identical quality raw wastewater. The Berlin CAS exhibited significantly better benzotriazole removal and slightly better sulfamethoxazole and 4-tolyltriazole removal than its MBR counterpart. Pilot MBR tests (MLSS of 12 g/L) in Aachen, Germany, showed that operating flux significantly affected the resulting membrane fouling rate, but the removal rates of dissolved organic matter and of bisphenol A were not affected.

Thermochemical treatment of sewage sludge ash with sodium salt additives for phosphorus fertilizer production--Analysis of underlying chemical reactions.

PubMed

Stemann, Jan; Peplinski, Burkhard; Adam, Christian

2015-11-01

Stocks of high grade phosphate rock are becoming scarce, and there is growing concern about potentially harmful impurities in conventional phosphorus fertilizers. Sewage sludge ash is a promising secondary phosphorus source. However, to remove heavy metals and convert the phosphorus contained in sewage sludge ash into mineral phases available to plants, an after-treatment is required. Laboratory-scale calcination experiments of sewage sludge ash blended with sodium salts using dried sewage sludge as a reducing agent were carried out at 1000°C. Thus, the Ca3(PO4)2 or whitlockite component of raw sewage sludge ash, which is not readily plant available, was converted to CaNaPO4 (buchwaldite). Consequently, nearly complete phosphorus solubility in ammonium citrate (a well-established indicator for plant availability) was achieved. Moreover, it was shown that Na2CO3 may be replaced by moderately priced Na2SO4. However, molar ratios of Na/P>2 were required to achieve >80% phosphorus solubility. Such over-stoichiometric Na consumption is largely caused by side reactions with the SiO2 component of the sewage sludge ash - an explanation for which clear evidence is provided for the first time. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sludge-Drying Lagoons: a Potential Significant Methane Source in Wastewater Treatment Plants.

PubMed

Pan, Yuting; Ye, Liu; van den Akker, Ben; Ganigué Pagès, Ramon; Musenze, Ronald S; Yuan, Zhiguo

2016-02-02

"Sludge-drying lagoons" are a preferred sludge treatment and drying method in tropical and subtropical areas due to the low construction and operational costs. However, this method may be a potential significant source of methane (CH4) because some of the organic matter would be microbially metabolized under anaerobic conditions in the lagoon. The quantification of CH4 emissions from lagoons is difficult due to the expected temporal and spatial variations over a lagoon maturing cycle of several years. Sporadic ebullition of CH4, which cannot be easily quantified by conventional methods such as floating hoods, is also expected. In this study, a novel method based on mass balances was developed to estimate the CH4 emissions and was applied to a full-scale sludge-drying lagoon over a three year operational cycle. The results revealed that processes in a sludge-drying lagoon would emit 6.5 kg CO2-e per megaliter of treated sewage. This would represent a quarter to two-thirds of the overall greenhouse gas (GHG) emissions from wastewater-treatment plants (WWTPs). This work highlights the fact that sludge-drying lagoons are a significant source of CH4 that adds substantially to the overall GHG footprint of WWTPs despite being recognized as a cheap and energy-efficient means of drying sludge.

Ultrasound pre-treatment for anaerobic digestion improvement.

PubMed

Pérez-Elvira, S; Fdz-Polanco, M; Plaza, F I; Garralón, G; Fdz-Polanco, F

2009-01-01

Prior research indicates that ultrasounds can be used in batch reactors as pre-treatment before anaerobic digestion, but the specific energy required at laboratory-scale is too high. This work evaluates both the continuous ultrasound device performance (efficiency and solubilisation) and the operation of anaerobic digesters continuously fed with sonicated sludge, and presents energy balance considerations. The results of sludge solubilisation after the sonication treatment indicate that, applying identical specific energy, it is better to increase the power than the residence time. Working with secondary sludge, batch biodegradability tests show that by applying 30 kWh/m3 of sludge, it is possible to increase biogas production by 42%. Data from continuous pilot-scale anaerobic reactors (V=100 L) indicate that operating with a conventional HRT=20 d, a reactor fed with pre-treated sludge increases the volatile solids removal and the biogas production by 25 and 37% respectively. Operating with HRT=15 d, the removal efficiency is similar to the obtained with a reactor fed with non-hydrolysed sludge at HTR=20 d, although the specific biogas productivity per volume of reactor is higher for the pretreated sludge. Regarding the energy balance, although for laboratory-scale devices it is negative, full-scale suppliers state a net generation of 3-10 kW per kW of energy used.

Correlations between trans-membrane pressure (TMP) and sludge properties in submerged membrane electro-bioreactor (SMEBR) and conventional membrane bioreactor (MBR).

PubMed

Hasan, Shadi W; Elektorowicz, Maria; Oleszkiewicz, Jan A

2012-09-01

The influence of sludge properties in SMEBR and conventional MBR pilot systems on membrane fouling was investigated. Generated data were analyzed using statistical analysis Pearson's product momentum correlation coefficient (r(p)). Analysis showed that TMP had strong direct (r(p)=0.9182) and inverse (r(p)=-0.9205) correlations to mean particle size diameter in MBR and SMEBR, respectively. TMP in SMEBR had a strong direct correlation to the sludge mixed liquor suspended solids concentration (MLSS) (r(p)=0.7757) while a weak direct correlation (r(p)=0.1940) was observed in MBR. SMEBR showed a moderate inverse correlation (r(p)=-0.6118) between TMP and soluble carbohydrates (EPS(c)) and a very weak direct correlation (r(p)=0.3448) to soluble proteins (EPS(p)). Conversely, EPS(p) in MBR had more significant impact (r(p)=0.4856) on membrane fouling than EPS(c) (r(p)=0.3051). The results provide insight into optimization of operational conditions in SMEBR system to overcome membrane fouling. Copyright © 2012 Elsevier Ltd. All rights reserved.

Synthetic Musk Fragrances in a Conventional Drinking Water Treatment Plant with Lime Softening

PubMed Central

Wombacher, William D.; Hornbuckle, Keri C.

2009-01-01

Synthetic musk fragrances are common personal care product additives and wastewater contaminants that are routinely detected in the environment. This study examines the presence eight synthetic musk fragrances (AHTN, HHCB, ATII, ADBI, AHMI, musk xylene, and musk ketone) in source water and the removal of these compounds as they flow through a Midwestern conventional drinking water plant with lime softening. The compounds were measured in water, waste sludge, and air throughout the plant. HHCB and AHTN were detected in 100% of the samples and at the highest concentrations. A mass balance on HHCB and AHTN was performed under warm and cold weather conditions. The total removal efficiency for HHCB and AHTN, which averaged between 67% to 89%, is dominated by adsorption to water softener sludge and its consequent removal by sludge wasting and media filtration. Volatilization, chlorine disinfection, and the disposal of backwash water play a minor role in the removal of both compounds. As a result of inefficient overall removal, HHCB and AHTN are a constant presence at low levels in finished drinking water. PMID:20126513

Synthetic Musk Fragrances in a Conventional Drinking Water Treatment Plant with Lime Softening.

PubMed

Wombacher, William D; Hornbuckle, Keri C

2009-11-01

Synthetic musk fragrances are common personal care product additives and wastewater contaminants that are routinely detected in the environment. This study examines the presence eight synthetic musk fragrances (AHTN, HHCB, ATII, ADBI, AHMI, musk xylene, and musk ketone) in source water and the removal of these compounds as they flow through a Midwestern conventional drinking water plant with lime softening. The compounds were measured in water, waste sludge, and air throughout the plant. HHCB and AHTN were detected in 100% of the samples and at the highest concentrations. A mass balance on HHCB and AHTN was performed under warm and cold weather conditions. The total removal efficiency for HHCB and AHTN, which averaged between 67% to 89%, is dominated by adsorption to water softener sludge and its consequent removal by sludge wasting and media filtration. Volatilization, chlorine disinfection, and the disposal of backwash water play a minor role in the removal of both compounds. As a result of inefficient overall removal, HHCB and AHTN are a constant presence at low levels in finished drinking water.

Enrichment of anammox bacteria from three sludge sources for the startup of monosodium glutamate industrial wastewater treatment system.

PubMed

Li-dong, Shen; An-hui, Hu; Ren-cun, Jin; Dong-qing, Cheng; Ping, Zheng; Xiang-yang, Xu; Bao-lan, Hu

2012-01-15

Three activated sludges from a landfill leachate treatment plant (S1), a municipal sewage treatment plant (S2) and a monosodium glutamate (MSG) wastewater treatment plant (S3) were used as inocula to enrich anaerobic ammonium oxidation (anammox) bacteria for the startup of MSG industrial wastewater treatment system. After 360 days of cultivation using MSG wastewater, obvious anammox activity was observed in all three cultures. The maximum specific anammox activities of cultures S1, S2 and S3 were 0.11 kg N kg(-1) VSS day(-1), 0.09 kg N kg(-1) VSS day(-1) and 0.16 kg N kg(-1) VSS day(-1), respectively. Brownish-red anammox granules having diameters in the range of 0.2-1.0mm were visible in cultures S1 and S2, and large red granules having diameters in the range of 0.5-2.5mm were formed in culture S3 after 420 days of cultivation. Phylogenetic analysis of 16S rRNA genes showed that Kuenenia organisms were the dominant anammox species in all three cultures. The copy numbers of 16S rRNA genes of anammox bacteria in cultures S1, S2 and S3 were 6.8 × 10(7) copies mL(-1), 9.4 × 10(7) copies mL(-1) and 7.5 × 10(8) copies mL(-1), respectively. The results of this study demonstrated that anammox cultivation from conventional activated sludges was highly possible using MSG wastewater. Thus the anammox process has possibility of applying to the nitrogen removal from MSG wastewater. Copyright © 2011 Elsevier B.V. All rights reserved.

Fate and removal of pharmaceuticals and illicit drugs in conventional and membrane bioreactor wastewater treatment plants and by riverbank filtration.

PubMed

Petrovic, Mira; de Alda, Maria Jose Lopez; Diaz-Cruz, Silvia; Postigo, Cristina; Radjenovic, Jelena; Gros, Meritxell; Barcelo, Damià

2009-10-13

Pharmaceutically active compounds (PhACs) and drugs of abuse (DAs) are two important groups of emerging environmental contaminants that have raised an increasing interest in the scientific community. A number of studies revealed their presence in the environment. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, being able to reach surface and groundwater and subsequently, drinking waters. This paper reviews the data regarding the levels of pharmaceuticals and illicit drugs detected in wastewaters and gives an overview of their removal by conventional treatment technologies (applying activated sludge) as well as advanced treatments such as membrane bioreactor. The paper also gives an overview of bank filtration practices at managed aquifer recharge sites and discusses the potential of this approach to mitigate the contamination by PhACs and DAs.

Biotransformation and sorption of trace organic compounds in biological nutrient removal treatment systems.

PubMed

Lakshminarasimman, Narasimman; Quiñones, Oscar; Vanderford, Brett J; Campo-Moreno, Pablo; Dickenson, Eric V; McAvoy, Drew C

2018-05-28

This study determined biotransformation rates (k bio ) and sorption-distribution coefficients (K d ) for a select group of trace organic compounds (TOrCs) in anaerobic, anoxic, and aerobic activated sludge collected from two different biological nutrient removal (BNR) treatment systems located in Nevada (NV) and Ohio (OH) in the United States (US). The NV and OH facilities operated at solids retention times (SRTs) of 8 and 23 days, respectively. Using microwave-assisted extraction, the biotransformation rates of the chosen TOrCs were measured in the total mixed liquor. Sulfamethoxazole, trimethoprim, and atenolol biotransformed in all three redox regimes irrespective of the activated sludge source. The biotransformation of N, N-diethyl-3-methylbenzamide (DEET), triclosan, and benzotriazole was observed in aerobic activated sludge from both treatment plants; however, anoxic biotransformation of these three compounds was seen only in anoxic activated sludge from NV. Carbamazepine was recalcitrant in all three redox regimes and both sources of activated sludge. Atenolol and DEET had greater biotransformation rates in activated sludge with a higher SRT (23 days), while trimethoprim had a higher biotransformation rate in activated sludge with a lower SRT (8 days). The remaining compounds did not show any dependence on SRT. Lyophilized, heat inactivated sludge solids were used to determine the sorption-distribution coefficients. Triclosan was the most sorptive compound followed by carbamazepine, sulfamethoxazole, DEET, and benzotriazole. The sorption-distribution coefficients were similar across redox conditions and sludge sources. The biotransformation rates and sorption-distribution coefficients determined in this study can be used to improve fate prediction of the target TOrCs in BNR treatment systems. Copyright © 2018. Published by Elsevier B.V.

Reducing capacities and redox potentials of humic substances extracted from sewage sludge.

PubMed

Yang, Zhen; Du, Mengchan; Jiang, Jie

2016-02-01

Humic substances (HS) are redox active organic materials that can be extracted from sewage sludge generated in wastewater treatment processes. Due to the poor understanding of reducing capacity, redox potentials and redox active functional groups of HS in sewage sludge, the potential contribution of sludge HS in transformation of wastewater contaminants is unclear. In the present study, the number of electrons donated or accepted by sewage sludge HS were quantified before and after reduction by iron compounds that possess different redox potentials and defined as the reducing capacity of the sewage sludge. In contrast to previous studies of soil and commercial humic acids (HA), reduced sludge HA showed a lower reducing capacity than that of native HA, which implies formation of semiquinone radicals since the semiquinone radical/hydroquinone pair has a much higher redox potential than the quinone/hydroquinone pair. It is novel that reducing capacities of sludge HA were determined in the redox potential range from -314 to 430 mV. The formation of semiquinone radicals formed during the reduction of quinone moieties in sludge HA is shown by three-dimensional excitation/emission matrix fluorescence spectroscopies information, increasing fluorescence intensities and blue-shifting of the excitation/emission peak of reduced sludge HA. Knowledge of sludge HS redox potentials and corresponding reducing capacities makes it possible to predict the transformation of redox active pollutants and facilitate manipulation and optimization of sludge loading wastewater treatment processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Research on the treatment of wastewater containing PVA by ozonation-activated sludge process].

PubMed

Xing, Xiao-Qiong; Huang, Cheng-Lan; Liu, Min; Chen, Ying

2012-11-01

The wastewater containing polyvinyl alcohol (PVA) was characterized with poor biodegradability, and was difficult to remove. In order to find an economically reasonable and practical technology, the research on the removal efficiency of different concentration wastewater containing PVA by ozonation-activated sludge process was studied, and the result was compared with the traditional activated sludge process. The results showed that the ozonation-activated sludge process was not suitable for treating influent with COD below 500 mg x L(-1) and the wastewater PVA concentration was 10-30 mg x L(-1). When the influent COD was between 500-800 mg x L(-1) and the PVA concentration was 15-60 mg x L(-1), the system had advantages on dealing with this kind of wastewater, and the average removal efficiency of COD and PVA were 92.8% and 57.4%, which were better than the traditional activated sludge process 4.1% and 15.2% respectively. In addition, the effluent concentrations of COD could keep between 30-60 mg x L(-1). When the influent COD was 1 000-1 200 mg x L(-1) and the PVA concentration was 20-70 mg x L(-1), the average removal efficiencies of COD and PVA were 90.9% and 45.3%, which were better than the traditional activated sludge process 12.8% and 12.1% respectively, but the effluent should to be further treated. Compared with the traditional activated sludge process, ozonation-activated sludge process had high treatment efficiency, stable running effect, and effectively in dealing with industrial wastewater containing PVA.

Three-dimensional three-phase model for simulation of hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification in an oxidation ditch.

PubMed

Lei, Li; Ni, Jinren

2014-04-15

A three-dimensional three-phase fluid model, supplemented by laboratory data, was developed to simulate the hydrodynamics, oxygen mass transfer, carbon oxidation, nitrification and denitrification processes in an oxidation ditch. The model provided detailed phase information on the liquid flow field, gas hold-up distribution and sludge sedimentation. The three-phase model described water-gas, water-sludge and gas-sludge interactions. Activated sludge was taken to be in a pseudo-solid phase, comprising an initially separated solid phase that was transported and later underwent biological reactions with the surrounding liquidmedia. Floc parameters were modified to improve the sludge viscosity, sludge density, oxygen mass transfer rate, and carbon substrate uptake due to adsorption onto the activated sludge. The validation test results were in very satisfactory agreement with laboratory data on the behavior of activated sludge in an oxidation ditch. By coupling species transport and biological process models, reasonable predictions are made of: (1) the biochemical kinetics of dissolved oxygen, chemical oxygen demand (COD) and nitrogen variation, and (2) the physical kinematics of sludge sedimentation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Feasibility of a multi-component additive for efficient control of activated sludge filamentous bulking.

PubMed

Seka, A M; Van De Wiele, T; Verstraete, W

2001-08-01

Instantaneous improvement of the settling of bulking filamentous activated sludge can be achieved by the addition of a polymer or a large amount (up to 100% of the MLSS concentration) of talc powder to the sludge. Long-term improvement relies on repeated additions, as these additives have no adverse effects on the causative filaments. A multi-component additive was compared to the traditional additives in lab-scale activated sludge units using three highly filamentous sludges from different industrial treatment plants. The study demonstrated that the multi-component additive was superior to the traditional remedies. It was shown that, in the case of severe filamentous bulking, a single addition of the new additive immediately improved sludge settling and exerted a destructive effect on the causative filamentous bacteria. Thus, the latter additive also ensured a long-term sludge sedimentation improvement. The traditional additives exhibited an immediate and short-term effect. The novel additive also retarded sludge rising due to denitrification and it improved sludge dewaterability. The study revealed Nostocoido limicola II, with slightly hydrophobic cell wall, to be somewhat resistant to the quaternary ammonium salt present as biocide in the additive.

Combined mesophilic anaerobic and thermophilic aerobic digestion process: effect on sludge degradation and variation of sludge property.

PubMed

Cheng, Jiehong; Ji, Yuehong; Kong, Feng; Chen, Xian

2013-12-01

One-stage autothermal thermophilic aerobic digestion (ATAD) is effective for the reduction of volatile solids (VSs) and pathogen in sewage sludges. A novel process of combining mesophilic (<35 °C) anaerobic digestion with a thermophilic (55 °C) aerobic digestion process (AN/TAD) occurred in a one-stage digester, which was designed for aeration energy savings. The efficiency of sludge degradation and variation of sludge properties by batch experiments were evaluated for the AN/TAD digester with an effective volume of 23 L for 30 days compared with conventional thermophilic aerobic digestion (TAD). The AN/TAD system can efficiently achieve sludge stabilization on the 16th day with a VS removal rate of 38.1 %. The AN/TAD system was operated at lower ORP values in a digestion period with higher contents of total organic compounds, volatile fatty acids, protein, and polysaccharide in the soluble phase than those of the TAD system, which can rapidly decreased and had low values in the late period of digestion for the AN/TAD system. In the AN/TAD system, intracellular substances had lysis because of initial hydrolytic acidification.

Occurrence and activity of Archaea in aerated activated sludge wastewater treatment plants.

PubMed

Gray, Neil D; Miskin, Ian P; Kornilova, Oksana; Curtis, Thomas P; Head, Ian M

2002-03-01

The occurrence, distribution and activity of archaeal populations within two aerated, activated sludge wastewater treatment systems, one treating domestic waste and the second treating mixed domestic and industrial wastewater, were investigated by denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified ribosomal RNA gene fragments and process measurements. In the plant receiving mixed industrial and domestic waste the archaeal populations found in the mixed liquor were very similar to those in the influent sewage, though a small number of DGGE bands specific to the mixed liquor were identified. In contrast, the activated sludge treating principally domestic waste harboured distinct archaeal populations associated with the mixed liquor that were not prevalent in the influent sewage. We deduce that the Archaea in the plant treating mixed wastewater were derived principally from the influent, whereas those in the plant treating solely domestic waste were actively growing in the treatment plant. Archaeal 16S rRNA gene sequences related to the Methanosarcinales, Methanomicrobiales and the Methanobacteriales were detected. Methanogenesis was measured in activated sludge samples incubated under oxic and anoxic conditions, demonstrating that the methanogens present in both activated sludge plants were active only in anoxic incubations. The relatively low rates of methanogenesis measured indicated that, although active, the methanogens play a minor role in carbon turnover in activated sludge.

Epoxy matrix composites filled with micro-sized LD sludge: wear characterization and analysis

NASA Astrophysics Data System (ADS)

Purohit, Abhilash; Satapathy, Alok

2016-02-01

Owing to the very high cost of conventional filler materials in polymer composites, exploring the possibility of using low cost minerals and industrial wastes for this purpose has become the need of the hour. In view of this, the present work includes the development and the wear performance evaluation of a new class of composites consisting of epoxy and microsized LD sludge. LD sludge or the Linz-Donawitz Sludge (LDS) are the fine solid particles recovered after wet cleaning of the gas emerging from LD convertors during steel making. Epoxy composites filled with different proportions (0, 5, 10, 15 and 20 wt %) of LDS are fabricated by conventional hand lay-up technique. Dry sliding wear trials are performed on the composite specimens under different test conditions as per ASTM G 99 following a design of experiment approach based on Taguchi's orthogonal arrays. The Taguchi approach leads to the recognition of most powerful variables that predominantly control the wear rate. This parametric analysis reveals that LDS content and sliding velocity affects the specific wear rate more significantly than normal load and sliding distance. Furthermore with increase in LDS content specific wear rate of the composite decreases for a constant sliding velocity. The sliding wear behavior of these composites under an extended range of test conditions is predicted by a model based on the artificial neural network (ANN).

Fluorescence-based monitoring of tracer and substrate distribution in an UASB reactor.

PubMed

Lou, S J; Tartakovsky, B; Zeng, Y; Wu, P; Guiot, S R

2006-11-01

In this work, rhodamine-related fluorescence was measured on-line at four reactor heights in order to study hydrodynamics within an upflow anaerobic sludge bed reactor. A linear dependence of the dispersion coefficient (D) on the upflow velocity was observed, while the influence of the organic loading rate (OLR) was insignificant. Furthermore, the Bodenstein number of the reactor loaded with granulated sludge was found to be position-dependent with the largest values measured at the bottom of the sludge bed. This trend was not observed in the reactor without sludge. Chemical oxygen demand (COD) and volatile fatty acid (VFA) concentrations were measured at the same reactor heights as in rhodamine tests using conventional off-line analytical methods and on-line multiwavelength fluorometry. Significant spatial COD and VFA gradients were observed at organic loading rates above 6g COD l(R)(-1)d(-1) and linear upflow velocities below 0.8m h(-1).

Fate and occurrence of alkylphenolic compounds in sewage sludges determined by liquid chromatography tandem mass spectrometry.

PubMed

Koh, Y K K; Chiu, T Y; Paterakis, N; Boobis, A; Scrimshawe, M D; Lester, J N; Cartmell, E

2009-12-01

An analytical method has been developed and applied to determine the concentrations of the nonionic alkylphenol polyethoxylate surfactants and their metabolites, alkylphenoxy carboxylates and alkyphenols, in sewage sludges. The compounds were extracted with methanol/acetone (1:1 v/v) from sludge, and concentrated extracts were cleaned by silica solid-phase extraction prior to determination by liquid chromatography tandem mass spectrometry. The recoveries, determined by spiking sewage sludge at two concentrations, ranged from 51% to 89% with method detection limits from 6 microg kg(-1) to 60 microg kg(-1). The methodology was subsequently applied to sludge samples obtained from a carbonaceous activated sludge plant, a nitrifying/denitrifying activated sludge plant and a nitrifying/ denitrifying activated sludge plant with phosphorus removal. Concentrations of nonylphenolic compounds were two to three times higher than their octyl analogues. Long-chain nonylphenol polyethoxylates (NP3-12EO) ranged from 16 microg kg(-1) to 11754 microg kg(-1). The estrogenic metabolite nonylphenol was present at concentrations ranging from 33 microg kg(-1) to 6696 microg kg(-1).

Adsorption behavior of sulfamethazine in an activated sludge process treating swine wastewater.

PubMed

Ben, Weiwei; Qiang, Zhimin; Yin, Xiaowei; Qu, Jiuhui; Pan, Xun

2014-08-01

Swine wastewater is an important pollution source of antibiotics entering the aquatic environment. In this work, the adsorption behavior of sulfamethazine (SMN), a commonly-used sulfonamide antibiotic, on activated sludge from a sequencing batch reactor treating swine wastewater was investigated. The results show that the adsorption of SMN on activated sludge was an initially rapid process and reached equilibrium after 6hr. The removal efficiency of SMN from the water phase increased with an increasing concentration of mixed liquor suspended solids, while the adsorbed concentration of SMN decreased. Solution pH influenced both the speciation of SMN and the surface properties of activated sludge, thus significantly impacting the adsorption process. A linear partition model could give a good fit for the equilibrium concentrations of SMN at the test temperatures (i.e., 10, 20 and 30°C). The partition coefficient (Kd) was determined to be 100.5L/kg at 20°C, indicating a quite high adsorption capacity for SMN. Thermodynamic analysis revealed that SMN adsorption on activated sludge was an exothermic process. This study could help to clarify the fate and behavior of sulfonamide antibiotics in the activated sludge process and assess consequent environmental risks arising from sludge disposal as well. Copyright © 2014. Published by Elsevier B.V.

A full scale worm reactor for efficient sludge reduction by predation in a wastewater treatment plant.

PubMed

Tamis, J; van Schouwenburg, G; Kleerebezem, R; van Loosdrecht, M C M

2011-11-15

Sludge predation can be an effective solution to reduce sludge production at a wastewater treatment plant. Oligochaete worms are the natural consumers of biomass in benthic layers in ecosystems. In this study the results of secondary sludge degradation by the aquatic Oligochaete worm Aulophorus furcatus in a 125 m(3) reactor and further sludge conversion in an anaerobic tank are presented. The system was operated over a period of 4 years at WWTP Wolvega, the Netherlands and was fed with secondary sludge from a low loaded activated sludge process. It was possible to maintain a stable and active population of the aquatic worm species A. furcatus during the full period. Under optimal conditions a sludge conversion of 150-200 kg TSS/d or 1.2-1.6 kg TSS/m(3)/d was established in the worm reactor. The worms grew as a biofilm on carrier material in the reactor. The surface specific conversion rate reached 140-180 g TSS/m(2)d and the worm biomass specific conversion rate was 0.5-1 g TSS sludge/g dry weight worms per day. The sludge reduction under optimal conditions in the worm reactor was 30-40%. The degradation by worms was an order of magnitude larger than the endogenous conversion rate of the secondary sludge. Effluent sludge from the worm reactor was stored in an anaerobic tank where methanogenic processes became apparent. It appeared that besides reducing the sludge amount, the worms' activity increased anaerobic digestibility, allowing for future optimisation of the total system by maximising sludge reduction and methane formation. In the whole system it was possible to reduce the amount of sludge by at least 65% on TSS basis. This is a much better total conversion than reported for anaerobic biodegradability of secondary sludge of 20-30% efficiency in terms of TSS reduction. Copyright © 2011 Elsevier Ltd. All rights reserved.

Anaerobic co-digestion of waste activated sludge and greasy sludge from flotation process: batch versus CSTR experiments to investigate optimal design.

PubMed

Girault, R; Bridoux, G; Nauleau, F; Poullain, C; Buffet, J; Peu, P; Sadowski, A G; Béline, F

2012-02-01

In this study, the maximum ratio of greasy sludge to incorporate with waste activated sludge was investigated in batch and CSTR experiments. In batch experiments, inhibition occurred with a greasy sludge ratio of more than 20-30% of the feed COD. In CSTR experiments, the optimal greasy sludge ratio was 60% of the feed COD and inhibition occurred above a ratio of 80%. Hence, batch experiments can predict the CSTR yield when the degradation phenomenon are additive but cannot be used to determine the maximum ratio to be used in a CSTR configuration. Additionally, when the ratio of greasy sludge increased from 0% to 60% of the feed COD, CSTR methane production increased by more than 60%. When the greasy sludge ratio increased from 60% to 90% of the feed COD, the reactor yield decreased by 75%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Improving the amenability of municipal waste activated sludge for biological pretreatment by phase-separated sludge disintegration method.

PubMed

Kavitha, S; Adish Kumar, S; Kaliappan, S; Yeom, Ick Tae; Rajesh Banu, J

2014-10-01

The significance of citric acid, a cation binding agent, was investigated for the exclusion of extracellular polymeric substance (EPS) from waste activated sludge (WAS) and anaerobic biodegradability following enzymatic bacterial pretreatment. EPS was removed with 0.05 g/g SS of citric acid. The results of pretreatment found that the suspended solids reduction and chemical oxygen demand solubilisation were 21.4% and 16.2% for deflocculated-bacterially pretreated sludge, 14.28% and 10.0% for flocculated sludge (without EPS removal and bacterially pretreated) and 8.5% and 6.5% for control sludge (raw sludge), respectively. Further assessing anaerobic biodegradability, the biogas yield potential of deflocculated and bacterially pretreated, flocculated, and control sludges were found to be 0.455 L/(g VS), 0.343 L/(g VS), and 0.209 L/(g VS), respectively. Thus, phase-separated disintegration enhanced anaerobic biodegradability efficiently. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microbial Ecology of Activated Sludge

PubMed Central

Dias, F. F.; Bhat, J. V.

1964-01-01

Over 300 bacterial strains were isolated from seven samples of activated sludge by plating on sewage agar. Gram-negative bacteria of the genera Zoogloea and Comamonas predominated. Many isolates (51%) showed sudanophilic inclusions of poly-β-hydroxybutyric acid, whereas 34% accumulated iodophilic material on media containing starch. A large number required either vitamins or amino acids, or both, for growth. None of the isolates tested for their ability to bring about changes in autoclaved sewage produced an effluent comparable in quality to the activated sludge control, although the Zoogloea did produce activated sludgelike flocs. A study of 150 bacterial strains isolated from raw sewage revealed that they differed from the sludge isolates in several respects. Coliforms, which constitute nearly a quarter of the sewage isolates, were rarely encountered in sludge. PMID:14215970

Fate of personal care and household products in source separated sanitation.

PubMed

Butkovskyi, A; Rijnaarts, H H M; Zeeman, G; Hernandez Leal, L

2016-12-15

Removal of twelve micropollutants, namely biocides, fragrances, ultraviolet (UV)-filters and preservatives in source separated grey and black water treatment systems was studied. All compounds were present in influent grey water in μg/l range. Seven compounds were found in influent black water. Their removal in an aerobic activated sludge system treating grey water ranged from 59% for avobenzone to >99% for hexylcinnamaldehyde. High concentrations of hydrophobic micropollutants in sludge of aerobic activated sludge system indicated the importance of sorption for their removal. Six micropollutants were found in sludge of an Up-flow anaerobic sludge blanket (UASB) reactor treating black water, with four of them being present at significantly higher concentrations after addition of grey water sludge to the reactor. Hence, addition of grey water sludge to the UASB reactor is likely to increase micropollutant content in UASB sludge. This approach should not be followed when excess UASB sludge is designed to be reused as soil amendment. Copyright © 2016 Elsevier B.V. All rights reserved.

Cultivation of a bacterial consortium with the potential to degrade total petroleum hydrocarbon using waste activated sludge.

PubMed

Sivakumar, S; Song, Y C; Kim, S H; Jang, S H

2015-11-01

Waste activated sludge was aerobically treated to demonstrate multiple uses such as cultivating an oil degrading bacterial consortium; studying the influence of a bulking agent (peat moss) and total petroleum hydrocarbon concentration on bacterial growth and producing a soil conditioner using waste activated sludge. After 30 days of incubation, the concentration of oil-degrading bacteria was 4.3 x 10(8) CFU g(-1) and 4.5 x 10(8) CFU g(-1) for 5 and 10 g of total petroleum hydrocarbon, respectively, in a mixture of waste activated sludge (1 kg) and peat moss (0.1 kg). This accounts for approximately 88.4 and 91.1%, respectively, of the total heterotrophic bacteria (total-HB). The addition of bulking agent enhanced total-HB population and total petroleum hydrocarbon-degrading bacterial population. Over 90% of total petroleum hydrocarbon degradation was achieved by the mixture of waste activated sludge, bulking agent and total petroleum hydrocarbon. The results of physico-chemical parameters of the compost (waste activated sludge with and without added peat moss compost) and a substantial reduction in E. coli showed that the use of this final product did not exhibit risk when used as soil conditioner. Finally, the present study demonstrated that cultivation of total petroleum hydrocarbon-degrading bacterial consortium and production of compost from waste activated sludge by aerobic treatment was feasible.

Change in the fouling propensity of sludge in membrane bioreactors (MBR) in relation to the accumulation of biopolymer clusters.

PubMed

Sun, Fei-yun; Wang, Xiao-mao; Li, Xiao-yan

2011-04-01

A membrane bioreactor (MBR) and an activated sludge process (ASP) were operated side by side to evaluate the change of sludge supernatant characteristics and the evolution of the sludge fouling propensity. The MBR sludge had a higher organic concentration and more biopolymer clusters (BPC) in the supernatant compared with ASP. BPC increased in both concentration and size in the MBR. The results show that the change in the liquid-phase property had a profound effect on the sludge fouling propensity. MBR operation transformed typical activated sludge to MBR sludge with a higher fouling propensity. Distinct from the ASP, membrane filtration retained soluble microbial products (SMP) within the MBR, and the vast membrane surface provided a unique environment for the transformation of SMP to large size BPC, leading to further sludge deposition on the membrane surface. Thus, membrane filtration is the crucial cause of the inevitable fouling problem in submerged MBRs. Copyright © 2011 Elsevier Ltd. All rights reserved.

A simple empirical model for the clarification-thickening process in wastewater treatment plants.

PubMed

Zhang, Y K; Wang, H C; Qi, L; Liu, G H; He, Z J; Fan, H T

2015-01-01

In wastewater treatment plants (WWTPs), activated sludge is thickened in secondary settling tanks and recycled into the biological reactor to maintain enough biomass for wastewater treatment. Accurately estimating the activated sludge concentration in the lower portion of the secondary clarifiers is of great importance for evaluating and controlling the sludge recycled ratio, ensuring smooth and efficient operation of the WWTP. By dividing the overall activated sludge-thickening curve into a hindered zone and a compression zone, an empirical model describing activated sludge thickening in the compression zone was obtained by empirical regression. This empirical model was developed through experiments conducted using sludge from five WWTPs, and validated by the measured data from a sixth WWTP, which fit the model well (R² = 0.98, p < 0.001). The model requires application of only one parameter, the sludge volume index (SVI), which is readily incorporated into routine analysis. By combining this model with the conservation of mass equation, an empirical model for compression settling was also developed. Finally, the effects of denitrification and addition of a polymer were also analysed because of their effect on sludge thickening, which can be useful for WWTP operation, e.g., improving wastewater treatment or the proper use of the polymer.

Cloning of a heavy-metal-binding protein derived from activated-sludge microorganisms.

PubMed

Sano, Daisuke; Myojo, Ken; Omura, Tatsuo

2006-09-01

A gene of the heavy-metal-binding protein (HMBP) was newly isolated from a genetic DNA library of activated-sludge microorganisms. HMBP was produced by transformed Escherichia coli, and the copper-binding ability of HMBP was confirmed. HMBP derived from activated sludge could be available as heavy metal adsorbents in water and wastewater treatments.

Agronomic value of sewage sludge and corn cob biochar in an infertile Oxisol

NASA Astrophysics Data System (ADS)

Deenik, J. L.; Cooney, M. J.; Antal, M. J., Jr.

2013-12-01

Disposal of sewage sludge and other agricultural waste materials has become increasingly difficult in urban environments with limited land space. Carbonization of the hazardous waste produces biochar as a soil amendment with potential to improve soil quality and productivity. A series of greenhouse pot experiments were conducted to assess the agrnomic value of two biochars made from domestic wastewater sludge and corn cob waste. The ash component of the sewage sludge biochar was very high (65.5%) and high for the corn cob (11.4%) biochars. Both biochars contained low concentrations of heavy metals and met EPA land application criteria. The sewage sludge biochar was a better liming material and source of mineral nutrients than the corn cob biochar, but the corn cob biochar showed the greatest increase in soil carbon and total nitrogen. Both biochar materials increased soil pH compared with soils not receiving biochar, but the sewage sludge biochar was a more effective liming material maintaining elevated soil pH throughout the 3 planting cycles. The sewage sludge biochar also showed the greatest increase in extractable soil P and base cations. In the first planting cycle, both biochars in combination with conventional fertilizers produced significantly higher corn seedling growth than the fertilized control. However, the sewage sludge biochar maintained beneficial effects corn seedling growth through the third planting cycle showing 3-fold increases in biomass production compared with the control in the third planting. The high ash content and associated liming properties and mineral nutrient contributions in the sewage sludge biochar explain benefits to plant growth. Conversion of sewage sludge waste into biochar has the potential to effectively address several environmental issues: 1) convert a hazardous waste into a valuable soil amendment, 2) reduce land and water contamination, and 3) improve soil quality and productivity.

Lipid profiling in sewage sludge.

PubMed

Zhu, Fenfen; Wu, Xuemin; Zhao, Luyao; Liu, Xiaohui; Qi, Juanjuan; Wang, Xueying; Wang, Jiawei

2017-06-01

High value-added reutilization of sewage sludge from wastewater treatment plants (WWTPs) is essential in sustainable development in WWTPs. However, despite the advantage of high value reutilization, this process must be based on a detailed study of organics in sludge. We used the methods employed in life sciences to determine the profile of lipids (cellular lipids, free fatty acids (FFAs), and wax/gum) in five sludge samples obtained from three typical WWTPs in Beijing; these samples include one sludge sample from a primary sedimentation tank, two activated sludge samples from two Anaerobic-Anoxic-Oxic (A2/O) tanks, and two activated sludge samples from two membrane bioreactor tanks. The percentage of total raw lipids varied from 2.90% to 12.3%. Sludge from the primary sedimentation tank showed the highest concentrations of lipid, FFA, and wax/gum and the second highest concentration of cellular lipids. All activated sludge contained an abundance of cellular lipids (>54%). Cells in sludge can from plants, animals, microbes and so on in wastewater. Approximately 14 species of cellular lipids were identified, including considerable high value-potential ceramide (9567-38774 mg/kg), coenzyme (937-3897 mg/kg), and some phosphatidylcholine (75-548 mg/kg). The presence of those lipid constituents would thus require a wider range of recovery methods for sludge. Both cellular lipids and FFAs contain an abundance of C16-C18 lipids at high saturation level, and they serve as good resources for biodiesel production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption of mercury by activated carbon prepared from dried sewage sludge in simulated flue gas.

PubMed

Park, Jeongmin; Lee, Sang-Sup

2018-04-25

Conversion of sewage sludge to activated carbon is attractive as an alternative method to ocean dumping for the disposal of sewage sludge. Injection of activated carbon upstream of particulate matter control devices has been suggested as a method to remove elemental mercury from flue gas. Activated carbon was prepared using various activation temperatures and times and was tested for their mercury adsorption efficiency using lab-scale systems. To understand the effect of the physical property of the activated carbon, its mercury adsorption efficiency was investigated as a function of their Brunauer-Emmett-Teller (BET) surface area. Two simulated flue gas conditions: (1) without hydrogen chloride (HCl) and (2) with 20 ppm HCl, were used to investigate the effect of flue gas composition on the mercury adsorption capacity of activated carbon. Despite very low BET surface area of the prepared sewage sludge activated carbons, their mercury adsorption efficiencies were comparable under both simulated flue gas conditions to those of pinewood and coal activated carbons. After injecting HCl into the simulated flue gas, all sewage sludge activated carbons demonstrated high adsorption efficiencies, i.e., more than 87%, regardless of their BET surface area. IMPLICATIONS We tested activated carbons prepared from dried sewage sludge to investigate the effect of their physical properties on their mercury adsorption efficiency. Using two simulated flue gas conditions, we conducted mercury speciation for the outlet gas. We found that the sewage sludge activated carbon had comparable mercury adsorption efficiency to pinewood and coal activated carbons, and the presence of HCl minimized the effect of physical property of the activated carbon on its mercury adsorption efficiency.

Monitoring of activated sludge settling ability through image analysis: validation on full-scale wastewater treatment plants.

PubMed

Mesquita, D P; Dias, O; Amaral, A L; Ferreira, E C

2009-04-01

In recent years, a great deal of attention has been focused on the research of activated sludge processes, where the solid-liquid separation phase is frequently considered of critical importance, due to the different problems that severely affect the compaction and the settling of the sludge. Bearing that in mind, in this work, image analysis routines were developed in Matlab environment, allowing the identification and characterization of microbial aggregates and protruding filaments in eight different wastewater treatment plants, for a combined period of 2 years. The monitoring of the activated sludge contents allowed for the detection of bulking events proving that the developed image analysis methodology is adequate for a continuous examination of the morphological changes in microbial aggregates and subsequent estimation of the sludge volume index. In fact, the obtained results proved that the developed image analysis methodology is a feasible method for the continuous monitoring of activated sludge systems and identification of disturbances.

Enhancing anaerobic digestion of waste activated sludge by pretreatment: effect of volatile to total solids.

PubMed

Wang, Xiao; Duan, Xu; Chen, Jianguang; Fang, Kuo; Feng, Leiyu; Yan, Yuanyuan; Zhou, Qi

2016-01-01

In this study the effect of volatile to total solids (VS/TS) on anaerobic digestion of waste activated sludge (WAS) pretreated by alkaline, thermal and thermal-alkaline strategies was studied. Experimental results showed that the production of methane from sludge was increased with VS/TS. When anaerobic digesters were fed with sludge pretreated by the thermal-alkaline method, the average methane yield was improved from 2.8 L/d at VS/TS 0.35 to 4.7 L/d at VS/TS 0.56. Also, the efficiency of VS reduction during sludge anaerobic digestion varied between 18.9% and 45.6%, and increased gradually with VS/TS. Mechanism investigation of VS/TS on WAS anaerobic digestion suggested that the general activities of anaerobic microorganisms, activities of key enzymes related to sludge hydrolysis, acidification and methanogenesis, and the ratio of Archaea to Bacteria were all increased with VS/TS, showing good agreement with methane production.

A Novel Model for the Entire Settling-Thickening Process in a Secondary Settling Tank.

PubMed

He, Zhijiang; Zhang, Yuankai; Wang, Hongchen; Qi, Lu; Yin, Xunfei; Zhang, Xiaojun; Wen, Yang

2016-12-01

  Sludge settling and thickening occur simultaneously in secondary settling tanks (SSTs). The ability to accurately calculate the settling and thickening capacity of activated sludge was of great importance. Despite extensive studies on the development of settling velocity models for use with SSTs, these models have not been applied due to the difficulty in calibrating the related parameters. Additionally, there have been some studies of the thickening behavior of the activated sludge in SSTs. In this study, a novel settling and thickening model for activated sludge was developed, and the model was validated using experimental data (R2 = 0.830 to 0.963, p < 0.001), which is more reasonable for the characterization of the settling and thickening behavior of the activated sludge in an SST. The application of these models requires only one critical parameter, namely, the stirred sludge volume index SSVI3.5, which is readily available in a water resource recovery facility.

Occurrence and risk assessment of nonylphenol and nonylphenol ethoxylates in sewage sludge from different conventional treatment processes.

PubMed

González, M M; Martín, J; Santos, J L; Aparicio, I; Alonso, E

2010-01-01

In the present work, the concentrations of the organic pollutants nonylphenol (NP) and nonylphenol mono- and diethoxylates (NP1EO and NP2EO, respectively) in primary, secondary, mixed, aerobically-digested, anaerobically-digested, dehydrated, compost and lagoon sludge samples from different sludge treatments have been evaluated. Toxicological risk assessment of these compounds in sludge and sludge-amended soil has also been reported. NP, NP1EO and NP2EO were monitored in sludge samples obtained from treatment plants located in Andalusia (south of Spain) based on anaerobic treatments (11 anaerobic-digestion wastewater treatment plants and 3 anaerobic wastewater stabilization ponds) or on aerobic treatments (3 aerobic-digestion wastewater treatment plants, 1 dehydration treatment plant and 2 composting plants). The sum of NP, NP1EO and NP2EO (NPE) concentrations has been evaluated in relation to the limit value of 50 mg/kg set by the European Union Sludge Directive draft published in April 2000 (Working Document on Sludge). In most of the samples, NP was present at higher concentration levels (mean value 88.0 mg/kg dm) than NP1EO (mean value 33.8 mg/kg dm) and NP2EO (mean value 14.0 mg/kg dm). The most contaminated samples were compost, anaerobically-digested sludge, lagoon sludge and aerobically-digested sludge samples, which contained NPE concentrations in the ranges 44-962 mg/kg dm, 8-669 mg/kg dm, 27-319 mg/kg dm and 61-282 mg/kg dm, respectively. Risk quotients, expressed as the ratios between environmental concentrations and the predicted no-effect concentrations, were higher than 1 for NP, NP1EO and NP2EO in the 99%, 92% and 36% of the studied samples, respectively; and higher than 1 in the 86%, 6% and 2%, respectively, after sludge application to soil, leading to a significant ecotoxicological risk mainly due to the presence of NP.

Influence of loosely bound extracellular polymeric substances (EPS) on the flocculation, sedimentation and dewaterability of activated sludge.

PubMed

Li, X Y; Yang, S F

2007-03-01

Laboratory experiments on the activated sludge (AS) process were carried out to investigate the influence of microbial extracellular polymeric substances (EPS), including loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS), on biomass flocculation, sludge settlement and dewaterability. The heat EPS extraction method was modified to include a mild step and a harsh step for extracting the LB-EPS and TB-EPS, respectively, from the sludge suspension. Six lab-scale AS reactors were used to grow AS with different carbon sources of glucose and sodium acetate, and different sludge retention times (SRTs) of 5, 10 and 20 days. The variation in the bioreactor condition produced sludge with different abundances of EPS and different flocculation and separation characteristics. The sludge that was fed on glucose had more EPS than the sludge that was fed on acetate. For any of the feeding substrates, the sludge had a nearly consistent TB-EPS value regardless of the SRT, and an LB-EPS content that decreased with the SRT. The acetate-fed sludge performed better than the glucose-fed sludge in terms of bioflocculation, sludge sedimentation and compression, and sludge dewaterability. The sludge flocculation and separation improved considerably as the SRT lengthened. The results demonstrate that the LB-EPS had a negative effect on bioflocculation and sludge-water separation. The parameters for the performance of sludge-water separation were much more closely correlated with the amount of LB-EPS than with the amount of TB-EPS. It is argued that although EPS is essential to sludge floc formation, excessive EPS in the form of LB-EPS could weaken cell attachment and the floc structure, resulting in poor bioflocculation, greater cell erosion and retarded sludge-water separation.

The effect of lime-dried sewage sludge on the heat-resistance of eco-cement.

PubMed

Li, Wen-Quan; Liu, Wei; Cao, Hai-Hua; Xu, Jing-Cheng; Liu, Jia; Li, Guang-Ming; Huang, Juwen

2016-01-01

The treatment and disposal of sewage sludge is a growing problem for sewage treatment plants. One method of disposal is to use sewage sludge as partial replacement for raw material in cement manufacture. Although this process has been well researched, little attention has been given to the thermal properties of cement that has had sewage sludge incorporated in the manufacturing process. This study investigated the fire endurance of eco-cement to which lime-dried sludge (LDS) had been added. LDS was added in proportions of 0%, 3%, 6%, 9%, and 12% (by weight) to the raw material. The eco-cement was exposed to 200, 400, or 600 °C for 3 h. The residual strength and the microstructural properties of eco-cement were then studied. Results showed that the eco-cement samples suffered less damage than conventional cement at 600 °C. The microstructural studies showed that LDS incorporation could reduce Ca(OH)(2) content. It was concluded that LDS has the potential to improve the heat resistance of eco-cement products.

Combined System of Activated Sludge and Ozonation for the Treatment of Kraft E1 Effluent

PubMed Central

Assalin, Marcia Regina; dos Santos Almeida, Edna; Durán, Nelson

2009-01-01

The treatment of paper mill effluent for COD, TOC, total phenols and color removal was investigated using combined activated sludge-ozonation processes and single processes. The combined activated sludge-O3/pH 10 treatment was able to remove around 80% of COD, TOC and color from Kraft E1 effluent. For the total phenols, the efficiency removal was around 70%. The ozonation post treatment carried out at pH 8.3 also showed better results than the single process. The COD, TOC, color and total phenols removal efficiency obtained were 75.5, 59.1, 77 and 52.3%, respectively. The difference in the concentrations of free radical produced by activated sludge-O3/pH 10 and activated sludge-O3/pH 8.3 affected mainly the TOC and total phenol removal values. PMID:19440438

[Inhibition of Denitrification by Total Phenol Load of Coal Gasification Wastewater].

PubMed

Zhang, Yu-ying; Chen, Xiu-rong; Wang, Lu; Li, Jia-hui; Xu, Yan; Zhuang, You-jun; Yu, Ze-ya

2016-03-15

High loaded phenolic pollutants, refractory and high toxic, which existed in coal gasification wastewater, could cause the inhibition of sludge activity. In biological denitrification process of activated sludge treatment system, people tend to focus on the phenol inhibition on the efficiency and activity of nitrifying bacteria while there are few researches on the denitrification process. In order to investigate the inhibition of phenolic compounds from coal gasification wastewater on the denitrification and sludge activity, we used anoxic denitrification system to indentify the influence of different phenol load on denitrification efficiency (removal efficiency of NO₃⁻-N and NO₂⁻-N) as well as the stress and degradation activity of sludge. The results showed that when the concentration of total phenol was changed from 50 mg · L⁻¹ to 200 mg · L⁻¹, the removal rates of NO₃⁻-N and NO₂⁻-N were changed from 55% and 25% to 83% and 83% respectively. In the process of sludge domestication, the characteristics of denitrifying sludge were influenced to a certain degree.

Effects of irradiation intensity and pH on nutrients release and solids destruction of waste activated sludge using the microwave-enhanced advanced oxidation process.

PubMed

Chan, W I; Liao, P H; Lo, K V

2010-11-01

Using the microwave-enhanced advanced oxidation process (MW/H2O2-AOP), the pH and irradiation intensity on waste activated sludge samples were investigated to provide insight to the athermal effects on nutrients release, solids destruction, particle size distribution and dewaterability, and to demonstrate their interrelationships. Carbonaceous matters and nutrients released into solution depended on the irradiation intensity and time. Higher irradiation levels tended to be more effective in the solubilization of nutrients and had more pronounced effects in the dewaterability of sludge. In terms of particle size distribution, detectable particles increased in size for treatments in acidic conditions, while the dewaterability of treated sludge was improved. In treatments under neutral and alkaline conditions, the particle size range increased, with more small particles formed, thereby significantly deteriorating the dewaterability of sludge treated in alkaline conditions. The best results for the solubilization of nutrients were in alkaline conditions with high irradiation power, but dewaterability of the sludge was compromised. Sludge treatment with the MW/H2O2-AOP in acidic conditions with high irradiation power yielded the best dewaterable sludge and significant nutrient solubilization; therefore, it is the recommended treatment condition for activated sludge.

Effects of mechanical disintegration of activated sludge on the activity of nitrifying and denitrifying bacteria and phosphorus accumulating organisms.

PubMed

Zubrowska-Sudol, Monika; Walczak, Justyna

2014-09-15

The purpose of the study was to analyse the impact of hydrodynamic disintegration of thickened excess activated sludge, performed at different levels of energy density (70, 140 and 210 kJ/L), on the activity of microorganisms involved in nutrient removal from wastewater, i.e. nitrifiers, denitrifiers and phosphorus accumulating organisms (PAOs). Ammonium and nitrogen utilisation rates and phosphorus release rates for raw and disintegrated sludge were determined using batch tests. The experiment also included: 1) analysis of organic and nutrient compound release from activated sludge flocs, 2) determination of the sludge disintegration degree (DD), and 3) evaluation of respiratory activity of the biomass by using the oxygen uptake rate (OUR) batch test. It was shown that the activity degree of the examined groups of microorganisms depended on energy density and related sludge disintegration degree, and that inactivation of individual groups of microorganisms occurred at different values of DD. Least resistant to the destruction of activated sludge flocs turned out to be phosphorus accumulating organisms, while the most resistant were denitrifiers. A decrease of 20-40% in PAO activity was noted already at DD equal to 3-5%. The threshold values of DD, after crossing which the inactivation of nitrifiers and denitrifiers occurred, were equal to 8% and 10%, respectively. At lesser DD values an increase in the activity of these groups of microorganisms was observed, averaging 20.2-41.7% for nitrifiers and 9.98-36.3% for denitrifiers. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhancement of activated sludge disintegration and dewaterability by Fenton process

NASA Astrophysics Data System (ADS)

Heng, G. C.; Isa, M. H.

2016-06-01

Municipal and industrial wastewater treatment plants produce large amounts of sludge. This excess sludge is an inevitable drawback inherent to the activated sludge process. In this study, the waste activated sludge was obtained from the campus wastewater treatment plant at Universiti Teknologi PETRONAS (UTP), Malaysia. Fenton pretreatment was optimized by using the response surface methodology (RSM) to study the effects of three operating conditions including the dosage of H2O2 (g H2O2/kg TS), the molar ratio of H2O2/Fe2+ and reaction time. The optimum operating variables to achieve MLVSS removal 65%, CST reduction 28%, sCOD 11000 mg/L and EPS 500 mg/L were: 1000 g H2O2/kg TS, H2O2/Fe2+ molar ratio 70 and reaction time 45 min. Fenton process was proved to be able to enhance the sludge disintegration and dewaterability.

Effect of enzyme secreting bacterial pretreatment on enhancement of aerobic digestion potential of waste activated sludge interceded through EDTA.

PubMed

Kavitha, S; Adish Kumar, S; Yogalakshmi, K N; Kaliappan, S; Rajesh Banu, J

2013-12-01

In this study, the effect of Ethylene diamine tetra acetic acid (EDTA) on Extracellular polymeric substance (EPS) removal tailed with bacterial enzymatic pretreatment on aerobic digestion of activated sludge was studied. In order to enhance the accessibility of sludge to the enzyme secreting bacteria; the extracellular polymeric substances were removed using EDTA. EDTA efficiently removed the EPS with limited cell lysis and enhanced the sludge enzyme activity at its lower concentration of 0.2 g/g SS. The sludge was then subjected to bacterial pretreatment to enhance the aerobic digestion. In aerobic digestion the best results in terms of Suspended solids (SS) reduction (48.5%) and COD (Chemical oxygen demand) solubilization (47.3%) was obtained in experimental reactor than in control. These results imply that aerobic digestion can be enhanced efficiently through bacterial pretreatment of EPS removed sludge. Copyright © 2013 Elsevier Ltd. All rights reserved.

SUMMARY REPORT: THE CAUSES AND CONTROL OF ACTIVATED SLUDGE BULKING AND FOAMING

EPA Science Inventory

This 92-page Technology Transfer Summary Report provides reference material on the causes and controls of sludge bulking and foaming in activated sludge treatment that can be readily understood, and it includes sufficient detail to help plant operators control their systems. The ...

Perfluoroalkyl substances (PFASs) in wastewater treatment plants and drinking water treatment plants: Removal efficiency and exposure risk.

PubMed

Pan, Chang-Gui; Liu, You-Sheng; Ying, Guang-Guo

2016-12-01

Perfluoroalkyl substances (PFASs) are a group of chemicals with wide industrial and commercial applications, and have been received great attentions due to their persistence in the environment. The information about their presence in urban water cycle is still limited. This study aimed to investigate the occurrence and removal efficiency of eighteen PFASs in wastewater treatment plants (WWTPs) and drinking water plants (DWTPs) with different treatment processes. The results showed that both perfluorobutane sulfonic acid (PFBS) and perfluorooctane sulfonic acid (PFOS) were the predominant compounds in the water phase of WWTPs and DWTPs, while PFOS was dominant in dewatered sludge of WWTPs. The average total PFASs concentrations in the three selected WWTPs were 19.6-232 ng/L in influents, 15.5-234 ng/L in effluents, and 31.5-49.1 ng/g dry weight in sludge. The distribution pattern of PFASs differed between the wastewater and sludge samples, indicating strong partition of PFASs with long carbon chains to sludge. In the WWTPs, most PFASs were not eliminated efficiently in conventional activated sludge treatment, while the membrane bio-reactor (MBR) and Unitank removed approximately 50% of long chain (C ≥ 8) perfluorocarboxylic acids (PFCAs). The daily mass loads of total PFASs in WWTPs were in the range of 1956-24773 mg in influent and 1548-25085 mg in effluent. PFASs were found at higher concentrations in the wastewater from plant A with some industrial wastewater input than from the other two plants (plant B and plant C) with mainly domestic wastewater sources. Meanwhile, the average total PFASs concentrations in the two selected DWTPs were detected at 4.74-14.3 ng/L in the influent and 3.34-13.9 ng/L in the effluent. In DWTPs, only granular activated carbon (GAC) and powder activated carbon (PAC) showed significant removal of PFASs. The PFASs detected in the tap water would not pose immediate health risks in the short term exposure. The findings from this study showed that effective treatment technology should be applied to eliminate this group of chemicals in the urban water cycle based on the precautionary principle. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of anaerobic digestion processes for short sludge-age waste activated sludge combined with anammox treatment of digestate liquor.

PubMed

Ge, Huoqing; Batstone, Damien; Keller, Jurg

2016-01-01

The need to reduce energy input and enhance energy recovery from wastewater is driving renewed interest in high-rate activated sludge treatment (i.e. short hydraulic and solids retention times (HRT and SRT, respectively)). This process generates short SRT activated sludge stream, which should be highly degradable. However, the evaluation of anaerobic digestion of short SRT sludge has been limited. This paper assesses anaerobic digestion of short SRT sludge digestion derived from meat processing wastewater under thermophilic and mesophilic conditions. The thermophilic digestion system (55°C) achieved 60 and 68% volatile solids destruction at 8 day and 10 day HRT, respectively, compared with 50% in the mesophilic digestion system (35°C, 10 day HRT). The digestion effluents from the thermophilic (8-10 day HRT) and mesophilic systems were stable, as assessed by residual methane potentials. The ammonia rich sludge dewatering liquor was effectively treated by a batch anammox process, which exhibited comparable nitrogen removal rate as the tests using a control synthetic ammonia solution, indicating that the dewatering liquor did not have inhibiting/toxic effects on the anammox activity.

Complete solids retention activated sludge process.

PubMed

Amanatidou, E; Samiotis, G; Trikoilidou, E; Pekridis, G; Tsikritzis, L

2016-01-01

In a slaughterhouse's full-scale extended aeration activated sludge wastewater treatment plant (WWTP), operating under complete solids retention time, the evolution of mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) concentration, food to micro-organisms ratio (F/M) and substrate utilization rate (SUR) were studied for over a year. Biomass growth phases in correlation to sludge biological and morphological characteristics were studied. Three distinguished growth phases were observed during the 425 days of monitoring. The imposed operational conditions led the process to extended biomass starvation conditions, minimum F/M, minimum SUR and predator species growth. MLSS and MLVSS reached a stabilization phase (plateau phase) where almost zero sludge accumulation was observed. The concept of degradation of the considered non-biodegradable particulate compounds in influent and in biomass (cell debris) was also studied. Comparison of evolution of observed sludge yields (Yobs) in the WWTP with Yobs predictions by activated sludge models verified the degradation concept for the considered non-biodegradable compounds. Control of the sedimentation process was achieved, by predicting the solids loading rate critical point using state point analysis and stirred/unstirred settling velocity tests and by applying a high return activated sludge rate. The nitrogen gas related sedimentation problems were taken into consideration.

Preparation of thiol-functionalized activated carbon from sewage sludge with coal blending for heavy metal removal from contaminated water.

PubMed

Li, Juan; Xing, Xing; Li, Jiao; Shi, Mei; Lin, Aijun; Xu, Congbin; Zheng, Jianzhong; Li, Ronghua

2018-03-01

Sewage sludge produced from wastewater treatment is a pressing environmental issue. Mismanagement of the massive amount of sewage sludge would threat our valuble surface and shallow ground water resources. Use of activated carbon prepared from carbonization of these sludges for heavy metal removal can not only minimize and stabilize these hazardous materials but also realize resources reuse. In this study, thiol-functionalized activated carbon was synthesized from coal-blended sewage sludge, and its capacity was examined for removing Cu(II), Pb(II), Cd(II) and Ni(II) from water. Pyrolysis conditions to prepare activated carbons from the sludge and coal mixture were examined, and the synthesized material was found to achieve the highest BET surface area of 1094 m 2 /g under 500 °C and 30 min. Batch equilibrium tests indicated that the thiol-functionalized activated carbon had a maximum sorption capacity of 238.1, 96.2, 87.7 and 52.4 mg/g for Pb(II), Cd(II), Cu(II) and Ni(II) removal from water, respectively. Findings of this study suggest that thiol-functionalized activated carbon prepared from coal-blended sewage sludge would be a promising sorbent material for heavy metal removal from waters contaminated with Cu(II), Pb(II), Cd(II) and Ni(II). Copyright © 2017 Elsevier Ltd. All rights reserved.

A pilot-scale study on PVA gel beads based integrated fixed film activated sludge (IFAS) plant for municipal wastewater treatment.

PubMed

Kumar Singh, Nitin; Singh, Jasdeep; Bhatia, Aakansha; Kazmi, A A

2016-01-01

In the present study, a pilot-scale reactor incorporating polyvinyl alcohol gel beads as biomass carrier and operating in biological activated sludge mode (a combination of moving bed biofilm reactor (MBBR) and activated sludge) was investigated for the treatment of actual municipal wastewater. The results, during a monitoring period of 4 months, showed effective removal of chemical oxygen demand (COD), biological oxygen demand (BOD) and NH3-N at optimum conditions with 91%, ∼92% and ∼90% removal efficiencies, respectively. Sludge volume index (SVI) values of activated sludge varied in the range of 25-72 mL/g, indicating appreciable settling characteristics. Furthermore, soluble COD and BOD in the effluent of the pilot plant were reduced to levels well below discharge limits of the Punjab Pollution Control Board, India. A culture dependent method was used to enrich and isolate abundant heterotrophic bacteria in activated sludge. In addition to this, 16S rRNA genes analysis was performed to identify diverse dominant bacterial species in suspended and attached biomass. Results revealed that Escherichia coli, Pseudomonas sp. and Nitrosomonas communis played a significant role in biomass carrier, while Acinetobactor sp. were dominant in activated sludge of the pilot plant. Identification of ciliated protozoa populations rendered six species of ciliates in the plant, among which Vorticella was the most dominant.

Sorption and Release of Organics by Primary, Anaerobic, and Aerobic Activated Sludge Mixed with Raw Municipal Wastewater

PubMed Central

Modin, Oskar; Saheb Alam, Soroush; Persson, Frank; Wilén, Britt-Marie

2015-01-01

New activated sludge processes that utilize sorption as a major mechanism for organics removal are being developed to maximize energy recovery from wastewater organics, or as enhanced primary treatment technologies. To model and optimize sorption-based activated sludge processes, further knowledge about sorption of organics onto sludge is needed. This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed. Batch sorption assays were carried out without aeration at a mixing velocity of 200 rpm. Only aerobic activated sludge showed net sorption of organics. Sorption of dissolved organics occurred by a near-instantaneous sorption event followed by a slower process that obeyed 1st order kinetics. Sorption of particulates also followed 1st order kinetics but there was no instantaneous sorption event; instead there was a release of particles upon mixing. The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics. The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215–230 nm were also rapidly removed. PMID:25768429

Polyhydroxyalkanoate production potential of heterotrophic bacteria in activated sludge.

PubMed

Inoue, Daisuke; Suzuki, Yuta; Uchida, Takahiro; Morohoshi, Jota; Sei, Kazunari

2016-01-01

This study was conducted to evaluate the polyhydroxyalkanoate (PHA) production potential of cultivable heterotrophic bacteria in activated sludge by genotypic and phenotypic characterizations. A total of 114 bacterial strains were isolated from four activated sludge samples taken from a lab-scale sequencing batch reactor and three wastewater treatment processes of two municipal wastewater treatment plants. PCR detection of the phaC genes encoding class I and II PHA synthase revealed that 15% of the total isolates possessed phaC genes, all of which had the closest similarities to known phaC genes of α- and β-Proteobacteria and Actinobacteria. PHA production experiments under aerobic and nitrogen-limited conditions showed that 68% of the total isolates were capable of producing PHA from at least one of the six substrates used (acetate, propionate, lactate, butyrate, glucose and glycerol). Genotypic and phenotypic characterizations revealed that 75% of the activated sludge bacteria had PHA production potential. Our results also indicated that short-chain fatty acids would be the preferable substrates for PHA production by activated sludge bacteria, and that there might be a variety of unidentified phaC genes in activated sludge. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Dynamic modeling of nitrogen removal for a three-stage integrated fixed-film activated sludge process treating municipal wastewater.

PubMed

Moretti, Paul; Choubert, Jean-Marc; Canler, Jean-Pierre; Buffière, Pierre; Pétrimaux, Olivier; Lessard, Paul

2018-02-01

The integrated fixed-film activated sludge (IFAS) process is being increasingly used to enhance nitrogen removal for former activated sludge systems. The aim of this work is to evaluate a numerical model of a new nitrifying/denitrifying IFAS configuration. It consists of two carrier-free reactors (anoxic and aerobic) and one IFAS reactor with a filling ratio of 43% of carriers, followed by a clarifier. Simulations were carried out with GPS-X involving the nitrification reaction combined with a 1D heterogeneous biofilm model, including attachment/detachment processes. An original iterative calibration protocol was created comprising four steps and nine actions. Experimental campaigns were carried out to collect data on the pilot in operation, specifically for modelling purpose. The model used was able to predict properly the variations of the activated sludge (bulk) and the biofilm masses, the nitrification rates of both the activated sludge and the biofilm, and the nitrogen concentration in the effluent for short (4-10 days) and long (300 days) simulation runs. A calibrated parameter set is proposed (biokinetics, detachment, diffusion) related to the activated sludge, the biofilm and the effluent variables to enhance the model prediction on hourly and daily data sets.

Enhancement of methane production in anaerobic digestion of sewage sludge by thermal hydrolysis pretreatment.

PubMed

Choi, Jae-Min; Han, Sun-Kee; Lee, Chae-Young

2018-07-01

This study was performed to optimize thermal hydrolysis pretreatment (THP) of sewage sludge for enhanced anaerobic digestion (AD). Using the response surface methodology (RSM), the optimal conditions were found 180 °C of reaction temperature and 76 min of reaction time. Through THP under optimal conditions, high molecular substances in sewage sludge such as soluble microbial by-products (SMPs) and extracellular polymeric substances (EPSs) were hydrolyzed into low molecular ones without the generation of refractory compounds. The microbial community analysis revealed that relative abundances of Methanomicrobia such as Methanosarcina, Methanosaeta (acetoclastic methanogens), and Methanoculleus (hydrogenotrophic methanogens) in AD with THP were higher than those in conventional AD. Copyright © 2018. Published by Elsevier Ltd.

[Amelioration effects of wastewater sludge biochars on red soil acidity and their environmental risk].

PubMed

Lu, Zai-Liang; Li, Jiu-Yu; Jiang, Jun; Xu, Ren-Kou

2012-10-01

Biochars were prepared from wastewater sludge from two wastewater treatment plants in Nanjing using a pyrolysis method at 300, 500 and 700 degrees C. The properties of the biochars were measured, and their amelioration effects on the acidity of a red soil and environmental risk of application of sludge biochars were examined to evaluate the possibility of agricultural application of wastewater sludge biochars in red soils. Results indicated that incorporation of both sludge and sludge biochar increased soil pH due to the alkalinity of sludge and sludge biochar, and the mineralization of organic N and nitrification of ammonium N from wastewater sludge induced soil pH fluctuated during incubation. The amelioration effects of biochars generated at 500 and 700 degrees C on the soil were significantly greater than that of sludge significantly. Sludge and sludge biochar contain ample base cations of Ca2+, Mg2+, K+ and Na+ and thus incorporation of sludge and sludge biochar increased the contents of soil exchangeable base cations and decreased soil exchangeable aluminum and H+. Contents of heavy metals in sludge biochars were greater than these in their feedstock sludge, while the contents of Cu, Pb, Ni and As in sludge biochars were lower than the standard values of heavy metals were wastewater sludge for agricultural use in acid soils in China except for Zn and Cd. The contents of available forms of heavy metals in the biochars generated from sludge from Chengdong wastewater treatment plant was lower than these in the corresponding sludge, suggesting that pyrolysis proceed decreased the activity of heavy metals in wastewater sludge. After 90-day incubation of the soil with sludge and sludge biochar, the differences in the contents of soil available heavy metals were not significant between the biochars and their feedstock sludge from Jiangxizhou wastewater treatment plant, and the contents in the treatments with biochars added was lower than these in the treatments with the corresponding sludge from Chengdong wastewater treatment plant for most of heavy metals. It can be concluded that the biochars from wastewater sludge could be used as soil amendments to adjust soil acidity. Application of sludge biochars did not increase activity and availability of heavy metals compared with direct incorporation of the sludge.

40 CFR 503.24 - Management practices.

Code of Federal Regulations, 2011 CFR

2011-07-01

... event. (h) The leachate collection system for an active sewage sludge unit that has a liner and leachate... three years after the sewage sludge unit closes. (i) Leachate from an active sewage sludge unit that has a liner and leachate collection system shall be collected and shall be disposed in accordance with...

40 CFR 503.24 - Management practices.

Code of Federal Regulations, 2013 CFR

2013-07-01

... event. (h) The leachate collection system for an active sewage sludge unit that has a liner and leachate... three years after the sewage sludge unit closes. (i) Leachate from an active sewage sludge unit that has a liner and leachate collection system shall be collected and shall be disposed in accordance with...

40 CFR 503.24 - Management practices.

Code of Federal Regulations, 2014 CFR

2014-07-01

... event. (h) The leachate collection system for an active sewage sludge unit that has a liner and leachate... three years after the sewage sludge unit closes. (i) Leachate from an active sewage sludge unit that has a liner and leachate collection system shall be collected and shall be disposed in accordance with...

40 CFR 503.24 - Management practices.

Code of Federal Regulations, 2012 CFR

2012-07-01

... event. (h) The leachate collection system for an active sewage sludge unit that has a liner and leachate... three years after the sewage sludge unit closes. (i) Leachate from an active sewage sludge unit that has a liner and leachate collection system shall be collected and shall be disposed in accordance with...

Determination of Microbial Growth by Protein Assay in an Air-Cathode Single Chamber Microbial Fuel Cell.

PubMed

Li, Na; Kakarla, Ramesh; Moon, Jung Mi; Min, Booki

2015-07-01

Microbial fuel cells (MFCs) have gathered attention as a novel bioenergy technology to simultaneously treat wastewater with less sludge production than the conventional activated sludge system. In two different operations of the MFC and aerobic process, microbial growth was determined by the protein assay method and their biomass yields using real wastewater were compared. The biomass yield on the anode electrode of the MFC was 0.02 g-COD-cell/g- COD-substrate and the anolyte planktonic biomass was 0.14 g-COD-cell/g-COD-substrate. An MFC without anode electrode resulted in the biomass yield of 0.07 ± 0.03 g-COD-cell/g-COD-substrate, suggesting that oxygen diffusion from the cathode possibly supported the microbial growth. In a comparative test, the biomass yield under aerobic environment was 0.46 ± 0.07 g-COD-cell/g-COD-substrate, which was about 3 times higher than the total biomass value in the MFC operation.

Economic and environmental sustainability of submerged anaerobic MBR-based (AnMBR-based) technology as compared to aerobic-based technologies for moderate-/high-loaded urban wastewater treatment.

PubMed

Pretel, R; Robles, A; Ruano, M V; Seco, A; Ferrer, J

2016-01-15

The objective of this study was to assess the economic and environmental sustainability of submerged anaerobic membrane bioreactors (AnMBRs) in comparison with aerobic-based technologies for moderate-/high-loaded urban wastewater (UWW) treatment. To this aim, a combined approach of steady-state performance modelling, life cycle analysis (LCA) and life cycle costing (LCC) was used, in which AnMBR (coupled with an aerobic-based post-treatment) was compared to aerobic membrane bioreactor (AeMBR) and conventional activated sludge (CAS). AnMBR with CAS-based post-treatment for nutrient removal was identified as a sustainable option for moderate-/high-loaded UWW treatment: low energy consumption and reduced sludge production could be obtained at given operating conditions. In addition, significant reductions can be achieved in different aspects of environmental impact (global warming potential (GWP), abiotic depletion, acidification, etc.) and LCC over existing UWW treatment technologies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Aerobic sludge granulation for simultaneous anaerobic decolorization and aerobic aromatic amines mineralization for azo dye wastewater treatment.

PubMed

Yan, Lawrence K Q; Fung, Ka Y; Ng, Ka M

2018-06-01

In this study, the capability of using aerobic granules to undergo simultaneous anaerobic decolorization and aerobic aromatic amines degradation was demonstrated for azo dye wastewater treatment. An integrated acclimation-granulation process was devised, with Mordant Orange 1 as the model pollutant. Performance tests were carried out in a batch column reactor to evaluate the effect of various operating parameters. The optimal condition was to use 1.0-1.7 mm (1.51 ± 0.33 mm) granules, 5 g/L biomass, and 4000 mg/L organics as nutrient; and supplement the wastewater with 1  mg/L dissolved oxygen. This led to a dye mineralization of 61 ± 2%, an anaerobic dye removal of 88 ± 1%, and an aerobic aromatic amines removal of 70 ± 3% within 48 h. This study showed that simultaneous anaerobic/aerobic process by aerobic granules could be a possible alternative to the conventional activated sludge process.

MBR pilot plant for textile wastewater treatment and reuse.

PubMed

Lubello, C; Caffaz, S; Mangini, L; Santianni, D; Caretti, C

2007-01-01

An experimental study was carried out in order to evaluate the possibility of upgrading the conventional activated sludge WWTP of Seano (Prato, Italy) which treats municipal and textile wastewaters, by using membrane bioreactor (MBR) technology. The MBR pilot plant, set up within Seano WWTP, was fed with mixed municipal-industrial wastewaters during the first experimental period and with pure industrial wastewaters during the second. Performances and operation of the MBR were evaluated in terms of permeate characteristics and variability (COD, colour, surfactants, total N and P) and other operational parameters (sludge growth and observed yield). According to the experimental results the MBR permeate quality was always superior to the Seano WWTP one and it was suitable for industrial reuse in the textile district of the Prato area. Respirometric tests provided a modified IWA ASM1 model which fits very well the experimental data and can be used for the design and the monitoring of a full-scale MBR pilot plant.

Performance indicators and indices of sludge management in urban wastewater treatment plants.

PubMed

Silva, C; Saldanha Matos, J; Rosa, M J

2016-12-15

Sludge (or biosolids) management is highly complex and has a significant cost associated with the biosolids disposal, as well as with the energy and flocculant consumption in the sludge processing units. The sludge management performance indicators (PIs) and indices (PXs) are thus core measures of the performance assessment system developed for urban wastewater treatment plants (WWTPs). The key PIs proposed cover the sludge unit production and dry solids concentration (DS), disposal/beneficial use, quality compliance for agricultural use and costs, whereas the complementary PIs assess the plant reliability and the chemical reagents' use. A key PI was also developed for assessing the phosphorus reclamation, namely through the beneficial use of the biosolids and the reclaimed water in agriculture. The results of a field study with 17 Portuguese urban WWTPs in a 5-year period were used to derive the PI reference values which are neither inherent to the PI formulation nor literature-based. Clusters by sludge type (primary, activated, trickling filter and mixed sludge) and by digestion and dewatering processes were analysed and the reference values for sludge production and dry solids were proposed for two clusters: activated sludge or biofilter WWTPs with primary sedimentation, sludge anaerobic digestion and centrifuge dewatering; activated sludge WWTPs without primary sedimentation and anaerobic digestion and with centrifuge dewatering. The key PXs are computed for the DS after each processing unit and the complementary PXs for the energy consumption and the operating conditions DS-determining. The PX reference values are treatment specific and literature based. The PI and PX system was applied to a WWTP and the results demonstrate that it diagnosis the situation and indicates opportunities and measures for improving the WWTP performance in sludge management. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impact of sludge treatments on the extractability and fate of acetyl sulfamethoxazole residues in amended soils.

PubMed

Geng, Chunnu; Bergheaud, Valérie; Garnier, Patricia; Zhu, Yong-Guan; Haudin, Claire-Sophie

2018-03-01

Sludge recycled in agriculture may bring antibiotics into cropped soils. The nature, total amount, and availability of the antibiotics in soil partly depend on the sludge treatments. Our paper compares the fate of N-acetyl sulfamethoxazole (AC-SMX) residues between soils incubated with the same sludge but submitted to different processes before being added in soil. The fate of 14 C-AC-SMX residues was studied in mixtures of soil and sludges at different treatment levels: 1) activated and 2) centrifuged sludges, both enriched with 14 C-AC-SMX, and 3) limed and 4) heat-dried sludges obtained by treating the previously contaminated centrifuged sludge. The evolution of the extractability of 14 C residues (CaCl 2 , methanol) and their mineralization were followed during 119 days. More than 80% of the initial 14 C-activity was no longer extractable after 14 days, except in soil with limed sludge. Liming and drying the centrifuged sludge decreased the mineralized 14 C fraction from 5.7-6.4% to 1.2-1.8% and consequently, the corresponding soils contained more 14 C residues after 119 days. Although 14 C residues were more CaCl 2 -extractable in soil with limed sludge, they seemed to be poorly bioavailable for biodegradation. For all solid sludges, the mineralization rate of 14 C-AC-SMX residues was strongly correlated to that of sludge organic carbon, with a coefficient three times lower for the limed and dried sludges than for the centrifuged sludge after 14 days. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elimination of Cu(II) toxicity by powdered waste sludge (PWS) addition to an activated sludge unit treating Cu(II) containing synthetic wastewater.

PubMed

Pamukoglu, M Yunus; Kargi, Fikret

2007-09-05

Copper(II) ion toxicity onto activated sludge organisms was eliminated by addition of powdered waste sludge (PWS) to the feed wastewater for removal of Cu(II) ions by biosorption before biological treatment. The synthetic feed wastewater containing 14 or 22 mgl(-1) Cu(II) was mixed with PWS in a mixing tank where Cu(II) ions were adsorbed onto PWS and the mixture was fed to a sedimentation tank to separate Cu(II) containing PWS from the feed wastewater. The activated sludge unit fed with the effluent of the sedimentation tank was operated at a hydraulic residence time (HRT) of 10h and sludge age (SRT) of 10 days. To investigate Cu(II), COD and toxicity removal performance of the activated sludge unit at different PWS loadings, the system was operated at different PWS loading rates (0.1-1 gPWSh(-1)) while the Cu(II) loading rate was constant throughout the operation. Percent copper, COD and toxicity removals increased with increasing PWS loading rate due to increased adsorption of Cu(II) onto PWS yielding low Cu(II) contents in the feed. Biomass concentration in the aeration tank increased and the sludge volume index (SVI) decreased with increasing PWS loading rate due to elimination of Cu(II) from the feed wastewater by PWS addition. PWS addition to the Cu(II) containing wastewater was proven to be effective for removal of Cu(II) by biosorption before biological treatment. Approximately, 1 gPWSh(-1) should be added for 28 mgCuh(-1) loading rate for complete removal of Cu(II) from the feed wastewater to obtain high COD removals in the activated sludge unit.

Effects of potassium ferrate on extracellular polymeric substances (EPS) and physicochemical properties of excess activated sludge.

PubMed

Ye, Fenxia; Liu, Xinwen; Li, Ying

2012-01-15

The activated sludge process of wastewater results in the generation of a considerable amount of excess activated sludge. In many wastewater treatment plants, the bottleneck of the sludge handling system is the dewatering operation. This paper investigated the effect of potassium ferrate pretreatment on the physicochemical properties of the excess activated sludge at various dosages of potassium ferrate. The particle size, extracellular polymeric substances (EPS) content and chemical components, and sludge disintegration degree were measured to explain the observed changes of physicochemical properties. It was expected that potassium ferrate could enhance the filterability and dewaterability of the sludge. However, the results showed that potassium ferrate had a negative effect on the filterability by measuring the capillary suction time (CST), but improved the settleability and dewaterability extent by determining the water content in the dewatered cake, although the flocs size reduced slightly. Loosely bound EPS (LB-EPS) content, polysaccharides (PS) and proteins (PN) contents in LB-EPS all increased with increasing the amount of potassium ferrate. However, Tightly bound EPS (TB-EPS) content, PS and PN contents in TB-EPS did not changed significantly at first, and decreased slightly under higher dosage of potassium ferrate. EPS, especially LB-EPS played more important role in the observed changes of the settleability and filterability than the sludge particle size. Copyright © 2011 Elsevier B.V. All rights reserved.

Enhancing dewaterability of waste activated sludge by combined oxidative conditioning process with zero-valent iron and peroxymonosulfate.

PubMed

Zhou, Xu; Jin, Wenbiao; Chen, Hongyi; Chen, Chuan; Han, Songfang; Tu, Renjie; Wei, Wei; Gao, Shu-Hong; Xie, Guo-Jun; Wang, Qilin

2017-11-01

The enhancement of sludge dewaterability is of great importance for facilitating the sludge disposal during the operation of wastewater treatment plants. In this study, a novel oxidative conditioning approach was applied to enhance the dewaterability of waste activated sludge by the combination of zero-valent iron (ZVI) and peroxymonosulfate (PMS). It was found that the dewaterability of sludge was significantly improved after the addition of ZVI (0-4 g/g TSS) (TSS: total suspended solids) and PMS (0-1 g/g TSS). The optimal addition amount of ZVI and PMS was 0.25 g/g TSS and 0.1 g/g TSS, respectively, under which the capillary suction time of the sludge was reduced by approximately 50%. The decomposition of sludge flocs could contribute to the improved sludge dewaterability. Economic analysis demonstrated that the proposed conditioning process with ZVI and PMS was more economical than the ZVI + peroxydisulfate and the traditional Fenton conditioning processes.

Bacterial Community Dynamics in Full-Scale Activated Sludge Bioreactors: Operational and Ecological Factors Driving Community Assembly and Performance

PubMed Central

Valentín-Vargas, Alexis; Toro-Labrador, Gladys; Massol-Deyá, Arturo A.

2012-01-01

The assembling of bacterial communities in conventional activated sludge (CAS) bioreactors was thought, until recently, to be chaotic and mostly unpredictable. Studies done over the last decade have shown that specific, and often, predictable random and non-random factors could be responsible for that process. These studies have also motivated a “structure–function” paradigm that is yet to be resolved. Thus, elucidating the factors that affect community assembly in the bioreactors is necessary for predicting fluctuations in community structure and function. For this study activated sludge samples were collected during a one-year period from two geographically distant CAS bioreactors of different size. Combining community fingerprinting analysis and operational parameters data with a robust statistical analysis, we aimed to identify relevant links between system performance and bacterial community diversity and dynamics. In addition to revealing a significant β-diversity between the bioreactors’ communities, results showed that the largest bioreactor had a less dynamic but more efficient and diverse bacterial community throughout the study. The statistical analysis also suggests that deterministic factors, as opposed to stochastic factors, may have a bigger impact on the community structure in the largest bioreactor. Furthermore, the community seems to rely mainly on mechanisms of resistance and functional redundancy to maintain functional stability. We suggest that the ecological theories behind the Island Biogeography model and the species-area relationship were appropriate to predict the assembly of bacterial communities in these CAS bioreactors. These results are of great importance for engineers and ecologists as they reveal critical aspects of CAS systems that could be applied towards improving bioreactor design and operation. PMID:22880016

Excess sludge disruption and pollutant removal from tannery effluent by upgraded activated sludge system.

PubMed

Sodhi, Vijay; Bansal, Ajay; Jha, Mithilesh Kumar

2018-04-30

This study proposed a maintenance metabolism based upgraded activated sludge as MANODOX system that restricts excess biosludge generation from high strength real tannery effluent. The MANODOX experimental demonstration has been done using a sequenced operational arrangement of a MBBR, anaerobic digester, and oxidation ditch connected to CAS reactor, discussed in detail manner. Experimental trends revealed a prominently lower sludge yield upto 0.271 gVSS/gCOD (72% overall sludge reduction) that corresponds to parallel run CAS (0.92 gVSS/gCOD). MANODOX implementation confirmed high quality treated effluent with prominent COD and suspended solids reduction upto 97.1% and 96% respectively. The biodegradability observation was further supported by anaerobic and aerobic batch digestion analysis. The variation of soluble component turbidity analysis reflects the enriched non-flocculating predatory microbial population appears to may have been responsible for sludge reduction. MANODOX system provided a sustainable practical alternative for under capacity activated sludge based treatment facilities for a variety of wastewater types. Copyright © 2018 Elsevier Ltd. All rights reserved.

Solubilization of municipal sewage waste activated sludge by novel lytic bacterial strains.

PubMed

Lakshmi, M Veera; Merrylin, J; Kavitha, S; Kumar, S Adish; Banu, J Rajesh; Yeom, Ick-Tae

2014-02-01

Extracellular polymeric substances (EPS) are an extracellular matrix found in sludge which plays a crucial role in flocculation by interacting with the organic solids. Therefore, to enhance pretreatment of sludge, EPS have to be removed. In this study, EPS were removed with a chemical extractant, NaOH, to enhance the bacterial pretreatment. A lysozyme secreting bacterial consortium was isolated from the waste activated sludge (WAS). The result of density gradient gel electrophoresis (DGGE) analysis revealed that the isolated consortium consists of two strains. The two novel strains isolated were named as Jerish03 (NCBI accession number KC597266) and Jerish 04 (NCBI accession number KC597267) and they belong to the genus Bacillus. Pretreatment with these novel strains enhances the efficiency of the aerobic digestion of sludge. Sludge treated with the lysozyme secreting bacterial consortium produced 29 % and 28.5 % increase in suspended solids (SS) reduction and chemical oxygen demand (COD) removal compared to the raw activated sludge (without pretreatment) during aerobic digestion. It is specified that these two novel strains had a high potential to enhance WAS degradation efficiency in aerobic digestion.

Incorporation of hydrophobized mineral particles in activated sludge flocs: a way to assess ballasting efficiency.

PubMed

Defontaine, G; Thormann, J; Lartiges, B S; El Samrani, A G; Barrs, O

2005-01-01

The role of mineral surface hydrophobicity in attachment to activated sludge flocs was investigated. Fluorite and quartz particles of similar granulometry were hydrophobized by adsorbing sodium oleate and dodecylamine chloride, respectively. Mineral hydrophobicity was assessed by flotation expriments. The attachment of particles to microbial flocs was determined by optical microscopy. The results indicate that hydrophobized particles are always better incorporated within activated sludge flocs than non-coated particles. A comparison with Aquatal particles used as sludge ballast reveals that hydrophobized minerals are associated with microbial flocs to the same extent.

In-situ sludge reduction and carbon reuse in an anoxic/oxic process coupled with hydrocyclone breakage.

PubMed

Xu, Yinxiang; Fang, Yuanyuan; Wang, Zhenhua; Guo, Dan; Liu, Yi; Huang, Yuan; Fu, Pengbo; Jin, Juehui; Wei, Chenwen; Wang, Hualin; Zeng, Tao

2018-05-09

The long-term performance of an anoxic-oxic-hydrocyclone (AOH) process with an in-situ hydrocyclone treatment unit in the mixed liquid return line for sludge reduction and carbon reuse has been observed, in comparison with a conventional anoxic-oxic (AO) process. Three parallel side-stream systems, including one AOH 25 system with a 25-mm hydrocyclone, one AOH 35 system with a 35-mm hydrocyclone and one AO system, were built and fed with real wastewater for a comparative study in a wastewater treatment plant. The results demonstrate that the hydrocyclone in the AOH process was able to break macro-flocs into smaller flocs. And the desorption of the extracellular polymeric substance from return activated sludge (AS) leaded to an average increase of 62.97% and 36.36% in SCOD in the AOH 25 and AOH 35 system, respectively. In addition, shear forces, centrifugal forces of revolution and flocs' rotation in the hydrocyclone were proposed to be the main influence mechanism of hydrocyclone treatment on AS properties. Compared with the AO process, the SCOD concentration in the effluent of the AOH processes presented a decrease of 12.0 mg/L and the TN was reduced by 21.50% owing to the released carbon sources reuse. Moreover, the sludge production was reduced by 36.81% and 35.92% in the AOH 25 and AOH 35 process, respectively. By contrast, the AOH 25 system was better than the AOH 35 system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Environmental optimization of chromium recovery from tannery sludge using a life cycle assessment approach.

PubMed

Kiliç, Eylem; Puig, Rita; Baquero, Grau; Font, Joaquim; Colak, Selime; Gürler, Deniz

2011-08-15

Life cycle assessment (LCA) was used to evaluate the environmental impact of an oxidative chromium recovery method from tannery sludge, in comparison with the usual landfilling process. Three improvement options (water reduction, byproduct use and anaerobic sludge digestion) were considered. The results showed that the proposed chromium recovery process would be better environmentally than conventional landfilling in all the evaluated impact categories if the amount of chromium recovered was 43 kg per ton of sludge. This amount could be recovered if the chromium concentration was about 20 times higher than that considered in this study. Alternatively, a lower chromium concentration would produce a better result if the recovery method was optimized and implemented at industrial rather than laboratory scale, and if more accurate data were provided on environmental credits for avoiding the chromium production process. Thus, the recovery method is environmentally beneficial when tannery sludge contains a chromium concentration of about 100,000 ppm. According to the literature, such concentrations are not unusual. The results could serve as the basis for further environmental improvements in chromium recovery and tannery sludge management and should be used in decision-making processes, especially for end-of-pipe treatments. Copyright © 2011 Elsevier B.V. All rights reserved.

Utilization and Conversion of Sewage Sludge as Metal Sorbent

NASA Astrophysics Data System (ADS)

Gong, Xu Dong; Li, Loretta Y.

2013-04-01

Most biosolids are disposed on land. With improvements in wastewater treatment processes and upgrading of treatment plants across Canada, biosolids generation will increase dramatically. These biosolids will need to be dealt with because they contain various contaminants, including heavy metals and several classes of emerging contaminants. A number of researchers have recently focused on preparation of sewage sludge-based adsorbents by carbonation, physical activation and chemical activation for decontamination of air and wastewater. These previous studies have indicated that sludge-based activated carbon can have good adsorption performance for organic substances in dye wastewater. The overall results suggest that activated carbon from sewage sludge can produce a useful adsorbent, while also reducing the amount of sewage sludge to be disposed. However, sludge-derived activated carbon has not been extensively studied, especially for adsorption of heavy metal ions in wastewater and for its capacity to remove emerging contaminants, such as poly-fluorinated compounds (PFCs). Previous research has indicated that commercial activated carbons adsorb organic compounds more efficiently than heavy metal ions. 45 Activated carbon can be modified to enhance its adsorption capacity for special heavy metal ions,46 e.g. by addition of inorganic and organic reagents. The modifications which are successful for commercial activated carbon should also be effective for sludge-derived activated carbon, but this needs to be confirmed. Our research focuses on (a) investigation of techniques for converting sewage sludge (SS) to activated carbon (AC) as sorbents; (b) exploration of possible modification of the activated carbon (MAC) to improve its sorption capacity; (c) examination of the chemical stability of the activated carbon and the leachability of contaminants from activated carbon,; (d) comparison of adsorptivity with that of other sorbents. Based on XRD and FT-IR, we successfully converted SS to AC and further modified it to improve absorption. SSMAC has large specific surface areas based on the BET technique. Batch adsorption results indicate that metal adsorption for SSMAC > SSAC, with adsorption occurring within the first 5 minutes of contact. Comparison of the adsorptivity of various sorbents such as commercial activated carbon (CAC), mineral sorbents such as perlite, clinoptilolite and illite indicates that SSMAC × CAC × clinoptilolite > kaolite.

Evaluation of solar sludge drying alternatives by costs and area requirements.

PubMed

Kurt, Mayıs; Aksoy, Ayşegül; Sanin, F Dilek

2015-10-01

Thermal drying is a common method to reach above 90% dry solids content (DS) in sludge. However, thermal drying requires high amount of energy and can be expensive. A greenhouse solar dryer (GSD) can be a cost-effective substitute if the drying performance, which is typically 70% DS, can be increased by additional heat. In this study feasibility of GSD supported with solar panels is evaluated as an alternative to thermal dryers to reach 90% DS. Evaluations are based on capital and O&M costs as well as area requirements for 37 wastewater treatment plants (WWTPs) with various sludge production rates. Costs for the supported GSD system are compared to that of conventional and co-generation thermal dryers. To calculate the optimal costs associated with the drying system, an optimization model was developed in which area limitation was a constraint. Results showed that total cost was minimum when the DS in the GSD (DS(m,i)) was equal to the maximum attainable value (70% DS). On average, 58% of the total cost and 38% of total required area were associated with the GSD. Variations in costs for 37 WWTPs were due to differences in initial DS (DS(i,i)) and sludge production rates, indicating the importance of dewatering to lower drying costs. For large plants, GSD supported with solar panels provided savings in total costs especially in long term when compared to conventional and co-generation thermal dryers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modelling carbon oxidation in pulp mill activated sludge systems: calibration of Activated Sludge Model No 3.

PubMed

Barañao, P A; Hall, E R

2004-01-01

Activated Sludge Model No 3 (ASM3) was chosen to model an activated sludge system treating effluents from a mechanical pulp and paper mill. The high COD concentration and the high content of readily biodegradable substrates of the wastewater make this model appropriate for this system. ASM3 was calibrated based on batch respirometric tests using fresh wastewater and sludge from the treatment plant, and on analytical measurements of COD, TSS and VSS. The model, developed for municipal wastewater, was found suitable for fitting a variety of respirometric batch tests, performed at different temperatures and food to microorganism ratios (F/M). Therefore, a set of calibrated parameters, as well as the wastewater COD fractions, was estimated for this industrial wastewater. The majority of the calibrated parameters were in the range of those found in the literature.

Soil and pasture P concentration in a Fraxinus excelsior L. silvopastoral system fertilised with different types of sewage sludge

NASA Astrophysics Data System (ADS)

Ferreiro-Domínguez, Nuria; Nair, Vimala; Rigueiro-Rodríguez, Antonio; Rosa Mosquera-Losada, María

2015-04-01

In Europe, sewage sludge should be stabilised before using as fertiliser in agriculture. Depending on the stabilisation process that is used, sewage sludge has different characteristics, nutrient contents and soil nutrient incorporation rates. Sewage sludge is usually applied on a plant-available N or total metal concentration basic, and therefore, P concentrations can be well above crop needs. Leaching of excess P can threaten surface and ground waters with eutrophication. In this context, recent studies have demonstrated that the implementation of agroforestry systems could reduce the P leaching risk compared with conventional agricultural systems due to the different localisation of tree and crop roots which enhance nutrient uptake. The aim of this study was to evaluate during three consecutive years the effect of municipal sewage sludge stabilised by anaerobic digestion, composting, and pelletisation on concentration of P in soil and pasture compared to control treatments (mineral and no fertilisation) in a silvopastoral system established under Fraxinus excelsior L. in Galicia (Spain). The results showed that at the beginning of the study, the fertilisation with mineral increased more the total and available P in soil than the fertilisation with sewage sludge probably because the sludge nutrient release rate is slower than those from mineral fertilisers. The increment of soil available P caused by the mineral fertiliser implied an improvement of the P concentration in the pasture. However, in the last year of the experiment it was observed a positive effect of the fertilisation with pelletised sludge on the concentration of P in pasture compared with the composted sludge and the mineral fertiliser probably due to the annual application of this type of sludge. Therefore, the establishment of silvopastoral systems and their fertilisation with pelletized sludge should be recommended because the pelletized sludge increases the concentration of P in the pasture and reduces the application and storage costs due to its lower proportion of water than the other types of sludge tested. At the same time, the integration of trees in agricultural areas decreases the problem of environmental impact resulting from addition of organic and inorganic fertilisers on soils.

Enhanced biodegradation of hydrocarbons in petroleum tank bottom oil sludge and characterization of biocatalysts and biosurfactants.

PubMed

Suganthi, S Hepziba; Murshid, Shabnam; Sriram, Sriswarna; Ramani, K

2018-08-15

Petroleum hydrocarbon removal from tank bottom oil sludge is a major issue due to its properties. Conventional physicochemical treatment techniques are less effective. Though the bioremediation is considered for the hydrocarbon removal from tank bottom oil sludge, the efficiency is low and time taking due to the low yield of biocatalysts and biosurfactants. The focal theme of the present investigation is to modify the process by introducing the intermittent inoculation for the enhanced biodegradation of hydrocarbons in the tank bottom oil sludge by maintaining a constant level of biocatalysts such as oxidoreductase, catalase, and lipase as well as biosurfactants. In addition, the heavy metal removal was also addressed. The microbial consortia comprising Shewanalla chilikensis, Bacillus firmus, and Halomonas hamiltonii was used for the biodegradation of oil sludge. One variable at a time approach was used for the optimum of culture conditions. The bacterial consortia degraded the oil sludge by producing biocatalysts such as lipase (80 U/ml), catalase (46 U/ml), oxidoreductase (68 U/ml) along with the production of lipoprotein biosurfactant (152 mg/g of oil sludge) constantly and achieved 96% reduction of total petroleum hydrocarbon. The crude enzymes were characterized by FT-IR and the biosurfactant was characterized by surface tension reduction, emulsification index, FT-IR, TLC, and SDS-PAGE. GC-MS and NMR also revealed that the hydrocarbons present in the oil sludge were effectively degraded by the microbial consortia. The ICP-OES result indicated that the microbial consortium is also effective in removing the heavy metals. Hence, bioremediation using the hydrocarbonoclastic microbial consortium can be considered as an environmentally friendly process for disposal of tank bottom oil sludge from petroleum oil refining industry. Copyright © 2018 Elsevier Ltd. All rights reserved.

Full-scale evaluation of a multi-component additive for efficient control of activated sludge filamentous bulking.

PubMed

Seka, M A; Van DeWiele, T; Verstraete, W

2002-01-01

A multi-component additive formulated for a more efficient control of activated sludge filamentous bulking was evaluated at a full-scale treatment plant experiencing severe filamentous bulking. It was found that, besides offering an immediate improvement of sludge settling, the multi-component additive was able to eliminate the filamentous bacteria causing the bulking. Hence, contrary to ordinary additives, this novel additive yielded immediate as well as long-term improvements in sludge sedimentation upon a few additions. Preliminary lab-scale toxicity tests showed that the treatment of the sludge by the additive should not impart any toxicity to the resulting effluent.

In situ identification of nocardioform actinomycetes in activated sludge using fluorescent rRNA-targeted oligonucleotide probes.

PubMed

Schuppler, M; Wagner, M; Schön, G; Göbel, U B

1998-01-01

Hitherto, few environmental samples have been investigated by a 'full cycle rRNA analysis'. Here the results of in situ hybridization experiments with specific rRNA-targeted oligonucleotide probes developed on the basis of new sequences derived from a previously described comparative 16S rRNA analysis of nocardioform actinomycetes in activated sludge are reported. Application of the specific probes enabled identification and discrimination of the distinct populations of nocardioform actinomycetes in activated sludge. One of the specific probes (DLP) detected rod-shaped bacteria which were found in 13 of the 16 investigated sludge samples from various wastewater treatment plants, suggesting their importance in the wastewater treatment process. Another probe (GLP2) hybridized with typically branched filaments of nocardioforms mainly found in samples from enhanced biological phosphorus removal plants, suggesting that these bacteria are involved in sludge foaming. The combination of in situ hybridization with fluorescently labelled rRNA-targeted oligonucleotide probes and confocal laser scanning microscopy improved the detection of nocardioform actinomycetes, which often showed only weak signals inside the activated-sludge flocs.

Use of hydrodynamic disintegration to accelerate anaerobic digestion of surplus activated sludge.

PubMed

Grübel, Klaudiusz; Machnicka, Alicja

2009-12-01

Hydrodynamic disintegration of activated sludge resulted in organic matter and polymers transfer from the solid phase into the liquid phase. Disintegration by hydrodynamic cavitation had a positive effect on the degree and rate of excess sludge anaerobic digestion. Also, addition of a part of anaerobic digested sludge containing adapted microorganisms resulted in acceleration of the process. The disruption of cells of foam microorganisms and addition to the digestion process led to an increase of biogas production.

[Harvest of the carbon source in wastewater by the adsorption and desorption of activated sludge].

PubMed

Liu, Hong-Bo; Wen, Xiang-Hua; Zhao, Fang; Mei, Yi-Jun

2011-04-01

The carbon source in municipal wastewater was adsorbed by activated sludge and then harvested through the hydrolysis of activated sludge. Results indicated that activated sludge had high absorbing ability towards organic carbon and phosphorus under continuous operation mode, and the average COD and TP absorption rate reached as high as 63% and 76%, respectively. Moreover, about 50% of the soluble carbon source was outside of the sludge cell and could be released under mild hydrolysis condition. Whereas the absorbed amount of nitrogen was relatively low, and the removal rate of ammonia was only 13% . Furthermore, the releases of organic carbon, nitrogen and phosphorus from the sludge absorbing pollutants in the wastewater were studied. By comparing different hydrolysis conditions of normal (pH 7.5, 20 degrees C), heating (pH 7.5, 60 degrees C) and the alkaline heating (pH 11, 60 degrees C), the last one presented the optimum hydrolysis efficiency. Under which, the release rate of COD could reach 320 mg/g after 24 hours, whereas nitrogen and phosphorus just obtained low release rates of 18 mg/g and 2 mg/g, respectively. Results indicate that the carbon source in wastewater could be harvested by the adsorption and desorption of activated sludge, and the concentrations of nitrogen and phosphorus are low and would not influence the reuse of the harvested carbon source.

Heavy metal-binding proteins from metal-stimulated bacteria as a novel adsorbent for metal removal technology.

PubMed

Sano, D; Myojo, K; Omura, T

2006-01-01

Water pollution with toxic heavy metals is of growing concern because heavy metals could bring about serious problems for not only ecosystems in the water environment but also human health. Some metal removal technologies have been in practical use, but much energy and troublesome treatments for chemical wastes are required to operate these conventional technologies. In this study, heavy metal-binding proteins (HMBPs) were obtained from metal-stimulated activated sludge culture with affinity chromatography using copper ion as a ligand. Two-dimensional electrophoresis revealed that a number of proteins in activated sludge culture were recovered as HMBPs for copper ion. N-termini of five HMBPs were determined, and two of them were found to be newly discovered proteins for which no amino acid sequences in protein databases were retrieved at more than 80% identities. Metal-coordinating amino acids occupied 38% of residues in one of the N-terminal sequences of the newly discovered HMBPs. Since these HMBPs were expected to be stable under conditions of water and wastewater treatments, it would be possible to utilize HMBPs as novel adsorbents for heavy metal removal if mass volume of HMBPs can be obtained with protein cloning techniques.

Biotreatment of oily wastewater by rhamnolipids in aerated active sludge system*

PubMed Central

Zhang, Hong-zi; Long, Xu-wei; Sha, Ru-yi; Zhang, Guo-liang; Meng, Qin

2009-01-01

Oily wastewater generated by various industries creates a major ecological problem throughout the world. The traditional methods for the oily wastewater treatment are inefficient and costly. Surfactants can promote the biodegradation of petroleum hydrocarbons by dispersing oil into aqueous environment. In the present study, we applied rhamnolipid-containing cell-free culture broth to enhance the biodegradation of crude oil and lubricating oil in a conventional aerobically-activated sludge system. At 20 °C, rhamnolipids (11.2 mg/L) increased the removal efficiency of crude oil from 17.7% (in the absence of rhamnolipids) to 63%. At 25 °C, the removal efficiency of crude oil was over 80% with the presence of rhamnolipids compared with 22.3% in the absence of rhamnolipids. Similarly, rhamnolipid treatment (22.5 mg/L) for 24 h at 20 °C significantly increased the removal rate of lubricating oil to 92% compared with 24% in the absence of rhamnolipids. The enhanced removal of hydrocarbons was mainly attributed to the improved solubility and the reduced interfacial tension by rhamnolipids. We conclude that a direct application of the crude rhamnolipid solution from cell culture is effective and economic in removing oily contaminants from wastewater. PMID:19882761

Ion Trapping of Amines in Protozoa: A Novel Removal Mechanism for Micropollutants in Activated Sludge.

PubMed

Gulde, Rebekka; Anliker, Sabine; Kohler, Hans-Peter E; Fenner, Kathrin

2018-01-02

To optimize removal of organic micropollutants from the water cycle, understanding the processes during activated sludge treatment is essential. In this study, we hypothesize that aliphatic amines, which are highly abundant among organic micropollutants, are partly removed from the water phase in activated sludge through ion trapping in protozoa. In ion trapping, which has been extensively investigated in medical research, the neutral species of amine-containing compounds diffuse through the cell membrane and further into acidic vesicles present in eukaryotic cells such as protozoa. There they become trapped because diffusion of the positively charged species formed in the acidic vesicles is strongly hindered. We tested our hypothesis with two experiments. First, we studied the distribution of the fluorescent amine acridine orange in activated sludge by confocal fluorescence imaging. We observed intense fluorescence in distinct compartments of the protozoa, but not in the bacterial biomass. Second, we investigated the distribution of 12 amine-containing and eight control micropollutants in both regular activated sludge and sludge where the protozoa had been inactivated. In contrast to most control compounds, the amine-containing micropollutants displayed a distinctly different behavior in the noninhibited sludge compared to the inhibited one: (i) more removal from the liquid phase; (ii) deviation from first-order kinetics for the removal from the liquid phase; and (iii) higher amounts in the solid phase. These results provide strong evidence that ion trapping in protozoa occurs and that it is an important removal mechanism for amine-containing micropollutants in batch experiments with activated sludge that has so far gone unnoticed. We expect that our findings will trigger further investigations on the importance of this process in full-scale wastewater treatment systems, including its relevance for accumulation of ammonium.

Enhanced nitrogen removal in the combined activated sludge-biofilter system of the Southpest Wastewater Treatment Plant.

PubMed

Jobbágy, A; Tardy, G M; Literáthy, B

2004-01-01

In 1999 the existing activated sludge unit of the Southpest Wastewater Treatment Plant was supplemented by a two-stage biofilter system aiming for nitrification and post-denitrification. In this arrangement excess biomass of the filters is wasted through the activated sludge unit, facilitating backseeding, and recirculation of the nitrate-rich effluent of the N-filter serves for decreasing the methanol demand of the DN-filter and for saving aeration energy at the same time. The paper reports on the development of an ASM1-based mathematical model that proved to be adequate for describing the interactions in the combined system and was used to compare the efficiency of different treatment options. Full-scale results verified that backseeding may considerably improve performance. However, nitrification ability of the activated sludge unit depends on the treatment temperature and, if unexpected, can be limited by insufficient oxygen supply. The upgrading possibilities outlined may serve as a new perspective for implementation of combined activated sludge-biofilter systems.

Zero-valent iron enhanced methanogenic activity in anaerobic digestion of waste activated sludge after heat and alkali pretreatment.

PubMed

Zhang, Yaobin; Feng, Yinghong; Quan, Xie

2015-04-01

Heat or alkali pretreatment is the effective method to improve hydrolysis of waste sludge and then enhance anaerobic sludge digestion. However the pretreatment may inactivate the methanogens in the sludge. In the present work, zero-valent iron (ZVI) was used to enhance the methanogenic activity in anaerobic sludge digester under two methanogens-suppressing conditions, i.e. heat-pretreatment and alkali condition respectively. With the addition of ZVI, the lag time of methane production was shortened, and the methane yield increased by 91.5% compared to the control group. The consumption of VFA was accelerated by ZVI, especially for acetate, indicating that the acetoclastic methanogenesis was enhanced. In the alkali-condition experiment, the hydrogen produced decreased from 27.6 to 18.8 mL when increasing the ZVI dosage from 0 to 10 g/L. Correspondingly, the methane yield increased from 1.9 to 32.2 mL, which meant that the H2-utilizing methanogenes was enriched. These results suggested that the addition of ZVI into anaerobic digestion of sludge after pretreated by the heat or alkali process could efficiently recover the methanogenic activity and increase the methane production and sludge reduction. Copyright © 2015 Elsevier Ltd. All rights reserved.

40 CFR 503.20 - Applicability.

Code of Federal Regulations, 2014 CFR

2014-07-01

... who prepares sewage sludge that is placed on a surface disposal site, to the owner/operator of a surface disposal site, to sewage sludge placed on a surface disposal site, and to a surface disposal site... sludge remains is not an active sewage sludge unit. The demonstration shall include the following...

40 CFR 503.20 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-07-01

... who prepares sewage sludge that is placed on a surface disposal site, to the owner/operator of a surface disposal site, to sewage sludge placed on a surface disposal site, and to a surface disposal site... sludge remains is not an active sewage sludge unit. The demonstration shall include the following...

40 CFR 503.20 - Applicability.

Code of Federal Regulations, 2013 CFR

2013-07-01

... who prepares sewage sludge that is placed on a surface disposal site, to the owner/operator of a surface disposal site, to sewage sludge placed on a surface disposal site, and to a surface disposal site... sludge remains is not an active sewage sludge unit. The demonstration shall include the following...

40 CFR 503.20 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

... who prepares sewage sludge that is placed on a surface disposal site, to the owner/operator of a surface disposal site, to sewage sludge placed on a surface disposal site, and to a surface disposal site... sludge remains is not an active sewage sludge unit. The demonstration shall include the following...

EFFECT OF RECYCLING THERMOPHILICALLY DIGESTED SLUDGE ON THE ACTIVATED SLUDGE PROCESS

EPA Science Inventory

A full-scale investigation was undertaken at Chicago's Hanover Park Water Reclamation Plant (WRP) to study whether the net sludge production from the WRP could be reduced by implementing a scheme developed by W. Torpey et al. (1984). n this process, sludge is withdrawn from a the...

A pilot-scale microwave technology for sludge sanitization and drying.

PubMed

Mawioo, Peter M; Garcia, Hector A; Hooijmans, Christine M; Velkushanova, Konstantina; Simonič, Marjana; Mijatović, Ivan; Brdjanovic, Damir

2017-12-01

Large volumes of sludge are produced from onsite sanitation systems in densely populated areas (e.g. slums and emergency settlements) and wastewater treatment facilities that contain high amounts of pathogens. There is a need for technological options which can effectively treat the rapidly accumulating sludge under these conditions. This study explored a pilot-scale microwave (MW) based reactor as a possible alternative for rapid sludge treatment. The reactor performance was examined by conducting a series of batch tests using centrifuged waste activated sludge (C-WAS), non-centrifuged waste activated sludge (WAS), faecal sludge (FS), and septic tank sludge (SS). Four kilograms of each sludge type were subjected to MW treatment at a power of 3.4kW for various time durations ranging from 30 to 240min. During the treatment the temperature change, bacteria inactivation (E. coli, coliforms, Staphylococcus aureus, and enterococcus faecalis) and sludge weight/volume reduction were measured. Calorific values (CV) of the dried sludge and the nutrient content (total nitrogen (TN) and total phosphorus (TP)) in both the dried sludge and the condensate were also determined. It was found that MW treatment was successful to achieve a complete bacterial inactivation and a sludge weight/volume reduction above 60%. Besides, the dried sludge and condensate had high energy (≥16MJ/kg) and nutrient contents (solids; TN≥28mg/g TS and TP≥15mg/g TS; condensate TN≥49mg/L TS and TP≥0.2mg/L), having the potential to be used as biofuel, soil conditioner, fertilizer, etc. The MW reactor can be applied for the rapid treatment of sludge in areas such as slums and emergency settlements. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Enhanced anaerobic digestion of waste activated sludge digestion by the addition of zero valent iron.

PubMed

Feng, Yinghong; Zhang, Yaobin; Quan, Xie; Chen, Suo

2014-04-01

Anaerobic digestion is promising technology to recover energy from waste activated sludge. However, the sludge digestion is limited by its low efficiency of hydrolysis-acidification. Zero valent iron (ZVI) as a reducing material is expected to enhance anaerobic process including the hydrolysis-acidification process. Considering that, ZVI was added into an anaerobic sludge digestion system to accelerate the sludge digestion in this study. The results indicated that ZVI effectively enhanced the decomposition of protein and cellulose, the two main components of the sludge. Compared to the control test without ZVI, the degradation of protein increased 21.9% and the volatile fatty acids production increased 37.3% with adding ZVI. More acetate and less propionate are found during the hydrolysis-acidification with ZVI. The activities of several key enzymes in the hydrolysis and acidification increased 0.6-1 time. ZVI made the methane production raise 43.5% and sludge reduction ratio increase 12.2 percent points. Fluorescence in situ hybridization analysis showed that the abundances of hydrogen-consuming microorganisms including homoacetogens and hydrogenotrophic methanogens with ZVI were higher than the control, which reduced the H2 accumulation to create a beneficial condition for the sludge digestion in thermodynamics. Copyright © 2013 Elsevier Ltd. All rights reserved.

MiDAS: the field guide to the microbes of activated sludge.

PubMed

McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

2015-01-01

The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes--knowledge that will be an invaluable resource for the optimal design and operation of these systems. © The Author(s) 2015. Published by Oxford University Press.

Influence of tetracycline on tetracycline-resistant heterotrophs and tet genes in activated sludge process.

PubMed

Yu, Jie; Liu, Dongfang; Li, Kexun

2015-03-01

The concentrations of tetracycline-intermediate resistant, tetracycline-resistant heterotrophic bacteria, and total heterotrophic bacteria were examined to assess the influence of tetracycline on tetracycline-resistant heterotrophs by the R2A agar cultivation method in the tetracycline fortified activated sludge process and in the natural background. Results showed that the percentages of both tetracycline-intermediate resistant and tetracycline-resistant heterotrophic bacteria in total heterotrophic bacteria were significantly increased, after tetracycline was fed to activated sludge for a 3 months period under four different operating conditions, as compared with the background. In order to investigate the mechanism of activated sludge resistance to tetracycline, polymerase chain reaction experiments were carried out to analyze the existence and evolution of tet genes in the presence of tetracycline. Results revealed that only tet A and tet B genes out of the 11 target tet genes were observed in tetracycline treated activated sludge while no tet gene was detected in background. This indicated that tet A gene could accumulate in activated sludge with slower and continuous influent, while the accumulation of tet B gene could be attributed to shorter hydraulic retention time. Therefore, it was proposed in this study that tetracycline-resistant genes created by efflux pumps spread earlier and quicker to encode resistance to tetracycline, which facilitated the increase in tetracycline-resistance.

MiDAS: the field guide to the microbes of activated sludge

PubMed Central

McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

2015-01-01

The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes—knowledge that will be an invaluable resource for the optimal design and operation of these systems. Database URL: http://www.midasfieldguide.org PMID:26120139

Conditioning of sewage sludge by Fenton's reagent combined with skeleton builders.

PubMed

Liu, Huan; Yang, Jiakuan; Shi, Yafei; Li, Ye; He, Shu; Yang, Changzhu; Yao, Hong

2012-06-01

Physical conditioners, often known as skeleton builders, are commonly used to improve the dewaterability of sewage sludge. This study evaluated a novel joint usage of Fenton's reagent and skeleton builders, referred to as the F-S inorganic composite conditioner, focusing on their efficacies and the optimization of the major operational parameters. The results demonstrate that the F-S composite conditioner for conditioning sewage sludge is a viable alternative to conventional organic polymers, especially when ordinary Portland cement (OPC) and lime are used as the skeleton builders. Experimental investigations confirmed that Fenton reaction required sufficient time (80 min in this study) to degrade organics in the sludge. The optimal condition of this process was at pH=5, Fe(2+)=40 mg g(-1) (dry solids), H(2)O(2)=32 mg g(-1), OPC=300 mg g(-1) and lime=400 mg g(-1), in which the specific resistance to filtration reduction efficiency of 95% was achieved. Copyright © 2012 Elsevier Ltd. All rights reserved.

Process performance of high-solids batch anaerobic digestion of sewage sludge.

PubMed

Liao, Xiaocong; Li, Huan; Cheng, Yingchao; Chen, Nan; Li, Chenchen; Yang, Yuning

2014-01-01

The characteristics of high-solids anaerobic digestion (AD) of sewage sludge were investigated by comparison with conventional low-solids processes. A series of batch experiments were conducted under mesophilic condition and the initial solid contents were controlled at four levels of 1.79%, 4.47%, 10.28% and 15.67%. During these experiments, biogas production, organic degradation and intermediate products were monitored. The results verified that high-solids batch AD of sewage sludge was feasible. Compared with the low-solids AD with solid contents of 1.79% or 4.47%, the high-solids processes decreased the specific biogas yield per gram of sludge volatile solids slightly, achieved the same organic degradation rate of about 40% within extended degradation time, but increased the volumetric biogas production rate and the treatment capability of digesters significantly. The blocked mass and energy transfer, the low substrate to inoculum rate and the excessive cumulative free ammonia were the main factors impacting the performance of high-solids batch AD.

Stable aerobic granules in continuous-flow bioreactor with self-forming dynamic membrane.

PubMed

Liu, Hongbo; Li, Yajie; Yang, Changzhu; Pu, Wenhong; He, Liu; Bo, Fu

2012-10-01

A novel continuous-flow bioreactor with aerobic granular sludge and self-forming dynamic membrane (CGSFDMBR) was developed for efficient wastewater treatment. Under continuous-flow operation, aerobic granular sludge was successfully cultivated and characterized with small particle size of about 0.1-1.0mm, low settling velocity of about 15-25 m/h, loose structure and high water content of about 96-98%. To maintain the stability of aerobic granular sludge, strategies based on the differences of settling velocity and particle-size between granular and flocculent sludge were implemented. Moreover, in CGSFDMBR, membrane fouling was greatly relieved. Dynamic membrane was just cleaned once in more than 45 days' operation. CGSFDMBR presented good performance in treating septic tank wastewater, obtaining average COD, NH(4)(+)-N, TN and TP removal rates of 83.3%, 73.3%, 67.3% and 60%, respectively, which was more efficient than conventional bioreactors since that carbon, nitrogen and phosphorus were simultaneously removed in a single aerobic reactor. Copyright © 2012 Elsevier Ltd. All rights reserved.

ATAD control goals through the analysis of process variables and evaluation of quality, production and cost.

PubMed

Nájera, S; Gil-Martínez, M; Zambrano, J A

2015-01-01

The aim of this paper is to establish and quantify different operational goals and control strategies in autothermal thermophilic aerobic digestion (ATAD). This technology appears as an alternative to conventional sludge digestion systems. During the batch-mode reaction, high temperatures promote sludge stabilization and pasteurization. The digester temperature is usually the only online, robust, measurable variable. The average temperature can be regulated by manipulating both the air injection and the sludge retention time. An improved performance of diverse biochemical variables can be achieved through proper manipulation of these inputs. However, a better quality of treated sludge usually implies major operating costs or a lower production rate. Thus, quality, production and cost indices are defined to quantify the outcomes of the treatment. Based on these, tradeoff control strategies are proposed and illustrated through some examples. This paper's results are relevant to guide plant operators, to design automatic control systems and to compare or evaluate the control performance on ATAD systems.

Reduction of selenite to elemental selenium nanoparticles by activated sludge.

PubMed

Jain, Rohan; Matassa, Silvio; Singh, Satyendra; van Hullebusch, Eric D; Esposito, Giovanni; Lens, Piet N L

2016-01-01

Total selenium removal by the activated sludge process, where selenite is reduced to colloidal elemental selenium nanoparticles (BioSeNPs) that remain entrapped in the activated sludge flocs, was studied. Total selenium removal efficiencies with glucose as electron donor (2.0 g chemical oxygen demand (COD) L(-1)) at neutral pH and 30 °C gave 2.9 and 6.8 times higher removal efficiencies as compared to the electron donors lactate and acetate, respectively. Total selenium removal efficiencies of 79 (±3) and 86 (±1) % were achieved in shake flasks and fed batch reactors, respectively, at dissolved oxygen (DO) concentrations above 4.0 mg L(-1) and 30 °C when fed with 172 mg L(-1) (1 mM) Na2SeO3 and 2.0 g L(-1) COD of glucose. Continuously operated reactors operating at neutral pH, 30 °C and a DO >3 mg L(-1) removed 33.98 and 36.65 mg of total selenium per gram of total suspended solids (TSS) at TSS concentrations of 1.3 and 3.0 g L(-1), respectively. However, selenite toxicity to the activated sludge led to failure of a continuously operating activated sludge reactor at the applied loading rates. This suggests that a higher hydraulic retention time (HRT) or different reactor configurations need to be applied for selenium-removing activated sludge processes. Graphical Abstract Scheme representing the possible mechanisms of selenite reduction at high and low DO levels in the activated sludge process.

Long-term operation of submerged membrane bioreactor (MBR) for the treatment of synthetic wastewater containing styrene as volatile organic compound (VOC): Effect of hydraulic retention time (HRT).

PubMed

Fallah, N; Bonakdarpour, B; Nasernejad, B; Alavi Moghadam, M R

2010-06-15

In this study, the membrane bioreactor (MBR) was utilized to remove styrene from a synthetic wastewater having a chemical oxygen demand (COD) and styrene concentration of 1500 mg/L and 50 mg/L, respectively. At two hydraulic retention times (HRTs) of 24 h and 18 h, the MBR was operated for a period in excess of 100 days. The HRT effects were studied and it was found out that the removal efficiency of COD and styrene for both HRTs was consistently higher than 99%. Unlike conventional activated sludge processes (CASPs), no styrene was detected in the exhaust air, which meant that biodegradation was the major styrene removal mechanism at both HRTs. The transmembrane pressure (TMP) profile during the operation of the MBR showed a fairly low and constant TMP up to day 70, after which, the TMP showed a dramatic rise, as a result of the occurrence of severe membrane fouling. It was thought that an increase in styrene loading rate, when HRT was reduced to 18 h, resulted in the release of extracellular polymeric substance (EPS) from the bacterial cells, which in turn was responsible for the rise in soluble microbial product (SMP) and sludge deflocculation. The severe fouling observed during operation of MBR at HRT of 18 h was attributed to the rise in SMP concentrations and decrease in mean floc size and increase in the proportion of small particles in the activated sludge. Copyright 2010 Elsevier B.V. All rights reserved.

Investigating the fate of activated sludge extracellular proteins in sludge digestion using sodium dodecyl sulfate polyacrylamide gel electrophoresis.

PubMed

Park, Chul; Helm, Richard F; Novak, John T

2008-12-01

The fate of activated sludge extracellular proteins in sludge digestion was investigated using three different cation-associated extraction methods and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Extraction methods used were the cation exchange resin (CER) method for extracting calcium (Ca2+) and magnesium (Mg2+), sulfide extraction for removing iron, and base treatment (pH 10.5) for dissolving aluminum. Extracellular polymeric substances extracted were then subjected to SDS-PAGE, and the resultant protein profiles were examined before and after sludge digestion. The SDS-PAGE results showed that three methods led to different SDS-PAGE profiles for both undigested and digested sludges. The results further revealed that CER-extracted proteins remained mainly undegraded in anaerobic digestion, but were degraded in aerobic digestion. While the fate of sulfide- and base-extracted proteins was not clear for aerobic digestion, their changes in anaerobic digestion were elucidated. Most sulfide-extracted proteins were removed by anaerobic digestion, while the increase in protein band intensity and diversity was observed for base-extracted proteins. These results suggest that activated sludge flocs contain different fractions of proteins that are distinguishable by their association with certain cations and that each fraction undergoes different fates in anaerobic and aerobic digestion. The proteins that were resistant to degradation and generated during anaerobic digestion were identified by liquid chromatography tandem mass spectrometry. Protein identification results and their putative roles in activated sludge and anaerobic digestion are discussed in this study.

Partial nitritation of raw anaerobic sludge digester liquor by swim-bed and swim-bed activated sludge processes and comparison of their sludge characteristics.

PubMed

Qiao, Sen; Kawakubo, Yuki; Koyama, Toichiro; Furukawa, Kenji

2008-11-01

This study evaluated performance of swim-bed (SB) reactors packed with a novel acrylic fiber carrier (BF) and swim-bed activated sludge (SBAS) reactor for partial nitritation of anaerobic sludge digester liquor from a municipal wastewater treatment plant. Comparison of characteristics of sludge obtained from both the reactors was also made. The average conversion rates of ammonium to nitrite were 52.3% and 40.0% under relatively high nitrogen loading rates over 3.0 kg-N/m(3)/d, respectively in two reactors. The average BOD(5) removal efficiencies were 74.3% and 64.4%, respectively in the two reactors. The size of the sludge pellets taken from SB and SBAS reactors was found to be approximately three times (229 mum versus 88 mum) of that of the seed sludge. This sludge also had relatively high extracellular proteins levels indicating better sludge settling capability as compared to the sludge taken from SBAS reactor. Although the effluent nitrite/ammonium ratios had fluctuated in both reactor in some extent, the low dissolved oxygen concentration (average of 2.5 versus 0.35 mg/l), low suspended solids (average of 33.3 versus 33.5 mg/l), and about 50% ammonium conversion to nitrite demonstrated the application potential of anammox process for nitrogen removal.

Effect of Malathion on the Microbial Ecology of Activated Sludge

DTIC Science & Technology

2015-03-26

EFFECT OF MALATHION ON THE MICROBIAL ECOLOGY OF ACTIVATED SLUDGE THESIS Seth K. Martin, Senior Master Sergeant, USAF AFIT-ENV-MS-15-M-095 DEPARTMENT...Government and is not subject to copyright protection in the United States. AFIT-ENV-MS-15-M-095 EFFECT OF MALATHION ON THE MICROBIAL ECOLOGY OF ACTIVATED...UNLIMITED. AFIT-ENV-MS-15-M-095 EFFECT OF MALATHION ON THE MICROBIAL ECOLOGY OF ACTIVATED SLUDGE THESIS Seth K. Martin, B.S. Senior Master Sergeant

[Research on change process of nitrosation granular sludge in continuous stirred-tank reactor].

PubMed

Yin, Fang-Fang; Liu, Wen-Ru; Wang, Jian-Fang; Wu, Peng; Shen, Yao-Liang

2014-11-01

In order to investigate the effect of different types of reactors on the nitrosation granular sludge, a continuous stirred-tank reactor (CSTR) was studied, using mature nitrosation granular sludge cultivated in sequencing batch reactor (SBR) as seed sludge. Results indicated that the change of reactor type and influent mode could induce part of granules to lose stability with gradual decrease in sludge settling ability during the initial period of operation. However, the flocs in CSTR achieved fast granulation in the following reactor operation. In spite of the changes of particle size distribution, e. g. the decreasing number of granules with diameter larger than 2.5 mm and the increasing number of granules with diameter smaller than 0.3 mm, granular sludge held the absolute predominance of sludge morphology in CSTR during the entire experimental period. Moreover, results showed that the change of reactor type and influent mode didn't affect the nitrite accumulation rate which was still kept at about 85% in effluent. Additionally, the average activity of the sludge in CSTR was stronger than that of the seed sludge, because the newly generated small particles in CSTR had higher specific reactive activity than the larger granules.

Fate of return activated sludge after ozonation: an optimization study for sludge disintegration.

PubMed

Demir, Ozlem; Filibeli, Ayse

2012-09-01

The effects of ozonation on sludge disintegration should be investigated before the application of ozone during biological treatment, in order to minimize excess sludge production. In this study, changes in sludge and supernatant after ozonation of return activated sludge were investigated for seven different ozone doses. The optimum ozone dose to avoid inhibition of ozonation and high ozone cost was determined in terms of disintegration degree as 0.05 g O3/gTS. Suspended solid and volatile suspended solid concentrations of sludge decreased by 77.8% and 71.6%, respectively, at the optimum ozone dose. Ozonation significantly decomposed sludge flocs. The release of cell contents was proved by the increase of supernatant total nitrogen (TN) and phosphorus (TP). While TN increased from 7 mg/L to 151 mg/L, TP increased from 8.8 to 33 mg/L at the optimum ozone dose. The dewaterability and filterability characteristics of the ozonated sludge were also examined. Capillary suction time increased with increasing ozone dosage, but specific resistance to filtration increased to a specific value and then decreased dramatically. The particle size distribution changed significantly as a result of floc disruption at an optimum dose of 0.05 gO3/gTS.

Addition of polyaluminiumchloride (PACl) to waste activated sludge to mitigate the negative effects of its sticky phase in dewatering-drying operations.

PubMed

Peeters, Bart; Dewil, Raf; Vernimmen, Luc; Van den Bogaert, Benno; Smets, Ilse Y

2013-07-01

This paper presents a new application of polyaluminiumchloride (PACl) as a conditioner for waste activated sludge prior its dewatering and drying. It is demonstrated at lab scale with a shear test-based protocol that a dose ranging from 50 to 150 g PACl/kg MLSS (mixed liquor suspended solids) mitigates the stickiness of partially dried sludge with a dry solids content between 25 and 60 %DS (dry solids). E.g., at a solids dryness of 46% DS the shear stress required to have the pre-consolidated sludge slip over a steel surface is reduced with 35%. The salient feature of PACl is further supported by torque data from a full scale decanter centrifuge used to dewater waste sludge. The maximal torque developed by the screw conveyor inside the decanter centrifuge is substantially reduced with 20% in the case the sludge feed is conditioned with PACl. The beneficial effect of waste sludge conditioning with PACl is proposed to be the result of the bound water associated with the aluminium polymers in PACl solutions which act as a type of lubrication for the intrinsically sticky sludge solids during the course of drying. It can be anticipated that PACl addition to waste sludge will become a technically feasible and very effective method to avoid worldwide fouling problems in direct sludge dryers, and to reduce torque issues in indirect sludge dryers as well as in sludge decanter centrifuges. Copyright © 2013 Elsevier Ltd. All rights reserved.

Kinetic model of excess activated sludge thermohydrolysis.

PubMed

Imbierowicz, Mirosław; Chacuk, Andrzej

2012-11-01

Thermal hydrolysis of excess activated sludge suspensions was carried at temperatures ranging from 423 K to 523 K and under pressure 0.2-4.0 MPa. Changes of total organic carbon (TOC) concentration in a solid and liquid phase were measured during these studies. At the temperature 423 K, after 2 h of the process, TOC concentration in the reaction mixture decreased by 15-18% of the initial value. At 473 K total organic carbon removal from activated sludge suspension increased to 30%. It was also found that the solubilisation of particulate organic matter strongly depended on the process temperature. At 423 K the transfer of TOC from solid particles into liquid phase after 1 h of the process reached 25% of the initial value, however, at the temperature of 523 K the conversion degree of 'solid' TOC attained 50% just after 15 min of the process. In the article a lumped kinetic model of the process of activated sludge thermohydrolysis has been proposed. It was assumed that during heating of the activated sludge suspension to a temperature in the range of 423-523 K two parallel reactions occurred. One, connected with thermal destruction of activated sludge particles, caused solubilisation of organic carbon and an increase of dissolved organic carbon concentration in the liquid phase (hydrolysate). The parallel reaction led to a new kind of unsolvable solid phase, which was further decomposed into gaseous products (CO(2)). The collected experimental data were used to identify unknown parameters of the model, i.e. activation energies and pre-exponential factors of elementary reactions. The mathematical model of activated sludge thermohydrolysis appropriately describes the kinetics of reactions occurring in the studied system. Copyright © 2012 Elsevier Ltd. All rights reserved.

Study of the effect of electron irradiation on the density of the activated sludge in aqueous solution

NASA Astrophysics Data System (ADS)

Kupchishin, A. I.; Niyazov, M. N.; Taipova, B. G.; Voronova, N. A.; Khodarina, N. N.

2018-01-01

Complex experimental studies on the effect of electron irradiation on the deposition rate of active sludge in aqueous systems by the optical method have been carried out. The obtained dependences of density (ρ) on time (t) are of the same nature for different radiation sources. The experimental curves of the dependence of the active sludge density on time are satisfactorily described by an exponential model.

A novel conditioning process for enhancing dewaterability of waste activated sludge by combination of zero-valent iron and persulfate.

PubMed

Zhou, Xu; Wang, Qilin; Jiang, Guangming; Liu, Peng; Yuan, Zhiguo

2015-06-01

Improvement of sludge dewaterability is crucial for reducing the costs of sludge disposal in wastewater treatment plants. This study presents a novel conditioning method for improving waste activated sludge dewaterability by combination of persulfate and zero-valent iron. The combination of zero-valent iron (0-30g/L) and persulfate (0-6g/L) under neutral pH substantially enhanced the sludge dewaterability due to the advanced oxidization reactions. The highest enhancement of sludge dewaterability was achieved at 4g persulfate/L and 15g zero-valent iron/L, with which the capillary suction time was reduced by over 50%. The release of soluble chemical oxygen demand during the conditioning process implied the decomposition of sludge structure and microorganisms, which facilitated the improvement of dewaterability due to the release of bound water that was included in sludge structure and microorganism. Economic analysis showed that the proposed conditioning process with persulfate and ZVI is more economically favorable for improving WAS dewaterability than classical Fenton reagent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of ultrasonic and ozone pre-treatments on pharmaceutical waste activated sludge's solubilisation, reduction, anaerobic biodegradability and acute biological toxicity.

PubMed

Pei, Jin; Yao, Hong; Wang, Hui; Shan, Dan; Jiang, Yichen; Ma, Lanqianya; Yu, Xiaohua

2015-09-01

Ultrasonic and ozone pre-treatment technologies were employed in this study to improve the anaerobic digestion efficiency of pharmaceutical waste activated sludge. The sludge solubilisation achieved 30.01% (150,000 kJ/kg TS) and 28.10% (0.1g O3/g TS) after ultrasonic treatment and ozone treatment. The anaerobic biodegradability after ultrasonic treatment was higher compared to ozonation due to the higher cumulative methane volume observed after 6 days (249 ml vs 190 ml). The ozonated sludge released the highest concentration of Cu(2+) into the liquid phase (6.640 mg L(-1)) compared to 0.530 mg/L for untreated sludge and 0.991 mg/L for sonicated sludge. The acute toxicity test measured by luminescent bacteria showed that anaerobic digestion could degrade toxic compounds and result in a reduction in toxicity. The main mechanism of action led to some differences in the treated sludge exhibiting higher potential for methane production from pharmaceutical waste sludge with ultrasonic treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of activated sludge culture conditions on Waxberry wastewater

NASA Astrophysics Data System (ADS)

Shi, Liang; He, Lingfeng; Zhang, Yongli

2018-03-01

Treated activated sludge is suitable for the treatment of wastewater. Biochemical method is used to treat the wastewater, and the influence of time on the COD index is investigated. The results showed that time had a significant effect on COD, and then affected the performance of activated sludge. Under different time, according to the order of time from short to long, COD decreases in turn. Under the action of activated sludge, the degradation of myrica rubra wastewater samples, after 25 h aeration for 96 h, the effect is better. Under this condition, the COD value was reduced at 72 mg/L, and the COD removal efficiency of myrica rubra wastewater was up to 93.39 %, and reached the two level discharge standard of municipal wastewater treatment.

Isolation, identification of sludge-lysing strain and its utilization in thermophilic aerobic digestion for waste activated sludge.

PubMed

Li, Xuesong; Ma, Hongzhi; Wang, Qunhui; Matsumoto, Shoichiro; Maeda, Toshinari; Ogawa, Hiroaki I

2009-05-01

A strain of sludge-lysing bacteria was isolated from waste activated sludge (WAS) in this study. The result of 16S rRNA gene analysis demonstrated that it was a species of new genus Brevibacillus (named Brevibacillus sp. KH3). The strain could release the protease with molecule weight of about 40 kDa which could enhance the efficiency of sludge thermophilic aerobic digestion. During the sterilized sludge digestion experiment inoculated with Brevibacillus sp. KH3, the maximum protease activity was 0.41 U/ml at pH 8 and 50 degrees C, and maximum TSS removal ratio achieved 32.8% after 120 h digestion at pH 8 and 50 degrees C. In the case of un-sterilized sludge digestion inoculated with Brevibacillus sp. KH3, TSS removal ratio in inoculated-group was 54.8%, increasing at 11.86% compared with un-inoculation (46.2%). The result demonstrated that inoculation of Brevibacillus sp. KH3 could help to degrade the EPS and promote the collapse of cells and inhibit the growth of certain kinds of microorganisms. It indicated that Brevibacillus sp. KH3 strain had a high potential to enhance WAS-degradation efficiency in thermophilic aerobic digestion.

Fate of stable strontium in the sewage treatment process as an analog for radiostrontium released by nuclear accidents.

PubMed

Kamei-Ishikawa, Nao; Ito, Ayumi; Umita, Teruyuki

2013-09-15

Radionuclides were widely released into the environment due to the nuclear accident at the Fukushima Daiichi Nuclear Power Plant. Some of these radionuclides have flowed into municipal sewage treatment plants through sewer systems. We have observed the fate of stable Sr in the sewage treatment process as a means to predict the fate of radiostrontium. Concentrations of stable Sr were determined in sewage influent, effluent, dewatered sludge, and incinerated sewage sludge ash collected from a sewage treatment plant once a month from July to December 2011. In the mass balance of Sr in the sewage treatment plant, 76% of the Sr entering the plant was discharged to the receiving water on average. Additionally, 14% of the Sr flowing through the plant was transferred to the sewage sludge and then concentrated in the sludge ash without being released to the atmosphere. We also investigated Sr sorption by activated sludge in a batch experiment. Measurements at 3 and 6h after the contact showed Sr was sorbed in the activated sludge; however, the measurements indicated Sr desorption from activated sludge occurred 48 h after the contact. Copyright © 2013 Elsevier B.V. All rights reserved.

Stabilization of chromium-bearing electroplating sludge with MSWI fly ash-based Friedel matrices.

PubMed

Qian, Guangren; Yang, Xiaoyan; Dong, Shixiang; Zhou, Jizhi; Sun, Ying; Xu, Yunfeng; Liu, Qiang

2009-06-15

This work investigated the feasibility and effectiveness of MSWI fly ash-based Friedel matrices on stabilizing/solidifying industrial chromium-bearing electroplating sludge using MSWI fly ash as the main raw material with a small addition of active aluminum. The compressive strength, leaching behavior and chemical speciation of heavy metals and hydration phases of matrices were characterized by TCLP, XRD, FTIR and other experimental methods. The results revealed that MSWI fly ash-based Friedel matrices could effectively stabilize chromium-bearing electroplating sludge, the formed ettringite and Friedel phases played a significant role in the fixation of heavy metals in electroplating sludge. The co-disposal of chromium-bearing electroplating sludge and MSWI fly ash-based Friedel matrices with a small addition of active aluminum is promising to be an effective way of stabilizing chromium-bearing electroplating sludge.

Disintegration of excess activated sludge--evaluation and experience of full-scale applications.

PubMed

Zábranská, J; Dohányos, M; Jenícek, P; Kutil, J

2006-01-01

Anaerobic digestion of sewage sludge can be improved by introducing a disintegration of excess activated sludge as a pretreatment process. The disintegration brings a deeper degradation of organic matter and less amount of output sludge for disposal, a higher production of biogas and consequently energy yield, in some cases suppression of digesters foaming and better dewaterability. The full-scale application of disintegration by a lysate-thickening centrifuge was monitored long term in three different WWTPs. The evaluation of contribution of disintegration to biogas production and digested sludge quality was assessed and operational experience is discussed. Increment of specific biogas production was evaluated in the range of 15-26%, organic matter in digested sludge significantly decreased to 48-49%. Results proved that the installation of a disintegrating centrifuge in WWTPs of different sizes and conditions would be useful and beneficial.

Characterization of Industrial Wastewater Sludge in Oman from Three Different Regions and Recommendations for Alternate Reuse Applications.

PubMed

Baawain, Mahad S; Al-Jabri, Mohsin; Choudri, B S

2015-11-01

Domestic and industrial wastewaters are mostly treated by biological process such as activated sludge, aerobic pond, and anaerobic treatment. This study focuses on characterizing the quality of sewage sludge in the Sultanate of Oman chosen from three industrial sewage treatment plants (STPs): Rusayl Industrial Estate (RSL.IE); Sohar Industrial Estate (SIE); and Raysut Industrial Estate (RIE). Samples of recycled activated sludge (RAS) and wasted activated sludge (WAS) were collected over a period of 12 months across above mentioned STPs. Parameters analyzed are electrical conductivity (EC), potential of hydrogen (pH), cations, anions and volatile content (VC). The obtained values for pH and EC were low for both RAS and WAS samples, except EC values of RIE that was more than 1000 μS/cm. The range of VC percentages in RAS and WAS samples were 44 to 86% and 41 to 77%, respectively. The measured values for chloride, sulfate, nitrate and phosphate were higher than the other anions. The average values of the cations in RAS and WAS samples were within the Omani Standards, suitable for the re-use of sludge in agriculture except for Cd in RSL.IE. The study recommends that a regular maintenance should be performed at the studied STPs to prevent any accumulation of some harmful substances, which may affect the sludge quality, and the sludge drying beds should be large enough to handle the produced sludge for better management.

Characterization of Industrial Wastewater Sludge in Oman from Three Different Regions and Recommendations for Alternate Reuse Applications

PubMed Central

BAAWAIN, Mahad S.; AL-JABRI, Mohsin; CHOUDRI, B.S.

2015-01-01

Background: Domestic and industrial wastewaters are mostly treated by biological process such as activated sludge, aerobic pond, and anaerobic treatment. This study focuses on characterizing the quality of sewage sludge in the Sultanate of Oman chosen from three industrial sewage treatment plants (STPs): Rusayl Industrial Estate (RSL.IE); Sohar Industrial Estate (SIE); and Raysut Industrial Estate (RIE). Methods: Samples of recycled activated sludge (RAS) and wasted activated sludge (WAS) were collected over a period of 12 months across above mentioned STPs. Parameters analyzed are electrical conductivity (EC), potential of hydrogen (pH), cations, anions and volatile content (VC). Results: The obtained values for pH and EC were low for both RAS and WAS samples, except EC values of RIE that was more than 1000 μS/cm. The range of VC percentages in RAS and WAS samples were 44 to 86% and 41 to 77%, respectively. The measured values for chloride, sulfate, nitrate and phosphate were higher than the other anions. Conclusion: The average values of the cations in RAS and WAS samples were within the Omani Standards, suitable for the re-use of sludge in agriculture except for Cd in RSL.IE. The study recommends that a regular maintenance should be performed at the studied STPs to prevent any accumulation of some harmful substances, which may affect the sludge quality, and the sludge drying beds should be large enough to handle the produced sludge for better management. PMID:26744704

Combining SBR systems for chemical and biological treatment: the destruction of the nerve agent VX.

PubMed

Irvine, R L; Haraburda, S S; Galbis-Reig, C

2004-01-01

The US Army is pilot testing the neutralization of VX nerve agent stockpiled at Newport, Indiana using caustic hydrolysis in a Sequencing Batch Reactor (SBR). The resulting hydrolysate was tested at the bench-scale for treatment with activated sludge biodegradation in two distinct studies, one in the SBR and another, in the PACT process. The feed to both biological systems was pretreated to enhance the biodegradability of the hydrolysis products. Both biodegradation studies demonstrated that the hydrolysate could easily meet the Chemical Weapons Convention treaty and US environmental regulations following pretreatment.

Degradation of slime extracellular polymeric substances and inhibited sludge flocs destruction contribute to sludge dewaterability enhancement during fungal treatment of sludge using filamentous fungus Mucor sp. GY-1.

PubMed

Wang, Zhenyu; Zheng, Guanyu; Zhou, Lixiang

2015-09-01

Mechanisms responsible for the sludge dewaterability enhanced by filamentous fungi during fungal treatment of sludge were investigated in the present study. The filamentous fungus Mucor sp. GY-1, isolated from waste activated sludge, enhanced sludge dewaterability by 82.1% to achieve the lowest value of normalized sludge specific resistance to filtration (SRF), 8.18 × 10(10) m · L/kg · g-TSS. During the fungal treatment of sludge, 57.8% of slime extracellular polymeric substances (EPS) and 51.1% of polysaccharide in slime EPS were degraded, respectively, by Mucor sp. GY-1, contributing to the improvement of sludge dewaterability. Slime EPS is much more available for Mucor sp. GY-1 than either LB-EPS or TB-EPS that bound with microbial cells. In addition, filamentous fungus Mucor sp. GY-1 entrapped small sludge particles and inhibited the destruction of sludge flocs larger than 100 μm, thus enhancing sludge dewaterability, during fungal treatment of sludge using Mucor sp. GY-1. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Influence of accessories mixing ratio on sludge biophysical co-drying].

PubMed

Yang, Jin-Long; Du, Qiong; Li, Dong; Han, Rong; Zhao, Yan; Wang, Hong-Tao

2011-08-01

Parameters (temperature, water content and so on) in the process of sludge biophysical co-drying were studied in self-made biophysical co-drying reactor. The sludge: tree bark: recycled sludge was set as 7: 3: 0.5, 9: 3: 0.5, 12: 3: 0.5 respectively. The results suggested that sludge temperature first increased then decreased along with drying time, water content decreased in the first 96 h, then had no obvious variability. While sludge: tree bark: recycled sludge was 9: 3: 0.5, the temperature of sludge spiraling, received to max 67 degrees C at 48 h under three different accessories mixture ratio, and was kept for 72 h above 55 degrees C, then spiraling, the final water content of sludge decreased from 74.1% to 61.8%, received the optimal water content removing rate 43.5%. Accessories mixing ratio had important influence on the process of sludge biophysical co-drying, sludge with proper mixing ratio can modify the structure of sludge, improve sludge permeability, arouse and keep microorganic activity, which will enhance sludge temperature and strengthen water content removal rate.

EVALUATION OF ACTIVATED BIOFILTRATION AND ACTIVATED BIOFILTRATION/ACTIVATED SLUDGE TECHNOLOGIES

EPA Science Inventory

The paper presents the results of a review and investigation of the activated biofilter (ABF) and activated biofilter/activated sludge (ABF/AS) technologies and a review of operating records of several municipal plants in the U.S. using these technologies. The overall objective o...

Biotransformation of arsenic species by activated sludge and removal of bio-oxidised arsenate from wastewater by coagulation with ferric chloride.

PubMed

Andrianisa, Harinaivo Anderson; Ito, Ayumi; Sasaki, Atsushi; Aizawa, Jiro; Umita, Teruyuki

2008-12-01

The potential of activated sludge to catalyse bio-oxidation of arsenite [As(III)] to arsenate [As(V)] and bio-reduction of As(V) to As(III) was investigated. In batch experiments (pH 7, 25 degrees C) using activated sludge taken from a treatment plant receiving municipal wastewater non-contaminated with As, As(III) and As(V) were rapidly biotransformed to As(V) under aerobic condition and As(III) under anaerobic one without acclimatisation, respectively. Sub-culture of the activated sludge using a minimal liquid medium containing 100mg As(III)/L and no organic carbon source showed that aerobic arsenic-resistant bacteria were present in the activated sludge and one of the isolated bacteria was able to chemoautotrophically oxidise As(III) to As(V). Analysis of arsenic species in a full-scale oxidation ditch plant receiving As-contaminated wastewater revealed that both As(III) and As(V) were present in the influent, As(III) was almost completely oxidised to As(V) after supply of oxygen by the aerator in the oxidation ditch, As(V) oxidised was reduced to As(III) in the anaerobic zone in the ditch and in the return sludge pipe, and As(V) was the dominant species in the effluent. Furthermore, co-precipitation of As(V) bio-oxidised by activated sludge in the plant with ferric hydroxide was assessed by jar tests. It was shown that the addition of ferric chloride to mixed liquor as well as effluent achieved high removal efficiencies (>95%) of As and could decrease the residual total As concentrations in the supernatant from about 200 microg/L to less than 5 microg/L. It was concluded that a treatment process combining bio-oxidation with activated sludge and coagulation with ferric chloride could be applied as an alternative technology to treat As-contaminated wastewater.

Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor.

PubMed

Lin, Shanshan; Jin, Y; Fu, L; Quan, C; Yang, Y S

2009-06-15

Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index (H) and Species evenness (E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the beta-Proteobacteria group, then gamma-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with gamma-Proteobacteria, then beta-Proteobacteria and CFB. Shannon's index (H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness (E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 x 10(5) microg/ microl, twice that in ASR of 4.67 x 10(5) microg/ microl under normal operation of two reactors. But the MLSS in GCOR was only 4.5mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa both in GCOR (15 no. per 20 ml) and in ASR (15 no. per 20 ml); the next abundant group was attachment plants 10 no. per 20 ml in GCOR and 4 no. per 20 ml in ASR, respectively. Rotifers and copepoda belonging to metazoan were only present in GCOR (8 no. per 20 ml for both rotifers and copepoda). The microbial diversity and population difference both in the GCOR carriers and ASR sludge indicated that the diverse microbes, a large amount of biomass forming longer microbial food chains attached on the carriers may be the main functions for the excess sludge reduction in GCOR.

Effect of humic acids with different characteristics on fermentative short-chain fatty acids production from waste activated sludge.

PubMed

Liu, Kun; Chen, Yinguang; Xiao, Naidong; Zheng, Xiong; Li, Mu

2015-04-21

Recently, the use of waste activated sludge to bioproduce short-chain fatty acids (SCFA) has attracted much attention as the sludge-derived SCFA can be used as a preferred carbon source to drive biological nutrient removal or biopolymer (polyhydroxyalkanoates) synthesis. Although large number of humic acid (HA) has been reported in sludge, the influence of HA on SCFA production has never been documented. This study investigated the effects on sludge-derived SCFA production of two commercially available humic acids (referred to as SHHA and SAHA purchased respectively from Shanghai Reagent Company and Sigma-Aldrich) that differ in chemical structure, hydrophobicity, surfactant properties, and degree of aromaticity. It was found that SHHA remarkably enhanced SCFA production (1.7-3.5 folds), while SAHA had no obvious effect. Mechanisms study revealed that all four steps (solubilization, hydrolysis, acidification, and methanogenesis) involved in sludge fermentation were unaffected by SAHA. However, SHHA remarkably improved the solubilization of sludge protein and carbohydrate and the activity of hydrolysis enzymes (protease and α-glucosidase) owing to its greater hydrophobicity and protection of enzyme activity. SHHA also enhanced the acidification step by accelerating the bioreactions of glyceradehyde-3P → d-glycerate 1,3-diphosphate, and pyruvate → acetyl-CoA due to its abundant quinone groups which served as electron acceptor. Further investigation showed that SHHA negatively influenced the activity of acetoclastic methanogens for its competition for electrons and inhibition on the reaction of acetyl-CoA → 5-methyl-THMPT, which caused less SCFA being consumed. All these observations were in correspondence with SHHA significantly enhancing the production of sludge derived SCFA.

Bioflocculation of mesophilic and thermophilic activated sludge.

PubMed

Vogelaar, J C T; De Keizer, A; Spijker, S; Lettinga, G

2005-01-01

Thermophilic activated sludge treatment is often hampered by a turbid effluent. Reasons for this phenomenon are so far unknown. Here, the hypothesis of the temperature dependency of the hydrophobic interaction as a possible cause for diminished thermophilic activated sludge bioflocculation was tested. Adsorption of wastewater colloidal particles was monitored on different flat surfaces as a function of temperature. Adsorption on a hydrophobic surface varied with temperature between 20 and 60 degrees C and no upward or downward trend could be observed. This makes the hydrophobic interaction hypothesis unlikely in explaining the differences in mesophilic and thermophilic activated sludge bioflocculation. Both mesophilic and thermophilic biomass did not flocculate with wastewater colloidal particles under anaerobic conditions. Only in the presence of oxygen, with biologically active bacteria, the differences in bioflocculation behavior became evident. Bioflocculation was shown only to occur with the combination of wastewater and viable mesophilic biomass at 30 degrees C, in the presence of oxygen. Bioflocculation did not occur in case the biomass was inactivated or when oxygen was absent. Thermophilic activated sludge hardly showed any bioflocculation, also under mesophilic conditions. Despite the differences in bioflocculation behavior, sludge hydrophobicity and sludge zetapotentials were almost similar. Theoretical calculations using the DLVO (Derjaguin, Landau, Verweij and Overbeek) theory showed that flocculation is unlikely in all cases due to long-range electrostatic forces. These calculations, combined with the fact that bioflocculation actually did occur at 30 degrees C and the unlikelyness of the hydrophobic interaction, point in the direction of bacterial exo-polymers governing bridging flocculation. Polymer interactions are not included in the DLVO theory and may vary as a function of temperature.

Microbial community related to lysozyme digestion process for boosting waste activated sludge biodegradability.

PubMed

Xin, Xiao-Dong; He, Jun-Guo; Qiu, Wei; Tang, Jian; Liu, Tian-Tian

2015-01-01

Waste activated sludge from a lab-scale sequencing batch reactor was used to investigate the potential relation of microbial community with lysozyme digestion process for sludge solubilization. The results showed the microbial community shifted conspicuously as sludge suffered lysozyme digestion. Soluble protein and polysaccharide kept an increasing trend in solution followed with succession of microbial community. The rise of lysozyme dosage augmented the dissimilarity among communities in various digested sludge. A negative relationship presented between community diversity and lysozyme digestion process under various lysozyme/TS from 0 to 240min (correlation coefficient R(2) exceeded 0.9). Pareto-Lorenz curves demonstrated that microbial community tended to be even with sludge disintegration process by lysozyme. Finally, with diversity (H) decrease and community distribution getting even, the SCOD/TCOD increased steadily in solution which suggested the sludge with high community diversity and uneven population distribution might have tremendous potential for improving their biodegradability by lysozyme digestion. Copyright © 2014 Elsevier Ltd. All rights reserved.

The hydrolysis and biogas production of complex cellulosic substrates using three anaerobic biomass sources.

PubMed

Keating, C; Cysneiros, D; Mahony, T; O'Flaherty, V

2013-01-01

In this study, the ability of various sludges to digest a diverse range of cellulose and cellulose-derived substrates was assessed at different temperatures to elucidate the factors affecting hydrolysis. For this purpose, the biogas production was monitored and the specific biogas activity (SBA) of the sludges was employed to compare the performance of three anaerobic sludges on the degradation of a variety of complex cellulose sources, across a range of temperatures. The sludge with the highest performance on complex substrates was derived from a full-scale bioreactor treating sewage at 37 °C. Hydrolysis was the rate-limiting step during the degradation of complex substrates. No activity was recorded for the synthetic cellulose compound carboxymethylcellulose (CMC) using any of the sludges tested. Increased temperature led to an increase in hydrolysis rates and thus SBA values. The non-granular nature of the mesophilic sludge played a positive role in the hydrolysis of solid substrates, while the granular sludges proved more effective on the degradation of soluble compounds.

Up-to-date modification of the anaerobic sludge digestion process introducing a separate sludge digestion mode.

PubMed

Sato, K; Ochi, S; Mizuochi, M

2001-01-01

Sewage treatment plants in Japan are subjected to advanced treatment to remove nutrients and hence control eutrophication problems in lakes and bays. This paper discusses the advantages and disadvantages of the separate digestion treatment mode for sludge generated from advanced wastewater treatment. In the separate digestion only primary sludge is digested and the excess activated sludge is directly dewatered. Separate digestion can reduce the return load of nutrients to approximately one third, and has major potential for the beneficial use of sludge.

Cost effective and advanced phosphorus removal in membrane bioreactors for a decentralised wastewater technology.

PubMed

Gnirss, R; Lesjean, B; Adam, C; Buisson, H

2003-01-01

Future stringent phosphorus regulations (down to 50 microg/L in some cases) together with the availability of more cost effective and/or innovative membrane processes, are the bases for this project. In contrast to conventional activated sludge plants, process parameters are not optimised and especially enhanced biological phosphorus (Bio-P) removal in membrane bioreactors (MBRs) are not proven yet. Current practice of P-removal in MBRs is the addition of coagulants in a co-precipitation mode. Enhanced biological phosphorus removal, when adapted to MBR technology, might be a cost-effective process. For very stringent effluent criteria additional P-adsorption on activated clay after membrane filtration can be also an interesting solution. The objective of this research project is to identify and test various phosphorus removal processes or process combinations, including MBR technologies. This should enable us to establish efficient and cost effective P-removal strategies for upgrading small sewage treatment units (up to 10,000 PE), as needed in some decentralised areas of Berlin. In particular, enhanced Bio-P removal technology was developed and optimised in MBR. Combinations of co-precipitation and post-adsorption will be tested when low P-values down to 50 microg/L are required in the effluent. One MBR bench-scale plant of 200 to 250 L and two MBR pilot plants of 1 to 3 m3 each were operated in parallel to a conventional wastewater treatment plant (Ruhleben WWTP, Berlin, Germany). The MBR bench-scale and pilot plants were operated under sludge ages of respectively 15 and 25 days. In both cases, Bio-P was possible, and phosphorus effluent concentration of about 0.1 mg/L could be achieved. A similar effluent quality was observed with the conventional WWTP. Investigations with lab columns indicated that P-adsorption could lead to concentrations down to 50 microg/L and no particle accumulation occurred in the filter media. The three tested materials exhibited great differences in break-through curves. Granulated ferric hydroxyde (GEH) showed higher capacity than activated alumina and FerroSorpPlus.

Micropollutant removal by attached and suspended growth in a hybrid biofilm-activated sludge process.

PubMed

Falås, P; Longrée, P; la Cour Jansen, J; Siegrist, H; Hollender, J; Joss, A

2013-09-01

Removal of organic micropollutants in a hybrid biofilm-activated sludge process was investigated through batch experiments, modeling, and full-scale measurements. Batch experiments with carriers and activated sludge from the same full-scale reactor were performed to assess the micropollutant removal rates of the carrier biofilm under oxic conditions and the sludge under oxic and anoxic conditions. Clear differences in the micropollutant removal kinetics of the attached and suspended growth were demonstrated, often with considerably higher removal rates for the biofilm compared to the sludge. For several micropollutants, the removal rates were also affected by the redox conditions, i.e. oxic and anoxic. Removal rates obtained from the batch experiments were used to model the micropollutant removal in the full-scale process. The results from the model and plant measurements showed that the removal efficiency of the process can be predicted with acceptable accuracy (± 25%) for most of the modeled micropollutants. Furthermore, the model estimations indicate that the attached growth in hybrid biofilm-activated sludge processes can contribute significantly to the removal of individual compounds, such as diclofenac. Copyright © 2013 Elsevier Ltd. All rights reserved.

Protists as bioindicators in activated sludge: Identification, ecology and future needs.

PubMed

Foissner, Wilhelm

2016-08-01

When the activated sludge process was developed, operators and scientists soon recognized protists as valuable indicators. However, only when Curds et al. (1968) showed with a few photographs the need of ciliates for a clear plant effluent, sewage protistology began to bloom but was limited by the need of species identification. Still, this is a major problem although several good guides are available. Thus, molecular kits should be developed for identification. Protists are indicators in two stages of wastewater treatment, viz., in the activated sludge and in the environmental water receiving the plant effluent. Continuous control of the protist and bacterial communities can prevent biological sludge foaming and bulking and may greatly save money for sludge oxygenation because several protist species are excellent indicators for the amount of oxygen present. The investigation of the effluent-receiving rivers gives a solid indication about the long term function of sewage works. The literature on protist bioindication in activated sludge is widely distributed. Thus, I compiled the data in a simple Table, showing which communities and species indicate good, mediocre, or poor plant performance. Further, many details on indication are provided, such as sludge loading and nitrifying conditions. Such specific features should be improved by appropriate statistics and more reliable identification of species. Then, protistologists have a fair chance to become important in wastewater works. Activated sludge is a unique habitat for particular species, often poorly or even undescribed. As an example, I present two new species. The first is a minute (∼30μm) Metacystis that makes an up to 300μm-sized mucous envelope mimicking a sludge floc. The second is a Phialina that is unique in having the contractile vacuole slightly posterior to mid-body. Finally, I provide a list of species which have the type locality in sewage plants. Copyright © 2016 Elsevier GmbH. All rights reserved.

Determination of the acute toxicities of physicochemical pretreatment and advanced oxidation processes applied to dairy effluents on activated sludge.

PubMed

Sivrioğlu, Özge; Yonar, Taner

2015-04-01

In this study, the acute toxicities of raw, physicochemical pre-treated, ozonated, and Fenton reagent applied samples of dairy wastewater toward activated sludge microorganisms, evaluated using the International Organization for Standardization's respiration inhibition test (ISO 8192), are presented. Five-day biological oxygen demand (BOD5) was measured to determine the biodegradability of physicochemical treatment, ozonation, Fenton oxidation or no treatment (raw samples) of dairy wastewater. Chemical pretreatment positively affected biodegradability, and the inhibition exhibited by activated sludge was removed to a considerable degree. Ozonation and the Fenton process exhibited good chemical oxygen demand removal (61%) and removal of toxins. Low sludge production was observed for the Fenton process applied to dairy effluents. We did not determine the inhibitory effect of the Fenton-process on the activated sludge mixture. The pollutant-removal efficiencies of the applied processes and their associated operating costs were determined. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Industrial activated sludge exhibit unique bacterial community composition at high taxonomic ranks.

PubMed

Ibarbalz, Federico M; Figuerola, Eva L M; Erijman, Leonardo

2013-07-01

Biological degradation of domestic and industrial wastewater by activated sludge depends on a common process of separation of the diverse self-assembled and self-sustained microbial flocs from the treated wastewater. Previous surveys of bacterial communities indicated the presence of a common core of bacterial phyla in municipal activated sludge, an observation consistent with the concept of ecological coherence of high taxonomic ranks. The aim of this work was to test whether this critical feature brings about a common pattern of abundance distribution of high bacterial taxa in industrial and domestic activated sludge, and to relate the bacterial community structure of industrial activated sludge with relevant operational parameters. We have applied 454 pyrosequencing of 16S rRNA genes to evaluate bacterial communities in full-scale biological wastewater treatment plants sampled at different times, including seven systems treating wastewater from different industries and one plant that treats domestic wastewater, and compared our datasets with the data from municipal wastewater treatment plants obtained by three different laboratories. We observed that each industrial activated sludge system exhibited a unique bacterial community composition, which is clearly distinct from the common profile of bacterial phyla or classes observed in municipal plants. The influence of process parameters on the bacterial community structure was evaluated using constrained analysis of principal coordinates (CAP). Part of the differences in the bacterial community structure between industrial wastewater treatment systems were explained by dissolved oxygen and pH. Despite the ecological relevance of floc formation for the assembly of bacterial communities in activated sludge, the wastewater characteristics are likely to be the major determinant that drives bacterial composition at high taxonomic ranks. Copyright © 2013 Elsevier Ltd. All rights reserved.

Oxygen transfer and uptake, nutrient removal, and energy footprint of parallel full-scale IFAS and activated sludge processes.

PubMed

Rosso, Diego; Lothman, Sarah E; Jeung, Matthew K; Pitt, Paul; Gellner, W James; Stone, Alan L; Howard, Don

2011-11-15

Integrated fixed-film activated sludge (IFAS) processes are becoming more popular for both secondary and sidestream treatment in wastewater facilities. These processes are a combination of biofilm reactors and activated sludge processes, achieved by introducing and retaining biofilm carrier media in activated sludge reactors. A full-scale train of three IFAS reactors equipped with AnoxKaldnes media and coarse-bubble aeration was tested using off-gas analysis. This was operated independently in parallel to an existing full-scale activated sludge process. Both processes achieved the same percent removal of COD and ammonia, despite the double oxygen demand on the IFAS reactors. In order to prevent kinetic limitations associated with DO diffusional gradients through the IFAS biofilm, this systems was operated at an elevated dissolved oxygen concentration, in line with the manufacturer's recommendation. Also, to avoid media coalescence on the reactor surface and promote biofilm contact with the substrate, high mixing requirements are specified. Therefore, the air flux in the IFAS reactors was much higher than that of the parallel activated sludge reactors. However, the standardized oxygen transfer efficiency in process water was almost same for both processes. In theory, when the oxygen transfer efficiency is the same, the air used per unit load removed should be the same. However, due to the high DO and mixing requirements, the IFAS reactors were characterized by elevated air flux and air use per unit load treated. This directly reflected in the relative energy footprint for aeration, which in this case was much higher for the IFAS system than activated sludge. Copyright © 2011 Elsevier Ltd. All rights reserved.

Improvement of activated sludge dewaterability by humus soil induced bioflocculation.

PubMed

Choi, Young-Gyun; Kim, Seong-Hong; Kim, Hee-Jun; Kim, Gyu Dong; Chung, Tai-Hak

2004-01-01

Effects of humus soil particles on the dewaterability of activated sludge were investigated. Cations leaching increased proportionally with the dosage of humus soil, and the leaching was not significant after 2 h. Divalent cations, Ca2+ and Mg2+, leaching from the humus soil played an important role in improving dewaterability of the biological sludge. On the contrary, dewaterability was not affected or slightly deteriorated by the monovalent cations, K+ and Na+ leached from the humus soil. Improvement in dewaterability of the sludge by addition of humus soil was higher than that of equivalent cations mixture. It seemed that the decrease of supracolloidal bio-particles (1 to 100 microm in diameter) resulted in diminishing of the blinding effect on cake and filter medium. SRF (specific resistance to filtration) of the humus soil added sludge varied in parallel with the M/D (monovalent to divalent cation) ratio, and the M/D ratio could be utilized as a useful tool for evaluation of the sludge dewatering characteristics. Long-term effects of humus soil on the improvement of activated sludge dewaterability were clearly identified by continuous operation results of a bench-scale MLE (Modified Ludzack Ettinger) system combined with a humus soil contactor. On the other hand, dewaterability of the control sludge was only slightly improved by a decrease in M/D ratio of the wastewater influent.

Effect of humic acid in leachate on specific methanogenic activity of anaerobic granular sludge.

PubMed

Guo, Mengfei; Xian, Ping; Yang, Longhui; Liu, Xi; Zhan, Longhui; Bu, Guanghui

2015-01-01

In order to find out the effects of humic acid (HA) in anaerobic-treated landfill leachate on granular sludge, the anaerobic biodegradability of HA as well as the influences of HA on the total cumulative methane production, the anaerobic methanization process and the specific methanogenic activity (SMA) of granular sludge are studied in this paper. Experimental results show that as a non-biodegradable organic pollutant, HA is also difficult to be decomposed by microbes in the anaerobic reaction process. Presence of HA and changes in the concentration have no significant influences on the total cumulative methane production and the anaerobic methanization process of granular sludge. Besides, the total cumulative methane production cannot reflect the inhibition of toxics on the methanogenic activity of granular sludge on the premise of sufficient reaction time. Results also show that HA plays a promoting role on SMA of granular sludge. Without buffering agent the SMA value increased by 19.2% on average due to the buffering and regulating ability of HA, while with buffering agent the SMA value increased by 5.4% on average due to the retaining effect of HA on the morphology of the sludge particles. However, in the presence of leachate the SMA value decreased by 27.6% on average, because the toxic effect of the toxics in the leachate on granular sludge is much larger than the promoting effect of HA.

Coupled heating/acidification pretreatment of chemical sludge for dewatering by using waste sulfuric acid at low temperature.

PubMed

Bian, Bo; Zhang, Limin; Zhang, Qin; Zhang, Shaopeng; Yang, Zhen; Yang, Weiben

2018-08-01

A cost-effective approach for pretreatment of chemical sludge for further dewatering, based on the idea of "using waste to treat waste", is provided. It is a coupled heating/acidification pretreatment method, where waste sulfuric acid is employed and relatively low temperatures (<100 °C) are applied. Effects of reaction time, temperature, and dosage of waste acid on dewatering performance (both dewatering speed and degree) are studied. Under the optimal conditions (reaction time: 30 min; temperature: 90 °C; waste acid dosage: 0.175 g/(g dried sludge)), the method of this work demonstrates three advantages compared to the conventional method using lime+polyacrylamide: lower moisture content of treated sludge; higher calorific value for incineration process; and lower cost. Detailed mechanism of the pretreatment for dewatering is investigated via characterizations and statistical analyses of various parameters, among which zeta potential, particle size, protein and polysaccharide contents, soluble chemical oxygen demand (SCOD), reduction of combined water and volatile suspended solid (VSS), are associated with dewatering performance. Both heating and acidification generate disintegration of cells in sludge, giving rise to two phenomena: more organic matters are released into solution and more bound water turns into free water. Meantime, the released organic polymers flocculate sludge particles, further accelerating the solid-liquid separation process. Copyright © 2018 Elsevier Ltd. All rights reserved.

Analysis of polyhydroxyalkanoate (PHA) synthase gene and PHA-producing bacteria in activated sludge that produces PHA containing 3-hydroxydodecanoate.

PubMed

Yang, Chao; Zhang, Wei; Liu, Ruihua; Zhang, Chi; Gong, Ting; Li, Qiang; Wang, Shufang; Song, Cunjiang

2013-09-01

Activated sludge is an alternative to pure cultures for polyhydroxyalkanoate (PHA) production due to the presence of many PHA-producing bacteria in activated sludge community. In this study, activated sludge was submitted to aerobic dynamic feeding in a sequencing batch reactor. During domestication, the changes of bacterial community structure were observed by terminal restriction fragment length polymorphism analysis. Furthermore, some potential PHA-producing bacteria, such as Thauera, Acinetobacter and Pseudomonas, were identified by denaturing gradient gel electrophoresis analysis. The constructed PHA synthase gene library was analyzed by DNA sequencing. Of the 80 phaC genes obtained, 76 belonged to the Class I PHA synthase, and four to the Class II PHA synthase. Gas chromatography-mass spectrometry analysis showed that PHA produced by activated sludge was composed of three types of monomers: 3-hydroxybutyrate, 3-hydroxyvalerate and 3-hydroxydodecanoate (3HDD). This is the first report of production of medium-chain-length PHAs (PHAMCL ) containing 3HDD by activated sludge. Further studies suggested that a Pseudomonas strain may play an important role in the production of PHAMCL containing 3HDD. Moreover, a Class II PHA synthase was found to have a correlation with the production of 3HDD-containing PHAMCL . © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

[Treatment of carbonization effluent by the ultrasonic radiation and activated sludge process].

PubMed

Ning, Ping; Xu, Jinqiu; Huang, Dongbin; Ma, Xiaoli; Xu, Xiaojun; Li, Ziyan

2003-05-01

The paper deals with the degradation of organic pollutants by the ultrasonic irradiation-activated sludge process. The treatment of the real coking wastewater of Kunming coke making-gas plant was studied with the water quality model. Using the ultrasonic irradiation-activated sludge process the organic pollutants in the real coking wastewater can be degraded effectively. The influence factors of the ultrasonic degradation effect such as initial concentration, aerated gas and ultrasonic density were investigated and mechanism was explored. The result shows that the ultrasonic degradation effect was high with the decrease of initial concentration of the CODCr, the presence of aerated gas and the increase of ultrasonic density. At the initial CODCr concentration of 807 mg/L, when air acted as aerated gas and only air itself (no ultrasound) was exerted on the wastewater, the degradation rate of the CODCr will be 4.5%. However, when the ultrasound of the intensity of 119.4 kW/m2 was exerted on the wastewater, the degradation rate of the CODCr will be 65%. Compared with the activated sludge process alone, the combination of the ultrasonic irradiation and activated sludge process can increase the degradation rate of the CODCr from 45% to 81%. The oxygen consumption rate of the carbonization effluent obviously decreased in the presence of the activated sludge. This shows the carbonization effluent is not biotoxic behind the ultrasonic irradiation.

Co-production of activated carbon, fuel-gas, and oil from the pyrolysis of corncob mixtures with wet and dried sewage sludge.

PubMed

Shao, Linlin; Jiang, Wenbo; Feng, Li; Zhang, Liqiu

2014-06-01

This study explored the amount and composition of pyrolysis gas and oil derived from wet material or dried material during the preparation of sludge-corncob activated carbon, and evaluated the physicochemical and surface properties of the obtained two types of sludge-corncob-activated carbons. For wet material, owing to the presence of water, the yields of sludge-corncob activated carbon and the oil fraction slightly decreased while the yield of gases increased. The main pyrolysis gas compounds were H2 and CO2, and more H2 was released from wet material than dried material, whereas the opposite holds for CO2 Heterocyclics, nitriles, organic acids, and steroids were the major components of pyrolysis oil. Furthermore, the presence of water in wet material reduced the yield of polycyclic aromatic hydrocarbons from 6.76% to 5.43%. The yield of furfural, one of heterocyclics, increased sharply from 3.51% to 21.4%, which could be explained by the enhanced hydrolysis of corncob. In addition, the surface or chemical properties of the two sludge-corncob activated carbons were almost not affected by the moisture content of the raw material, although their mesopore volume and diameter were different. In addition, the adsorption capacities of the two sludge-corncob activated carbons towards Pb and nitrobenzene were nearly identical. © The Author(s) 2014.

Retrofitting activated sludge systems to intermittent aeration for nitrogen removal.

PubMed

Hanhan, O; Artan, N; Orhon, D

2002-01-01

The paper provides the basis and the conceptual approach of applying process kinetics and modelling to the design of alternating activated sludge systems for retrofitting existing activated sludge plants to intermittent aeration for nitrogen removal. It shows the significant role of the two specific parameters, namely, the aerated fraction and the cycle time ratio on process performance through model simulations and proposes a way to incorporate them into a design procedure using process stoichiometry and mass balance. It illustrates the effect of these parameters, together with the sludge age, in establishing the balance between the denitrification potential and the available nitrogen created in the anoxic/aerobic sequences of system operation.

Evaluation of activated sludge for biodegradation of propylene glycol as an aircraft deicing fluid.

PubMed

Delorit, Justin D; Racz, LeeAnn

2014-04-01

Aircraft deicing fluid used at airport facilities is often collected for treatment or disposal in order to prevent serious ecological threats to nearby surface waters. This study investigated lab scale degradation of propylene glycol, the active ingredient in a common aircraft deicing fluid, by way of a laboratory-scale sequencing batch reactor containing municipal waste water treatment facility activated sludge performing simultaneous organic carbon oxidation and nitrification. The ability of activated sludge to remove propylene glycol was evaluated by studying the biodegradation and sorption characteristics of propylene glycol in an activated sludge medium. The results indicate sorption may play a role in the fate of propylene glycol in AS, and the heterotrophic bacteria readily degrade this compound. Therefore, a field deployable bioreactor may be appropriate for use in flight line applications.

Ultrasonic waste activated sludge disintegration for recovering multiple nutrients for biofuel production.

PubMed

Xie, Guo-Jun; Liu, Bing-Feng; Wang, Qilin; Ding, Jie; Ren, Nan-Qi

2016-04-15

Waste activated sludge is a valuable resource containing multiple nutrients, but is currently treated and disposed of as an important source of pollution. In this work, waste activated sludge after ultrasound pretreatment was reused as multiple nutrients for biofuel production. The nutrients trapped in sludge floc were transferred into liquid medium by ultrasonic disintegration during first 30 min, while further increase of pretreatment time only resulted in slight increase of nutrients release. Hydrogen production by Ethanoligenens harbinense B49 from glucose significantly increased with the concentration of ultrasonic sludge, and reached maximum yield of 1.97 mol H2/mol glucose at sludge concentration of 7.75 g volatile suspended solids/l. Without addition of any other chemicals, waste molasses rich in carbohydrate was efficiently turned into hydrogen with yield of 189.34 ml H2/g total sugar by E. harbinense B49 using ultrasonic sludge as nutrients. The results also showed that hydrogen production using pretreated sludge as multiple nutrients was higher than those using standard nutrients. Acetic acid produced by E. harbinense B49 together with the residual nutrients in the liquid medium were further converted into hydrogen (271.36 ml H2/g total sugar) by Rhodopseudomonas faecalis RLD-53 through photo fermentation, while ethanol was the sole end product with yield of 220.26 mg/g total sugar. Thus, pretreated sludge was an efficient nutrients source for biofuel production, which could replace the standard nutrients. This research provided a novel strategy to achieve environmental friendly sludge disposal and simultaneous efficient biofuel recovery from organic waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of Domestic Wastewater Sludge in Oman from Three Different Regions and Recommendations for Alternative Reuse Applications.

PubMed

Baawain, Mahad S; Al-Jabri, Mohsin; Choudri, B S

2014-02-01

There are more than 350 wastewater treatment plants distributed across different parts of Oman. Some of them produce large quantities of domestic sewage sludge, particularly this study focused on characterizing domestic sludge of six treatment plants that may contain various pollutants, therefore the proper management of domestic sewage sludge is essential. Samples of domestic sewage sludge were collected for each month over a period of one year in 2010. Samples of retained/recycled activated sludge (RAS) and waste activated sludge (WAS) were analyzed for elec-trical conductivity (EC), potential of hydrogen (pH), cations, anions and volatile content. All tests were conducted according to the Standard Method for the Examination of Water and Wastewater. Monitoring ofelectrical conductivity, nitrite and nitrate, the presence of chloride, sulfate and phosphate were higher than the other anions, the phosphate was found very high in all domestic STPs. The average obtained values of the cations in both domestic RAS and WAS samples were within the Omani Standards. The study showed the very high concentration of phosphate, it might be worth to further investigate on the sources of phosphate. Cations in both domestic RAS and WAS samples were low and suggest that the domestic sludge can be re used in agriculture. A regular maintenance should be performed to prevent any accumulation of some harmful substances which may affect the sludge quality and the sludge drying beds should be large enough to handle the produced sludge for better management.

Reduction of excess sludge in a sequencing batch reactor by lysis-cryptic growth using quick lime for disintegration under low temperature.

PubMed

Lv, Xiao-Mei; Song, Ju-Sheng; Li, Ji; Zhai, Kun

2017-08-01

In the present study, quick-lime-based thermal-alkaline sludge disintegration (SD) under low temperature was combined with cryptic growth to investigate the excess sludge reduction efficiency in the sequencing batch reactor (SBR). The optimized condition of SD was as follows: T = 80℃, pH = 11, t = 180 min, and the SD rate was about 42.1%. With 65.6% of excess sludge disintegrated and returned to the SBR, the system achieved sludge reduction rate of about 40.1%. The lysis-cryptic growth still obtained satisfactory sludge reduction efficiency despite the comparative low SD rate, which suggested that disintegration rate might not be the decisive factor for cryptic-growth-based sludge reduction. Lysis-cryptic growth did not impact the effluent quality, yet the phosphorus removal performance was enhanced, with effluent total phosphorus concentration decreased by 0.3 mg/L (33%). Crystal compounds of calcium phosphate precipitate were detected in the system by Fourier transform infrared spectroscopy and X-ray diffraction, which indicated the phosphorus removal potential of SD using lime. Moreover, endogenous dehydrogenase activity of activated sludge in the lysis-cryptic system was enhanced, which was beneficial for sludge reduction. SD and cryptic growth in the present study demonstrates an economical and effective approach for sludge reduction.

Synergetic pretreatment of waste activated sludge by hydrodynamic cavitation combined with Fenton reaction for enhanced dewatering.

PubMed

Cai, Meiqiang; Hu, Jianqiang; Lian, Guanghu; Xiao, Ruiyang; Song, Zhijun; Jin, Micong; Dong, Chunying; Wang, Quanyuan; Luo, Dewen; Wei, Zongsu

2018-04-01

The dewatering of waste activated sludge by integrated hydrodynamic cavitation (HC) and Fenton reaction was explored in this study. We first investigated the effects of initial pH, sludge concentration, flow rate, and H 2 O 2 concentration on the sludge dewaterability represented by water content, capillary suction time and specific resistance to filtration. The results of dewatering tests showed that acidic pH and low sludge concentration were favorable to improve dewatering performance in the HC/Fenton system, whereas optimal flow rate and H 2 O 2 concentration applied depended on the system operation. To reveal the synergism of HC/Fenton treatment, a suite of analysis were implemented: three-dimensional excitation emission matrix (3-DEEM) spectra of extracellular polymeric substances (EPS) such as proteins and polysaccharides, zeta potential and particle size of sludge flocs, and SEM/TEM imaging of sludge morphology. The characterization results indicate a three-step mechanism, namely HC fracture of different EPS in sludge flocs, Fenton oxidation of the released EPS, and Fe(III) re-flocculation, that is responsible for the synergistically enhanced sludge dewatering. Results of current study provide a basis to improve our understanding on the sludge dewatering performance by HC/Fenton treatment and possible scale-up of the technology for use in wastewater treatment plants. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhancement of waste activated sludge aerobic digestion by electrochemical pre-treatment.

PubMed

Song, Li-Jie; Zhu, Nan-Wen; Yuan, Hai-Ping; Hong, Ying; Ding, Jin

2010-08-01

Electrochemical technology with a pair of RuO(2)/Ti mesh plate electrode is first applied to pre-treat Waste Activated Sludge (WAS) prior to aerobic digestion in this study. The effects of various operating conditions were investigated including electrolysis time, electric power, current density, initial pH of sludge and sludge concentration. The study showed that the sludge reduction increased with the electrolysis time, electric power or current density, while decreased with the sludge concentration. Additionally, higher or lower pH than 7.0 was propitious to remove organic matters. The electrochemical pre-treatment removed volatile solids (VS) and volatile suspended solids (VSS) by 2.75% and 7.87%, respectively, with a WAS concentration of 12.9 g/L, electrolysis time of 30 min, electric power of 5 W and initial sludge pH of 10. In the subsequent aerobic digestion, the sludge reductions for VS and VSS after solids retention time (SRT) of 17.5 days were 34.25% and 39.59%, respectively. However, a SRT of 23.5 days was necessary to achieve equivalent reductions without electrochemical pre-treatment. Sludge analysis by Scanning Electron Microscope (SEM) images and infrared (IR) spectra indicated that electrochemical pre-treatment can rupture sludge cells, remove and solubilize intracellular substances, especially protein and polysaccharide, and consequently enhance the aerobic digestion. (c) 2010 Elsevier Ltd. All rights reserved.

Effects of sewage sludge fertilizer on heavy metal accumulation and consequent responses of sunflower (Helianthus annuus).

PubMed

Belhaj, Dalel; Elloumi, Nada; Jerbi, Bouthaina; Zouari, Mohamed; Abdallah, Ferjani Ben; Ayadi, Habib; Kallel, Monem

2016-10-01

Use of sewage sludge, a biological residue produced from sewage treatment processes in agriculture, is an alternative disposal technique of waste. To study the usefulness of sewage sludge amendment for Helianthus annuus, a pot experiment was conducted by mixing sewage sludge at 2.5, 5, and 7.5 % (w/w) amendment ratios to the agricultural soil. Soil pH decreased whereas electrical conductivity, organic matter, total N, available P, and exchangeable Na, K, and Ca increased in soil amended with sewage sludge in comparison to unamended soil. Sewage sludge amendment led to significant increase in Pb, Ni, Cu, Cr, and Zn concentrations of soil. The increased concentration of heavy metals in soil due to sewage sludge amendment led to increases in shoot and root concentrations of Cr, Cu, Ni, and Zn in plant as compared to those grown on unamended soil. Accumulation was more in roots than shoots for most of the heavy metals. Moreover, high metal removal for the harvestable parts of the crops was recorded. Sewage sludge amendment increased root and shoot length, leaves number, biomass, and antioxidant activities of sunflower. Significant increases in the activities of antioxidant enzymes and in the glutathione, proline, and soluble sugar content in response to amendment with sewage sludge may be defense mechanisms induced in response to heavy metal stress. Graphical abstract Origin, fate and behavior of sewage sludge fertilizer.

Performance intensification of Prague wastewater treatment plant.

PubMed

Novák, L; Havrlíková, D

2004-01-01

Prague wastewater treatment plant was intensified during 1994--1997 by construction of new regeneration tank and four new secondary settling tanks. Nevertheless, more stringent effluent limits and operational problems gave rise to necessity for further intensification and optimisation of plant performance. This paper describes principal operational problems of the plant and shows solutions and achieved results that have lead to plant performance stabilisation. The following items are discussed: low nitrification capacity, nitrification bioaugmentation, activated sludge bulking, insufficient sludge disposal capacity, chemical precipitation of raw wastewater, simultaneous precipitation, sludge chlorination, installation of denitrification zones, sludge rising in secondary settling tanks due to denitrification, dosage of cationic polymeric organic flocculant to secondary settling tanks, thermophilic operation of digestors, surplus activated sludge pre-thickening, mathematical modelling.

Impact of liming and drying municipal sewage sludge on the amount and availability of (14)C-acetyl sulfamethoxazole and (14)C-acetaminophen residues.

PubMed

Geng, Chunnu; Bergheaud, Valérie; Garnier, Patricia; Zhu, Yong-Guan; Haudin, Claire-Sophie

2016-01-01

Acetyl Sulfamethoxazole (AC-SMX) and acetaminophen (ACM) can be found in municipal sewage sludge, and their content and availability may be influenced by sludge treatments, such as drying and liming. A sludge similarly centrifuged with/without a flocculant was spiked with (14)C-labelled AC-SMX or ACM. Then, it was either limed (20% CaO) or/and dried under different laboratory conditions (1 week at ambient temperature; and 48 h at 40 or 80 °C). The total amount and distribution of the (14)C-compounds among several chemical fractions, based on the sludge floc definition, were assessed at the end of the treatments. All the (14)C-activity brought initially was recovered in the limed and/or dried sludges for AC-SMX but only between 44.4 and 84.9% for ACM, with the highest rate obtained for the limed sludge. Drying at 80 °C or liming increased the percentage of the sludge total organic carbon recovered in the extracts containing soluble extracellular polymeric substances (S-EPS) and the percentage of the total (14)C-activity extracted simultaneously. The non-extractable residues represented only 3.9-11.6% of the total (14)C-activity measured in the treated sludges for AC-SMX and 16.9-21.8% for ACM. The presence of AC-SMX and ACM residues in the treated sludges, after liming and drying under different conditions, was shown using some (14)C-labelled molecules. At this time scale and according to the extraction method selected, most of the (14)C-residues remained soluble and easily extractable for both compounds. This result implies that certain precautions should be taken when storing sludges before being spread on the field. Sludge piles, particularly the limed sludge, should be protected from rain to limit the production of lixiviates, which may contain residues of AC-SMX and ACM. Copyright © 2015 Elsevier Ltd. All rights reserved.

IASON - Intelligent Activated Sludge Operated by Nanotechnology - Hydrogel Microcarriers in Wastewater Treatment

NASA Astrophysics Data System (ADS)

Fleit, E.; Melicz, Z.; Sándor, D.; Zrínyi, M.; Filipcsei, G.; László, K.; Dékány, I.; Király, Z.

Performance of biological wastewater treatment depends to a large extent on mechanical strength, size distribution, permeability and other textural properties of the activated sludge flocs. A novel approach was developed in applying synthetic polymer materials to organize floc architecture instead of spontaneously formed activated sludge floc. Developed microcarrier polymer materials were used in our experiments to mitigate technological goals. Preliminary results suggest that the PVA-PAA (polyvinyl alcohol-polyacrylic acid copolymer) is a feasible choice for skeleton material replacing "traditional" activated sludge floc. Use of PVA-PAA hydrogel material as microreactors and methods for biofilm formation of wastewater bacteria on the carrier material are described. Laboratory scale experimental results with microscopic size bioreactors and their potential application for simultaneous nitrification and denitrification are presented.

Virus elimination in activated sludge systems: from batch tests to mathematical modeling.

PubMed

Haun, Emma; Ulbricht, Katharina; Nogueira, Regina; Rosenwinkel, Karl-Heinz

2014-01-01

A virus tool based on Activated Sludge Model No. 3 for modeling virus elimination in activated sludge systems was developed and calibrated with the results from laboratory-scale batch tests and from measurements in a municipal wastewater treatment plant (WWTP). The somatic coliphages were used as an indicator for human pathogenic enteric viruses. The extended model was used to simulate the virus concentration in batch tests and in a municipal full-scale WWTP under steady-state and dynamic conditions. The experimental and modeling results suggest that both adsorption and inactivation processes, modeled as reversible first-order reactions, contribute to virus elimination in activated sludge systems. The model should be a useful tool to estimate the number of viruses entering water bodies from the discharge of treated effluents.

Adsorption mechanisms and impact factors of oxytetracycline on activated sludge

NASA Astrophysics Data System (ADS)

Xiancai, Song; Dongfang, Liu; Lejun, Zhao

2017-03-01

The adsorption mechanisms and the effect of Oxytetracycline (OTC) onto activated sludge were studied. The results show that the adsorption of Oxytetracycline (OTC) onto activated sludge was coincident with the Pseudo-second-order kinetic model which suggested that chemical adsorption mechanism was dominant. The influences including pH and metal ions on the OTC were examined. It was demonstrated that the adsorption process was highly pH-dependant, which indicate that cationic exchange mechanisms may play an important role in the adsorption process. Na+, K+, Ca2+, Mg2+ and Cd2+ ions more or less inhibited the adsorption of OTC on activated sludge while Cu2+ enhanced the adsorption ability. The phenomenon may reflect the result that a surface complexation mechanism could involved in the adsorption.

Reduction of sludge generation by the addition of support material in a cyclic activated sludge system for municipal wastewater treatment.

PubMed

Araujo, Moacir Messias de; Lermontov, André; Araujo, Philippe Lopes da Silva; Zaiat, Marcelo

2013-09-01

An innovative biomass carrier (Biobob®) was tested for municipal wastewater treatment in an activated sludge system to evaluate the pollutant removal performance and the sludge generation for different carrier volumes. The experiment was carried out in a pilot-scale cyclic activated sludge system (CASS®) built with three cylindrical tanks in a series: an anoxic selector (2.1 m(3)), an aerobic selector (2.5 m(3)) and the main aerobic reactor (25.1 m(3)). The results showed that by adding the Biobob® carrier decreased the MLVSS concentration, which consequently reduced the waste sludge production of the system. Having 7% and 18% (v/v) support material in the aerobic reactor, the observed biomass yield decreased 18% and 36%, respectively, relative to the reactor operated with suspended biomass. The addition of media did not affect the system's performance for COD and TSS removal. However, TKN and TN removal were improved by 24% and 14%, respectively, using 18% (v/v) carrier. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhancing anaerobic digestion of waste activated sludge by the combined use of NaOH and Mg(OH)2: Performance evaluation and mechanism study.

PubMed

Huang, Cheng; Lai, Jia; Sun, Xiuyun; Li, Jiansheng; Shen, Jinyou; Han, Weiqing; Wang, Lianjun

2016-11-01

In this study, the combination treatment of NaOH and Mg(OH)2 was applied to anaerobic digestion of waste activated sludge (WAS) for simultaneously enhancement of volatile fatty acids (VFAs) production, nutrients removal and sludge dewaterability. The maximum VFAs production (461mg COD/g VSS) was obtained at the NaOH/Mg(OH)2 ratio of 75:25, which was much higher than that of the blank or sole NaOH. Moreover, nutrients removal and sludge dewaterability were improved by the combined using of NaOH and Mg(OH)2. Mechanism investigations revealed that the presence of Mg(OH)2 could maintain alkaline environment, which contributed to inhibit the activity of methanogens. Also, the bridging between Mg(2+) and extracellular polymeric substances (EPS) plays an important role in the solubilization and dewatering of sludge. High-throughput sequencing analysis demonstrated that the abundance of bacteria involved in sludge hydrolysis and VFAs accumulation was greatly enriched with the mixtures of NaOH and Mg(OH)2. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fate of pharmaceuticals in full-scale source separated sanitation system.

PubMed

Butkovskyi, A; Hernandez Leal, L; Rijnaarts, H H M; Zeeman, G

2015-11-15

Removal of 14 pharmaceuticals and 3 of their transformation products was studied in a full-scale source separated sanitation system with separate collection and treatment of black water and grey water. Black water is treated in an up-flow anaerobic sludge blanket (UASB) reactor followed by oxygen-limited autotrophic nitrification-denitrification in a rotating biological contactor and struvite precipitation. Grey water is treated in an aerobic activated sludge process. Concentration of 10 pharmaceuticals and 2 transformation products in black water ranged between low μg/l to low mg/l. Additionally, 5 pharmaceuticals were also present in grey water in low μg/l range. Pharmaceutical influent loads were distributed over two streams, i.e. diclofenac was present for 70% in grey water, while the other compounds were predominantly associated to black water. Removal in the UASB reactor fed with black water exceeded 70% for 9 pharmaceuticals out of the 12 detected, with only two pharmaceuticals removed by sorption to sludge. Ibuprofen and the transformation product of naproxen, desmethylnaproxen, were removed in the rotating biological contactor. In contrast, only paracetamol removal exceeded 90% in the grey water treatment system while removal of other 7 pharmaceuticals was below 40% or even negative. The efficiency of pharmaceutical removal in the source separated sanitation system was compared with removal in the conventional sewage treatment plants. Furthermore, effluent concentrations of black water and grey water treatment systems were compared with predicted no-effect concentrations to assess toxicity of the effluent. Concentrations of diclofenac, ibuprofen and oxazepam in both effluents were higher than predicted no-effect concentrations, indicating the necessity of post-treatment. Ciprofloxacin, metoprolol and propranolol were found in UASB sludge in μg/g range, while pharmaceutical concentrations in struvite did not exceed the detection limits. Copyright © 2015 Elsevier Ltd. All rights reserved.

Post-anaerobic digestion thermal hydrolysis of sewage sludge and food waste: Effect on methane yields, dewaterability and solids reduction.

PubMed

Svensson, Kine; Kjørlaug, Oda; Higgins, Matthew J; Linjordet, Roar; Horn, Svein J

2018-04-01

Post-anaerobic digestion (PAD) treatment technologies have been suggested for anaerobic digestion (AD) to improve process efficiency and assure hygenization of organic waste. Because AD reduces the amount of organic waste, PAD can be applied to a much smaller volume of waste compared to pre-digestion treatment, thereby improving efficiency. In this study, dewatered digestate cakes from two different AD plants were thermally hydrolyzed and dewatered, and the liquid fraction was recirculated to a semi-continuous AD reactor. The thermal hydrolysis was more efficient in relation to methane yields and extent of dewaterability for the cake from a plant treating waste activated sludge, than the cake from a plant treating source separated food waste (SSFW). Temperatures above 165 °C yielded the best results. Post-treatment improved volumetric methane yields by 7% and the COD-reduction increased from 68% to 74% in a mesophilic (37 °C) semi-continuous system despite lowering the solid retention time (from 17 to 14 days) compared to a conventional system with pre-treatment of feed substrates at 70 °C. Results from thermogravimetric analysis showed an expected increase in maximum TS content of dewatered digestate cake from 34% up to 46% for the SSFW digestate cake, and from 17% up to 43% in the sludge digestate cake, after the PAD thermal hydrolysis process (PAD-THP). The increased dewatering alone accounts for a reduction in wet mass of cake leaving the plant of 60% in the case of sludge digestate cake. Additionaly, the increased VS-reduction will contribute to further reduce the mass of wet cake. Copyright © 2018 Elsevier Ltd. All rights reserved.

Using low frequency and intensity ultrasound to enhance start-up and operation performance of Anammox process inoculated with the conventional sludge.

PubMed

Wang, Tao; Zhang, Diandian; Sun, Yating; Zhou, Shanshan; Li, Lin; Shao, Jingjing

2018-04-01

A lab-scale ultrasound enhancing Anammox reactor (R1) was established and irradiated once a week by ultrasound with the optimal parameter (frequency of 25 kHz, intensity of 0.2 W cm -2 and exposure time of 3 min) obtained by batch experiments. R1 and the controlled Anammox reactor (R2) without exposure to the ultrasound were operated in parallel. The start-up period of Anammox process (53 days) in R1 was shorter than that (61 days) in R2. The nitrogen loading-enhancing period (day 53-day 135) in R1 was also shorter than that (day 61-day 151) in R2. At the end of the nitrogen loading-enhancing period, NLR (0.76 kg N m -3  d -1 ) and NRR (0.68 kg N m -3  d -1 ) of R1 were both higher than NLR (0.66 kg N m -3  d -1 ) and NRR (0.56 kg N m -3  d -1 ) of R2. Moreover, The stability of Anammox process in R1 was better than that in R2. The results demonstrated that the periodical irradiation of ultrasound enhanced the start-up and operational performance of Anammox reactor. Microbial community analysis indicated that the ultrasound accelerated the microbial succession from some other bacteria to Anammox bacteria so that shorten the start-up period of Anammox process from the conventional activated sludge. It also indicated that the ultrasound strengthened the competitive advantage of Candidatus Kuenenia stuttgartiensis in Anammox bacteria of the mature sludge so as to enhance the nitrogen removal performance of the Anammox reactor under the operation condition of high nitrogen loading. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrochemical pretreatment of waste activated sludge: effect of process conditions on sludge disintegration degree and methane production.

PubMed

Ye, Caihong; Yuan, Haiping; Dai, Xiaohu; Lou, Ziyang; Zhu, Nanwen

2016-11-01

Waste activated sludge (WAS) requires a long digestion time because of a rate-limiting hydrolysis step - the first phase of anaerobic digestion (AD). Pretreatment can be used prior to AD to facilitate the hydrolysis step and improve the efficiency of WAS digestion. This study evaluated a novel application of electrochemical (EC) technology employed as the pretreatment method prior to AD of WAS, focusing on the effect of process conditions on sludge disintegration and subsequent AD process. A superior process condition of EC pretreatment was obtained by reaction time of 30 min, electrolysis voltage of 20 V, and electrode distance of 5 cm, under which the disintegration degree of WAS ranged between 9.02% and 9.72%. In the subsequent batch AD tests, 206 mL/g volatile solid (VS) methane production in EC pretreated sludge was obtained, which was 20.47% higher than that of unpretreated sludge. The AD time was 19 days shorter for EC pretreated sludge compared to the unpretreated sludge. Additionally, the EC + AD reactor achieved 41.84% of VS removal at the end of AD. The analysis of energy consumption showed that EC pretreatment could be effective in enhancing sludge AD with reduced energy consumption when compared to other pretreatment methods.

An examination of the treatment of iron-dosed waste activated sludge by anaerobic digestion.

PubMed

Johnson, D K; Carliell-Marquet, C M; Forster, C F

2003-08-01

Anaerobic digestion is an important sludge treatment process enabling stabilisation of the organic fraction of sewage sludge prior to land application. Any practice which might retard the anaerobic digestion process will jeopardize the stability of the resulting digested sludge. This paper reports on an investigation into the relative digestibility of iron-dosed waste activated sludge (WAS) from a sewage treatment works (STW) with chemical phosphorus removal (CPR), in comparison to WAS from a works without phosphorus removal. Two laboratory scale anaerobic digesters (51) were fed initially with non iron-dosed WAS (Works M) at a solids retention time of 19 days. After 2 months the iron-dosed CPR sludge (Works R) was introduced into the second digester, resulting in a 32% decrease in biogas production and an increase in the methane content of the biogas from an average of 74% to 81%. Pre-treatment of the CPR sludge with sodium sulphide and shear, both alone and in combination, caused the gas production to deteriorate further. Pre-acidification and pre-treatment with EDTA did result in an enhanced gas production but it was still not comparable with that of the digester being fed with non-iron-dosed sludge. The daily gas production was found to be linearly related to the amount of bound iron in the sludge.

Release of antibiotic resistant bacteria and genes in the effluent and biosolids of five wastewater utilities in Michigan.

PubMed

Munir, Mariya; Wong, Kelvin; Xagoraraki, Irene

2011-01-01

The purpose of this study was to quantify the occurrence and release of antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) into the environment through the effluent and biosolids of different wastewater treatment utilities including an MBR (Membrane Biological Reactor) utility, conventional utilities (Activated Sludge, Oxidative Ditch and Rotatory Biological Contactors-RBCs) and multiple sludge treatment processes (Dewatering, Gravity Thickening, Anaerobic Digestion and Lime Stabilization). Samples of raw wastewater, pre- and post-disinfected effluents, and biosolids were monitored for tetracycline resistant genes (tetW and tetO) and sulfonamide resistant gene (Sul-I) and tetracycline and sulfonamide resistant bacteria. ARGs and ARB concentrations in the final effluent were found to be in the range of ND(non-detectable)-2.33 × 10(6) copies/100 mL and 5.00 × 10(2)-6.10 × 10(5) CFU/100 mL respectively. Concentrations of ARGs (tetW and tetO) and 16s rRNA gene in the MBR effluent were observed to be 1-3 log less, compared to conventional treatment utilities. Significantly higher removals of ARGs and ARB were observed in the MBR facility (range of removal: 2.57-7.06 logs) compared to that in conventional treatment plants (range of removal: 2.37-4.56 logs) (p < 0.05). Disinfection (Chlorination and UV) processes did not contribute in significant reduction of ARGs and ARB (p > 0.05). In biosolids, ARGs and ARB concentrations were found to be in the range of 5.61 × 10(6)-4.32 × 10(9) copies/g and 3.17 × 10(4)-1.85 × 10(9) CFU/g, respectively. Significant differences (p < 0.05) were observed in concentrations of ARGs (except tetW) and ARB between the advanced biosolid treatment methods (i.e., anaerobic digestion and lime stabilization) and the conventional dewatering and gravity thickening methods. Copyright © 2010 Elsevier Ltd. All rights reserved.

A multi-disciplinary approach to the removal of emerging contaminants in municipal wastewater treatment plans in New York State, 2003-2004

USGS Publications Warehouse

Philips, Patrick J.; Stinson, Beverley; Zaugg, Steven D.; Furlong, Edward T.; Kolpin, Dana W.; Esposito, Kathleen; Bodniewicz, B.; Pape, R.; Anderson, J.

2005-01-01

The second phase of the study focused on one of the most common wastewater treatment processes operated in the United States, the Activated Sludge process. Using four controlled parallel activated sludge pilots, a more detailed assessment of the impact of Sludge Retention Time (SRT) on the reduction or removal of ECs was performed.

On the Occurrence of Anoxic Microniches, Denitrification, and Sulfate Reduction in Aerated Activated Sludge

PubMed Central

Schramm, Andreas; Santegoeds, Cecilia M.; Nielsen, Helle K.; Ploug, Helle; Wagner, Michael; Pribyl, Milan; Wanner, Jiri; Amann, Rudolf; de Beer, Dirk

1999-01-01

A combination of different methods was applied to investigate the occurrence of anaerobic processes in aerated activated sludge. Microsensor measurements (O2, NO2−, NO3−, and H2S) were performed on single sludge flocs to detect anoxic niches, nitrate reduction, or sulfate reduction on a microscale. Incubations of activated sludge with 15NO3− and 35SO42− were used to determine denitrification and sulfate reduction rates on a batch scale. In four of six investigated sludges, no anoxic zones developed during aeration, and consequently denitrification rates were very low. However, in two sludges anoxia in flocs coincided with significant denitrification rates. Sulfate reduction could not be detected in any sludge in either the microsensor or the batch investigation, not even under short-term anoxic conditions. In contrast, the presence of sulfate-reducing bacteria was shown by fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes and by PCR-based detection of genes coding for the dissimilatory sulfite reductase. A possible explanation for the absence of anoxia even in most of the larger flocs might be that oxygen transport is not only diffusional but enhanced by advection, i.e., facilitated by flow through pores and channels. This possibility is suggested by the irregularity of some oxygen profiles and by confocal laser scanning microscopy of the three-dimensional floc structures, which showed that flocs from the two sludges in which anoxic zones were found were apparently denser than flocs from the other sludges. PMID:10473433

Potential of activated sludge disintegration.

PubMed

Boehler, M; Siegrist, H

2006-01-01

The disposal of sewage sludge and the agricultural use of stabilised sludge are decreasing due to more stringent regulations in Europe. An increasing fraction of sewage sludge must therefore be dewatered, dried, incinerated and the ashes disposed of in landfills. These processes are cost-intensive and also lead to the loss of valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Disintegration of biological sludge by mechanical, thermal and physical methods could significantly reduce excess sludge production, improve the settling properties of the sludge and reduce bulking and scumming. The solubilised COD could also improve denitrification if the treated sludge is recycled to the anoxic zone. However, disintegration partly inhibits and kills nitrifiers and could therefore shorten their effective solid retention time, thus reducing the safety of the nitrification. This paper discusses the potential of disintegration on sludge reduction, the operating stability of nitrification, the improvement of denitrification and also presents an energy and cost evaluation.

Activated-Sludge Nitrification in the Presence of Linear and Branched-Chain Alkyl Benzene Sulfonates

PubMed Central

Baillod, Charles R.; Boyle, W. C.

1968-01-01

The effects of biodegradable linear alkyl benzene sulfonate and branched-chain alkyl benzene sulfonate detergents on activated-sludge nitrification were investigated by administering a synthetic waste containing up to 23 mg of each detergent per liter to eight bench-scale, batch, activated-sludge units. It was found that both detergents tended to promote complete oxidation of ammonia to nitrate, whereas control units produced approximately equal amounts of nitrite and nitrate. Various hypotheses are offered to explain the phenomenon. PMID:5636474

The influences of inoculants from municipal sludge and solid waste on compost stability, maturity and enzyme activities during chicken manure composting.

PubMed

Li, Shuyan; Li, Jijin; Yuan, Jing; Li, Guoxue; Zang, Bing; Li, Yangyang

2017-07-01

The aim of this study was to investigate the influence of inoculants on compost stability, maturity and enzyme activities during composting of chicken manure and cornstalk. Two microbial inoculants (originated from aerobic municipal sludge and municipal solid waste, respectively) were used in composting at the rate of 0.3% of initial raw materials (wet weight). No microbial inoculums were added to the control. The experiment was conducted under aerobic conditions for 53 days. The results show that enzyme activity is an important index to comprehensively evaluate the composting stability and maturity. Microbes originated from sludge works best in terms of composting stability and maturity (C:N ratio decreased from 15.5 to 10, and germination index increased to 109%). Microbial inoculums originated from sludge and municipal solid waste extended the time of thermophilic phase for 11 and 7 days, respectively. Microbial inoculums originated from sludge and MSW significantly increased the average of catalase activity (by 15.0% and 12.1%, respectively), urease activity (by 21.5% and 12.2%, respectively) and cellulase activity (by 32.1% and 26.1%, respectively) during composting.

An energy- and resource-saving technology for utilizing the sludge from thermal power station water treatment facilities

NASA Astrophysics Data System (ADS)

Nikolaeva, L. A.; Khusaenova, A. Z.

2014-05-01

A method for utilizing production wastes is considered, and a process circuit arrangement is proposed for utilizing a mixture of activated silt and sludge from chemical water treatment by incinerating it with possible heat recovery. The sorption capacity of the products from combusting a mixture of activated silt and sludge with respect to gaseous emissions is experimentally determined. A periodic-duty adsorber charged with a fixed bed of sludge is calculated, and the heat-recovery boiler efficiency is estimated together with the technical-economic indicators of the proposed utilization process circuit arrangement.

Impact of initial biodegradability on sludge anaerobic digestion enhancement by thermal pretreatment.

PubMed

Carrère, Hélène; Bougrier, Claire; Castets, Delphine; Delgenès, Jean Philippe

2008-11-01

Thermal treatments with temperature ranging from 60 to 210 degrees C were applied to 6 waste-activated sludge samples originating from high or medium load, extended aeration wastewater treatment processes that treated different wastewaters (urban, urban and industrial or slaughterhouse). COD sludge solubilisation was linearly correlated with the treatment temperature on the whole temperature range and independently of the sludge samples. Sludge batch mesophilic biodegradability increased with treatment temperature up to 190 degrees C. In this temperature range, biodegradability enhancement or methane production increase by thermal hydrolysis was shown to be a function of sludge COD solubilisation but also of sludge initial biodegradability. The lower the initial biodegradability means the higher efficiency of thermal treatment.

Sorption and biodegradation of sulfonamide antibiotics by activated sludge: experimental assessment using batch data obtained under aerobic conditions.

PubMed

Yang, Sheng-Fu; Lin, Cheng-Fang; Lin, Angela Yu-Chen; Hong, Pui-Kwan Andy

2011-05-01

This study investigated the adsorption, desorption, and biodegradation characteristics of sulfonamide antibiotics in the presence of activated sludge with and without being subjected to NaN(3) biocide. Batch experiments were conducted and the relative contributions of adsorption and biodegradation to the observed removal of sulfonamide antibiotics were determined. Three sulfonamide antibiotics including sulfamethoxazole (SMX), sulfadimethoxine (SDM), and sulfamonomethoxine (SMM), which had been detected in the influent and the activated sludge of wastewater treatment plants (WWTP) in Taiwan, were selected for this study. Experimental results showed that the antibiotic compounds were removed via sorption and biodegradation by the activated sludge, though biodegradation was inhibited in the first 12 h possibly due to competitive inhibition of xenobiotic oxidation by readily biodegradable substances. The affinity of sulfonamides to sterilized sludge was in the order of SDM > SMM > SMX. The sulfonamides existed predominantly as anions at the study pH of 6.8, which resulted in a low level of adsorption to the activated sludge. The adsorption/desorption isotherms were of a linear form, as well described by the Freundlich isotherm with the n value approximating unity. The linear distribution coefficients (K(d)) were determined from batch equilibrium experiments with values of 28.6 ± 1.9, 55.7 ± 2.2, and 110.0 ± 4.6 mL/g for SMX, SMM, and SDM, respectively. SMX, SMM, and SDM desorb reversibly from the activated sludge leaving behind on the solids 0.9%, 1.6%, and 5.2% of the original sorption dose of 100 μg/L. The sorbed antibiotics can be introduced into the environment if no further treatments were employed to remove them from the biomass. Copyright © 2011 Elsevier Ltd. All rights reserved.

Impact of aerobic stabilization on the characteristics of treatment sludge in the leather tanning industry.

PubMed

Cokgor, Emine Ubay; Aydinli, Ebru; Tas, Didem Okutman; Zengin, Gulsum Emel; Orhon, Derin

2014-01-01

The efficiency of aerobic stabilization on the treatment sludge generated from the leather industry was investigated to meet the expected characteristics and conditions of sludge prior to landfill. The sludge types subjected to aerobic stabilization were chemical treatment sludge, biological excess sludge, and the mixture of both chemical and biological sludges. At the end of 23 days of stabilization, suspended solids, volatile suspended solids and total organic carbon removal efficiencies were determined as 17%, 19% and 23% for biological sludge 31%, 35% and 54% for chemical sludge, and 32%, 34% and 63% for the mixture of both chemical and biological sludges, respectively. Model simulations of the respirometric oxygen uptake rate measurements showed that the ratio of active biomass remained the same at the end of the stabilization for all the sludge samples. Although mixing the chemical and biological sludges resulted in a relatively effective organic carbon and solids removal, the level of stabilization achieved remained clearly below the required level of organic carbon content for landfill. These findings indicate the potential risk of setting numerical restrictions without referring to proper scientific support.

Micropollutant removal from black water and grey water sludge in a UASB-GAC reactor.

PubMed

Butkovskyi, A; Sevenou, L; Meulepas, R J W; Hernandez Leal, L; Zeeman, G; Rijnaarts, H H M

2018-02-01

The effect of granular activated carbon (GAC) addition on the removal of diclofenac, ibuprofen, metoprolol, galaxolide and triclosan in a up-flow anaerobic sludge blanket (UASB) reactor was studied. Prior to the reactor studies, batch experiments indicated that addition of activated carbon to UASB sludge can decrease micropollutant concentrations in both liquid phase and sludge. In continuous experiments, two UASB reactors were operated for 260 days at an HRT of 20 days, using a mixture of source separated black water and sludge from aerobic grey water treatment as influent. GAC (5.7 g per liter of reactor volume) was added to one of the reactors on day 138. No significant difference in COD removal and biogas production between reactors with and without GAC addition was observed. In the presence of GAC, fewer micropollutants were washed out with the effluent and a lower accumulation of micropollutants in sludge and particulate organic matter occurred, which is an advantage in micropollutant emission reduction from wastewater. However, the removal of micropollutants by adding GAC to a UASB reactor would require more activated carbon compared to effluent post-treatment. Additional research is needed to estimate the effect of bioregeneration on the lifetime of activated carbon in a UASB-GAC reactor.

Cost-performance analysis of nutrient removal in a full-scale oxidation ditch process based on kinetic modeling.

PubMed

Li, Zheng; Qi, Rong; Wang, Bo; Zou, Zhe; Wei, Guohong; Yang, Min

2013-01-01

A full-scale oxidation ditch process for treating sewage was simulated with the ASM2d model and optimized for minimal cost with acceptable performance in terms of ammonium and phosphorus removal. A unified index was introduced by integrating operational costs (aeration energy and sludge production) with effluent violations for performance evaluation. Scenario analysis showed that, in comparison with the baseline (all of the 9 aerators activated), the strategy of activating 5 aerators could save aeration energy significantly with an ammonium violation below 10%. Sludge discharge scenario analysis showed that a sludge discharge flow of 250-300 m3/day (solid retention time (SRT), 13-15 days) was appropriate for the enhancement of phosphorus removal without excessive sludge production. The proposed optimal control strategy was: activating 5 rotating disks operated with a mode of "111100100" ("1" represents activation and "0" represents inactivation) for aeration and sludge discharge flow of 200 m3/day (SRT, 19 days). Compared with the baseline, this strategy could achieve ammonium violation below 10% and TP violation below 30% with substantial reduction of aeration energy cost (46%) and minimal increment of sludge production (< 2%). This study provides a useful approach for the optimization of process operation and control.

Development of quantitative methods for the detection of enteroviruses in sewage sludges during activation and following land disposal.

PubMed Central

Hurst, C J; Farrah, S R; Gerba, C P; Melnick, J L

1978-01-01

The development and evaluation of methods for the quantitative recovery of enteroviruses from sewage sludge are reported. Activated sewage sludge solids were collected by centrifugation, and elution of the solid-associated virus was accomplished by mechanical agitation in glycine buffer at pH 11.0. Eluted viruses were concentrated either onto an aluminum hydroxide floc or by association with a floc which formed de novo upon adjustment of the glycine eluate to pH 3.5. Viruses which remained in the liquid phase after lowering the pH of glycine eluate were concentrated by adsorption to and elution from membrane filters. The method of choice included high pH glycine elution and subsequent low pH concentration; it yielded an efficiency of recovery from activated sludge of 80% for poliovirus type 1, 68% for echovirus type 7, and 75% for coxsackievirus B3. This method was used to study the survival of naturally occurring virus in sludge at a sewage treatment plant and after subsequent land disposal of the solids after aerobic digestion. Reduction of enterovirus titers per gram (dry weight) of solids were modest during sludge activation but increased to a rate of 2 log 10/week after land disposal. PMID:29559

Development of quantitative methods for the detection of enteroviruses in sewage sludges during activation and following land disposal.

PubMed

Hurst, C J; Farrah, S R; Gerba, C P; Melnick, J L

1978-07-01

The development and evaluation of methods for the quantitative recovery of enteroviruses from sewage sludge are reported. Activated sewage sludge solids were collected by centrifugation, and elution of the solid-associated virus was accomplished by mechanical agitation in glycine buffer at pH 11.0. Eluted viruses were concentrated either onto an aluminum hydroxide floc or by association with a floc which formed de novo upon adjustment of the glycine eluate to pH 3.5. Viruses which remained in the liquid phase after lowering the pH of glycine eluate were concentrated by adsorption to and elution from membrane filters. The method of choice included high pH glycine elution and subsequent low pH concentration; it yielded an efficiency of recovery from activated sludge of 80% for poliovirus type 1, 68% for echovirus type 7, and 75% for coxsackievirus B3. This method was used to study the survival of naturally occurring virus in sludge at a sewage treatment plant and after subsequent land disposal of the solids after aerobic digestion. Reduction of enterovirus titers per gram (dry weight) of solids were modest during sludge activation but increased to a rate of 2 log 10/week after land disposal.

Optimization of Ozonation Process for the Reduction of Excess Sludge Production from Activated Sludge Process of Sago Industry Wastewater Using Central Composite Design

PubMed Central

Subha, B.; Muthukumar, M.

2012-01-01

Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R 2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction. PMID:22593666

Influence of activated carbon and biochar on phytotoxicity of air-dried sewage sludges to Lepidium sativum.

PubMed

Oleszczuk, Patryk; Rycaj, Marcin; Lehmann, Johannes; Cornelissen, Gerard

2012-06-01

The goal of the research was to determine the phytotoxicity (using Lepidium sativum) of two activated carbon/biochar-amended sewage sludges. Apart from the impact of the AC/biochar dose, the influence of biochar particle diameter (<300, 300-500 and >500 μm) and the influence of the contact time (7, 60, 90 days) between AC/biochar and sewage sludges on their phytotoxicity was also assessed. No negative impact of sewage sludges on seed germination was observed (P>0.05). The application of AC or biochar to the sludges positively affected root growth by reducing the harmful effect by 7.8 to 42% depending on the material used. Furthermore, the reduction range clearly depended on the type of sewage sludge. No differences were observed in the inhibition of the toxic effect between both biochar types used and the biochar particle size. The extension of the contact time between AC/biochar and sewage sludges had a negative impact on root growth. Copyright © 2012 Elsevier Inc. All rights reserved.

Extracellular polymers of ozonized waste activated sludge.

PubMed

Liu, J C; Lee, C H; Lai, J Y; Wang, K C; Hsu, Y C; Chang, B V

2001-01-01

Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% < 1,000 Da (low MW), 30% from 1,000 to 10,000 Da (medium MW), and 31% > 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.

The enhancement of anaerobic biodegradability of waste activated sludge by surfactant mediated biological pretreatment.

PubMed

Kavitha, S; Jayashree, C; Adish Kumar, S; Yeom, Ick Tae; Rajesh Banu, J

2014-09-01

In this study, the role of sodium dodecyl sulfate (SDS) was explored for the removal of extracellular polymeric substance (EPS) from waste activated sludge (WAS) followed by enzymatic bacterial pretreatment, which enhanced the subsequent anaerobic biodegradability. EPS was removed with 0.02 g/g SS of SDS. In the results of pretreatment, the suspended solids reduction and chemical oxygen demand solubilization were found to be 25.7% and 19.79% for deflocculated and bacterially pretreated sludge, whereas they were found to be 15.7% and 11% for flocculated sludge (without EPS removal and bacterially pretreated) and 7.85% and 6% for control sludge (raw sludge), respectively. Upon examining the anaerobic biodegradability, the biogas yield potential of deflocculated and bacterially pretreated, flocculated, deflocculated alone, and control sludges were found to be 0.467 L/(g VS), 0.355 L/(g VS), 0.315 L/(g VS), and 0.212 L/(g VS), respectively. Thus, the deflocculation and bacterial pretreatment improved the anaerobic biodegradability efficiently. Copyright © 2014 Elsevier Ltd. All rights reserved.

Toxicities of triclosan, phenol, and copper sulfate in activated sludge.

PubMed

Neumegen, Rosalind A; Fernández-Alba, Amadeo R; Chisti, Yusuf

2005-04-01

The effect of toxicants on the BOD degradation rate constant was used to quantitatively establish the toxicity of triclosan, phenol, and copper (II) against activated sludge microorganisms. Toxicities were tested over the following ranges of concentrations: 0-450 mg/L for phenol, 0-2 mg/L for triclosan, and 0-35 mg/L for copper sulfate (pentahydrate). According to the EC(50) values, triclosan was the most toxic compound tested (EC(50) = 1.82 +/- 0.1 mg/L), copper (II) had intermediate toxicity (EC(50) = 18.3 +/- 0.37 mg/L), and phenol was the least toxic (EC(50) = 270 +/- 0.26 mg/L). The presence of 0.2% DMSO had no toxic effect on the activated sludge. The toxicity evaluation method used was simple, reproducible, and directly relevant to activated sludge wastewater treatment processes.

Nitrogen removal and intentional nitrous oxide production from reject water in a coupled nitritation/nitrous denitritation system under real feed-stream conditions.

PubMed

Weißbach, Max; Thiel, Paul; Drewes, Jörg E; Koch, Konrad

2018-05-01

A Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) was performed over five months to investigate the performance and dynamics of nitrogen elimination and nitrous oxide production from digester reject water under real feed-stream conditions. A 93% conversion of ammonium to nitrite could be maintained for adapted seed sludge in the first stage (nitritation). The second stage (nitrous denitritation), inoculated with conventional activated sludge, achieved a conversion of 70% of nitrite to nitrous oxide after only 12 cycles of operation. The development of an alternative feeding strategy and the addition of a coagulant (FeCl 3 ) facilitated stable operation and process intensification. Under steady-state conditions, nitrite was reliably eliminated and different nitrous oxide harvesting strategies were assessed. Applying continuous removal increased N 2 O yields by 16% compared to the application of a dedicated stripping phase. These results demonstrate the feasible application of the CANDO process for nitrogen removal and energy recovery from ammonia rich wastewater. Copyright © 2018 Elsevier Ltd. All rights reserved.

Technical potential of microalgal bacterial floc raceway ponds treating food-industry effluents while producing microalgal bacterial biomass: An outdoor pilot-scale study.

PubMed

Van Den Hende, Sofie; Beelen, Veerle; Julien, Lucie; Lefoulon, Alexandra; Vanhoucke, Thomas; Coolsaet, Carlos; Sonnenholzner, Stanislaus; Vervaeren, Han; Rousseau, Diederik P L

2016-10-01

To replace costly mechanical aeration by photosynthetical aeration, upflow anaerobic sludge blanket (UASB) effluent of food-industry was treated in an outdoor MaB-floc raceway pond. Photosynthetic aeration was sufficient for nitrification, but the raceway effluent quality was below current discharge limits, despite the high hydraulic retention time (HRT) of 35days. Hereafter, conventional activated sludge (CAS) effluent of food-industry was treated in this pond to recover phosphorus. The two-day HRT results in a more realistic pond area, but the phosphorus removal efficiency was low (20%). High biomass productivities were obtained, i.e. 31.3 and 24.9ton total suspended solids hapond(-1)year(-1) for UASB and CAS effluent, respectively. Bioflocculation enabled successful harvesting of CAS effluent-fed MaB-flocs by settling and filtering at 150-250μm to 22.7% total solids. To conclude, MaB-floc raceway ponds cannot be recommended as the sole treatment for these food-industry effluents, but huge potential lies in added-value biomass production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of Domestic Wastewater Sludge in Oman from Three Different Regions and Recommendations for Alternative Reuse Applications

PubMed Central

BAAWAIN, Mahad S.; AL-JABRI, Mohsin; CHOUDRI, B.S.

2014-01-01

Abstract Background There are more than 350 wastewater treatment plants distributed across different parts of Oman. Some of them produce large quantities of domestic sewage sludge, particularly this study focused on characterizing domestic sludge of six treatment plants that may contain various pollutants, therefore the proper management of domestic sewage sludge is essential. Methods Samples of domestic sewage sludge were collected for each month over a period of one year in 2010. Samples of retained/recycled activated sludge (RAS) and waste activated sludge (WAS) were analyzed for elec-trical conductivity (EC), potential of hydrogen (pH), cations, anions and volatile content. All tests were conducted according to the Standard Method for the Examination of Water and Wastewater. Results Monitoring ofelectrical conductivity, nitrite and nitrate, the presence of chloride, sulfate and phosphate were higher than the other anions, the phosphate was found very high in all domestic STPs. The average obtained values of the cations in both domestic RAS and WAS samples were within the Omani Standards. Conclusion The study showed the very high concentration of phosphate, it might be worth to further investigate on the sources of phosphate. Cations in both domestic RAS and WAS samples were low and suggest that the domestic sludge can be re used in agriculture. A regular maintenance should be performed to prevent any accumulation of some harmful substances which may affect the sludge quality and the sludge drying beds should be large enough to handle the produced sludge for better management. PMID:26060740

Efficient azo dye decolorization in a continuous stirred tank reactor (CSTR) with built-in bioelectrochemical system.

PubMed

Cui, Min-Hua; Cui, Dan; Gao, Lei; Cheng, Hao-Yi; Wang, Ai-Jie

2016-10-01

A continuous stirred tank reactor with built-in bioelectrochemical system (CSTR-BES) was developed for azo dye Alizarin Yellow R (AYR) containing wastewater treatment. The decolorization efficiency (DE) of the CSTR-BES was 97.04±0.06% for 7h with sludge concentration of 3000mg/L and initial AYR concentration of 100mg/L, which was superior to that of the sole CSTR mode (open circuit: 54.87±4.34%) and the sole BES mode (without sludge addition: 91.37±0.44%). The effects of sludge concentration and sodium acetate (NaAc) concentration on azo dye decolorization were investigated. The highest DE of CSTR-BES for 4h was 87.66±2.93% with sludge concentration of 12,000mg/L, NaAc concentration of 2000mg/L and initial AYR concentration of 100mg/L. The results in this study indicated that CSTR-BES could be a practical strategy for upgrading conventional anaerobic facilities against refractory wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sewage sludge drying method combining pressurized electro-osmotic dewatering with subsequent bio-drying.

PubMed

Li, Qian; Lu, Xuebin; Guo, Haigang; Yang, Zengjun; Li, Yingte; Zhi, Suli; Zhang, Keqiang

2018-04-30

In this study, pressurized electro-osmotic dewatering (PEOD) as a pretreatment process, instead of the conventional practice of adding bulking agents, for sewage sludge bio-drying was proposed. Initially, various parameters were optimized for obtaining dewatered sewage sludge (DSS), treated by an efficient, quick, and energy-saving PEOD process. The results show that the moisture content (MC) of sewage sludge could decrease from 83.41% to 60.0% within 7.5 min in the optimum conditions of the PEOD process. Subsequently, two DSS bio-drying tests were carried out to investigate the effects of inoculation. The highest temperature (68.1 °C) was obtained for T2 (inoculation), which was 3.6 °C higher than that for T1 (non- inoculation). The MC accumulative removal rate for T1 (41.49%) was slightly less than that for T2 (44.60%). Lastly, the volatile solid degradation dynamics model parameters were measured. The degradation rate constants (k) for T1 and T2 were 0.00501 and 0.00498, respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Presence of radionuclides in sludge from conventional drinking water treatment plants. A review.

PubMed

Fonollosa, E; Nieto, A; Peñalver, A; Aguilar, C; Borrull, F

2015-03-01

The analysis of sludge samples generated during water treatment processes show that different radioisotopes of uranium, thorium and radium, among others can accumulate in that kind of samples, even the good removal rates obtained in the aqueous phase (by comparison of influent and effluent water concentrations). Inconsequence, drinking water treatment plants are included in the group of Naturally Occurring Radioactive Material (NORM) industries. The accumulation of radionuclides can be a serious problem especially when this sludge is going to be reused, so more exhaustive information is required to prevent the possible radiological impact of these samples in the environment and also on the people. The main aim of this review is to outline the current situation regarding the different studies reported in the literature up to date focused on the analysis of the radiological content of these sludge samples from drinking water treatment plants. In this sense, special attention is given to the recent approaches for their determination. Another important aim is to discuss about the final disposal of these samples and in this regard, sludge reuse (including for example direct agricultural application or also as building materials) are together with landfilling the main reported strategies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Optimization of municipal sludge and grease co-digestion using disintegration technologies.

PubMed

Bouchy, L; Pérez, A; Camacho, P; Rubio, P; Silvestre, G; Fernández, B; Cano, R; Polanco, M; Díaz, N

2012-01-01

Many drivers tend to foster the development of renewable energy production in wastewater treatment plants as many expectations rely upon energy recovery from sewage sludge, for example through biogas use. This paper is focused on the assessment of grease waste (GW) as an adequate substrate for co-digestion with municipal sludge, as it has a methane potential of 479-710 LCH(4)/kg VS, as well as the evaluation of disintegration technologies as a method to optimize the co-digestion process. With this objective three different pre-treatments have been selected for evaluation: thermal hydrolysis, ultrasound and enzymatic treatment. Results have shown that co-digestion processes without pre-treatment had a maximum increment of 128% of the volumetric methane productivity when GW addition was 23% inlet (at 20 days of HRT and with an OLR of 3.0 kg COD/m(3)d), compared with conventional digestion of sewage sludge alone. Concerning the application of the selected disintegration technologies, all pre-treatments showed improvements in terms of methane yield (51.8, 89.5 and 57.6% more for thermal hydrolysis, ultrasound and enzymatic treatment, respectively, compared with non-pretreated wastes), thermal hydrolysis of GW and secondary sludge being the best configuration as it improved the solubilization of the organic matter and the hydrodynamic characteristics of digestates.

Waste management in the meat processing industry: Conversion of paunch and DAF sludge into solid fuel.

PubMed

Hamawand, Ihsan; Pittaway, Pam; Lewis, Larry; Chakrabarty, Sayan; Caldwell, Justin; Eberhard, Jochen; Chakraborty, Arpita

2017-02-01

This article addresses the novel dewatering process of immersion-frying of paunch and dissolved air flotation (DAF) sludge to produce high energy pellets. Literature have been analysed to address the feasibility of replacing conventional boiler fuel at meat processing facilities with high energy paunch-DAF sludge pellets (capsules). The value proposition of pelleting and frying this mixture into energy pellets is based on a Cost-Benefit Analysis (CBA). The CBA is based on information derived from the literature and consultation with the Australian Meat Processing Industry. The calorific properties of a mixture of paunch cake solids and DAF sludge were predicted from literature and industry consultation to validate the product. This study shows that the concept of pelletizing and frying paunch is economically feasible. The complete frying and dewatering of the paunch and DAF sludge mixture produces pellets with energy content per kilogram equivalent to coal. The estimated cost of this new product is half the price of coal and the payback period is estimated to be between 1.8 and 3.2years. Further research is required for proof of concept, and to identify the technical challenges associated with integrating this technology into existing meat processing plants. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Construction materials as a waste management solution for cellulose sludge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modolo, R., E-mail: regina.modolo@ua.pt; Ferreira, V.M.; Machado, L.M.

2011-02-15

Sustainable waste management system for effluents treatment sludge has been a pressing issue for pulp and paper sector. Recycling is always recommended in terms of environmental sustainability. Following an approach of waste valorisation, this work aims to demonstrate the technical viability of producing fiber-cement roof sheets incorporating cellulose primary sludge generated on paper and pulp mills. From the results obtained with preliminary studies it was possible to verify the possibility of producing fiber-cement sheets by replacing 25% of the conventional used virgin long fiber by primary effluent treatment cellulose sludge. This amount of incorporation was tested on an industrial scale.more » Environmental parameters related to water and waste, as well as tests for checking the quality of the final product was performed. These control parameters involved total solids in suspension, dissolved salts, chlorides, sulphates, COD, metals content. In the product, parameters like moisture, density and strength were controlled. The results showed that it is possible to replace the virgin long fibers pulp by primary sludge without impacts in final product characteristics and on the environment. This work ensures the elimination of significant waste amounts, which are nowadays sent to landfill, as well as reduces costs associated with the standard raw materials use in the fiber-cement industrial sector.« less

Evaluation of sewage sludge incineration ash as a potential land reclamation material.

PubMed

Lin, Wenlin Yvonne; Ng, Wei Cheng; Wong, Belinda Shu Ee; Teo, Serena Lay-Ming; Sivananthan, Gayathiri D/O; Baeg, Gyeong Hun; Ok, Yong Sik; Wang, Chi-Hwa

2018-05-23

This study evaluated the potential of utilising sewage sludge incineration ash as a land reclamation material. Toxicity assessment of the leachate of the ash was carried out for both terrestrial and marine organisms. Both the fruit fly Drosophila melanogaster and barnacle Amphibalanus amphitrite showed that both bottom and fly ash leached at liquid-to-solid (L/S) ratio 5 did not substantially affect viabilities. The leachate carried out at L/S 10 was compared to the European Waste Acceptance Criteria and the sewage sludge ashes could be classified as non-hazardous waste. The geotechnical properties of the sewage sludge ash were studied and compared to sand, a conventional land reclamation material, for further evaluation of its potential as a land reclamation material. It was found from direct shear test that both bottom and fly ashes displayed similar and comparable shear strength to that of typical compacted sandy soil based on the range of internal friction angle obtained. However, the consolidation profile of bottom ash was significantly different from sand, while that of fly ash was more similar to sand. Our study showed that the sewage sludge ash has the potential to be used as a land reclamation material. Copyright © 2018 Elsevier B.V. All rights reserved.

Seasonal changes in the body size of two rotifer species living in activated sludge follow the Temperature-Size Rule.

PubMed

Kiełbasa, Anna; Walczyńska, Aleksandra; Fiałkowska, Edyta; Pajdak-Stós, Agnieszka; Kozłowski, Jan

2014-12-01

Temperature-Size Rule (TSR) is a phenotypic body size response of ectotherms to changing temperature. It is known from the laboratory studies, but seasonal patterns in the field were not studied so far. We examined the body size changes in time of rotifers inhabiting activated sludge. We hypothesize that temperature is the most influencing parameter in sludge environment, leading sludge rotifers to seasonally change their body size according to TSR, and that oxygen content also induces the size response. The presence of TSR in Lecane inermis rotifer was tested in a laboratory study with two temperature and two food-type treatments. The effect of interaction between temperature and food was significant; L. inermis followed TSR in one food type only. The seasonal variability in the body sizes of the rotifers L. inermis and Cephalodella gracilis was estimated by monthly sampling and analyzed by multiple regression, in relation to the sludge parameters selected as the most influential by multivariate analysis, and predicted to alter rotifer body size (temperature and oxygen). L. inermis varied significantly in size throughout the year, and this variability is explained by temperature as predicted by the TSR, but not by oxygen availability. C. gracilis also varied in size, though this variability was explained by both temperature and oxygen. We suggest that sludge age acts as a mortality factor in activated sludge. It may have a seasonal effect on the body size of L. inermis and modify a possible effect of oxygen. Activated sludge habitat is driven by both biological processes and human regulation, yet its resident organisms follow general evolutionary rule as they do in other biological systems. The interspecific response patterns differ, revealing the importance of taking species-specific properties into account. Our findings are applicable to sludge properties enhancement through optimizing the conditions for its biological component.

More than a decade of experience of landfill leachate treatment with a full-scale anammox plant combining activated sludge and activated carbon biofilm.

PubMed

Azari, Mohammad; Walter, Uwe; Rekers, Volker; Gu, Ji-Dong; Denecke, Martin

2017-05-01

The performance of biological treatment for high ammonium removal from landfill leachate has been demonstrated. The plant was upgraded combining the activated sludge process followed by activated carbon reactor. Based on a long-term analysis of data collected from 2006 to 2015, the average total nitrogen removal efficiency of 94% was achieved for wastewaters with a C: N ratio varying from 1 to 5 kg-COD kg-TN -1 . But without the presence of activated carbon reactor, the average of biological removal efficiency for total nitrogen was only 82% ± 6% for the activated sludge stage. It means that up to 20% of the nitrogen in the influent can only be eliminated by microorganisms attached to granular activated carbon. After upgrades of the plant, the energy efficiency showed a reduction in the specific energy demand from 1.6 to less than 0.2 kWh m -3 . Methanol consumption and sludge production was reduced by 91% and 96%, respectively. Fluorescent in situ Hybridization was used for microbial diversity analysis on floccular sludge and granular biofilm samples. Anaerobic ammonium oxidation (anammox) bacteria and nitrifiers were detected and Candidatus Scalindua was found in two forms of flocs and biofilms. Due to stochastic risk assessment based on the long-term data analysis given in this research, the treatment criteria were achieved and the combination of granular activated carbon biofilm process and activated sludge can be a novel and sought approach to better enrich anammox biomass for full-scale treatment applications to reduce operating costs and promote nutrient removal stability and efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of deflocculation on the efficiency of disperser induced dairy waste activated sludge disintegration and treatment cost.

PubMed

Devi, T Poornima; Ebenezer, A Vimala; Kumar, S Adish; Kaliappan, S; Banu, J Rajesh

2014-09-01

Excess sludge disintegration by energy intensive processes like mechanical pretreatment is considered to be high in cost. In this study, an attempt has been made to disintegrate excess sludge by disperser in a cost effective manner by deflocculating the sludge using sodium dodecyl sulphate (SDS) at a concentration of 0.04 g/g SS. The disperser pretreatment was effective at a specific energy input of 5013 kJ/kg TS where deflocculated sludge showed higher chemical oxygen demand solubilisation and suspended solids reduction of 26% and 22.9% than flocculated sludge and was found to be 18.8% and 18.6% for former and latter respectively. Higher accumulation of volatile fatty acid (700 mg/L) in deflocculated sludge indicates better hydrolysis of sludge by proposed method. The anaerobic biodegradability resulted in higher biogas production potential of 0.522 L/(g VS) for deflocculated sludge. Cost analysis of the study showed 43% net energy saving in deflocculated sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Behaviour and occurrence of estrogens in municipal sewage treatment plants--II. Aerobic batch experiments with activated sludge.

PubMed

Ternes, T A; Kreckel, P; Mueller, J

1999-01-12

Aerobic batch experiments containing a diluted slurry of activated sludge from a real sewage treatment plant (STP) near Frankfurt/Main were undertaken, in order to investigate the persistence of natural estrogens and contraceptives under aerobic conditions. The batch experiments showed that while in contact with activated sludge the natural estrogen 17 beta-estradiol was oxidized to estrone, which was further eliminated in the batch experiments in an approximate linear time dependence. Further degradation products of estrone were not observed. 16 alpha-hydroxyestrone was rapidly eliminated, again without detection of further degradation products. The contraceptive 17 alpha-ethinylestradiol was principally persistent under the selected aerobic conditions, whereas mestranol was rapidly eliminated and small portions of 17 alpha-ethinylestradiol were formed by demethylation. Additionally, two glucuronides of 17 beta-estradiol (17 beta-estradiol-17-glucuronide and 17 beta-estradiol-3-glucuronide) were cleaved in contact with the diluted activated sludge solution and thus 17 beta-estradiol was released. The glucuronidase activity of the activated sludge was further confirmed by the cleavage of 4-methylumbelliferyl-beta-D-glucuronide (MUF-beta-glucuronide) in a solution of a activated sludge slurry and Milli-Q-water (1:100, v/v). The turnover rate obtained was approximately steady state, with a turnover rate of 0.1 mumol/l for the released MUF. Hence, it is very likely that the glucuronic acid moiety of 17 beta-estradiol glucuronides and other estrogen glucuronides become cleaved in a real municipal STP, so that the concentrations of the free estrogens increase.

Quantifying in situ growth rate of a filamentous bacterial species in activated sludge using rRNA:rDNA ratio.

PubMed

Nguyen, Vivi L; He, Xia; de Los Reyes, Francis L

2016-11-01

If the in situ growth rate of filamentous bacteria in activated sludge can be quantified, researchers can more accurately assess the effect of operating conditions on the growth of filaments and improve the mathematical modeling of filamentous bulking. We developed a method to quantify the in situ specific growth rate of Sphaerotilus natans (a model filament) in activated sludge using the species-specific 16S rRNA:rDNA ratio. Primers targeting the 16S rRNA of S. natans were designed, and real-time PCR and RT-PCR were used to quantify DNA and RNA levels of S. natans, respectively. A positive linear relationship was found between the rRNA:rDNA ratio (from 440 to 4500) and the specific growth rate of S. natans (from 0.036 to 0.172 h -1 ) using chemostat experiments. The in situ growth rates of S. natans in activated sludge samples from three water reclamation facilities were quantified, illustrating how the approach can be applied in a complex environment such as activated sludge. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Zero valent iron significantly enhances methane production from waste activated sludge by improving biochemical methane potential rather than hydrolysis rate.

PubMed

Liu, Yiwen; Wang, Qilin; Zhang, Yaobin; Ni, Bing-Jie

2015-02-05

Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system.

Zero Valent Iron Significantly Enhances Methane Production from Waste Activated Sludge by Improving Biochemical Methane Potential Rather Than Hydrolysis Rate

PubMed Central

Liu, Yiwen; Wang, Qilin; Zhang, Yaobin; Ni, Bing-Jie

2015-01-01

Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system. PMID:25652244

Zero Valent Iron Significantly Enhances Methane Production from Waste Activated Sludge by Improving Biochemical Methane Potential Rather Than Hydrolysis Rate

NASA Astrophysics Data System (ADS)

Liu, Yiwen; Wang, Qilin; Zhang, Yaobin; Ni, Bing-Jie

2015-02-01

Anaerobic digestion has been widely applied for waste activated sludge (WAS) treatment. However, methane production from anaerobic digestion of WAS is usually limited by the slow hydrolysis rate and/or poor biochemical methane potential of WAS. This work systematically studied the effects of three different types of zero valent iron (i.e., iron powder, clean scrap and rusty scrap) on methane production from WAS in anaerobic digestion, by using both experimental and mathematical approaches. The results demonstrated that both the clean and the rusty iron scrap were more effective than the iron powder for improving methane production from WAS. Model-based analysis showed that ZVI addition significantly enhanced methane production from WAS through improving the biochemical methane potential of WAS rather than its hydrolysis rate. Economic analysis indicated that the ZVI-based technology for enhancing methane production from WAS is economically attractive, particularly considering that iron scrap can be freely acquired from industrial waste. Based on these results, the ZVI-based anaerobic digestion process of this work could be easily integrated with the conventional chemical phosphorus removal process in wastewater treatment plant to form a cost-effective and environment-friendly approach, enabling maximum resource recovery/reuse while achieving enhanced methane production in wastewater treatment system.

Removal of selected non-steroidal anti-inflammatory drugs (NSAIDs), gemfibrozil, carbamazepine, beta-blockers, trimethoprim and triclosan in conventional wastewater treatment plants in five EU countries and their discharge to the aquatic environment.

PubMed

Paxéus, N

2004-01-01

The removal of commonly used pharmaceuticals (ibuprofen, naproxen, diclofenac, gemfibrozil, carbamazepine, atenolol, metoprolol and trimethoprim) and a biocide (triclosan) in operating wastewater treatment plants in five EU countries has been studied. Under normal operating conditions the acidic drugs and triclosan were partially removed with removal rates varying from ca. 20 to >95%. The highest removal rate was found for ibuprofen and triclosan (>90%) followed by naproxen (80%), gemfibrozil (55%) and diclofenac (39%). Ibuprofen undergoes an oxidative transformation to corresponding hydroxy- and carboxy-metabolites, which contributes to its high removal rate. Disturbances in the activated sludge process resulted in lower removal rates for all acidic drugs, mostly for diclofenac (<10% removed) but also for ibuprofen (<60% removed). The treatment of wastewaters by activated sludge usually did not result in any practical removal (<10%) of neutral carbamazepine or basic atenolol, metoprolol and trimethoprim. The removal rates of the investigated drugs and triclosan are discussed in terms of mechanisms responsible for their removal. Discharges of carbamazepine, diclofenac, gemfibrozil, naproxen, triclosan and trimethoprim from WWTPs to the aquatic environment, expressed as the average concentration in the effluent and the daily discharged quantity per person served by WWTPs were assessed.

[Using Excess Activated Sludge Treated 4-Chlorophenol Contained Waste Water to Cultivate Chlorella vulgaris].

PubMed

Wang, Lu; Chen, Xiu-rong; Yan, Long; He, Yi-xuan; Shi, Zhen-dong

2015-04-01

Using different rations of sludge extracts and supernate from 4-Chlorophenol (4-CP) simulated wastewater's excess sludge after centrifugation to cultivate the Chlorella vulgaris to achieve the goal of excess sludge utilization together with chlorella cultivating. The experiments were performed in 500 mL flasks with different rations of sludge extracts & BG-11 and supernate & BG-11 in a light growth chamber respectively. Number of algal cells, Chlorophyll, enzyme activity, oil and water total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), toxicity index were investigated. Result showed that the nutrition supplies and toxicity in the excess sludge were removed efficiently via Chlorella vulgaris, the removal rates of TN and TP were at least 40% and 90% respectively; After 10 days cultivation, the density growth of 50% sludge extracts was 20 times higher of the beginning while its chlorophyll content was lower than that of the blank group. Sludge extracts could promote the proliferation of algae, but were not conducive to the synthesis of chlorophyll. The quantity of SOD in per cell showed Chlorella vulgaris gave a positive response via stimulation from toxicant in sludge extracts and supernate. The best time for collecting chlorella vulgaris was the fifth day of cultivation, taking neutral oil accumulation as the evaluating indicator for its utilization combined with the removal of supplies and toxicity.

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation.

PubMed

Chen, Zhan; Zhang, Weijun; Wang, Dongsheng; Ma, Teng; Bai, Runying; Yu, Dezhong

2016-10-15

The effects of combined calcium peroxide (CaO2) oxidation with chemical re-flocculation on dewatering performance and physicochemical properties of waste activated sludge was investigated in this study. The evolutions of extracellular polymeric substances (EPS) distribution, composition and morphological properties were analyzed to unravel the sludge conditioning mechanism. It was found that sludge filtration performance was enhanced by calcium peroxide oxidation with the optimal dosage of 20 mg/gTSS. However, this enhancement was not observed at lower dosages due to the absence of oxidation and the performance deteriorated at higher dosages because of the release of excess EPS, mainly as protein-like substances. The variation in soluble EPS (SEPS) component can be fitted well with pseudo-zero-order kinetic model under CaO2 treatment. At the same time, extractable EPS content (SEPS and loosely bound EPS (LB-EPS)) were dramatically increased, indicating sludge flocs were effectively broken and their structure became looser after CaO2 addition. The sludge floc structure was reconstructed and sludge dewaterability was significantly enhanced using chemical re-flocculation (polyaluminium chloride (PACl), ferric iron (FeCl3) and polyacrylamide (PAM)). The inorganic coagulants performed better in improving sludge filtration dewatering performance and reducing cake moisture content than organic polymer, since they could act as skeleton builders and decrease the sludge compressibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of Control Parameters for the Activated Sludge Process

ERIC Educational Resources Information Center

Stall, T. Ray; Sherrard, Josephy H.

1978-01-01

An evaluation of the use of the parameters currently being used to design and operate the activated sludge process is presented. The advantages and disadvantages for the use of each parameter are discussed. (MR)

Predicting the degradability of waste activated sludge.

PubMed

Jones, Richard; Parker, Wayne; Zhu, Henry; Houweling, Dwight; Murthy, Sudhir

2009-08-01

The objective of this study was to identify methods for estimating anaerobic digestibility of waste activated sludge (WAS). The WAS streams were generated in three sequencing batch reactors (SBRs) treating municipal wastewater. The wastewater and WAS properties were initially determined through simulation of SBR operation with BioWin (EnviroSim Associates Ltd., Flamborough, Ontario, Canada). Samples of WAS from the SBRs were subsequently characterized through respirometry and batch anaerobic digestion. Respirometry was an effective tool for characterizing the active fraction of WAS and could be a suitable technique for determining sludge composition for input to anaerobic models. Anaerobic digestion of the WAS revealed decreasing methane production and lower chemical oxygen demand removals as the SRT of the sludge increased. BioWin was capable of accurately describing the digestion of the WAS samples for typical digester SRTs. For extended digestion times (i.e., greater than 30 days), some degradation of the endogenous decay products was assumed to achieve accurate simulations for all sludge SRTs.

The thermal behaviour of the co-combustion between paper sludge and rice straw.

PubMed

Xie, Zeqiong; Ma, Xiaoqian

2013-10-01

The thermal characteristics and kinetics of paper sludge, rice straw and their blends were evaluated under combustion condition. The paper sludge was blended with rice straw in the range of 10-95 wt.% to investigate their co-combustion behaviour. There was significant interaction between rice straw and paper sludge in high temperature. The combustion of paper sludge and rice straw could be divided into two stages. The value of the activation energy obtained by the Friedman and the Ozawa-Flynn-Wall (OFW) first decreased and then increased with the conversion degree rising. The average activation energy did not monotonically decrease with increasing the percentage of rice straw in the blends. When the percentage of rice straw in the blends was 80%, the value of the average activation energy was the smallest, which was 139 kJ/mol obtained by OFW and 132 kJ/mol obtained by Friedman, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Toluene inhibition on an anaerobic reactor sludge in terms of potential activity and composition of acetoclastic methanogens.

PubMed

Ince, Orhan; Kolukirik, Mustafa; Cetecioglu, Zeynep; Eyice, Ozge; Inceoglu, Ozgul; Ince, Bahar

2009-12-01

The aim of this study was to determine the effect of toluene on an anaerobic sludge taken from a full-scale upflow anaerobic sludge blanket (UASB) reactor in terms of potential activity and composition of acetoclastic methanogens. Specific methanogenic activity (SMA) test results showed that 5%, 9.5%, 14%, 24%, 29%, 38% and 62% inhibition occurred in the potential methane production (PMP) rate of the sludge at toluene concentrations of 0.1 mM, 0.2 mM, 0.3 mM, 0.4 mM, 0.5 mM, 0.6 mM and 1 mM, respectively. Fluorescence in situ hybridization (FISH) results showed that relative abundance of archaeal cells was approx. 19% throughout the SMA tests. The anaerobic sludge was dominated by acetoclastic genus Methanosaeta which were slightly affected by increasing toluene concentrations do not have any effect on relative abundance of Methanosaeta spp., which was between 73% +/- 1.6 and 68% +/- 2.1 of the archaeal population.

Characterization of water treatment sludge and its reuse as coagulant.

PubMed

Ahmad, Tarique; Ahmad, Kafeel; Ahad, Abdul; Alam, Mehtab

2016-11-01

Coagulation-flocculation process results in the generation of large volume of waste or residue, known as water treatment sludge (WTS), in the purification of surface water for potable supplies. Sustainable management of the inevitable waste requires careful attention from the plant operators and sludge managers. In this study, WTS produced with the optimum alum dose of 30 ml/L at the laboratory scale has been treated with sulphuric acid to bring forth a product known as sludge reagent product (SRP). The performance of SRP is evaluated for its efficiency in removing the colloidal suspensions from the Yamuna river water over wide pH range of 2-13. 1% sludge acidified with sulphuric acid of normality 2.5 at the rate of 0.05 ml/ml sludge has been observed as the optimum condition for preparing SRP from WTS. The percentage turbidity removal is greater at higher pH value and increases with increasing the dosage of SRP. The optimum SRP dosage of 8 ml/L in the pH range of 6-8 performed well in removing the colloidal suspension and other impurities from the Yamuna water. The quality of treated water met the prescribed standards for most of the quality parameters. Thus, SRP has the potential to substitute the conventional coagulants partially or completely in the water treatment process, depending on the quality needed at the users end. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characteristics of the microwave pyrolysis and microwave CO2-assisted gasification of dewatered sewage sludge.

PubMed

Chun, Young Nam; Jeong, Byeo Ri

2017-07-28

Microwave drying-pyrolysis or drying-gasification characteristics were examined to convert sewage sludge into energy and resources. The gasification was carried out with carbon dioxide as a gasifying agent. The examination results were compared with those of the conventional heating-type electric furnace to compare both product characteristics. Through the pyrolysis or gasification, gas, tar, and char were generated as products. The produced gas was the largest component of each process, followed by the sludge char and the tar. During the pyrolysis process, the main components of the produced gas were hydrogen and carbon monoxide, with a small amount of hydrocarbons such as methane and ethylene. In the gasification process, however, the amount of carbon monoxide was greater than the amount of hydrogen. In microwave gasification, a large amount of heavy tar was produced. The largest amount of benzene in light tar was generated from the pyrolysis or gasification. Ammonia and hydrogen cyanide, which are precursors of NO x , were also generated. In the microwave heating method, the sludge char produced by pyrolysis and gasification had pores in the mesopore range. This could be explained that the gas obtained from the microwave pyrolysis or gasification of the wet sewage sludge can be used as an alternative fuel, but the tar and NO x precursors in the produced gas should be treated. Sludge char can be used as a biomass solid fuel or as a tar removal adsorbent if necessary.

Enhancing aerobic digestion potential of municipal waste-activated sludge through removal of extracellular polymeric substance.

PubMed

Merrylin, J; Kaliappan, S; Kumar, S Adish; Yeom, Ick-Tae; Banu, J Rajesh

2014-01-01

A protease-secreting bacteria was used to pretreat municipal sewage sludge to enhance aerobic digestion. To enhance the accessibility of the sludge to the enzyme, extracellular polymeric substances were removed using citric acid thereby removing the flocs in the sludge. The conditions for the bacterial pretreatment were optimized using response surface methodology. The results of the bacterial pretreatment indicated that the suspended solids reduction was 18% in sludge treated with citric acid and 10% in sludge not treated with citric acid whereas in raw sludge, suspended solids reduction was 5.3%. Solubilization was 10.9% in the sludge with extracellular polymeric substances removed in contrast to that of the sludge with extracellular polymeric substances, which was 7.2%, and that of the raw sludge, which was just 4.8%. The suspended solids reduction in the aerobic reactor containing pretreated sludge was 52.4% whereas that in the control reactor was 15.3%. Thus, pretreatment with the protease-secreting bacteria after the removal of extracellular polymeric substances is a cost-effective and environmentally friendly method.

Application of Biofilm Covered Activated Carbon Particles as a Microbial Inoculum Delivery System for Enhanced Bioaugmentation of PCBs in Contaminated Sediment

DTIC Science & Technology

2013-09-01

after anaerobic digestion at thermophilic conditions (60- 70C). Application of biofilm covered activated carbon particles as a microbial inoculum...Sludge Thickener; Sludge = Sludge after anaerobic digestion at thermophilic conditions (60- 70C). C3. Microscopic evaluation of dechlorinating...associated enzymes are capable of opening the biphenyl ring structure and transform the molecule into a linear structure, this changed structure was not

Influence of deflocculation on microwave disintegration and anaerobic biodegradability of waste activated sludge.

PubMed

Ebenezer, A Vimala; Kaliappan, S; Adish Kumar, S; Yeom, Ick-Tae; Banu, J Rajesh

2015-06-01

In the present study, the potential benefits of deflocculation on microwave pretreatment of waste activated sludge were investigated. Deflocculation in the absence of cell lysis was achieved through the removal of extra polymeric substances (EPS) by sodium citrate (0.1g sodium citrate/g suspended solids), and DNA was used as a marker for monitoring cell lysis. Subsequent microwave pretreatment yielded a chemical oxygen demand (COD) solubilisation of 31% and 21%, suspended solids (SS) reduction of 37% and 22%, for deflocculated and flocculated sludge, respectively, with energy input of 14,000kJ/kg TS. When microwave pretreated sludge was subjected to anaerobic fermentation, greater accumulation of volatile fatty acid (860mg/L) was noticed in deflocculated sludge, indicating better hydrolysis. Among the samples subjected to BMP (Biochemical methane potential test), deflocculated microwave pretreated sludge showed better amenability towards anaerobic digestion with high methane production potential of 0.615L (gVS)(-1). Copyright © 2015 Elsevier Ltd. All rights reserved.

Microwave pyrolysis of oily sludge with activated carbon.

PubMed

Chen, Yi-Rong

2016-12-01

The aim of this study is to explore catalytic microwave pyrolysis of crude oil storage tank sludge for fuels using granular activated carbon (GAC) as a catalyst. The effect of GAC loading on the yield of pyrolysis products was also investigated. Heating rate of oily sludge and yield of microwave pyrolysis products such as oil and fuel gas was found to depend on the ratio of GAC to oily sludge. The optimal GAC loading was found to be 10%, while much smaller and larger feed sizes adversely influenced production. During oily sludge pyrolysis, a maximum oil yield of 77.5% was achieved. Pyrolytic oils with high concentrations of diesel oil and gasoline (about 70 wt% in the pyrolytic oil) were obtained. The leaching of heavy metals, such as Cr, As and Pb, was also suppressed in the solid residue after pyrolysis. This technique provides advantages such as harmless treatment of oily sludge and substantial reduction in the consumption of energy, time and cost.

Roles of magnetite and granular activated carbon in improvement of anaerobic sludge digestion.

PubMed

Peng, Hong; Zhang, Yaobin; Tan, Dongmei; Zhao, Zhiqiang; Zhao, Huimin; Quan, Xie

2018-02-01

Granular activated carbon (GAC) or magnetite could promote methane production from organic wastes, but their roles in enhancing anaerobic sludge digestion have not been clarified. GAC, magnetite and their combination were complemented into sludge digesters, respectively. Experimental results showed that average methane production increased by 7.3% for magnetite, 13.1% for GAC, and 20% for the combination of magnetite and GAC, and the effluent TCOD of the control, magnetite, GAC and magnetite-GAC digesters on day 56 were 53.2, 49.6, 48.0 and 46.6 g/L, respectively. Scanning electron microscope (SEM), nitrogen adsorption, Fourier transform infrared spectroscopy (FTIR) and microbial analysis indicated that magnetite enriched iron-reducing bacteria responsible for sludge hydrolysis while GAC enhanced syntrophic metabolism between iron-reducing bacteria and methanogens due to its high electrical conductivity and large surface area. Supplementing magnetite and GAC together into an anaerobic digester simultaneously accelerated sludge hydrolysis and methane production, resulting in better sludge digestion performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of some characteristics of aerobic granules and sludge flocs from sequencing batch reactors.

PubMed

Li, J; Garny, K; Neu, T; He, M; Lindenblatt, C; Horn, H

2007-01-01

Physical, chemical and biological characteristics were investigated for aerobic granules and sludge flocs from three laboratory-scale sequencing batch reactors (SBRs). One reactor was operated as normal SBR (N-SBR) and two reactors were operated as granular SBRs (G-SBR1 and G-SBR2). G-SBR1 was inoculated with activated sludge and G-SBR2 with granules from the municipal wastewater plant in Garching (Germany). The following major parameters and functions were measured and compared between the three reactors: morphology, settling velocity, specific gravity (SG), sludge volume index (SVI), specific oxygen uptake rate (SOUR), distribution of the volume fraction of extracellular polymeric substances (EPS) and bacteria, organic carbon and nitrogen removal. Compared with sludge flocs, granular sludge had excellent settling properties, good solid-liquid separation, high biomass concentration, simultaneous nitrification and denitrification. Aerobic granular sludge does not have a higher microbial activity and there are some problems including higher effluent suspended solids, lower ratio of VSS/SS and no nitrification at the beginning of cultivation. Measurement with CLSM and additional image analysis showed that EPS glycoconjugates build one main fraction inside the granules. The aerobic granules from G-SBR1 prove to be heavier, smaller and have a higher microbial activity compared with G-SBR2. Furthermore, the granules were more compact, with lower SVI and less filamentous bacteria.

Recovery and reuse of sludge from active and passive treatment of mine drainage-impacted waters: a review.

PubMed

Rakotonimaro, Tsiverihasina V; Neculita, Carmen Mihaela; Bussière, Bruno; Benzaazoua, Mostafa; Zagury, Gérald J

2017-01-01

The treatment of mine drainage-impacted waters generates considerable amounts of sludge, which raises several concerns, such as storage and disposal, stability, and potential social and environmental impacts. To alleviate the storage and management costs, as well as to give the mine sludge a second life, recovery and reuse have recently become interesting options. In this review, different recovery and reuse options of sludge originating from active and passive treatment of mine drainage are identified and thoroughly discussed, based on available laboratory and field studies. The most valuable products presently recovered from the mine sludge are the iron oxy-hydroxides (ochre). Other by-products include metals, elemental sulfur, and calcium carbonate. Mine sludge reuse includes the removal of contaminants, such as As, P, dye, and rare earth elements. Mine sludge can also be reused as stabilizer for contaminated soil, as fertilizer in agriculture/horticulture, as substitute material in construction, as cover over tailings for acid mine drainage prevention and control, as material to sequester carbon dioxide, and in cement and pigment industries. The review also stresses out some of the current challenges and research needs. Finally, in order to move forward, studies are needed to better estimate the contribution of sludge recovery/reuse to the overall costs of mine water treatment.

Combined anaerobic and aerobic digestion for increased solids reduction and nitrogen removal.

PubMed

Novak, John T; Banjade, Sarita; Murthy, Sudhir N

2011-01-01

A unique sludge digestion system consisting of anaerobic digestion followed by aerobic digestion and then a recycle step where thickened sludge from the aerobic digester was recirculated back to the anaerobic unit was studied to determine the impact on volatile solids (VS) reduction and nitrogen removal. It was found that the combined anaerobic/aerobic/anaerobic (ANA/AER/ANA) system provided 70% VS reduction compared to 50% for conventional mesophilic anaerobic digestion with a 20 day SRT and 62% for combined anaerobic/aerobic (ANA/AER) digestion with a 15 day anaerobic and a 5 day aerobic SRT. Total Kjeldahl nitrogen (TKN) removal for the ANA/AER/ANA system was 70% for sludge wasted from the aerobic unit and 43.7% when wasted from the anaerobic unit. TKN removal was 64.5% for the ANA/AER system. Copyright © 2010 Elsevier Ltd. All rights reserved.

Polyhydroxyalkanoates (PHA) production using wastewater as carbon source and activated sludge as microorganisms.

PubMed

Yan, S; Tyagi, R D; Surampalli, R Y

2006-01-01

Activated sludge from different full-scale wastewater treatment plants (municipal, pulp and paper industry, starch manufacturing and cheese manufacturing wastewaters) was used as a source of microorganisms to produce biodegradable plastics in shake flask experiments. Acetate, glucose and different wastewaters were used as carbon sources. Pulp and paper wastewater sludge was found to accumulate maximum concentration (43% of dry weight of suspended solids) of polyhydroxy alkanoates (PHA) with acetate as carbon source. Among the different wastewaters tested as a source of carbon, pulp and paper industry and starch industry wastewaters were found to be the best source of carbon while employing pulp and paper activated sludge for maximum accumulation of PHA. High concentration of volatile fatty acids in these wastewaters was the probable reason.

The use of waste mussel shells for the adsorption of dyes and heavy metals

NASA Astrophysics Data System (ADS)

Papadimitriou, Chrysi A.; Krey, Grigorios; Stamatis, Nikolaos; Kallaniotis, Argyris

2016-04-01

Mussel culture is very important sector of the Greek agricultural economy. The majority of mussel culture activities take place in the area of Central Macedonia, Greece, 60% of total mussel production in Greece producing almost 12 tons of waste mussels shells on a daily basis. Currently there is no legislation concerning the disposal of mussel shells. In the present study the waste shells were used for the removal of dyes and heavy metals from aqueous solutions while powdered mussel shells were added in activated sludge processes for the removal of hexavalent chromium. Mussel shells were cleaned, dried and then crushed in order to form a powder. Powdered mussels shells were used in standard adsorption experiments for the removal of methylene blue and methyl red as well as for the removal of Cr (VI), Cd and Cu. Moreover the powdered mussel shells were added in laboratory scale activated sludge reactors treating synthetic wastewater with hexavalent chromium, in order investigate the effects in activated sludge processes and their potential attribution to the removal of hexavalent chromium. Adsorption experiments indicated almost 100% color removal, while adsorption was directly proportional to the amount of powdered mussel shells added in each case. The isotherms calculated for the case of methylene blue indicated similar adsorption capacity and properties to those of the commercially available activated carbon SAE 2, Norit. High removal efficiencies were observed for the metals, especially in the case of chromium and copper. The addition of powdered mussel shells in the activated sludge processes enhanced the removal of chromium and phosphorus, while enabled the formation of heavier activated sludge flocs and thus enhanced the settling properties of the activated sludge.

Ultrasonic sludge disintegration for enhanced methane production in anaerobic digestion: effects of sludge hydrolysis efficiency and hydraulic retention time.

PubMed

Kim, Dong-Jin; Lee, Jonghak

2012-01-01

Hydrolysis of waste activated sludge (WAS) has been regarded as the rate limiting step of anaerobic sludge digestion. Therefore, in this study, the effect of ultrasound and hydraulic residence time during sludge hydrolysis was investigated with the goal of enhancing methane production from anaerobic digestion (AD). WAS was ultrasonically disintegrated for hydrolysis, and it was semi-continuously fed to an anaerobic digesters at various hydraulic retention times (HRTs). The results of these experiments showed that the solids and chemical oxygen demand (COD) removal efficiencies when using ultrasonically disintegrated sludge were higher during AD than the control sludge. The longer the HRT, the higher the removal efficiencies of solids and COD, while methane production increased with lower HRT. Sludge with 30% hydrolysis produced 7 × more methane production than the control sludge. The highest methane yields were 0.350 m(3)/kg volatile solids (VS)(add) and 0.301 m(3)/kg COD(con) for 16 and 30% hydrolyzed sludge, respectively. In addition, we found that excess ultrasound irradiation may inhibit AD since the 50% hydrolyzed sludge produced lower methane yields than 16 and 30% hydrolyzed sludge.

Nonoxidative removal of organics in the activated sludge process

PubMed Central

Modin, Oskar; Persson, Frank; Wilén, Britt-Marie; Hermansson, Malte

2016-01-01

ABSTRACT The activated sludge process is commonly used to treat wastewater by aerobic oxidation of organic pollutants into carbon dioxide and water. However, several nonoxidative mechanisms can also contribute to removal of organics. Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics. Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products. Recently, several environmental, economic, and technological drivers have stimulated research on nonoxidative removal of organics for wastewater treatment. In this paper, we review these nonoxidative removal mechanisms as well as the existing and emerging process configurations that make use of them for wastewater treatment. Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants. PMID:27453679

New insights into co-digestion of activated sludge and food waste: Biogas versus biofertilizer.

PubMed

Ma, Yingqun; Yin, Yao; Liu, Yu

2017-10-01

This study explored two holistic approaches for co-digestion of activated sludge and food waste. In Approach 1, mixed activated sludge and food waste were first hydrolyzed with fungal mash, and produced hydrolysate without separation was directly subject to anaerobic digestion. In Approach 2, solid generated after hydrolysis of food waste by fungal mash was directly converted to biofertilizer, while separated liquid with high soluble COD concentration was further co-digested with activated sludge for biomethane production. Although the potential energy produced from Approach 1 was about 1.8-time higher than that from Approach 2, the total economic revenue generated from Approach 2 was about 1.9-fold of that from Approach 1 due to high market value of biofertilizer. It is expected that this study may lead to a paradigm shift in biosolid management towards environmental and economic sustainability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Two-year survey of specific hospital wastewater treatment and its impact on pharmaceutical discharges.

PubMed

Wiest, Laure; Chonova, Teofana; Bergé, Alexandre; Baudot, Robert; Bessueille-Barbier, Frédérique; Ayouni-Derouiche, Linda; Vulliet, Emmanuelle

2018-04-01

It is well known that pharmaceuticals are not completely removed by conventional activated sludge wastewater treatment plants. Hospital effluents are of major concern, as they present high concentrations of pharmaceutically active compounds. Despite this, these specific effluents are usually co-treated with domestic wastewaters. Separate treatment has been recommended. However, there is a lack of information concerning the efficiency of separate hospital wastewater treatment by activated sludge, especially on the removal of pharmaceuticals. In this context, this article presents the results of a 2-year monitoring of conventional parameters, surfactants, gadolinium, and 13 pharmaceuticals on the specific study site SIPIBEL. This site allows the characterization of urban and hospital wastewaters and their separate treatment using the same process. Flow proportional sampling, solid-phase extraction, and liquid chromatography coupled with tandem mass spectrometry were used in order to obtain accurate data and limits of quantification consistent with ultra-trace detection. Thanks to these consolidated data, an in-depth characterization of urban and hospital wastewaters was realized, as well as a comparison of treatment efficiency between both effluents. Higher concentrations of organic carbon, AOX, phosphates, gadolinium, paracetamol, ketoprofen, and antibiotics were observed in hospital wastewaters compared to urban wastewaters. Globally higher removals were observed in the hospital wastewater treatment plant, and some parameters were shown to be of high importance regarding removal efficiencies: hydraulic retention time, redox conditions, and ambient temperature. Eleven pharmaceuticals were still quantified at relevant concentrations in hospital and urban wastewaters after treatment (e.g., up to 1 μg/L for sulfamethoxazole). However, as the urban flow was about 37 times higher than the hospital flow, the hospital contribution appeared relatively low compared to domestic discharges. Thanks to the SIPIBEL site, data obtained from this 2-year program are useful to evaluate the relevance of separate hospital wastewater treatment.

Bacterial communities in different locations, seasons and segments of a dairy wastewater treatment system consisting of six segments.

PubMed

Hirota, Kikue; Yokota, Yuji; Sekimura, Toru; Uchiumi, Hiroshi; Guo, Yong; Ohta, Hiroyuki; Yumoto, Isao

2016-08-01

A dairy wastewater treatment system composed of the 1st segment (no aeration) equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments (activated sludge) in the 6th segment and sending the sediments beck to the 1st and 2nd segments. Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter (biological oxygen demand [BOD]), and dissolved oxygen (DO) content. Microbiota from five segments (1st and four successive aerobic segments) in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions (such as DO), suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study. Copyright © 2016. Published by Elsevier B.V.

JPL Activated Carbon Treatment System (ACTS) for sewage

NASA Technical Reports Server (NTRS)

1976-01-01

An Activated Carbon Treatment System (ACTS) was developed for sewage treatment and is being applied to a one-million gallon per day sewage treatment pilot plant in Orange County California. Activities reported include pyrolysis and activation of carbon-sewage sludge, and activated carbon treatment of sewage to meet ocean discharge standards. The ACTS Sewage treatment operations include carbon-sewage treatment, primary and secondary clarifiers, gravity (multi-media) filter, filter press dewatering, flash drying of carbon-sewage filter cake, and sludge pyrolysis and activation. Tests were conducted on a laboratory scale, 10,000 gallon per day demonstration plant and pilot test equipment. Preliminary economic studies are favorable to the ACTS process relative to activated sludge treatment for a 175,000,000 gallon per day sewage treatment plant.

Potentials of an integrated biomass utilization system: Estimation of carbon flow and energy consumption

NASA Astrophysics Data System (ADS)

Suzuki, Ryosuke; Nishimura, Motoki; Yuan, Lee Chang; Kamahara, Hirotsugu; Atsuta, Yoichi; Daimon, Hiroyuki

2017-10-01

Utilization of sewage sludge using anaerobic digestion has been promoted for decades. However, it is still relatively uncommon especially in Japan. As an approach to promote the utilization of sewage sludge using anaerobic digestion, an integrated system that combines anaerobic digestion with greenhouse, composting and seaweed cultivation was proposed. Based on the concept of the integrated system, not only sewage sludge can be treated using anaerobic digestion that creates green energy, but also the by-products such as CO2 and heat produced during the process can be utilized for crops production. In this study, the potentials of such integrated system were discussed through the estimation of possible commercialized scale as well as comparison of energy consumption with conventional approach for sewage sludge treatment, which is the incineration. The estimation of possible commercialized scale was calculated based on the carbon flow of the system. Results showed that 25% of the current total electricity of the wastewater treatment plant can be covered by the energy produced using anaerobic digestion of sewage sludge. It was estimated that the total energy consumption of the integrated system was actually 14% lower when compared to incineration approach. In addition to the large amount of crops that can be produced, all in all this study aimed to be the showcase of the potentials of sewage sludge as a biomass by implementing the proposed integrated system. The extra values of producing crops through the utilization of CO2 and heat can serve as a stimulus to the public, which would surely lead to higher interest to implement the utilization of sewage sludge using anaerobic digestion.

Bioleached sludge composting drastically reducing ammonia volatilization as well as decreasing bulking agent dosage and improving compost quality: A case study.

PubMed

Hu, Weitong; Zheng, Guanyu; Fang, Di; Cui, Chunhong; Liang, Jianru; Zhou, Lixiang

2015-10-01

Sludge bioleaching technology with Acidithiobacillus species has been commercially adopted for improving advanced dewatering of sludge in China since 2010. However, up to now, little information on bioleached dewatered sludge (BS) composting is available. Here, we report the changes of physicochemical and biological properties in BS composting and evaluate compost product quality compared to conventional dewatered sludge (CS) composting in an engineering scale composting facility. The results showed that the amount of bulking agents required in BS composting was only about 10% of CS composting to obtain optimum moisture content, reducing about 700 kg bulking agents per ton fresh sludge. pH of BS composting mixture was slightly lower consistently by about 0.2-0.3 pH units than that in CS mixture in the first 30 days. Organic matter biodegradation in BS system mainly occurred in the first 9 days of composting. In spite of higher content of NH4(+)-N was found in BS mixture in related to CS mixture; unexpectedly the cumulative ammonia volatilization in the former was only 51% of the latter, indicating that BS composting drastically reduced nitrogen loss. Compared to CS composting system, the relative lower pH, the higher intensity of microbial assimilation, and the presence of water soluble Fe in BS system might jointly reduce ammonia volatilization. Consequently, BS compost product exhibited higher fertilizer values (N+P2O5+K2O=8.38%) as well as lower heavy metal levels due to the solubilization of sludge-borne heavy metals during bioleaching process. Therefore, composting of BS possesses more advantages over the CS composting process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Total organic carbon in a soil recovered with sewage sludge and native species of the Atlantic Forest

NASA Astrophysics Data System (ADS)

Mara Lima Goulart, Lívia; Amaral Guerrini, Iraê; Fidalgo de Faria, Marianne; Spada, Grasiela; Proença Nalesso, Pedro Henrique; Willian Carlos, Guilherme

2017-04-01

The use of organic waste such as sewage sludge, in the recovery of degraded áreas have shown very satisfactory results, because they are constituted by high contentes of organic matter and nutrients, essential to improve the physical and chemical properties of the soil. Thus, the objective of this study was to verify the total organic carbon (TOC) of a degraded soil, up to a metre deep, after 10 years of application of sewage sludge and planting native species of the Atlantic forest. The experiment was conducted at Fazenda Entre-Rios, owned by Suzano Papel e Celulose, in Itatinga, São Paulo, Brazil. The experiment was designed as randomized block with four replications, six doses of sewage sludge (0, 2.5, 5, 10, 15 and 20 t ha-1), conventional chemical fertilizer and only with potassium application, totaling eight treatments. Samples were collected every 20 cm (0-20, 20-40, 40-60, 60-80 and 80-100 cm) until reaching a metre deep. Ten years after trial deployment, the sewage sludge application in degraded soil was significantly influenced the TOC at all depths sampled. The highest values of the COT were observed in plots that received 15 and 20 t ha-1 of sewage sludge, in all depths sampled, except for the layer of 80-100 cm, which presented the highest average COT in the treatment with 10 t ha-1 of residue. As observed for all treatments, the highest TOC averages were observed in the superficial layers of the soil (0-20 and 20-40 cm). The sewage sludge application is useful to recover degraded soils, as it improving their chemical characteristics and showing to be a good alternative to the final destination of this residue.

Waste Resources Utilization Program. Progress report, period ending September 30, 1975

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1975-12-01

The purpose of the Waste Resources Utilization Program is to develop a technology to constructively couple two major environmental problems, disposition of human and nuclear waste, in an attempt to provide a framework in which both will become useful resources. Sludge treated with thermoradiation offers considerable potential for use as a fertilizer in agriculture or a soil conditioner for land reclamation free of the serious potential health hazards associated with conventional methods of land disposal. In addition, the very real possibility exists that treated sludge may provide a low-cost substitute for high-nutritional components in ruminant diets. The liter size flow-throughmore » system is put into operation for the first time and provides sufficient quantities of treated sludge for good biological analysis and to start the animal feeding program at New Mexico State University. Approximately 3800 gal of sewage sludge were thermoradiation-treated with the system. The sludge was exposed to approximately 150 krads of gamma radiation at a temperature of 65$sup 0$C. The treated sludge was monitored for elimination of total coliforms and fecal strep. No fecal strep bacteria were found in 400 sample plates; three contained coliform growth. An intensive study of poliovirus inactivation in sewage sludge was completed this quarter. Source efficiencies were calculated for possible modification to the WESF capsule which would consist of inserting a hollow tube in the center of the capsule. This was proposed as a simple modification to the standard WESF capsule to reduce the self-shielding characteristic of the cesium. The calculations showed little or no advantage of adding the center tube. (TFD)« less

Leachates from solid wastes: chemical and eco(geno)toxicological differences between leachates obtained from fresh and stabilized industrial organic sludge.

PubMed

Chiochetta, Claudete G; Goetten, Luís C; Almeida, Sônia M; Quaranta, Gaetana; Cotelle, Sylvie; Radetski, Claudemir M

2014-01-01

The chemical and ecotoxicological characteristics of fresh and stabilized industrial organic sludge leachates were compared to obtain information regarding how the stabilization process can influence the ecotoxic potential of this industrial waste, which could be used for the amendment of degraded soil. Physicochemical analysis of the sludge leachates, as well as a battery of eco(geno)toxicity tests on bacteria, algae, daphnids, and higher plants (including Vicia faba genotoxicity test) and the determination of hydrolytic enzyme activity, was performed according to standard methods. The chemical comparison of the two types of leachate showed that the samples obtained from stabilized sludge had a lower organic content and higher metal content than leachates of the fresh sludge. The eco(geno)toxicological results obtained with aquatic organisms showed that the stabilized sludge leachate was more toxic than the fresh sludge leachate, both originating from the same industrial organic sludge sample. Nevertheless, phytotoxicity tests carried out with a reference peat soil irrigated with stabilized sludge leachate showed the same toxicity as the fresh sludge leachate. In the case of the industrial solid organic sludge studied, stabilization through a biodegradation process promoted a higher metal mobility/bioavailability/eco(geno)toxicity in the stabilized sludge leachate compared to the fresh sludge leachate.

Aerobic composting of waste activated sludge: Kinetic analysis for microbiological reaction and oxygen consumption

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamada, Y.; Kawase, Y.

2006-07-01

In order to examine the optimal design and operating parameters, kinetics for microbiological reaction and oxygen consumption in composting of waste activated sludge were quantitatively examined. A series of experiments was conducted to discuss the optimal operating parameters for aerobic composting of waste activated sludge obtained from Kawagoe City Wastewater Treatment Plant (Saitama, Japan) using 4 and 20 L laboratory scale bioreactors. Aeration rate, compositions of compost mixture and height of compost pile were investigated as main design and operating parameters. The optimal aerobic composting of waste activated sludge was found at the aeration rate of 2.0 L/min/kg (initial compostingmore » mixture dry weight). A compost pile up to 0.5 m could be operated effectively. A simple model for composting of waste activated sludge in a composting reactor was developed by assuming that a solid phase of compost mixture is well mixed and the kinetics for microbiological reaction is represented by a Monod-type equation. The model predictions could fit the experimental data for decomposition of waste activated sludge with an average deviation of 2.14%. Oxygen consumption during composting was also examined using a simplified model in which the oxygen consumption was represented by a Monod-type equation and the axial distribution of oxygen concentration in the composting pile was described by a plug-flow model. The predictions could satisfactorily simulate the experiment results for the average maximum oxygen consumption rate during aerobic composting with an average deviation of 7.4%.« less

Enhanced treatment of waste frying oil in an activated sludge system by addition of crude rhamnolipid solution.

PubMed

Zhang, Hongzi; Xiang, Hai; Zhang, Guoliang; Cao, Xia; Meng, Qing

2009-08-15

The presence of high-strength oil and grease (O&G) in wastewater poses serious challenges for environment. Addition of surfactant into the activated sludge bioreactor is feasible in reducing high concentrations of O&G via enhancing its bioavailability. In this paper, an aqueous biosurfactant solution of rhamnolipid as a cell-free culture broth of Pseudomonas aeruginosa zju.um1 was added into a batch of aerobic activated sludge system for treatment of the waste frying oil. This treatment was conducted on both bench and pilot-scales, whereas the removal efficiency of frying oil was determined by analyzing the residue concentration of O&G and chemical oxygen demand (COD). In the presence of varying concentrations of rhamnolipid from 22.5 mg/L to 90 mg/L, aerobic treatment for 30 h was enough to remove over 93% of O&G while this biodegradability was only 10% in the control system with the absence of rhamnolipids. The equivalent biodegradability was similarly obtained on COD under addition of rhamnolipid. Compared with bench studies, a higher treatment efficiency with the presence of rhamnolipids was achieved on a pilot-scale of activated sludge system, in which a short time of 12h was required for removing approximately 95% of O&G while the control treatment attained a low efficiency of 17%. Finally, foaming and biodegradability of rhamnolipids in activated sludge system were further examined in the whole treatment process. It seems that the addition of rhamnolipid-containing culture broth showed great potential for treatment of oily wastewater by activated sludge.

Design, experimentation, and modeling of a novel continuous biodrying process

NASA Astrophysics Data System (ADS)

Navaee-Ardeh, Shahram

Massive production of sludge in the pulp and paper industry has made the effective sludge management increasingly a critical issue for the industry due to high landfill and transportation costs, and complex regulatory frameworks for options such as sludge landspreading and composting. Sludge dewatering challenges are exacerbated at many mills due to improved in-plant fiber recovery coupled with increased production of secondary sludge, leading to a mixed sludge with a high proportion of biological matter which is difficult to dewater. In this thesis, a novel continuous biodrying reactor was designed and developed for drying pulp and paper mixed sludge to economic dry solids level so that the dried sludge can be economically and safely combusted in a biomass boiler for energy recovery. In all experimental runs the economic dry solids level was achieved, proving the process successful. In the biodrying process, in addition to the forced aeration, the drying rates are enhanced by biological heat generated through the microbial activity of mesophilic and thermophilic microorganisms naturally present in the porous matrix of mixed sludge. This makes the biodrying process more attractive compared to the conventional drying techniques because the reactor is a self-heating process. The reactor is divided into four nominal compartments and the mixed sludge dries as it moves downward in the reactor. The residence times were 4-8 days, which are 2-3 times shorter than the residence times achieved in a batch biodrying reactor previously studied by our research group for mixed sludge drying. A process variable analysis was performed to determine the key variable(s) in the continuous biodrying reactor. Several variables were investigated, namely: type of biomass feed, pH of biomass, nutrition level (C/N ratio), residence times, recycle ratio of biodried sludge, and outlet relative humidity profile along the reactor height. The key variables that were identified in the continuous biodrying reactor were the type of biomass feed and the outlet relative humidity profiles. The biomass feed is mill specific and since one mill was studied for this study, the nutrition level of the biomass feed was found adequate for the microbial activity, and hence the type of biomass is a fixed parameter. The influence of outlet relative humidity profile was investigated on the overall performance and the complexity index of the continuous biodrying reactor. The best biodrying efficiency was achieved at an outlet relative humidity profile which controls the removal of unbound water at the wet-bulb temperature in the 1st and 2nd compartments of the reactor, and the removal of bound water at the dry-bulb temperature in the 3rd and 4th compartments. Through a systematic modeling approach, a 2-D model was developed to describe the transport phenomena in the continuous biodrying reactor. The results of the 2-D model were in satisfactory agreement with the experimental data. It was found that about 30% w/w of the total water removal (drying rate) takes place in the 1st and 2nd compartments mainly under a convection dominated mechanism, whereas about 70% w/w of the total water removal takes place in the 3rd and 4th compartments where a bioheat-diffusion dominated mechanism controls the transport phenomena. The 2-D model was found to be an appropriate tool for the estimation of the total water removal rate (drying rate) in the continuous biodrying reactor when compared to the 1-D model. A dimensionless analysis was performed on the 2-D model and established the preliminary criteria for the scale-up of the continuous biodrying process. Finally, a techno-economic assessment of the continuous biodrying process revealed that there is great potential for the implementation of the biodrying process in Canadian pulp and paper mills. The techno-economic results were compared to the other competitive existing drying technologies. It was proven that the continuous biodrying process results in significant economic benefits and has great potential to address the current industrial problems associated with sludge management.

Effects of different sludge disintegration methods on sludge moisture distribution and dewatering performance.

PubMed

Jin, Lingyun; Zhang, Guangming; Zheng, Xiang

2015-02-01

A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge disintegration can destroy the sludge structure and cell wall, so as change the sludge floc structure and moisture distribution, thus affecting the dewatering performance of sludge. In this article, the disintegration methods were ultrasound treatment, K2FeO4 oxidation and KMnO4 oxidation. The degree of disintegration (DDCOD), sludge moisture distribution and the final water content of sludge cake after centrifuging were measured. Results showed that three disintegration methods were all effective, and K2FeO4 oxidation was more efficient than KMnO4 oxidation. The content of free water increased obviously with K2FeO4 and KMnO4 oxidations, while it decreased with ultrasound treatment. The changes of free water and interstitial water were in the opposite trend. The content of bounding water decreased with K2FeO4 oxidation, and increased slightly with KMnO4 oxidation, while it increased obviously with ultrasound treatment. The water content of sludge cake after centrifuging decreased with K2FeO4 oxidation, and did not changed with KMnO4 oxidation, but increased obviously with ultrasound treatment. In summary, ultrasound treatment deteriorated the sludge dewaterability, while K2FeO4 and KMnO4 oxidation improved the sludge dewaterability. Copyright © 2014. Published by Elsevier B.V.

Potential and optimization of two-phase anaerobic digestion of oil refinery waste activated sludge and microbial community study

PubMed Central

Wang, Qinghong; Liang, Ying; Zhao, Peng; Li, Qing X.; Guo, Shaohui; Chen, Chunmao

2016-01-01

Oil refinery waste activated sludge produced from oil wastewater biological treatment is a major industrial sludge. Two-phase anaerobic digestion of oil refinery waste activated sludge was studied for the first time. Thermal pretreatment under 170 °C is effective on sludge solubilization. At the optimum hydrolytic-acidogenic condition which was pH of 6.5, temperature of 55 °C and HRT of 2 days, 2754 mg/L volatile fatty acids (VFAs) were produced and acetic acid and butyric acid were the key components. Comparative studies of single-phase and two-phase anaerobic digestion in terms of organic removal, biogas production and methane concentration were conducted. The cumulative methane production and soluble COD (SCOD) removal efficiency in the two-phase system were 228 mL/g COD added and 77.8%, respectively, which were 1.6 and 2.1 times higher than those in single-phase anaerobic digestion. Such improved performance is attributed to intensification of dominant microbial population in separated reactors. Caloramator, Ureibacillus, Dechloromonas, Petrobacter, and T78 played important roles in hydrolytic-acidification and oil-organics degradation. Syntrophic bacteria in the family Porphyromonadaceae and the genus Anaerobranca provide acetate for methanogen. The results demonstrated the potential and operating condition of two-phase anaerobic digestion in treatment of oil refinery waste activated sludge. PMID:27905538

Potential and optimization of two-phase anaerobic digestion of oil refinery waste activated sludge and microbial community study

NASA Astrophysics Data System (ADS)

Wang, Qinghong; Liang, Ying; Zhao, Peng; Li, Qing X.; Guo, Shaohui; Chen, Chunmao

2016-12-01

Oil refinery waste activated sludge produced from oil wastewater biological treatment is a major industrial sludge. Two-phase anaerobic digestion of oil refinery waste activated sludge was studied for the first time. Thermal pretreatment under 170 °C is effective on sludge solubilization. At the optimum hydrolytic-acidogenic condition which was pH of 6.5, temperature of 55 °C and HRT of 2 days, 2754 mg/L volatile fatty acids (VFAs) were produced and acetic acid and butyric acid were the key components. Comparative studies of single-phase and two-phase anaerobic digestion in terms of organic removal, biogas production and methane concentration were conducted. The cumulative methane production and soluble COD (SCOD) removal efficiency in the two-phase system were 228 mL/g COD added and 77.8%, respectively, which were 1.6 and 2.1 times higher than those in single-phase anaerobic digestion. Such improved performance is attributed to intensification of dominant microbial population in separated reactors. Caloramator, Ureibacillus, Dechloromonas, Petrobacter, and T78 played important roles in hydrolytic-acidification and oil-organics degradation. Syntrophic bacteria in the family Porphyromonadaceae and the genus Anaerobranca provide acetate for methanogen. The results demonstrated the potential and operating condition of two-phase anaerobic digestion in treatment of oil refinery waste activated sludge.

Evaluation of the influence of mechanical activation on physical and chemical properties of municipal solid waste incineration sludge.

PubMed

Caprai, V; Florea, M V A; Brouwers, H J H

2018-06-15

Despite numerous studies concerning the application of by-products in the construction field, municipal solid waste incineration (MSWI) residues are not widely used as secondary building materials. In some European countries, washing treatment to the full bottom ash (BA) fraction (0-32 mm) is applied, isolating more contaminated particles, smaller than 0.063 mm. Therefore, a MWSI sludge is produced, having a high moisture content, and thus a limited presence of soluble species. In order to enhance its performance as building material, here, dry mechanical activation is applied on MSWI sludge. Thereafter, a reactivity comparison between reference BA and untreated and treated MSWI sludge is provided, evaluating their behaviour in the presence of cement and their pozzolanic activity. Moreover, the mechanical performances, as 25% substitution of Portland cement (PC) are assessed, based on the EN 450. Mechanical activation enhances MSWI sludge physically due to the improved particle morphology and packing. Chemically, the hydration degree of PC is enhanced by the MSWI sludge by ≈25%. The milling treatment proved to be beneficial to the residues performances in the presence of PC, providing 32% higher strength than untreated sample. Environmentally, the compliance with the unshaped material legislation is successfully verified, according to the Soil Quality Decree. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous Fluorescent Gram Staining and Activity Assessment of Activated Sludge Bacteria

PubMed Central

Forster, Scott; Snape, Jason R.; Lappin-Scott, Hilary M.; Porter, Jonathan

2002-01-01

Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that the relative proportions of gram-positive and gram-negative bacterial cells identified by traditional microscopy and hexidium iodide staining were not significantly different. Dual staining of cells for Gram status and activity proved effective in analyzing mixtures of cultured bacteria and wastewater populations. Levels of highly active organisms at two wastewater treatment plants, both gram positive and gram negative, ranged from 1.5% in activated sludge flocs to 16% in the activated sludge fluid. Gram-positive organisms comprised <5% of the total bacterial numbers but accounted for 19 and 55% of the highly active organisms within flocs at the two plants. Assessment of Gram status and activity within activated sludge samples over a 4-day period showed significant differences over time. This method provides a rapid, quantitative measure of Gram status linked with in situ activity within wastewater systems. PMID:12324319

Simultaneous fluorescent gram staining and activity assessment of activated sludge bacteria.

PubMed

Forster, Scott; Snape, Jason R; Lappin-Scott, Hilary M; Porter, Jonathan

2002-10-01

Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that the relative proportions of gram-positive and gram-negative bacterial cells identified by traditional microscopy and hexidium iodide staining were not significantly different. Dual staining of cells for Gram status and activity proved effective in analyzing mixtures of cultured bacteria and wastewater populations. Levels of highly active organisms at two wastewater treatment plants, both gram positive and gram negative, ranged from 1.5% in activated sludge flocs to 16% in the activated sludge fluid. Gram-positive organisms comprised <5% of the total bacterial numbers but accounted for 19 and 55% of the highly active organisms within flocs at the two plants. Assessment of Gram status and activity within activated sludge samples over a 4-day period showed significant differences over time. This method provides a rapid, quantitative measure of Gram status linked with in situ activity within wastewater systems.

Release and control of hydrogen sulfide during sludge thermal drying.

PubMed

Weng, Huanxin; Dai, Zhixi; Ji, Zhongqiang; Gao, Caixia; Liu, Chongxuan

2015-10-15

The release of hydrogen sulfide (H2S) during sludge drying is a major environmental problem because of its toxicity to human health. A series of experiments were performed to investigate the mechanisms and factors controlling the H2S release. Results of this study show that: (1) the biomass and activity of sulfate-reducing bacteria (SRB) in sludge were the major factors controlling the amount of H2S release, (2) the sludge drying temperature had an important effect on both the extent and the timing of H2S release from the sludge, and (3) decreasing sludge pH increased the H2S release. Based on the findings from this study, a new system that integrates sludge drying and H2S gas treatment was developed, by which 97.5% of H2S and 99.7% of smoke released from sludge treatments was eliminated. Copyright © 2015 Elsevier B.V. All rights reserved.

Release and control of hydrogen sulfide during sludge thermal drying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weng, Huanxin; Dai, Zhixin; Ji, Zhongqiang

2015-04-15

The release of hydrogen sulfide (H2S) during sludge drying is a major environmental problem because of its toxicity to human health. A series of experiments were performed to investigate the mechanisms and factors controlling the H2S release. Results of this study show that: 1) the biomass and activity of sulfate-reducing bacteria (SRB) in sludge were the major factors controlling the amount of H2S release, 2) the sludge drying temperature had an important effect on both the extent and the timing of H2S release from the sludge, and 3) decreasing sludge pH increased the H2S release. Based on the findings frommore » this study, a new system that integrates sludge drying and H2S gas treatment was developed to reduce the amount of H2S released from sludge treatments.« less

Activated Sludge.

ERIC Educational Resources Information Center

Saunders, F. Michael

1978-01-01

Presents the 1978 literature review of wastewater treatment. This review covers: (1) activated sludge process; (2) process control; (3) oxygen uptake and transfer; (4) phosphorus removal; (5) nitrification; (6) industrial wastewater; and (7) aerobic digestion. A list of 136 references is also presented. (HM)

Activated Sludge. Selected Instructional Activities and References. Instructional Resources Monograph Series.

ERIC Educational Resources Information Center

Shepard, Clinton L.; Walasek, James B.

This monograph contains a variety of selected materials related to wastewater treatment and water quality education and instruction. Part I presents a brief discussion of the activated sludge process in wastewater treatment operations. Part II, Instructional Units, contains selected portions of existing programs which may be utilized in…

Immobilized and MgSO4 induced cost effective bacterial disintegration of waste activated sludge for effective anaerobic digestion.

PubMed

Ushani, U; Rajesh Banu, J; Kavitha, S; Kaliappan, S; Yeom, Ick Tae

2017-05-01

In this study, an attempt was made to disintegrate waste activated sludge (WAS) in a cost-effective way. During the first phase of this study, effective break down of extracellular polymeric substance (EPS) was performed by deflocculating WAS with 0.1 g/g SS of MgSO 4 . Deflocculation rate was 92% with discharge rate of extractable EPS at 185 mg/L. In the second phase, effective bacterial cell disintegration was obtained at 36 h post treatment. Maximum solubilization of deflocculated sludge was approximately 21%, which was higher than that of flocculated sludge (14.2%) or the control (4.5%). Biodegradability studies were assessed through kinetic analysis by non-linear regression modeling. Results revealed that the deflocculated sludge had higher methane generation (at about 235.8 mL/gVs) compared to flocculated sludge (at 146.1 mL/gVs) or the control (at 34.8 mL/gVs). Cost assessment of the present work revealed that the net yield for each ton of the deflocculated sludge was about 32.99 USD. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biological Uptake of Phosphorus by Activated Sludge 1

PubMed Central

Yall, Irving; Boughton, William H.; Knudsen, Richard C.; Sinclair, Norval A.

1970-01-01

The ability of activated sludge to remove phosphates was studied by adding carrier-free 32P to raw sewage and measuring incorporation of the radioactivity into the cells over a period of time. Radioisotope determinations indicated that 48% of the 32P radioactivity was removed by 12 hr. However, chemical methods indicated that only 30% of the orthophosphate apparently disappeared from the sewage during this period. Experiments with sludge prelabeled with 32P indicated that considerable phosphate turnover occurred. The cells released large amounts of radioactivity as they were incorporating fresh phosphates. Starvation in isotonic saline for 18 hr caused the sludge to dump phosphate. When introduced into fresh sewage containing 32P, the starved sludge removed about 60% of the radioactivity in 6 hr with little phosphate turnover. The ability of sludge to remove 32P was inhibited approximately 83% by 10−3m 2,4-dinitrophenol. This inhibition was at the expense of the cell fraction that contained ribonucleic acid and deoxyribonucleic acid. The sludge cells released orthophosphate when exposed to the chemical agent. Experiments using 45Ca indicated that calcium phosphate precipitation plays a minor role in phosphate removal under our experimental conditions. PMID:5456935

Biological uptake of phosphorus by activated sludge.

PubMed

Yall, I; Boughton, W H; Knudsen, R C; Sinclair, N A

1970-07-01

The ability of activated sludge to remove phosphates was studied by adding carrier-free (32)P to raw sewage and measuring incorporation of the radioactivity into the cells over a period of time. Radioisotope determinations indicated that 48% of the (32)P radioactivity was removed by 12 hr. However, chemical methods indicated that only 30% of the orthophosphate apparently disappeared from the sewage during this period. Experiments with sludge prelabeled with (32)P indicated that considerable phosphate turnover occurred. The cells released large amounts of radioactivity as they were incorporating fresh phosphates. Starvation in isotonic saline for 18 hr caused the sludge to dump phosphate. When introduced into fresh sewage containing (32)P, the starved sludge removed about 60% of the radioactivity in 6 hr with little phosphate turnover. The ability of sludge to remove (32)P was inhibited approximately 83% by 10(-3)m 2,4-dinitrophenol. This inhibition was at the expense of the cell fraction that contained ribonucleic acid and deoxyribonucleic acid. The sludge cells released orthophosphate when exposed to the chemical agent. Experiments using (45)Ca indicated that calcium phosphate precipitation plays a minor role in phosphate removal under our experimental conditions.

[Method for Simultaneous Determination of 11 Veterinary Antibiotics in Piggery Wastewater and Sludge and Its Application in Biological Treatment].

PubMed

Ding, Jia-li; Liu, Rui; Zheng, Wei; Yu, Wei-juan; Ye, Zhao-xia; Chen, Lu-jun; Zhang, Yong-ming

2015-10-01

In order to determine eleven commonly used veterinary antibiotics (including four tetracyclines, two sulfonamides, three quinolones and two macrolides) in piggery wastewater and activated sludge in the Yangtze River Delta region, the conditions of solid phase extraction and high performance liquid chromatography-tandem mass spectrometry were optimized. The recovery rate and relative standard deviations of the method were confirmed as 73% - 105.2%, 3.1% - 10.2% for piggery wastewater (n = 3) and 57.4% - 104.6%, 1.9% - 10.9% (n = 3) respectively for the activated sludge. Removal of antibiotics was then studied in a membrane bioreactor. The results showed that antibiotics of both tetracycline and sulfonamide species took a large portion in the wastewater, while tetracycline species were the dominant in the sludge. Tetracycline species in the wastewater were removed by 85.2%, mainly through biodegradation (51.9%) and secondly by sludge adsorption (33.2%). By comparison, sulfonamide species was removed by 95.8%, almost all through biodegradation while little by sludge adsorption. Flask tests suggested that the accumulated antibiotics in the sludge give no significant influence on the microbial removal of organics and ammonium.

Microbial Population Dynamics and Ecosystem Functions of Anoxic/Aerobic Granular Sludge in Sequencing Batch Reactors Operated at Different Organic Loading Rates

PubMed Central

Szabó, Enikö; Liébana, Raquel; Hermansson, Malte; Modin, Oskar; Persson, Frank; Wilén, Britt-Marie

2017-01-01

The granular sludge process is an effective, low-footprint alternative to conventional activated sludge wastewater treatment. The architecture of the microbial granules allows the co-existence of different functional groups, e.g., nitrifying and denitrifying communities, which permits compact reactor design. However, little is known about the factors influencing community assembly in granular sludge, such as the effects of reactor operation strategies and influent wastewater composition. Here, we analyze the development of the microbiomes in parallel laboratory-scale anoxic/aerobic granular sludge reactors operated at low (0.9 kg m-3d-1), moderate (1.9 kg m-3d-1) and high (3.7 kg m-3d-1) organic loading rates (OLRs) and the same ammonium loading rate (0.2 kg NH4-N m-3d-1) for 84 days. Complete removal of organic carbon and ammonium was achieved in all three reactors after start-up, while the nitrogen removal (denitrification) efficiency increased with the OLR: 0% at low, 38% at moderate, and 66% at high loading rate. The bacterial communities at different loading rates diverged rapidly after start-up and showed less than 50% similarity after 6 days, and below 40% similarity after 84 days. The three reactor microbiomes were dominated by different genera (mainly Meganema, Thauera, Paracoccus, and Zoogloea), but these genera have similar ecosystem functions of EPS production, denitrification and polyhydroxyalkanoate (PHA) storage. Many less abundant but persistent taxa were also detected within these functional groups. The bacterial communities were functionally redundant irrespective of the loading rate applied. At steady-state reactor operation, the identity of the core community members was rather stable, but their relative abundances changed considerably over time. Furthermore, nitrifying bacteria were low in relative abundance and diversity in all reactors, despite their large contribution to nitrogen turnover. The results suggest that the OLR has considerable impact on the composition of the granular sludge communities, but also that the granule communities can be dynamic even at steady-state reactor operation due to high functional redundancy of several key guilds. Knowledge about microbial diversity with specific functional guilds under different operating conditions can be important for engineers to predict the stability of reactor functions during the start-up and continued reactor operation. PMID:28507540

Mechanical and hydraulic properties of sludge deposit on sludge drying reed beds (SDRBs): influence of sludge characteristics and loading rates.

PubMed

Vincent, Julie; Forquet, Nicolas; Molle, Pascal; Wisniewski, Christelle

2012-07-01

This work was designed to study the hydraulic properties of sludge deposit, focusing on the impact of operating conditions (i.e. loads and feeding frequencies) on air entrance (aerobic mineralization optimization) into the sludge deposit. The studied sludge deposits came from six 2m(2) pilot-scale SDRBs that had been in operation for 50 months with three different loads of 30, 50, and 70 kg of SSm(-2) y(-1). Two influents were assessed (i.e. activated sludge and septage) presenting different characteristics (i.e. pollutant contents, physical properties...). Two experimental approaches were employed based on establishing the water retention curve (capillary pressure versus volumetric water content) and the hydrotextural diagram to determine the hydraulic properties of sludge deposit. The study obtained valuable information for optimizing operating conditions, specifically for efficient management of loading frequency to optimize aerobic conditions within the sludge deposit. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of total solids content on waste activated sludge thermophilic anaerobic digestion and its sludge dewaterability.

PubMed

Wang, Tianfeng; Chen, Jie; Shen, Honglang; An, Dong

2016-10-01

The role of total solids content on sludge thermophilic anaerobic digestion was investigated in batch reactors. A range of total solids content from 2% to 10% was evaluated with two replicates. The lowest inhibitory concentration for free ammonia and total ammonia of sludge thermophilic anaerobic digestion was 110.9-171.4mg/L and 1313.1-1806.7mg/L, respectively. The volumetric biogas production rate increased with increasing of total solids content, but the corresponding biogas yield per gram volatile solid decreased. The result of normalized capillary suction time indicated that the dewaterability of digested sludge at high total solids content was poor, while solid content of sediment obtained by centrifuging sludge at 2000g for 10min increased with increasing of total solids content of sludge. The results suggest that thickened sludge mixed with dewatered sludge at an appropriate ratio could get high organic loading rate, high biogas yield and adequate dewatering effort. Copyright © 2016 Elsevier Ltd. All rights reserved.

Beyond the conventional life cycle inventory in wastewater treatment plants.

PubMed

Lorenzo-Toja, Yago; Alfonsín, Carolina; Amores, María José; Aldea, Xavier; Marin, Desirée; Moreira, María Teresa; Feijoo, Gumersindo

2016-05-15

The conventional approach for the environmental assessment of wastewater treatment plants (WWTPs) is typically based on the removal efficiency of organic load and nutrients as well as the quantification of energy and chemicals consumption. Current wastewater treatment research entails the monitoring of direct emissions of greenhouse gases (GHG) and emerging pollutants such as pharmaceutical and personal care products (PPCPs), which have been rarely considered in the environmental assessment of a wastewater treatment facility by life cycle assessment (LCA) methodology. As a result of that, the real environmental impacts of a WWTP may be underestimated. In this study, two WWTPs located in different climatic regions (Atlantic and Mediterranean) of Spain were evaluated in extensive sampling campaigns that included not only conventional water quality parameters but also direct GHG emissions and PPCPs in water and sludge lines. Regarding the GHG monitoring campaign, on-site measurements of methane (CH4) and nitrous oxide (N2O) were performed and emission factors were calculated for both WWTPs. GHG direct emissions accounted for 62% of the total global warming potential (GWP), much more relevant than indirect CO2 emissions associated with electricity use. Regarding PPCPs, 19 compounds were measured in the main streams: influent, effluent and sludge, to perform the evaluation of the toxicity impact categories. Although the presence of heavy metals in the effluent and the sludge as well as the toxicity linked to the electricity production may shade the toxicity impacts linked to PPCPs in some impact categories, the latter showed a notable influence on freshwater ecotoxicity potential (FETP). For this impact category, the removal of PPCPs within the wastewater treatment was remarkably important and arose as an environmental benefit in comparison with the non-treatment scenario. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermo-Oxidization of Municipal Wastewater Treatment Plant Sludge for Production of Class A Biosolids

EPA Science Inventory

Bench-scale reactors were used to test a novel thermo-oxidation process on municipal wastewater treatment plant (WWTP) waste activated sludge (WAS) using hydrogen peroxide (H₂O₂) to achieve a Class A sludge product appropriate for land application. Reactor ...

Role of indigenous iron in improving sludge dewaterability through peroxidation

PubMed Central

Zhou, Xu; Jiang, Guangming; Wang, Qilin; Yuan, Zhiguo

2015-01-01

Improvement of sludge dewaterability is important for reducing the total costs for the treatment and disposal of sludge in wastewater treatment plants. In this study, we investigate the use of hydrogen peroxide as an oxidizing reagent for the conditioning of waste activated sludge. Significant improvement to sludge dewaterability was attained after the addition of hydrogen peroxide at 30 mg/g TS and 28 mg/g TS under acidic conditions (pH = 3.0), with the highest reduction of capillary suction time being 68% and 56%, respectively, for sludge containing an iron concentration of 56 mg Fe/g TS and 25 mg Fe/g TS, respectively. The observations were due to Fenton reactions between the iron contained in sludge (indigenous iron) and hydrogen peroxide. For the sludge with an insufficient level of indigenous iron, the addition of ferrous chloride was found to be able to improve the sludge dewaterability. The results firstly indicated that indigenous iron can be utilized similarly as the externally supplied iron salt to improve sludge dewaterability through catalyzing the Fenton reactions. PMID:25559367

Enhancement of sludge dewaterability with filamentous fungi Talaromyces flavus S1 by depletion of extracellular polymeric substances or mycelium entrapment.

PubMed

Liu, He; Shi, Jiasheng; Xu, Xiaoyu; Zhan, Xinmin; Fu, Bo; Li, Yifei

2017-12-01

This study was conducted to explore the mechanism of dewaterability improvement of waste activated sludge by the filamentous fungus Talaromyces flavus S1. When the fungal spores were inoculated to the sterilized sludge, the sludge dewaterability was significantly improved by 48.1% and the reasons can be attributed to sludge pellet formation and degradation of extracellular polymeric substances, in particular the slime-EPS and loosely-bound EPS (LB-EPS). With the addition of fungal mycelium into the either sterilized sludge or non-sterilized sludge, the values of CST decreased by 74.0% and 43.7%, respectively, suggesting the fungal mycelium can improve the sludge dewaterability. After conditioned by the mycelium, the sludge cake by the diaphragm filter press was thicker and showed less water content than the control sludge. The results in this study demonstrated that the Talaromyces flavus S1 can serve as an environmentally friendly biological dewatering agent and has a promising application potential in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influences of Different Conditioners on Dehydration Ratio of Activated Sludge

NASA Astrophysics Data System (ADS)

Zhuo, Qiongfang; Zheng, Wenli; Yi, Hao; Chen, Sili; Xu, Zhencheng; Jin, Zhong; Lan, Yongzhe; Guo, Qingwei

2017-11-01

Excess sludge contains a large quantity of water with water content reaching about 97%-99%. Besides microorganisms and germs, the sludge is of complicated composition, including heavy metals, persistent organic pollutants, PPCPs, endocrine disrupters, etc. It covers a large area with harmfulness, so it needs further treatment. However, due to existence of extracellular polymeric substances in the sludge, the sludge has poor dehydration property, so how to improve dehydration of sludge is a difficult point in water treatment industry. Chemical conditioning—mechanical dehydration method is sludge dehydration technology which has been widely applied in China. Most sludge treatment plants use organic and inorganic conditioners like polyacrylamide (PAM), polyaluminum chloride (PAC) and polymerized ferrous sulfate (PFS), etc. With characteristics of low toxicity and degradation resistance, these conditioners pose potential risks to the environment and they are adverse to follow-up resource utilization. Therefore, influences of 17 conditioners on sludge dehydration ratio were discussed in this paper, expecting to seek for green, environmentally friendly and highly efficient conditioner so as to improve resource utilization ratio of sludge.

Fate and Persistence of a Pathogenic NDM-1-Positive Escherichia coli Strain in Anaerobic and Aerobic Sludge Microcosms

PubMed Central

Mantilla-Calderon, David

2017-01-01

ABSTRACT The presence of emerging biological pollutants in treated wastewater effluents has gained attention due to increased interest in water reuse. To evaluate the effectiveness of the removal of such contaminants by the conventional wastewater treatment process, the fate and decay kinetics of NDM-1-positive Escherichia coli strain PI7 and its plasmid-encoded antibiotic resistance genes (ARGs) were assessed in microcosms of anaerobic and aerobic sludge. Results showed that E. coli PI7 decayed at a significantly lower rate under anaerobic conditions. Approximate half-lives were 32.4 ± 1.4 h and 5.9 ± 0.9 h in the anaerobic and aerobic microcosms, respectively. In the aerobic microcosms, after 72 h of operation, E. coli PI7 remained detectable, but no further decay was observed. Instead, 1 in every 10,000 E. coli cells was identified to be recalcitrant to decay and persist indefinitely in the sludge. ARGs associated with the E. coli PI7 strain were detected to have transferred to other native microorganisms in the sludge or were released to the liquid fraction upon host decay. Extracellular DNA quickly degraded in the liquid fraction of the aerobic sludge. In contrast, no DNA decay was detected in the anaerobic sludge water matrix throughout the 24-h sampling period. This study suggests an increased likelihood of environmental dispersion of ARGs associated with anaerobically treated wastewater effluents and highlights the potential importance of persister cells in the dissemination of E. coli in the environment during reuse events of treated wastewater. IMPORTANCE This study examines the decay kinetics of a pathogenic and antibiotic resistant strain of Escherichia coli in microcosms simulating biological treatment units of aerobic and anaerobic sludge. The results of this study point at a significantly prolonged persistence of the E. coli and the associated antibiotic resistance gene in the anaerobic sludge. However, horizontal transfer of the plasmid encoding the antibiotic resistance gene was detected in the aerobic sludge by a cultivation method. A subpopulation of persister E. coli cells was also detected in the aerobic sludge. The findings of this study suggest potential areas of concern arising from pathogenic and antibiotic-resistant E. coli during both anaerobic and aerobic sludge treatment processes. PMID:28411227

Fate and Persistence of a Pathogenic NDM-1-Positive Escherichia coli Strain in Anaerobic and Aerobic Sludge Microcosms.

PubMed

Mantilla-Calderon, David; Hong, Pei-Ying

2017-07-01

The presence of emerging biological pollutants in treated wastewater effluents has gained attention due to increased interest in water reuse. To evaluate the effectiveness of the removal of such contaminants by the conventional wastewater treatment process, the fate and decay kinetics of NDM-1-positive Escherichia coli strain PI7 and its plasmid-encoded antibiotic resistance genes (ARGs) were assessed in microcosms of anaerobic and aerobic sludge. Results showed that E. coli PI7 decayed at a significantly lower rate under anaerobic conditions. Approximate half-lives were 32.4 ± 1.4 h and 5.9 ± 0.9 h in the anaerobic and aerobic microcosms, respectively. In the aerobic microcosms, after 72 h of operation, E. coli PI7 remained detectable, but no further decay was observed. Instead, 1 in every 10,000 E. coli cells was identified to be recalcitrant to decay and persist indefinitely in the sludge. ARGs associated with the E. coli PI7 strain were detected to have transferred to other native microorganisms in the sludge or were released to the liquid fraction upon host decay. Extracellular DNA quickly degraded in the liquid fraction of the aerobic sludge. In contrast, no DNA decay was detected in the anaerobic sludge water matrix throughout the 24-h sampling period. This study suggests an increased likelihood of environmental dispersion of ARGs associated with anaerobically treated wastewater effluents and highlights the potential importance of persister cells in the dissemination of E. coli in the environment during reuse events of treated wastewater. IMPORTANCE This study examines the decay kinetics of a pathogenic and antibiotic resistant strain of Escherichia coli in microcosms simulating biological treatment units of aerobic and anaerobic sludge. The results of this study point at a significantly prolonged persistence of the E. coli and the associated antibiotic resistance gene in the anaerobic sludge. However, horizontal transfer of the plasmid encoding the antibiotic resistance gene was detected in the aerobic sludge by a cultivation method. A subpopulation of persister E. coli cells was also detected in the aerobic sludge. The findings of this study suggest potential areas of concern arising from pathogenic and antibiotic-resistant E. coli during both anaerobic and aerobic sludge treatment processes. Copyright © 2017 Mantilla-Calderon and Hong.

Entomotoxicity, protease and chitinase activity of Bacillus thuringiensis fermented wastewater sludge with a high solids content.

PubMed

Brar, Satinder K; Verma, M; Tyagi, R D; Valéro, J R; Surampalli, R Y

2009-10-01

This study investigated the production of biopesticides, protease and chitinase activity by Bacillus thuringiensis grown in raw wastewater sludge at high solids concentration (30 g/L). The rheology of wastewater sludge was modified with addition of Tween-80 (0.2% v/v). This addition resulted in 1.6 and 1.3-fold increase in cell and spore count, respectively. The maximum specific growth rate (micro(max)) augmented from 0.17 to 0.22 h(-1) and entomotoxicity (Tx) increased by 29.7%. Meanwhile, volumetric mass transfer coefficient (k(L)a) showed marked variations during fermentation, and oxygen uptake rate (OUR) increased 2-fold. The proteolytic activity increased while chitinase decreased for Tween amended wastewater sludge, but the entomotoxicity increased. The specific entomotoxicity followed power law when plotted against spore concentration and the relation between Tx and protease activity was linear. The viscosity varied and volume percent of particles increased in Tween-80 amended wastewater sludge and particle size (D(50)) decreased at the end of fermentation. Thus, there was an increase in entomotoxicity at higher suspended solids (30 g/L) as Tween addition improved rheology (viscosity, particle size, surface tension); enhanced maximum growth rate and OUR.

Improved methane production from waste activated sludge with low organic content by alkaline pretreatment at pH 10.

PubMed

Feng, L Y; Yang, L Q; Zhang, L X; Chen, H L; Chen, J

2013-01-01

Sludge with low organic content always results in an unsatisfactory performance, even failure of anaerobic digestion. The alkaline pretreatment effect on anaerobic digestion of sludge with low organic content has seldom been studied although it gives many benefits for sludge with high organic content. In this study the influence of alkaline pretreatment (pH 10, an effective alkaline pH) on the solubilization and methane production from waste activated sludge (WAS) with low organic content was investigated. Results from biochemical methane potential (BMP) experiments showed that anaerobic biodegradability of WAS was greatly improved by alkaline pretreatment at pH 10. Methane production from the current WAS under conditions of pretreatment time 4 h and digestion time 15 d was 139.6 mL/g VS (volatile solids), much higher than that from the unpretreated WAS with digestion time of 20 d (75.2 mL/g VS). Also, the solubilization of WAS was significantly accelerated by alkaline pretreatment. Mechanism exploration indicated that the general activities of anaerobic microorganisms, specific activities of key enzymes and the amounts of methanogens were enhanced by alkaline pretreatment at pH 10, showing good agreement with methane production.