Combined effects of Fenton peroxidation and CaO conditioning on sewage sludge thermal drying.

PubMed

Liu, Huan; Liu, Peng; Hu, Hongyun; Zhang, Qiang; Wu, Zhenyu; Yang, Jiakuan; Yao, Hong

2014-12-01

Joint application of Fenton's reagent and CaO can dramatically enhance sludge dewaterability, thus are also likely to affect subsequent thermal drying process. This study investigated the synergistic effects of the two conditioners on the thermal drying behavior of sewage sludge and the emission characteristics of main sulfur-/nitrogen-containing gases. According to the results, Fenton peroxidation combined with CaO conditioning efficiently promoted sludge heat transfer, reduced the amounts of both free and bound water, and created porous structure in solids to provide evaporation channels, thus producing significant positive effects on sludge drying performance. In this case, the required time for drying was shortened to one-third. Additionally, joint usage of Fenton's reagent and CaO did not increase the losses of organic matter during sludge drying process. Meanwhile, they facilitated the formation of sulfate and sulfonic acid/sulfone, leading to sulfur retention in dried sludge. Both of Fenton peroxidation and CaO conditioning promoted the oxidation, decomposition, and/or dissolution of protein and inorganic nitrogen in sludge pre-treatment. As a consequence, the emissions of sulfurous and nitrogenous gases from dewatered sludge drying were greatly suppressed. These indicate that combining Fenton peroxidation with CaO conditioning is a promising strategy to improve drying efficiency of sewage sludge and to control sulfur and nitrogen contaminants during sludge thermal drying process. Copyright © 2014 Elsevier Ltd. All rights reserved.

A study on the dewatering of industrial waste sludge by fry-drying technology.

PubMed

Ohm, Tae-In; Chae, Jong-Seong; Kim, Jeong-Eun; Kim, Hee-Kyum; Moon, Seung-Hyun

2009-08-30

In sludge treatment, drying sludge using typical technology with high water content to a water content of approximately 10% is always difficult because of adhesive characteristics of sludge. Many methods have been applied, including direct and indirect heat drying, but these approaches of reducing water content to below 40% after drying is very inefficient in energy utilization of drying sludge. In this study, fry-drying technology with a high heat transfer coefficient of approximately 500 W/m(2) degrees C was used to dry industrial wastewater sludge. Also waste oil was used in the fry-drying process, and because the oil's boiling point is between 240 and 340 degrees C and the specific heat is approximately 60% of that of water. In the fry-drying system, the sludge is input by molding it into a designated form after heating the waste oil at temperatures between 120 and 170 degrees C. At these temperatures, the heated oil rapidly evaporates the water contained in the sludge, leaving the oil itself. After approximately 10 min, the water content of the sludge was less than 10%, and its heating value surpassed 5300 kcal/kg. Indeed, this makes the organic sludge appropriate for use as a solid fuel. The wastewater sludge used in this study was the designated waste discharged from chemical, leather and plating plants. These samples varied in characteristics, especially with regard to heavy metal concentration. After drying the three kinds of wastewater sludge at oil temperatures 160 degrees C for 10 min, it was found that the water content in the sludge from the chemical, leather, and plating plants reduced from 80.0 to 5.5%, 81.6 to 1.0%, and 65.4 to 0.8%, respectively. Furthermore, the heat values of the sludge from the chemical, leather, and plating plants prior to fry-drying were 217, 264, and 428 kcal/kg, respectively. After drying, these values of sludge increased to 5317, 5983 and 6031 kcal/kg, respectively. The heavy metals detected in the sludge after drying were aluminum, lead, zinc, mercury, and cadmium. Most importantly, if the dried sludge is used as a solid fuel, these heavy metals can be collected from the dust collector after combustion.

Leaching of heavy metals and alkylphenolic compounds from fresh and dried sewage sludge.

PubMed

Milinovic, Jelena; Vidal, Miquel; Lacorte, Silvia; Rigol, Anna

2014-02-01

Reusing sewage sludge as a soil fertiliser has become a common alternative to disposal. Although this practice has a few benefits, it may contribute to the medium- and long-term contamination of the trophic chain because sewage sludge may contain heavy metals and organic contaminants. As the leaching of contaminants may depend on the sludge pre-treatment, the leaching of heavy metals (Cu, Ni, Pb, Zn and Cr) and alkylphenolic compounds (APCs) (octylphenol (OP), nonylphenol (NP), nonylphenol-mono-ethoxylate (NP1EO)) was investigated in five fresh and 40 °C dried sewage sludge samples from north-eastern Spain. FT-IR analyses and full-scan GC-MS chromatograms showed that sludge drying changed the nature of organic compounds leading to changes in their solubility. Moreover, sludge drying led to a higher relative contribution of dissolved organic carbon than the particulate organic carbon in the leachates. Leaching of Pb, Zn and Cr was below 5 % in both fresh and dried sludge samples, whereas Cu and Ni leached at rates up to 12 and 43 %, respectively, in some of the dried sludge samples. The leaching yields of OP, NP and NP1EO ranged from 1.3 to 35 % for fresh samples, but they decreased from 0.8 to 3.4 % in dried samples. The decrease in the leachability of APCs observed in dried sludge samples might be attributed to the fact that these compounds are associated with particulate organic matter, with significantly lower concentration or even absent in dried sludge than in fresh sludge samples. Therefore, it is recommended to dry the sludge before its disposal.

The thin-layer drying characteristics of sewage sludge by the appropriate foaming pretreatment.

PubMed

Wang, Hui-Ling; Yang, Zhao-Hui; Huang, Jing; Wang, Li-Ke; Gou, Cheng-Liu; Yan, Jing-Wu; Yang, Jian

2014-01-01

As dewatered sludge is highly viscous and sticky, the combination of foaming pretreatment and drying process seems to be an alternative method to improve the drying performance of dewatered sludge. In this study, CaO addition followed by mechanical whipping was employed for foaming the dewatered sludge. It was found that the foams were stable and the diameters of bubbles mainly ranged from 0.1 to 0.3 mm. The drying experiments were carried out in a drying oven in the convective mode. The results indicated that foamed sludge at 0.70 g/cm(3) had the best drying performance at each level of temperature, which could save 35-45% drying time to reach 20% moisture content compared with the non-foamed sludge. The drying rate of foamed sludge at 0.70 g/cm(3) was improved with the increasing of drying temperature. The impact of sample thickness on drying rate was not obvious when the sample thickness increased from 2 to 8 mm. Different mathematical models were used for the simulation of foamed sludge drying curves. The Wang and Singh model represented the drying characteristics better than other models with coefficient of determination values over 0.99.

Resource recovery of organic sludge as refuse derived fuel by fry-drying process.

PubMed

Chang, Fang-Chih; Ko, Chun-Han; Wu, Jun-Yi; Wang, H Paul; Chen, Wei-Sheng

2013-08-01

The organic sludge and waste oil were collected from the industries of thin film transistor liquid crystal display and the recycled cooking oil. The mixing ratio of waste cooking oil and organic sludge, fry-drying temperatures, fry-drying time, and the characteristics of the organic sludge pellet grain were investigated. After the fry-drying process, the moisture content of the organic sludge pellet grain was lower than 5% within 25 min and waste cooking oil was absorbed on the dry solid. The fry-drying organic sludge pellet grain was easy to handle and odor free. Additionally, it had a higher calorific value than the derived fuel standards and could be processed into organic sludge derived fuels. Thus, the granulation and fry-drying processes of organic sludge with waste cooking oil not only improves the calorific value of organic sludge and becomes more valuable for energy recovery, but also achieves waste material disposal and cost reduction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sewage sludge open-air drying affects on keratinolytic, keratinophilic and actidione-resistant fungi.

PubMed

Ulfig, Krzysztof; Płaza, Grazyna; Terakowskip, Maciej; Janda-Ulfig, Katarzyna

2006-01-01

The study was to demonstrate the effect of sewage sludge open-air drying on the quantitative and qualitative composition of keratinolytic/keratinophilic and actidione-resistant fungi. The sludge was being dried for up to thirty days (on average fourteen days) at 25-30'C. The composition of these fungi was determined with the hair baiting method along with the dilution method, using the Wiegand medium supplemented with chloramphenicol (100 mgiL) and actidione (500 mg/L). The open-air drying altered the composition of keratinolytic fungi and considerably increased the population of keratinophilic and actidione-resistant fungi in the sludge. This phenomenon can be explained with that the drying process was associated with slow sludge moisture decrease, sludge laceration due to crumbling and the subsequent improvement of sludge aeration and organic matter biodegradation conditions. A considerable increase of fungal populations can be expected in sludges being dried in drying beds at wastewater treatment plants and in sludge-amended soils. Two sludge opportunistic fungi, i.e. Microsporum gypseum and Pseudallescheria boydii, require special attention from the epidemiological point of view. Sludge land applications may increase the number of these fungi in the environment and the subsequent risk to public health posed by them.

Pressurised electro-osmotic dewatering of activated and anaerobically digested sludges: electrical variables analysis.

PubMed

Citeau, M; Olivier, J; Mahmoud, A; Vaxelaire, J; Larue, O; Vorobiev, E

2012-09-15

Pressurised electro-osmotic dewatering (PEOD) of two sewage sludges (activated and anaerobically digested) was studied under constant electric current (C.C.) and constant voltage (C.V.) with a laboratory chamber simulating closely an industrial filter. The influence of sludge characteristics, process parameters, and electrode/filter cloth position was investigated. The next parameters were tested: 40 and 80 A/m², 20, 30, and 50 V-for digested sludge dewatering; and 20, 40 and 80 A/m², 20, 30, and 50 V-for activated sludge dewatering. Effects of filter cloth electric resistance and initial cake thickness were also investigated. The application of PEOD provides a gain of 12 points of dry solids content for the digested sludge (47.0% w/w) and for the activated sludge (31.7% w/w). In PEOD processed at C.C. or at C.V., the dewatering flow rate was similar for the same electric field intensity. In C.C. mode, both the electric resistance of cake and voltage increase, causing a temperature rise by ohmic effect. In C.V. mode, a current intensity peak was observed in the earlier dewatering period. Applying at first a constant current and later on a constant voltage, permitted to have better control of ohmic heating effect. The dewatering rate was not significantly affected by the presence of filter cloth on electrodes, but the use of a thin filter cloth reduced remarkably the energy consumption compared to a thicker one: 69% of reduction energy input at 45% w/w of dry solids content. The reduction of the initial cake thickness is advantageous to increase the final dry solids content. Copyright © 2012 Elsevier Ltd. All rights reserved.

On the understanding and control of the spontaneous heating of dried tannery wastewater sludge.

PubMed

Biasin, A; Della Zassa, M; Zerlottin, M; Refosco, D; Bertani, R; Canu, P

2014-04-01

We studied the spontaneous heating of dried sludge produced by treating wastewater mainly originating from tanneries. Heating up to burning has been observed in the presence of air and moisture, starting at ambient temperature. To understand and prevent the process we combined chemical and morphological analyses (ESEM) with thermal activity monitoring in insulated vessels. Selective additions of chemicals, either to amplify or depress the reactivity, have been used to investigate and identify both the chemical mechanism causing the sludge self-heating, and a prevention or a mitigation strategy. FeS additions accelerate the onset of reactivity, while S sustains it over time. On the contrary, Ca(OH)2, Na2CO3, NaHCO3, FeCl2, EDTA, NaClO can limit, up to completely preventing, the exothermic activity. All the experimental evidences show that the reactions supporting the dried sludge self-heating involve the Fe/S/O system. The total suppression of the reactivity requires amounts of additives that are industrially incompatible with waste reduction and economics. The best prevention requires reduction or removal of S and Fe from the dried solid matrix. Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigation of the effects of temperature and sludge characteristics on odors and VOC emissions during the drying process of sewage sludge.

PubMed

Ding, Wenjie; Li, Lin; Liu, Junxin

2015-01-01

Sludge drying is a necessary step for sludge disposal. In this study, sludge was collected from two wastewater treatment plants, and dried at different temperatures in the laboratory. The emission of odor and total volatile organic compounds (TVOCs) during the sludge drying process were determined by an online odor monitoring system. The volatile organic compounds (VOCs) in off-gas were analyzed by gas chromatography-mass spectrometry. Results showed that sludge with 30% moisture content could be obtained in 51 minutes under drying temperature 100 °C but only within 27 minutes under 150 °C. Concentration of odor, TVOCs, sulfur-containing compounds (SCCs), and amines were changed with drying temperature and sludge sources. The maximum concentration of odor, TVOCs, SCCs, and amines were 503.13 ppm, 3.01 ppm, 8.15 ppm, and 11.27 ppm, respectively, at drying temperature 100 °C. These values reached 1,250.79, 8.10, 53.51, and 37.80 ppm when sludge dried at 150 °C. Odor concentration had a close relationship with emission of SCCs, amines, and TVOCs. The main VOCs released were benzene series and organic acid. Potential migration of substances in sludge was examined via analysis of off-gas and condensate, aiming to provide scientific data for effective sludge treatment and off-gas control.

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.

Changes on sewage sludge stability after greenhouse drying

NASA Astrophysics Data System (ADS)

Soriano-Disla, J. M.; Houot, S.; Imhoff, M.; Valentin, N.; Gómez, I.; Navarro-Pedreño, J.

2009-04-01

The progressive implementation of the Urban Waste Water Treatment Directive 91/271/EEC in all the European member states is increasing the quantities of sewage sludge requiring disposal. Sludge application onto cultivated soils as organic fertilizers allows the recycling of nutrients. The application of only dehydrated sludges has generated many problems including unpleasant odours and difficult management (regarding transport and application) related to their high water content. One way to overcome these problems, in a cheap and clean way, is the drying of sludges using the energy of the sun under greenhouse conditions. This drying may affect sludge chemical characteristics including organic matter stability and nitrogen availability, parameters which have to be controlled for the proper management of dry sludge application onto soils. For this reason, the main aim of this work was to study the impact of greenhouse drying of different sewage sludges on their organic matter stability and nitrogen availability, assessed by biochemical fractionation and mineralization assays. Three sewage sludges were sampled before (dehydrated sludges) and after greenhouse drying (dried sludges). The analyses consisted of: humidity, organic matter, mineral and organic N contents, N and C mineralization during 91-day laboratory incubations in controlled conditions, and biochemical fractionation using the Van Soest procedure. Greenhouse drying decreased the water content from 70-80% to 10% and also the odours, both of which will improve the management of the final product from the perspective of application and transport. We also found that drying reduced the organic matter content of the sludges but not the biodegradability of the remaining carbon. Organic N mineralization occurred during greenhouse drying, explaining why mineral N content tended to increase and the potential mineralization of organic nitrogen decreased after greenhouse drying. The biochemical stability did not change so much except for the one of the sludges, which experienced an important reduction. According to the results, and from a point of view of future soil applications, the balance of the drying process could be considered as positive. It is using a free, renewable and clean energy, which reduces the water content and odours of sludge, thereby improving their management. Except for the water content, there was little modification of the behaviour in soil of greenhouse dried sludges compared to the dehydrated sludges, maintaining its large amount of available nitrogen after drying. Acknowledgements: Jose. M. Soriano-Disla gratefully acknowledges the Spanish Ministry of Innovation and Culture for a research fellowship (AP2005-0320).

Enhanced sludge dewatering by electrofiltration. A feasibility study.

PubMed

Saveyn, H; Huybregts, L; Van der Meeren, P

2001-01-01

Sludge treatment is a major issue in today's waste water treatment. One of the problems encountered is the limiting dewaterability of mainly biological sludges, causing high final treatment costs for incineration or landfill. Although during recent years, improvements are realised in the field of dewatering, the actual dry solids content after dewatering remains at a maximum value of about 35%. In order to increase the dry solids content, the technique of electrofiltration was investigated. Electrofiltration is the combination of two known techniques, traditional pressure filtration and electroosmotic/electrophoretic dewatering. Pressure filtration is based on pressure as the driving force for dewatering a sludge. Limitations hereby lie in the clogging of the filter cloth due to the build-up of the filtercake. Electroosmotic/electrophoretic dewatering is based on an electric field to separate sludge colloid particles from the surrounding liquid by placing the sludge liquor between two oppositely charged electrodes. In this case, mobile sludge particles will move to one electrode due to their natural surface charge, and the liquid phase will be collected at the oppositely charged electrode. Combination of both techniques makes it possible to create a more homogeneous filter cake and prevent the filter from clogging, resulting in higher cake dry solids contents and shorter filtration cycles. To investigate the feasibility of this technique for the dewatering of activated sludge, a filter unit was developed for investigations on lab scale. Multiple dewatering tests were performed in which the electric parameters for electrofiltration were varied. It was derived from these experiments that very high filter cake dry solids contents (to more than 60%), and short filtration cycles were attainable by using a relatively small electric DC field. The power consumption was very low compared to the power needed to dewater sludge by thermal drying techniques. For this reason, this technique seems very promising for the dewatering of biological sludges.

Predicting the drying properties of sludge based on hydrothermal treatment under subcritical conditions.

PubMed

Mäkelä, Mikko; Fraikin, Laurent; Léonard, Angélique; Benavente, Verónica; Fullana, Andrés

2016-03-15

The effects of hydrothermal treatment on the drying properties of sludge were determined. Sludge was hydrothermally treated at 180-260 °C for 0.5-5 h using NaOH and HCl as additives to influence reaction conditions. Untreated sludge and attained hydrochar samples were then dried under identical conditions with a laboratory microdryer and an X-ray microtomograph was used to follow changes in sample dimensions. The effective moisture diffusivities of sludge and hydrochar samples were determined and the effect of process conditions on respective mean diffusivities evaluated using multiple linear regression. Based on the results the drying time of untreated sludge decreased from approximately 80 min to 37-59 min for sludge hydrochar. Drying of untreated sludge was governed by the falling rate period where drying flux decreased continuously as a function of sludge moisture content due to heat and mass transfer limitations and sample shrinkage. Hydrothermal treatment increased the drying flux of sludge hydrochar and decreased the effect of internal heat and mass transfer limitations and sample shrinkage especially at higher treatment temperatures. The determined effective moisture diffusivities of sludge and hydrochar increased as a function of decreasing moisture content and the mean diffusivity of untreated sludge (8.56·10(-9) m(2) s(-1)) and sludge hydrochar (12.7-27.5·10(-9) m(2) s(-1)) were found statistically different. The attained regression model indicated that treatment temperature governed the mean diffusivity of hydrochar, as the effects of NaOH and HCl were statistically insignificant. The attained results enabled prediction of sludge drying properties through mean moisture diffusivity based on hydrothermal treatment conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Surplus activated sludge dewatering in pilot-scale sludge drying reed beds.

PubMed

Stefanakis, A I; Akratos, C S; Melidis, P; Tsihrintzis, V A

2009-12-30

A pilot-scale experiment on dewatering of surplus activated sludge (SAS) is presented, where two pilot-scale vertical flow, sludge drying reed beds (SDRBs), planted with Phragmites australis are used. The bottom of the beds is filled with cobbles, connected to the atmosphere through perforated PVC ventilation tubes, in order to achieve oxygen diffusion through the overlying porous medium that is colonized by roots and an abundant nitrifying biomass. Two layers of gravel, of decreasing size from bottom to top, make the drainage layer where the reeds are planted. The two beds were fed according to the following cycle: one week feeding with SAS at rates one 30 kg/m(2)/year and the other 75 kg/m(2)/year, and resting for three weeks. The results show that planted SDRBs can effectively dewater SAS from domestic sewage, the produced residual sludge presents a high dry weight content, the degree of volume reduction depends upon the initial SAS concentration and can be of the order of 90%, and decomposition of organic matter and high levels of mineralization can be achieved. Furthermore, the percolating water is not septic. The fertilizer value of the treated SAS, which contains no added chemicals, is comparable to that of SAS treated by other methods.

Effect of calcium oxide (CaO) and sawdust on adhesion and cohesion characteristics of sewage sludge under agitated and non-agitated drying conditions.

PubMed

Deng, Wen-Yi; Yuan, Min-Hao; Mei, Jing; Liu, Ya-Jun; Su, Ya-Xin

2017-03-01

Stickiness phenomenon is widely observed in sewage sludge drying practices. This paper is aimed at demonstrating and comparing the sticky properties of sewage sludge through non-agitated and agitated drying tests specially designed for sewage sludge. Special attentions were paid to the effects of additives, i.e. CaO, fine sawdust (FSD) and coarse sawdust (CSD), on the adhesive and cohesive characteristics of sewage sludge. The results indicated that the sticky properties of the sludge were markedly different under the different testing methods, and was also greatly influenced by CaO or sawdust addition. For instance, in the non-agitated drying tests, CaO can significantly enhance the maximum adhesive and cohesive stresses of the sludge, whereas in the agitated drying tests, the torque of agitation, which strongly correlated with the cohesive stress of the sludge, was lowered by CaO addition. During agitated drying process, sludge lump with CaO addition started to break up at higher moisture content than that of original sludge. On the other hand, sawdust also affected the sticky properties of sludge in a way that was totally different with CaO. After sawdust addition (at 5-10%WS (wet sludge basis)), the cohesive stress of the sludge was markedly increased due to strengthening of mechanical interlocking inside the sludge, whereas the adhesiveness of the sludge was lowered by sawdust addition. The influencing mechanisms of CaO and sawdust under the different testing methods were detailedly discussed in the paper. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reduction in greenhouse gas emissions from sludge biodrying instead of heat drying combined with mono-incineration in China.

PubMed

Liu, Hong-Tao; Wang, Yan-Wen; Liu, Xiao-Jie; Gao, Ding; Zheng, Guo-di; Lei, Mei; Guo, Guang-Hui; Zheng, Hai-Xia; Kong, Xiang-Juan

2017-02-01

Sludge is an important source of greenhouse gas (GHG) emissions, both in the form of direct process emissions and as a result of indirect carbon-derived energy consumption during processing. In this study, the carbon budgets of two sludge disposal processes at two well-known sludge disposal sites in China (for biodrying and heat-drying pretreatments, both followed by mono-incineration) were quantified and compared. Total GHG emissions from heat drying combined with mono-incineration was 0.1731 tCO 2 e t -1 , while 0.0882 tCO 2 e t -1 was emitted from biodrying combined with mono-incineration. Based on these findings, a significant reduction (approximately 50%) in total GHG emissions was obtained by biodrying instead of heat drying prior to sludge incineration. Sludge treatment results in direct and indirect greenhouse gas (GHG) emissions. Moisture reduction followed by incineration is commonly used to dispose of sludge in China; however, few studies have compared the effects of different drying pretreatment options on GHG emissions during such processes. Therefore, in this study, the carbon budgets of sludge incineration were analyzed and compared following different pretreatment drying technologies (biodrying and heat drying). The results indicate that biodrying combined with incineration generated approximately half of the GHG emissions compared to heat drying followed by incineration. Accordingly, biodrying may represent a more environment-friendly sludge pretreatment prior to incineration.

Research on the influence of anaerobic stabilization of various dairy sewage sludge on biodegradation of polycyclic aromatic hydrocarbons PAHs with the use of effective microorganisms.

PubMed

Boruszko, Dariusz

2017-05-01

Sewage sludge was taken from a dairy WWTP belonging to Mlekovita Cooperative in Wysokie Mazowieckie. There were excess sludge, flotation sludge and a mixture of excess and flotation sludge from pre-treatment of dairy sewage. The initial content of 16 PAHs in excess sludge before fermentation was approximately 689µg·kg -1 in dry mass, whereas in post-flotation sludge (which constituted around 30% of raw sludge) it was approximately 95µg·kg -1 in dry mass. A mixture of excess and flotation sludge had the content of 497,7µg·kg -1 in dry mass. Through comparison of particular hydrocarbons content in raw sewage sludge to the total PAHs content, it was shown that tricyclic compounds, which constituted 46,3% of the PAHs sum (excess sludge), and tetracyclic compounds, which constituted 60,0% of the PAHs sum (flotation sludge), were the dominating fractions. In the sludge subjected to fermentation in reactors with mixed sludge and surplus activated sludge, the general trend of the course of changes in concentrations of PAHs was similar. Both in the sludge inoculated with EM and in that not inoculated with EM, a significant increase in the total PAHs contents was observed in the first fermentation phase (acidic fermentation) after 7 days of the process. Addition of EM into the sludge did not prevent the PAHs release, and therefore higher concentrations of PAHs sum were recorded during the hydrolysis stage than in sludge before fermentation. A decrease in the sum of PAHs was observed after 2 weeks of fermentation in relation to the quantity observed after 1 week of fermentation (except from post-flotation sludge). In the following weeks, there was further decrease in the concentration of the 16 PAHs sum in all sludge types. However, in sludge without EM inoculation, it was lower than in sludge with EM inoculation. The loss of the majority of tested hydrocarbons was reported in the final phase of fermentation. Copyright © 2017 Elsevier Inc. All rights reserved.

Fluid dynamics simulation for design on sludge drying equipment

NASA Astrophysics Data System (ADS)

Li, Shuiping; Liang, Wang; Kai, Zhang

2017-10-01

Sludge drying equipment is a key component in the sludge drying disposal, the structure of drying equipment directly affects the drying disposal of the sludge, so it is necessary to analyse the performance of the drying equipment with different structure. Fluent software can be very convenient to get the distribution of the flow field and temperature field inside the drying equipment which reflects the performance of the structure. In this paper, the outlet position of the sludge and the shape of the sludge inlet are designed. The geometrical model of the drying equipment is established by using pre-processing software Gambit, and the meshing of the model is carried out. The Eulerian model is used to simulate the flow of each phase and the interaction between them, and the realizable turbulence model is used to simulate the turbulence of each phase. Finally, the simulation results of the scheme are compared and the optimal structure scheme is obtained, the operational requirement is proposed. The CFD theory provides a reliable basis for the drying equipment research and reduces the time and costs of the research.

Comparison of three different wastewater sludge and their respective drying processes: Solar, thermal and reed beds - Impact on organic matter characteristics.

PubMed

Collard, Marie; Teychené, Benoit; Lemée, Laurent

2017-12-01

Drying process aims at minimising the volume of wastewater sludge (WWS) before disposal, however it can impact sludge characteristics. Due to its high content in organic matter (OM) and lipids, sludge are mainly valorised by land farming but can also be considered as a feedstock for biodiesel production. As sludge composition is a major parameter for the choice of disposal techniques, the objective of this study was to determine the influence of the drying process. To reach this goal, three sludges obtained from solar, reed beds and thermal drying processes were investigated at the global and molecular scales. Before the drying step the sludges presented similar physico-chemical (OM content, elemental analysis, pH, infrared spectra) characteristics and lipid contents. A strong influence of the drying process on lipids and humic-like substances contents was observed through OM fractionation. Thermochemolysis-GCMS of raw sludge and lipids revealed similar molecular content mainly constituted with steroids and fatty acids. Molecular changes were noticeable for thermal drying through differences in branched to linear fatty acids ratio. Finally the thermal drying induced a weakening of OM whereas the solar drying led to a complexification. These findings show that smooth drying processes such as solar or reed-beds are preferable for amendment production whereas thermal process leads to pellets with a high lipid content which could be considered for fuel production. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

The evaporative drying of sludge by immersion in hot oil: Effects of oil type and temperature.

PubMed

Ohm, Tae-In; Chae, Jong-Seong; Lim, Kwang-Soo; Moon, Seung-Hyun

2010-06-15

We investigated the evaporative drying by immersion in hot oil (EDIHO) method for drying sludge. This involved heating oil to a temperature higher than that needed for moisture to be evaporated from the sludge by turbulent heat and mass transfer. We fry-dried sewage and leather plant sludge for 10 min in each of four different oils (waste engine, waste cooking, refined waste, and B-C heavy) and three different temperatures (140 degrees C, 150 degrees C, and 160 degrees C). Drying efficiency was found to be greater for higher temperatures. However, giving consideration to energy efficiency we suggest that the optimal temperature for fry-drying sludge is 150 degrees C. At 150 degrees C, the water content of sewage sludge reduced from 78.9% to between 1.5% (with waste cooking oil) and 3.8% (with waste engine oil). The reduction in water content for leather plant sludge fry-dried at 150 degrees C was from 81.6% to between 1% (with waste cooking oil) and 6.5% (with refined waste oil). The duration of the constant rate-drying period was also influenced by the type of oil used: refined waste oil>waste engine oil>B-C heavy oil>waste cooking oil. The duration at 150 degrees C with waste cooking oil was 3 min for sewage sludge and 2 min for leather plant sludge. It is likely that the drying characteristics of oil are influenced by its thermal properties, including its specific heat, and molecular weight. Copyright 2010 Elsevier B.V. All rights reserved.

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.

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.

Degradation of anionic surfactants during drying of UASBR sludges on sand drying beds.

PubMed

Mungray, Arvind Kumar; Kumar, Pradeep

2008-09-01

Anionic surfactant (AS) concentrations in wet up-flow anaerobic sludge blanket reactor (UASBR) sludges from five sewage treatment plants (STPs) were found to range from 4480 to 9,233 mg kg(-1)dry wt. (average 7,347 mg kg(-1)dry wt.) over a period of 18 months. After drying on sand drying beds (SDBs), AS in dried-stabilized sludges averaged 1,452 mg kg(-1)dry wt., a reduction of around 80%. The kinetics of drying followed simple first-order reduction of moisture with value of drying constant (k(d))=0.051 d(-1). Reduction of AS also followed first-order kinetics. AS degradation rate constant (k(AS)) was found to be 0.034 d(-1) and half-life of AS as 20 days. The order of rates of removal observed was k(d)>k(AS)>k(COD)>k(OM) (drying >AS degradation>COD reduction>organic matter reduction). For the three applications of dried-stabilized sludges (soil, agricultural soil, grassland), values of risk quotient (RQ) were found to be <1, indicating no risk.

Differences on nitrogen availability in a soil amended with fresh, composted and thermally-dried sewage sludge.

PubMed

Tarrasón, D; Ojeda, G; Ortiz, O; Alcañiz, J M

2008-01-01

Anaerobically-digested sludge called fresh sludge (F), composted sludge (C) and thermally-drying sludge (T), all from the same batch, were applied to the surface of a calcareous Udic Calciustept with loamy texture. Dosage equivalent was 10 t ha(-1) of dry matter. The concentration of mineral nitrogen (ammonium and nitrate) in the soil was measured in order to estimate the effects of the post-treatments to which the different kinds of sewage sludge are subjected in relation to the availability of N in the surface layer of the soil. The most significant differences in NH(4)-N and NO(3)-N concentrations due to the transformation of the organic matter were observed during the first three weeks following soil amendment. Thermally-dried and composted sludge initially displayed higher concentrations of ammonium and nitrate in soil. Five months after the amendment, soil applied with fresh sludge showed the highest concentrations of NH(4)-N and NO(3)-N (6.1 and 36.6 mg kg(-1), respectively). It is clear that the processes of composting and thermal-drying influence the bioavailability of nitrogen from the different types of sewage sludge.

Priority and emerging pollutants in sewage sludge and fate during sludge treatment.

PubMed

Mailler, R; Gasperi, J; Chebbo, G; Rocher, V

2014-07-01

This paper aims at characterizing the quality of different treated sludges from Paris conurbation in terms of micropollutants and assessing their fate during different sludge treatment processes (STP). To achieve this, a large panel of priority and emerging pollutants (n=117) have been monitored in different STPs from Parisian wastewater treatment plants including anaerobic digestion, thermal drying, centrifugation and a sludge cake production unit. Considering the quality of treated sludges, comparable micropollutant patterns are found for the different sludges investigated (in mg/kg DM - dry matter). 35 compounds were detected in treated sludges. Some compounds (metals, organotins, alkylphenols, DEHP) are found in every kinds of sludge while pesticides or VOCs are never detected. Sludge cake is the most contaminated sludge, resulting from concentration phenomenon during different treatments. As regards treatments, both centrifugation and thermal drying have broadly no important impact on sludge contamination for metals and organic compounds, even if a slight removal seems to be possible with thermal drying for several compounds by abiotic transfers. Three different behaviors can be highlighted in anaerobic digestion: (i) no removal (metals), (ii) removal following dry matter (DM) elimination (organotins and NP) and iii) removal higher than DM (alkylphenols - except NP - BDE 209 and DEHP). Thus, this process allows a clear removal of biodegradable micropollutants which could be potentially significantly improved by increasing DM removal through operational parameters modifications (retention time, temperature, pre-treatment, etc.). Copyright © 2014 Elsevier Ltd. All rights reserved.

[Comparison of PAHs distribution in stabilized sludge by sludge drying bed and reed bed].

PubMed

Cui, Yu-Bo; Sun, Hong-Jie; Ran, Chun-Qiu; Li, Jin-Feng; Xie, Yao

2013-03-01

The difference in the removal efficiencies of polycyclic aromatic hydrocarbons (PAHs) in planted and unplanted sludge drying bed was investigated. Pilot-scale sludge drying bed and reed bed had the same size of 3.0 m x 1.0 m x 1.3 m (L x W x H), and the bed height consisted of a 65 cm media layer and a 65 cm super height. Both beds had a ventilation pipe which was mounted on the drainage pipes. The experiment lasted for three years, and the first two years was the sludge loading period, and the third year was the natural stabilization period. In the first two years, a total thickness of 8.4 m of sludge was loaded and the average sludge loading rate was 41.3 kg x (m2 x a)(-1). After the three-year stabilization, the contents of the sixteen PAHs decreased with time in both the sludge drying bed and the reed bed. The total PAHs contents in the surface, middle and bottom sludge layers in the sludge drying bed were 4.161, 3.543 and 3.118 mg x kg(-1) (DW), corresponding to 26.91%, 37.77% and 45.23% of removal; and the values in the reed bed were 2.722, 1.648 and 1.218 mg x kg(-1) (DW), corresponding to 52.18%, 71.05% and 78.60% of removal. The average PAHs removal in the reed bed was 29.86% higher than that in the sludge drying bed. In the stabilized sludge, the removal of low-molecular-weight PAHs predominated. The results suggested that reed played a positive role in the removal of PAHs.

A comparative evaluation of dried activated sludge and mixed dried activated sludge with rice husk silica to remove hydrogen sulfide

PubMed Central

2013-01-01

The aim of this study was to investigate the effectiveness of dried activated sludge (DAS) and mixed dried activated sludge with rice husk silica (DAS & RHS) for removal of hydrogen sulfide (H2S). Two laboratory-scale filter columns (packed one litter) were operated. Both systems were operated under different conditions of two parameters, namely different inlet gas concentrations and different inlet flow rates. The DAS & RHS packed filter showed more than 99.96% removal efficiency (RE) with empty bed residence time (EBRT) of 45 to 90 s and 300 mg/L inlet concentration of H2S. However, the RE decreased to 96.87% with the EBRT of 30 s. In the same condition, the DAS packed filter showed 99.37% RE. Nonetheless, the RE was shown to have dropped to 82.09% with the EBRT of 30 s. The maximum elimination capacity (EC) was obtained in the DAS & RHS packed filter up to 52.32 g/m3h, with the RE of 96.87% and H2S mass loading rate of 54 g/m3h. The maximum EC in the DAS packed filter was obtained up to 44.33 g/m3h with the RE of 82.09% and the H2S mass loading rate of 54 g/m3h. After 53 days of operating time and 54 g/m3h of loading rates, the maximum pressure drop reached to 3.0 and 8.0 (mm H2O) for the DAS & RHS packed and DAS packed filters, respectively. Based on the findings of this study, the DAS & RHS could be considered as a more suitable packing material to remove H2S. PMID:23497048

Multifractality analysis of crack images from indirect thermal drying of thin-film dewatered sludge

NASA Astrophysics Data System (ADS)

Wang, Weiyun; Li, Aimin; Zhang, Xiaomin; Yin, Yulei

2011-07-01

Crack formation is inevitable during sludge drying because of the existence of uneven thermal stress. Experiments have been conducted to study crack pattern formation in thin film sludge. Crack images show that the thinner the sewage sludge film, the more even the crack distribution. The crack changes from a flaky texture to a banded structure with increasing thickness. Multifractal methods are proposed to analyze the crack image of four different thicknesses of dried sludge. Several parameters are conducted for quantification of the crack image and the results indicate that the width of spectra increases with thicker sludge film, that is to say, nonunifromity of crack distribution increases with increasing thickness, which proves that the multifractal method is sensitive enough to quantify the crack distribution and can be seen as a new approach for the changing research of crack images of sewage sludge drying.

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.

An Economic comparison of sludge irradiation and alternative methods of municipal sludge treatment

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

Ahlstrom, S.B.; McGuire, H.E.

1977-11-01

The relative economics of radiation treatment and other sludge treatment processes are reported. The desirability of radiation treatment is assessed in terms of cost and the quality of the treated sludge product. The major conclusions of this study are: radiation treatment is a high-level disinfection process. Therefore, it should only be considered if high levels of disinfection are required for widespread reuse of the sludge; the handling, transporting and pathogen growback problems associated with disinfected wet sludge makes it less attractive for reuse than dry sludge; radiation of composted sludge produces a product of similar quality at less cost thanmore » any thermal treatment and/or flash drying treatment option for situations where a high degree of disinfection is required; and heavy metal concerns, especially cadmium, may limit the reuse of sludge despite high disinfection levels. It is recommended that radiation treatment of sludge, particularly dry sludge, continue to be studied. A sensitivity analysis investigating the optimal conditions under which sludge irradiation operates should be instigated. Furthermore, costs of adding sludge irradiation to existing sludge treatment schemes should be determined.« less

A field study of lignite as a drying aid in the superheated steam drying of anaerobically digested sludge.

PubMed

Hoadley, A F A; Qi, Y; Nguyen, T; Hapgood, K; Desai, D; Pinches, D

2015-10-01

Dried sludge is preferred when the sludge is either to be incinerated or used as a soil amendment. This paper focuses on superheated steam drying which has many benefits, because the system is totally enclosed, thereby minimising odours and particulate emissions. This work reports on field trials at a wastewater treatment plant where anaerobically digested sludge is dried immediately after being dewatered by belt press. The trials showed that unlike previous off-site tests, the sludge could be dried without the addition of a filter aid at a low production rate. However, the trials also confirmed that the addition of the lignite (brown coal) into the anaerobically digested sludge led to a more productive drying process, improved product quality and a greater fraction of the product being in the desired product size range. It is concluded that these results were achieved because the lignite helped to control the granule size in the dryer. Furthermore neither Salmonella spp or E coli were detected in the dried samples. Tests on spontaneous combustion show that this risk is increased in proportion to the amount of lignite used as a drying aid. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Sewage sludge drying process integration with a waste-to-energy power plant.

PubMed

Bianchini, A; Bonfiglioli, L; Pellegrini, M; Saccani, C

2015-08-01

Dewatered sewage sludge from Waste Water Treatment Plants (WWTPs) is encountering increasing problems associated with its disposal. Several solutions have been proposed in the last years regarding energy and materials recovery from sewage sludge. Current technological solutions have relevant limits as dewatered sewage sludge is characterized by a high water content (70-75% by weight), even if mechanically treated. A Refuse Derived Fuel (RDF) with good thermal characteristics in terms of Lower Heating Value (LHV) can be obtained if dewatered sludge is further processed, for example by a thermal drying stage. Sewage sludge thermal drying is not sustainable if the power is fed by primary energy sources, but can be appealing if waste heat, recovered from other processes, is used. A suitable integration can be realized between a WWTP and a waste-to-energy (WTE) power plant through the recovery of WTE waste heat as energy source for sewage sludge drying. In this paper, the properties of sewage sludge from three different WWTPs are studied. On the basis of the results obtained, a facility for the integration of sewage sludge drying within a WTE power plant is developed. Furthermore, energy and mass balances are set up in order to evaluate the benefits brought by the described integration. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transformation of heavy metal speciation during sludge drying: mechanistic insights

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

Weng, Huanxin; Ma, Xue-Wen; Fu, Feng-Xia

2014-01-30

Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized the Cr, Cu, Cd and Pb in sludge by transforming acid-soluble, reducible andmore » oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge.« less

Effects of aeration strategy on the evolution of dissolved organic matter (DOM) and microbial community structure during sludge bio-drying.

PubMed

Zhang, Junya; Cai, Xing; Qi, Lu; Shao, Chunyan; Lin, Yang; Zhang, Jin; Zhang, Yuanli; Shen, Peihong; Wei, Yuansong

2015-09-01

Sludge bio-drying in which sludge is dried by means of the heat generated by the aerobic degradation of its own organic substances has been widely used for sludge treatment. A better understanding of the evolution of dissolved organic matter (DOM) and its degradation drivers during sludge bio-drying could facilitate its control. Aeration is one of the key factors that affect sludge bio-drying performance. In this study, two aeration strategies (pile I-the optimized and pile II-the current) were established to investigate their impacts on the evolution of DOM and the microbial community in a full-scale sludge bio-drying plant. A higher pile temperature in pile I caused pile I to enter the DOM and microbiology stable stage approximately2 days earlier than pile II. The degradation of easily degradable components in the DOM primarily occurred in the thermophilic phase; after that degradation, the DOM components changed a little. Along with the evolution of the DOM, its main degradation driver, the microbial community, changed considerably. Phyla Firmicutes and Proteobacteria were dominant in the thermophilic stage, and genus Ureibacillus, which was the primary thermophilic bacteria, was closely associated with the degradation of the DOM. In the mesophilic stage, the microbial community changed significantly at first and subsequently stabilized, and the genus Parapedobacter, which belongs to Bacteriodetes, became dominant. This study elucidates the interplay between the DOM and microbial community during sludge bio-drying.

From municipal/industrial wastewater sludge and FOG to fertilizer: A proposal for economic sustainable sludge management.

PubMed

Bratina, Božidar; Šorgo, Andrej; Kramberger, Janez; Ajdnik, Urban; Zemljič, Lidija Fras; Ekart, Janez; Šafarič, Riko

2016-12-01

After a ban on the depositing of untreated sludge in landfills, the sludge from municipal and industrial water-treatment plants can be regarded as a problem. Waste products of the water treatment process can be a problem or an opportunity - a source for obtaining raw materials. In the European Union, raw sludge and fats, oil and grease (FOG) from municipal and industrial wastewater treatment plants (WWTP) cannot be deposited in any natural or controlled environment. For this reason, it must be processed (stabilized, dried) to be used later as a fertilizer, building material, or alternative fuel source suitable for co-incineration in high temperature furnaces (power plants or concrete plants). The processes of drying sludge, where heat and electricity are used, are energy consuming and economically unattractive. Beside energy efficiency, the main problem of sludge drying is in its variability of quality as a raw material. In addition to this, sludge can be contaminated by a number of organic and inorganic pollutants and organisms. Due to the presence or absence of pollutants, different end products can be economically interesting. For example, if the dried sludge contains coliform bacteria, viruses, helminths eggs or smaller quantities of heavy metals, it cannot be used as a fertilizer but can still be used as a fuel. The objectives of the current article is to present a batch-processing pilot device of sludge or digestate that allows the following: (1) low pressure and low temperature energy effective drying of from 10 to 40% remaining water content, (2) disinfection of pathogen (micro)organisms, (3) heavy metal reduction, (4) production of products of predetermined quality (e.g. containing different quantities of water; it can be used as a fertilizer, or if the percentage of water in the dry sludge is decreased to 10%, then the dried sludge can be used as a fuel with a calorific value similar to coal). An important feature is also the utilization of low-pressure technology to prevent odorous gasses from spreading into the environment. There are presented two new technologies: a) Sewage sludge or digestate drying in the vacuum chamber consumes approx. 1 kWh/dm 3 of evaporated water and, therefore, reaches a price of 180-240 Euros/t Dry Matter (DM), and b) Heavy metals' reduction using adsorbing reaction with magnetite nanostructures can decrease the level of heavy metals in the sewage sludge or digestate up to 20% in one cycle, which can be repeated several times on the same sludge. The aim of the paper is to present a newly developed technology which can provide economic and safe use of moderate heavy metals polluted sewage sludge on agricultural lands as organic fertilizer and, therefore, returning the nutrients (nitrogen, phosphorous, potassium) back to the human food chain, instead of being incinerated or landfilled. The proposed drying technology is economically sustainable due to the low vacuum and temperature (35 °C-40 °C), that increases the efficiency of the heat pump (coefficient of performance 5-7,2) of the energy produced by the anaerobic digestion. Hence, the main emphasis is given to the development of: an efficient method for heavy metals' reduction in the sludge treatment chain by using chitosan covered magnetite nanoparticles, an efficient drying method in a vacuum with low temperature energy which can be exploited from sludge digestion to reduce organic matter, and an energy sustainable concept of sludge treatment, with the addition of fats, oil and grease (FOG) to produce enough biogas for sludge drying to produce fertilizer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sludge bio-drying: Effective to reduce both antibiotic resistance genes and mobile genetic elements.

PubMed

Zhang, Junya; Sui, Qianwen; Tong, Juan; Buhe, Chulu; Wang, Rui; Chen, Meixue; Wei, Yuansong

2016-12-01

Sewage sludge is considered as one of major contributors to the increased environmental burden of ARGs. Sludge bio-drying was increasingly adopted due to its faster sludge reduction compared with composting. The fate of ARGs during full-scale sludge bio-drying was investigated to determine whether it could effectively reduce ARGs, and the contributions of bacterial community, horizontal gene transfer (HGT) through mobile genetic elements (MGEs) and co-selection from heavy metals to ARGs profiles were discussed in detail. Two piles with different aeration strategies (Pile I, the improved and Pile II, the control) were operated to elucidate effects of aeration strategy on ARGs profiles. Results showed that sludge bio-drying could effectively reduce both most of targeted ARGs (0.4-3.1 logs) and MGEs (0.8-3.3 logs) by the improved aeration strategy, which also enhanced both the sludge bio-drying performance and ARGs reduction. The enrichment of ARGs including ermF, tetX and sulII could be well explained by the evolution of bioavailable heavy metals, not HGT through MGEs, and their potential host bacteria mainly existed in Bacteroidetes. Although changes of bacterial community contributed the most to ARGs profiles, HGT through MGEs should be paid more attention especially in the thermophilic stage of sludge bio-drying. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Moisture variation associated with water input and evaporation during sewage sludge bio-drying.

PubMed

Cai, Lu; Gao, Ding; Chen, Tong-Bin; Liu, Hong-Tao; Zheng, Guo-Di; Yang, Qi-Wei

2012-08-01

The variation of moisture during sewage sludge bio-drying was investigated. In situ measurements were conducted to monitor the bulk moisture and water vapor, while the moisture content, water generation, water evaporation and aeration water input of the bio-drying bulk were calculated based on the water mass balance. The moisture in the sewage sludge bio-drying material decreased from 66% to 54% in response to control technology for bio-drying. During the temperature increasing and thermophilic phases of sewage sludge bio-drying, the moisture content, water generation and water evaporation of the bulk initially increased and then decreased. The peak water generation and evaporation occurred during the thermophilic phase. During the bio-drying, water evaporation was much greater than water generation, and aeration facilitated the water evaporation. Copyright © 2012. Published by Elsevier Ltd.

Energy potential and alternative usages of biogas and sludge from UASB reactors: case study of the Laboreaux wastewater treatment plant.

PubMed

Rosa, A P; Conesa, J A; Fullana, A; Melo, G C B; Borges, J M; Chernicharo, C A L

2016-01-01

This work assessed the energy potential and alternative usages of biogas and sludge generated in upflow anaerobic sludge blanket reactors at the Laboreaux sewage treatment plant (STP), Brazil. Two scenarios were considered: (i) priority use of biogas for the thermal drying of dehydrated sludge and the use of the excess biogas for electricity generation in an ICE (internal combustion engine); and (ii) priority use of biogas for electricity generation and the use of the heat of the engine exhaust gases for the thermal drying of the sludge. Scenario 1 showed that the electricity generated is able to supply 22.2% of the STP power demand, but the thermal drying process enables a greater reduction or even elimination of the final volume of sludge to be disposed. In Scenario 2, the electricity generated is able to supply 57.6% of the STP power demand; however, the heat in the exhaust gases is not enough to dry the total amount of dehydrated sludge.

Evaluation on the air-borne ultrasound-assisted hot air convection thin-layer drying performance of municipal sewage sludge.

PubMed

Sun, G Y; Chen, M Q; Huang, Y W

2017-01-01

The thin-layer drying behavior of the municipal sewage sludge in a laboratory-scale hot air forced convective dryer assisted with air-borne ultrasound was investigated in between 70 and 130°C hot air temperatures. The drying kinetics in the convective process alone were compared to that for ultrasound-assist process at three ultrasound powers (30, 90, 150W). The average drying rates within whole drying temperature range at ultrasound powers of 30, 90 and 150W increased by about 22.6%, 27.8% and 32.2% compared with the convective drying alone (without ultrasound). As the temperature increasing from 70°C to 130°C, there were maximum increasing ratios for the effective moisture diffusivities of the sewage sludge in both falling rate periods at ultrasonic power of 30W in comparison with other two high powers. In between the ultrasound powers of 0 and 30W, the effect of the power on the drying rate was significant, while its effect was not obvious over 30W. Therefore, the low ultrasonic power can be just set in the drying process. The values of the apparent activation energy in the first falling rate period were down from 13.52 to 12.78kJmol -1 , and from 17.21 to 15.10kJmol -1 for the second falling rate period with increasing the ultrasonic power from 30 to 150W. The values of the apparent activation energy in two falling rate periods with the ultrasound-assist were less than that for the hot air convective drying alone. Copyright © 2016 Elsevier B.V. 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.

Research on the influence of anaerobic stabilization of various dairy sewage sludge on biodegradation of polycyclic aromatic hydrocarbons PAHs with the use of effective microorganisms

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

Boruszko, Dariusz, E-mail: d.boruszko@pb.edu.pl

Sewage sludge was taken from a dairy WWTP belonging to Mlekovita Cooperative in Wysokie Mazowieckie. There were excess sludge, flotation sludge and a mixture of excess and flotation sludge from pre-treatment of dairy sewage. The initial content of 16 PAHs in excess sludge before fermentation was approximately 689 µg·kg{sup −1} in dry mass, whereas in post-flotation sludge (which constituted around 30% of raw sludge) it was approximately 95 µg·kg{sup −1} in dry mass. A mixture of excess and flotation sludge had the content of 497,7 µg·kg{sup −1} in dry mass. Through comparison of particular hydrocarbons content in raw sewage sludgemore » to the total PAHs content, it was shown that tricyclic compounds, which constituted 46,3% of the PAHs sum (excess sludge), and tetracyclic compounds, which constituted 60,0% of the PAHs sum (flotation sludge), were the dominating fractions. In the sludge subjected to fermentation in reactors with mixed sludge and surplus activated sludge, the general trend of the course of changes in concentrations of PAHs was similar. Both in the sludge inoculated with EM and in that not inoculated with EM, a significant increase in the total PAHs contents was observed in the first fermentation phase (acidic fermentation) after 7 days of the process. Addition of EM into the sludge did not prevent the PAHs release, and therefore higher concentrations of PAHs sum were recorded during the hydrolysis stage than in sludge before fermentation. A decrease in the sum of PAHs was observed after 2 weeks of fermentation in relation to the quantity observed after 1 week of fermentation (except from post-flotation sludge). In the following weeks, there was further decrease in the concentration of the 16 PAHs sum in all sludge types. However, in sludge without EM inoculation, it was lower than in sludge with EM inoculation. The loss of the majority of tested hydrocarbons was reported in the final phase of fermentation. - Highlights: • The influence of applying Effective Microorganisms on PAHs degradation in dairy sewage sludge during fermentation has been examined. • To study the relationship between quantitative parameters and to describe the correlation strength, Spearman's rank correlation coefficient was used. • In order to verify whether there was a statistically significant change, the Wilcoxon test was applied for individual observation pairs.« less

Transformation of heavy metal speciation during sludge drying: mechanistic insights.

PubMed

Weng, Huan-Xin; Ma, Xue-Wen; Fu, Feng-Xia; Zhang, Jin-Jun; Liu, Zan; Tian, Li-Xun; Liu, Chongxuan

2014-01-30

Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized Cr, Cu, Cd, and Pb in sludge by transforming acid-soluble, reducible, and oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge. Copyright © 2013 Elsevier B.V. All rights reserved.

Utilisation of energy from digester gas and sludge incineration at Hamburg's Köhlbrandhöft WWTP.

PubMed

Thierbach, R D; Hanssen, H

2002-01-01

At Hamburg's Köhlbrandhöft WWTP the demand for external energy supply is minimised by state of the art sludge treatment. The sludge is subjected to thickening, anaerobic digestion, dewatering, drying and incineration. The digester gas is used in a combined gas and steam turbine process. The sludge incineration also produces steam, which is also used in the steam turbine that follows the gas turbine. The turbines produce electricity, partially expanded steam is used for the sludge drying process. Heat from the condensation of vapours from sludge drying is used to heat the anaerobic digesters. The overall process requires no external heat or fuel and produces 60% of the WWTP's electricity demand.

Occurrence of PBDEs and other alternative brominated flame retardants in sludge from wastewater treatment plants in Korea.

PubMed

Lee, Sunggyu; Song, Geum-Ju; Kannan, Kurunthachalam; Moon, Hyo-Bang

2014-02-01

Studies on the occurrence of polybrominated diphenyl ethers (PBDEs) and other alternative brominated flame retardants in the environment are scarce. In this study, PBDEs and non-PBDE brominated flame retardants (NBFRs), including decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), were measured in sludge collected from three types of wastewater treatment plants (WWTPs) in Korea. Total concentrations of PBDEs (∑PBDE) in sludge ranged from 298 to 48,000 (mean: 3240) ng/g dry weight. Among 10 NBFRs analyzed, DBDPE and BTBPE were the only ones detected in sludge samples. Concentrations of DBDPE and BTBPE ranged from 1) of DBDPE/BDE 209 were found in sludge from I-WWTPs, reflecting a shift in the usage pattern of BFRs by the Korean industry. The nationwide annual emission fluxes of ∑PBDE, DBDPE and BTBPE via WWTPs to the environment were estimated to be 7400, 480, and 3.7 kg/year, respectively. This is the first study on the occurrence of alternative brominated flame retardants in sludge from Korea. © 2013 Elsevier B.V. All rights reserved.

Experimental evaluation of drying characteristics of sewage sludge and hazelnut shell mixtures

NASA Astrophysics Data System (ADS)

Pehlivan, Hüseyin; Ateş, Asude; Özdemir, Mustafa

2016-11-01

In this study the drying behavior of organic and agricultural waste mixtures has been experimentally investigated. The usability of sewage sludge as an organic waste and hazelnut shell as an agricultural waste was assessed in different mixture range. The paper discusses the applicability of these mixtures as a recovery energy source. Moisture content of mixtures has been calculated in laboratory and plant conditions. Indoor and outdoor solar sludge drying plants were constructed in pilot scale for experimental purposes. Dry solids and climatic conditions were constantly measured. A total more than 140 samples including for drying has been carried out to build up results. Indoor and outdoor weather conditions are taken into consideration in winter and summer. The most effective drying capacity is obtained in mixture of 20 % hazelnut shell and 80 % sewage sludge.

Cumulative ventilation air drying potential as an indication of dry mass content in wastewater sludge in a thin-layer solar drying facility

NASA Astrophysics Data System (ADS)

Krawczyk, Piotr

2013-12-01

Controlling low-temperature drying facilities which utilise nonprepared air is quite difficult, due to very large variability of ventilation air parameters - both in daily and seasonal cycles. The paper defines the concept of cumulative drying potential of ventilation air and presents experimental evidence that there is a relation between this parameter and condition of the dried matter (sewage sludge). Knowledge on current dry mass content in the dried matter (sewage sludge) provides new possibilities for controlling such systems. Experimental data analysed in the paper was collected in early 2012 during operation of a test solar drying facility in a sewage treatment plant in Błonie near Warsaw, Poland.

[Characteristics of odors and VOCs from sludge direct drying process].

PubMed

Chen, Wen-He; Deng, Ming-Jia; Luo, Hui; Zhang, Jing-Ying; Ding, Wen-Jie; Liu, Jun-Xin; Liu, Jun-Xin

2014-08-01

Co-processing sewage sludge by using the high-temperature feature of cement kiln can realize harmless disposal and energy recycling. In this paper, investigation on characteristics of the flue gas from sludge drying process was carried out in Guangzhou Heidelberg Yuexiu Cement Co., LTD. The composition and the main source of odors and volatile organic compounds (VOCs) emitted during the drying process were analyzed, aimed to provide scientific basis for the treatment of sewage sludge. Results showed that there were a large number of malodorous substances and VOCs in the flue gas. Sulfur dioxide and other sulfur-containing compounds were the main components in the malodorous substances, while benzene derivatives were predominant in VOCs. The compositions of odors and VOCs were influenced by the characteristics of the sludge and the heat medium (kiln tail gas). Total organic compounds in the sludge were significantly decreased after drying. Other organic substances such as volatile fatty acid, protein, and polysaccharide were also obviously reduced. The organic matter in sludge was the main source of VOCs in the flue gas. Part of sulfurous substances, such as sulfur dioxide, carbon disulfide, were from sulfur-containing substances in the sludge, and the rest were from the kiln tail gas itself.

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.

Properties of wastepaper sludge in geopolymer mortars for masonry applications.

PubMed

Yan, Shiqin; Sagoe-Crentsil, Kwesi

2012-12-15

This paper presents the results of an investigation into the use of wastepaper sludge in geopolymer mortar systems for manufacturing construction products. The investigation was driven by the increasing demand for reuse options in paper-recycling industry. Both fresh and hardened geopolymer mortar properties are evaluated for samples incorporating dry wastepaper sludge, and the results indicate potential end-use benefits in building product manufacture. Addition of wastepaper sludge to geopolymer mortar reduces flow properties, primarily due to dry sludge absorbing water from the binder mix. The average 91-day compressive strength of mortar samples incorporating 2.5 wt% and 10 wt% wastepaper sludge respectively retained 92% and 52% of the reference mortar strength. However, contrary to the normal trend of increasing drying shrinkage with increasing paper sludge addition to Portland cement matrices, the corresponding geopolymer drying shrinkage decreased by 34% and 64%. Equally important, the water absorption of hardened geopolymer mortar decreased with increasing paper sludge content at ambient temperatures, providing good prospects of overall potential for wastepaper sludge incorporation in the production of building and masonry elements. The results indicate that, despite its high moisture absorbance due to the organic matter and residual cellulose fibre content, wastepaper sludge appears compatible with geopolymer chemistry, and hence serves as a potential supplementary additive to geopolymer cementitious masonry products. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sewage sludge dewatering using flowing liquid metals

DOEpatents

Carlson, Larry W.

1986-01-01

A method and apparatus for reducing the moisture content of a moist sewage sludge having a moisture content of about 50% to 80% and formed of small cellular micro-organism bodies having internally confined water is provided. A hot liquid metal is circulated in a circulation loop and the moist sewage sludge is injected in the circulation loop under conditions of temperature and pressure such that the confined water vaporizes and ruptures the cellular bodies. The vapor produced, the dried sludge, and the liquid metal are then separated. Preferably, the moist sewage sludge is injected into the hot liquid metal adjacent the upstream side of a venturi which serves to thoroughly mix the hot liquid metal and the moist sewage sludge. The venturi and the drying zone after the venturi are preferably vertically oriented. The dried sewage sludge recovered is available as a fuel and is preferably used for heating the hot liquid metal.

Production of a solid fuel using sewage sludge and spent cooking oil by immersion frying.

PubMed

Wu, Zhonghua; Zhang, Jing; Li, Zhanyong; Xie, Jian; Mujumdar, Arun S

2012-12-01

Sewage sludge and spent cooking oil are two main waste sources of modern Chinese cities. In this paper, the immersion frying method using spent cooking oil as the heating medium was applied to dry and convert wet sewage sludge into a solid fuel. The drying and oil uptake curves were plotted to demonstrate the fry-drying characteristics of the sewage sludge. Parametric studies were carried out to identify the governing parameters in the frying drying operation. It was found that at frying oil temperatures of 140-160°C, the wet sewage sludge could be dried completely in 6-9 min and converted into a solid fuel with a high calorific value of 21.55-24.08 MJ/kg. The fuel structure, chemical components, pyrolysis and combustion characteristics were investigated and the experimental results showed the solid fuel had a porous internal structure and a low ignition temperature of 250°C due to presence of oil. The frying drying mechanism was also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Drying or anaerobic digestion of fish sludge: Nitrogen fertilisation effects and logistics.

PubMed

Brod, Eva; Oppen, Johan; Kristoffersen, Annbjørg Øverli; Haraldsen, Trond Knapp; Krogstad, Tore

2017-12-01

Application of fish sludge as fertiliser to agricultural land can contribute to closing nutrient cycles in fish farming. The effect of different treatment technologies on the nitrogen fertilisation effects of fish sludge was studied by a bioassay with barley (Hordeum vulgare), an incubation and a field experiment. Dried fish sludge resulted in relative agronomic efficiency of 50-80% compared with mineral fertiliser. The anaerobic digestate based on fish sludge (20 vol%) and dairy manure did not increase nitrogen uptake in barley. Increasing the ratio of fish sludge in the digestate increased the fertilisation effect, but requires optimisation of the biogas process. A simple logistics analysis conducted for a case hatchery showed that on-site drying and co-digestion of fish sludge in a central biogas plant can be regarded as equal in terms of costs. Norway can become an exporter of fish sludge-based recycling fertilisers if current regulations are modified to facilitate nutrient recycling.

Influence of forced air volume on water evaporation during sewage sludge bio-drying.

PubMed

Cai, Lu; Chen, Tong-Bin; Gao, Ding; Zheng, Guo-Di; Liu, Hong-Tao; Pan, Tian-Hao

2013-09-01

Mechanical aeration is critical to sewage sludge bio-drying, and the actual water loss caused by aeration can be better understood from investigations of the relationship between aeration and water evaporation from the sewage sludge bio-drying pile based on in situ measurements. This study was conducted to investigate the effects of forced air volume on the evaporation of water from a sewage sludge bio-drying pile. Dewatered sewage sludge was bio-dried using control technology for bio-drying, during which time the temperature, superficial air velocity and water evaporation were measured and calculated. The results indicated that the peak air velocity and water evaporation occurred in the thermophilic phase and second temperature-increasing phase, with the highest values of 0.063 ± 0.027 m s(-1) and 28.9 kg ton(-1) matrix d(-1), respectively, being observed on day 4. Air velocity above the pile during aeration was 43-100% higher than when there was no aeration, and there was a significantly positive correlation between air volume and water evaporation from day 1 to 15. The order of daily means of water evaporation was thermophilic phase > second temperature-increasing phase > temperature-increasing phase > cooling phase. Forced aeration controlled the pile temperature and improved evaporation, making it the key factor influencing water loss during the process of sewage sludge bio-drying. Copyright © 2013 Elsevier Ltd. All rights reserved.

Relationships between waste physicochemical properties, microbial activity and vegetation at coal ash and sludge disposal sites.

PubMed

Woch, Marcin W; Radwańska, Magdalena; Stanek, Małgorzata; Łopata, Barbara; Stefanowicz, Anna M

2018-06-11

The aim of the study was to assess the relationships between vegetation, physicochemical and microbial properties of substrate at coal ash and sludge disposal sites. The study was performed on 32 plots classified into 7 categories: dried ash sedimentation ponds, dominated by a grass Calamagrostis epigejos (AH-Ce), with the admixture of Pinus sylvestris (AH-CePs) or Robinia pseudoacacia (AH-CeRp), dry ash landfill dominated by Betula pendula and Pinus sylvestris (AD-BpPs) or Salix viminalis (AD-Sv) and coal sludge pond with drier parts dominated by Tussilago farfara (CS-Tf) and the wetter ones by Cyperus flavescens (CS-Cf). Ash sites were covered with soil layer imported as a part of technical reclamation. Ash had relatively high concentrations of some alkali and alkaline earth metals, Mn and pH, while coal sludge had high water and C, S, P and K contents. Concentrations of heavy metals were lower than allowable limits in all substrate types. Microbial biomass and, particularly, enzymatic activity in ash and sludge were generally low. The only exception were CS-Tf plots characterized by the highest microbial biomass, presumably due to large deposits of organic matter that became available for aerobic microbial biomass when water level fell. The properties of ash and sludge adversely affected microbial biomass and enzymatic activity as indicated by significant negative correlations between the content of alkali/alkaline earth metals, heavy metals, and macronutrients with enzymatic activity and/or microbial biomass, as well as positive correlations of these parameters with metabolic quotient (qCO 2 ). Plant species richness and cover were relatively high, which may be partly associated with alleviating influence of soil covering the ash. The effect of the admixture of R. pseudoacacia or P. sylvestris to stands dominated by C. epigejos was smaller than expected. The former species increased NNH 4 , NNO 3 and arylsulfatase activity, while the latter reduced activity of the enzyme. Copyright © 2018 Elsevier B.V. All rights reserved.

Simulation of co-incineration of sewage sludge with municipal solid waste in a grate furnace incinerator.

PubMed

Lin, Hai; Ma, Xiaoqian

2012-03-01

Incineration is one of the most important methods in the resource recovery disposal of sewage sludge. The combustion characteristics of sewage sludge and an increasing number of municipal solid waste (MSW) incineration plants provide the possibility of co-incineration of sludge with MSW. Computational fluid dynamics (CFD) analysis was used to verify the feasibility of co-incineration of sludge with MSW, and predict the effect of co-incineration. In this study, wet sludge and semi-dried sludge were separately blended with MSW as mixed fuels, which were at a co-incineration ratios of 5 wt.% (wet basis, the same below), 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%. The result indicates that co-incineration of 10 wt.% wet sludge with MSW can ensure the furnace temperature, the residence time and other vital items in allowable level, while 20 wt.% of semi-dried sludge can reach the same standards. With lower moisture content and higher low heating value (LHV), semi-dried sludge can be more appropriate in co-incineration with MSW in a grate furnace incinerator. Copyright © 2011 Elsevier Ltd. All rights reserved.

Recovery of viruses from field samples of raw, digested, and lagoon-dried sludges*

PubMed Central

Sattar, Syed A.; Westwood, J. C. N.

1979-01-01

In a 22-month study, viruses were detected in 84% (62/74) of raw, 53% (19/36) of anaerobically digested, and 39% (11/28) of lagoon-dried sludge samples. Lagoon sludge contained detectable viruses (reovirus and enterovirus groups) even after 8 months of retention. Because of such prolonged virus survival in sludge, care must be taken in its disposal or utilization. PMID:311705

Grand Forks - East Grand Forks Urban Water Resources Study. Wastewater Management Appendix.

DTIC Science & Technology

1981-07-01

SLUIGES FROM AEROBIC DIGESTION . 2. LOADING RATE OF 20 LB/FT 2/YR APPLICABLE TO BIOLOGICAL SLUDGES FROM ANAEROBIC DIGESTION. 3. EXPECTED PERFORMANCE...plant size as follows: Sludge Handling Facilities Flow Range Biological Sludge Lime Sludge Flow <_ 3 MCD Flotation thickening, Gravity thicken & aerobic ... digestion , & drying beds. drying beds. 3 MGD < Mot; < 10 MGD Flotation thickening, Gravity thicken & anaerobic digestion, & vacuum filter. vacuum

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.

Less-costly activated carbon for sewage treatment

NASA Technical Reports Server (NTRS)

Ingham, J. D.; Kalvinskas, J. J.; Mueller, W. A.

1977-01-01

Lignite-aided sewage treatment is based on absorption of dissolved pollutants by activated carbon. Settling sludge is removed and dried into cakes that are pyrolyzed with lignites to yield activated carbon. Lignite is less expensive than activated carbon previously used to supplement pyrolysis yield.

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.

Characteristics of ammonia emission during thermal drying of lime sludge for co-combustion in cement kilns.

PubMed

Liu, Wei; Xu, Jingcheng; Liu, Jia; Cao, Haihua; Huang, Xiang-Feng; Li, Guangming

2015-01-01

Thermal drying was used to reduce sludge moisture content before co-combustion in cement kilns. The characteristics of ammonia (NH3) emission during thermal drying of lime sludge (LS) were investigated in a laboratory-scale tubular dry furnace under different temperature and time conditions. As the temperature increased, the NH3 concentration increased in the temperature range 100-130°C, decreased in the temperature range 130-220°C and increased rapidly at >220°C. Emission of NH3 also increased as the lime dosage increased and stabilized at lime dosages>5%. In the first 60 min of drying experiments, 55% of the NH3 was released. NH3 accounted for about 67-72% of the change in total nitrogen caused by the release of nitrogen-containing volatile compounds (VCs) from the sludge. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy revealed that the main forms of nitrogen in sludge were amides and amines. The addition of lime (CaO) could cause conversion of N-H, N-O or C-N containing compounds to NH3 during the drying process.

40 CFR 60.155 - Reporting.

Code of Federal Regulations, 2012 CFR

2012-07-01

.... (a) The owner or operator of any multiple hearth, fluidized bed, or electric sludge incinerator... kg/Mg (0.75 lb/ton) dry sludge input or less during the most recent performance test, a scrubber... particulate matter emission rate of greater than 0.38 kg/Mg (0.75 lb/ton) dry sludge input during the most...

40 CFR 60.155 - Reporting.

Code of Federal Regulations, 2013 CFR

2013-07-01

.... (a) The owner or operator of any multiple hearth, fluidized bed, or electric sludge incinerator... kg/Mg (0.75 lb/ton) dry sludge input or less during the most recent performance test, a scrubber... particulate matter emission rate of greater than 0.38 kg/Mg (0.75 lb/ton) dry sludge input during the most...

40 CFR 60.155 - Reporting.

Code of Federal Regulations, 2014 CFR

2014-07-01

.... (a) The owner or operator of any multiple hearth, fluidized bed, or electric sludge incinerator... kg/Mg (0.75 lb/ton) dry sludge input or less during the most recent performance test, a scrubber... particulate matter emission rate of greater than 0.38 kg/Mg (0.75 lb/ton) dry sludge input during the most...

40 CFR 60.155 - Reporting.

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (a) The owner or operator of any multiple hearth, fluidized bed, or electric sludge incinerator... kg/Mg (0.75 lb/ton) dry sludge input or less during the most recent performance test, a scrubber... particulate matter emission rate of greater than 0.38 kg/Mg (0.75 lb/ton) dry sludge input during the most...

[Evaluating the Significance of Odor Gas Released During the Directly Drying Process of Sludge: Based on the Multi-index Integrated Assessment Method].

PubMed

Ding, Wen-jie; Chen, Wen-he; Deng, Ming-jia; Luo, Hui; Li, Lin; Liu, Jun-xin

2016-02-15

Co-processing of sewage sludge using the cement kiln can realize sludge harmless treatment, quantity reduction, stabilization and reutilization. The moisture content should be reduced to below 30% to meet the requirement of combustion. Thermal drying is an effective way for sludge desiccation. Odors and volatile organic compounds are generated and released during the sludge drying process, which could lead to odor pollution. The main odor pollutants were selected by the multi-index integrated assessment method. The concentration, olfactory threshold, threshold limit value, smell security level and saturated vapor pressure were considered as indexes based on the related regulations in China and foreign countries. Taking the pollution potential as the evaluation target, and the risk index and odor emission intensity as evaluation indexes, the odor pollution potential rated evaluation model of the pollutants was built according to the Weber-Fechner law. The aim of the present study is to form the rating evaluation method of odor potential pollution capacity suitable for the directly drying process of sludge.

Initial Response of Pine Seedlings and Weeds to Dried Sewage Sludge in Rehabilitation of an Eroded Forest Site

Treesearch

Charles R. Berry

1977-01-01

Dried sewage sludge was applied at rates of 0, 17, 34, and 69 metric tons/ha on a badly eroded forest site in the Piedmont region of northeast Georgia. Production of weed bio mass varied directly with amount of sludge applied. Heigh growth for both shortleafand loblolly pine seedlings appeared to be greater on plots receiving 17 metric tons of sludge/ha, bu differences...

Assessment of Heavy Metals in Municipal Sewage Sludge: A Case Study of Limpopo Province, South Africa

PubMed Central

Shamuyarira, Kudakwashe K.; Gumbo, Jabulani R.

2014-01-01

Heavy metals in high concentrations can cause health and environmental damage. Nanosilver is an emerging heavy metal which has a bright future of use in many applications. Here we report on the levels of silver and other heavy metals in municipal sewage sludge. Five towns in Limpopo province of South Africa were selected and the sludge from their wastewater treatment plants (WWTPs) was collected and analysed. The acid digested sewage sludge samples were analysed using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) methods. The concentrations of silver found were low, but significant, in the range 0.22 to 21.93 mg/kg dry mass. The highest concentration of silver was found in Louis Trichardt town with a concentration of 21.93 ± 0.38 mg/kg dry mass while the lowest was Thohoyandou with a concentration of 6.13 ± 0.12 mg/kg dry mass. A control sludge sample from a pit latrine had trace levels of silver at 0.22 ± 0.01 mg/kg dry mass. The result showed that silver was indeed present in the wastewater sewage sludge and at present there is no DWAF guideline standard. The average Cd concentration was 3.10 mg/kg dry mass for Polokwane municipality. Polokwane and Louis Trichardt municipalities exhibited high levels of Pb, in excess DWAF guidelines, in sludge at 102.83 and 171.87 mg/kg respectfully. In all the WWTPs the zinc and copper concentrations were in excess of DWAF guidelines. The presence of heavy metals in the sewage sludge in excess of DWAF guidelines presents environmental hazards should the sludge be applied as a soil ameliorant. PMID:24595211

[Emissions of greenhouse gas and ammonia from the full process of sewage sludge composting and land application of compost].

PubMed

Zhong, Jia; Wei, Yuan-Song; Zhao, Zhen-Feng; Ying, Mei-Juan; Zhou, Guo-Sheng; Xiong, Jian-Jun; Liu, Pei-Cai; Ge, Zhen; Ding, Gang-Qiang

2013-11-01

There is a great uncertainty of greenhouse gas (GHG) reduction and nitrogen conservation from the full process of sludge composting and land application of compost in China due to the lack of emission data of GHG such as N2O and CH4 and ammonia (NH3). The purpose of this study is to get emission characteristics of GHGs and NH3 from the full process with on-site observation. Results showed that the total GHG emission factor from full process of the turning windrow (TW) system (eCO2/dry sludge, 196.21 kg x t(-1)) was 1.61 times higher of that from the ATP system. Among the full process, N2O was mostly from the land application of compost, whereas CH4 mainly resulted from the sludge composting. In the sludge composting of ATP, the GHG emission equivalence of the ATP (eCO2/dry sludge, 12.47 kg x t(-1) was much lower than that of the TW (eCO2/dry sludge, 86.84 kg x t(-1)). The total NH3 emission factor of the TW (NH3/dry sludge, 6.86 kg x t(-1)) was slightly higher than that of the ATP (NH3/dry sludge, 6.63 kg x t(-1)). NH3 was the major contributor of nitrogen loss in the full process. During the composting, the nitrogen loss as NH3 from both TW and ATP was nearly the same as 30% of TN loss from raw materials, and the N and C loss caused by N2O and CH4 were negligible. These results clearly showed that the ATP was a kind of environmentally friendly composting technology.

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.

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.

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.

Accelerating Aerobic Sludge Granulation by Adding Dry Sewage Sludge Micropowder in Sequencing Batch Reactors

PubMed Central

Li, Jun; Liu, Jun; Wang, Danjun; Chen, Tao; Ma, Ting; Wang, Zhihong; Zhuo, Weilong

2015-01-01

Micropowder (20–250 µm) made from ground dry waste sludge from a municipal sewage treatment plant was added in a sequencing batch reactor (R2), which was fed by synthetic wastewater with acetate as carbon source. Compared with the traditional SBR (R1), aerobic sludge granulation time was shortened 15 days in R2. Furthermore, filamentous bacteria in bulking sludge were controlled to accelerate aerobic granulation and form large granules. Correspondingly, the SVI decreased from 225 mL/g to 37 mL/g. X-ray Fluorescence (XRF) analysis demonstrated that Al and Si from the micropowder were accumulated in granules. A mechanism hypotheses for the acceleration of aerobic granulation by adding dry sludge micropowder is proposed: added micropowder acts as nuclei to induce bacterial attachment; dissolved matters from the micropowder increase abruptly the organic load for starved sludge to control overgrown filamentous bacteria as a framework for aggregation; increased friction from the movement of micropowder forces the filaments which extend outwards to shrink for shaping granules. PMID:26308025

Long-term simulation of the activated sludge process at the Hanover-Gümmerwald pilot WWTP.

PubMed

Makinia, Jacek; Rosenwinkel, Karl-Heinz; Spering, Volker

2005-04-01

The aim of this study was to obtain a validated model, consisting of the Activated Sludge Model No. 3 (ASM3) and the EAWAG bio-P module, which could be used as a decision tool for estimating the maximum allowable peak flow to wastewater treatment plants during stormwater conditions. The databases used for simulations originated from the Hanover-Gummerwald pilot plant subjected to a series of controlled, short-term hydraulic shock loading experiments. The continuous influent wastewater composition was generated using on-line measurements of only three parameters (COD, N-NH4+, P-PO4 3-). Model predictions were compared with on-line data from different locations in the activated sludge system including the aerobic zone (concentrations of N-NH4+, N-NO3-) and secondary effluent (concentrations of P-PO4 3-). The simulations confirmed experimental results concerning the capabilities of the system for handling increased flows during stormwater events. No (or minor) peaks of N-NH4+ were predicted for the line with the double dry weather flowrate, whereas peaks of N-NH4+ at the line with the quadruple dry weather flowrate were normally exceeding 8 g Nm(-3) (similar to the observations).

Experimental study on agitated drying characteristics of sewage sludge under the effects of different additive agents.

PubMed

Deng, Wenyi; Su, Yaxin

2014-07-01

Drying experiments of dewatered sewage sludge (DSS) were conducted on a agitated paddle dryer, and the effects of additive agents, i.e., CaO, pulverized coal (PC), heavy oil (HO), and dried sludge ("DS" through back mixing) on the agitated drying characteristics of DSS were investigated. The results indicated that CaO can significantly increase the drying rate of DSS. The drying rate at CaO/DSS (mass ratio)=1/100 was 135% higher than that of CaO/DSS=0. Pulverized coal has no obvious effect on drying rate, but the increase of PC/DSS can promote breaking up of sludge lump. Heavy oil was found to be slightly effective in improving the drying rate of DSS in the examined experimental range of HO/DSS=0-1/20. It is also found that HO can reduce the torque of the dryer shaft, due to its lubrication effect. Back mixing of DS was found to be effective in alleviating the unfavorable effect of the lumpy phase by improving the mixing effect of the paddle dryer. There was a marked increase of drying rate with an increase of the DS/DSS in the experimental range of DS/DSS=0-1/3. Copyright © 2014. Published by Elsevier B.V.

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

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.

Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units.

PubMed

Li, Shiyuan; Li, Yunyu; Lu, Qinggang; Zhu, Jianguo; Yao, Yao; Bao, Shaolin

2014-12-01

An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful. Copyright © 2014 Elsevier Ltd. All rights reserved.

Progress report Waste Resources Utilization Program period ending March 31, 1976. [Radiosterilization of sewage sludge for safe application as fertilizer or animal feed

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

Not Available

1976-06-01

This report describes the work on the Waste Resources Utilization Program for the quarter ending March 31, 1976. The purpose of this program is to develop technologies to utilize a /sup 137/Cs ..gamma.. source to modify sewage sludge for safe application as a fertilizer or an animal feed supplement. Results are reported from studies in microbiology, virology, and physical-chemical studies. Determinations were made of inactivation rates for Salmonella species, coliforms, and fecal strep in sewage sludge when radiation and thermoradiation were applied while bubbling oxygen through the sludge. Virology studies were continued investigating virucidal characteristics of anaerobically digested sludge. Anothermore » area of study was the dewatering of sewage sludge to reduce the drying time of the sewage sludge in the drying beds. A centrifuge was also installed to dewater treated sludge to approximately 30 percent solids. (auth)« less

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.

Dewatering and granulation of sewage sludge by biophysical drying and thermo-degradation performance of prepared sludge particles during succedent fast pyrolysis.

PubMed

Han, Rong; Liu, Jinwen; Zhang, Yuancheng; Fan, Xiaoqian; Lu, Wenjing; Wang, Hongtao

2012-03-01

A novel two-step technology, fast biophysical drying (BPD) coupling with fast pyrolysis (FP), was investigated for moisture removal and energy recovery from sewage sludge. For BPD, combined operations of extreme thermophilic amendment (with accelerated increasing and controllable maintenance of substrate temperature) and enhanced convective evaporation were conducted, both beneficial for moisture removal (moisture content reaching 23.1% for 7d) and organic preservation. Biophysical-dried sludge (BPDS) was characterized by homogeneous fine-particle morphology and well-developed porous microstructure. The synthesized BPDS particle preserved most organic components (92% volatile matters and 79% HHV of traditional thermal-dried sludge [TTDS]) attributable to the inhibitory effect of BPD adjustment, presenting considerable capacity for subsequent residue-derived energy. For FP, the distribution of products from BPDS pyrolysis indicated that syngas and char yields were higher than those of TTDS. The syngas from BPDS is a type of hydrogen-rich gas composed of 42.6 vol.% H(2) at 900°C. Copyright © 2011 Elsevier Ltd. All rights reserved.

Low-nitrogen oxides combustion of dried sludge using a pilot-scale cyclone combustor with recirculation.

PubMed

Shim, Sung Hoon; Jeong, Sang Hyun; Lee, Sang-Sup

2015-04-01

Recently, numerical and experimental studies have been conducted to develop a moderate or intense low-oxygen dilution (MILD) combustion technology for solid fuels. The study results demonstrated that intense recirculation inside the furnace by high-momentum air is a key parameter to achieve the MILD combustion of solid fuels. However, the high-velocity air requires a significant amount of electricity consumption. A cyclone-type MILD combustor was therefore designed and constructed in the authors' laboratory to improve the recirculation inside the combustor. The laboratory-scale tests yielded promising results for the MILD combustion of dried sewage sludge. To achieve pilot-scale MILD combustion of dried sludge in this study, the effects of geometric parameters such as the venturi tube configuration, the air injection location, and the air nozzle diameter were investigated. With the optimized geometric and operational conditions, the pilot-scale cyclone combustor demonstrated successful MILD combustion of dried sludge at a rate of 75 kg/hr with an excess air ratio of 1.05. A horizontal cyclone combustor with recirculation demonstrated moderate or intense low-oxygen dilution (MILD) combustion of dried sewage sludge at a rate of 75 kg/hr. Optimizing only geometric and operational conditions of the combustor reduced nitrogen oxide (NOx) emissions to less than 75 ppm. Because the operating cost of the MILD combustor is much lower than that of the selective catalytic reduction (SCR) applied to the conventional combustor, MILD combustion technology with the cyclone type furnace is an eligible option for reducing NOx emissions from the combustion of dried sewage sludge.

Study on the combined sewage sludge pyrolysis and gasification process: mass and energy balance.

PubMed

Wang, Zhonghui; Chen, Dezhen; Song, Xueding; Zhao, Lei

2012-12-01

A combined pyrolysis and gasification process for sewage sludge was studied in this paper for the purpose of its safe disposal with energy self-balance. Three sewage sludge samples with different dry basis lower heat values (LHV(db)) were used to evaluate the constraints on this combined process. Those samples were pre-dried and then pyrolysed within the temperature range of 400-550 degrees C. Afterwards, the char obtained from pyrolysis was gasified to produce fuel gas. The experimental results showed that the char yield ranged between 37.28 and 53.75 wt% of the dry sludge and it changed with ash content, pyrolysis temperature and LHV(db) of the sewage sludge. The gas from char gasification had a LHV around 5.31-5.65 MJ/Nm3, suggesting it can be utilized to supply energy in the sewage sludge drying and pyrolysis process. It was also found that energy balance in the combined process was affected by the LHV(db) of sewage sludge, moisture content and pyrolysis temperature. Higher LHV(db), lower moisture content and higher pyrolysis temperature benefit energy self-balance. For sewage sludge with a moisture content of 80 wt%, LHV(db) of sewage sludge should be higher than 18 MJ/kg and the pyrolysis temperature should be higher than 450 degrees C to maintain energy self-sufficiency when volatile from the pyrolysis process is the only energy supplier; when the LHV(db) was in the range of 14.65-18 MJ/kg, energy self-balance could be maintained in this combined process with fuel gas from char gasification as a supplementary fuel; auxiliary fuel was always needed if the LHV(db) was lower than 14.65 MJ/kg.

Thermophilic two-stage dry anaerobic digestion of model garbage with ammonia stripping.

PubMed

Yabu, Hironori; Sakai, Chikako; Fujiwara, Tomoko; Nishio, Naomichi; Nakashimada, Yutaka

2011-03-01

To avoid the inhibition of methane production by ammonia that occurs during the degradation of garbage, anaerobic digestion with prior ammonia production and subsequent stripping was investigated. In the ammonia production phase, the maximum ammonia concentration was approximately 2800 mg N/kg of total wet sludge in the range of 4 days of sludge retention time, indicating that only 43% of total nitrogen in the model garbage was converted to ammonia. The model garbage from which ammonia was produced and stripped was subjected to semi-continuous thermophilic dry anaerobic digestion over 180 days. The gas yield was in the range of 0.68 to 0.75 Nm(3)/kg volatile solid, and it decreased with the decrease of the sludge retention time. The ammonia-nitrogen concentration in the sludge was kept below 3000 mg N/kg total wet sludge. Microbial community structure analysis revealed that the phylum Firmicutes dominated in the ammonia production, but the community structure changed at different sludge retention times. In dry anaerobic digestion, the dominant bacteria shifted from the phylum Thermotogae to Firmicutes. The dominant archaeon was the genus Methanothermobacter, but the ratio of Methanosarcina increased during the process of dry anaerobic digestion. Copyright © 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Mesophilic and thermophilic anaerobic co-digestion of winery wastewater sludge and wine lees: An integrated approach for sustainable wine production.

PubMed

Da Ros, C; Cavinato, C; Pavan, P; Bolzonella, D

2017-12-01

In this work, winery wastes generated by a cellar producing approximately 300,000 hL of wine per year was monitored for a period of one year. On average, 196 L of wastewater, 0.1 kg of waste activated sludge (dry matter) and 1.6 kg of wine lees were produced per hectoliter of wine produced. Different winery wastes, deriving from different production steps, namely waste activated sludge from wastewater treatment and wine lees, were co-treated using an anaerobic digestion process. Testing was conducted on a pilot scale for both mesophilic and thermophilic conditions. The process was stable for a long period at 37 °C, with an average biogas production of 0.386 m 3 /kg COD fed . On the other hand, for thermophilic conditions, volatile fatty acids accumulated in the reactor and the process failed after one hydraulic retention time (23 days). In order to fix the biological process, trace elements (iron, cobalt and nickel) were added to the feed of the thermophilic reactor. Metals augmentation improved process stability and yields at 55 °C. The pH ranged between 7.8 and 8.0, and specific gas production was 0.450 m 3 /kg COD fed , which corresponded to dry matter and COD removals of 34% and 88%, respectively. Although the observed performances in terms of biogas production were good, the thermophilic process exhibited some limitations related to both the necessity of metals addition and the worse dewaterability properties. In fact, while the mesophilic digestates reached a good dewatering quality via the addition of 6.5 g of polymer per kg of dry matter, the required dosage for the thermophilic sludge was greater than 10 g/kg of dry matter. Copyright © 2016 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.

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.

Thermal characterization and syngas production from the pyrolysis of biophysical dried and traditional thermal dried sewage sludge.

PubMed

Han, Rong; Zhao, Chenxi; Liu, Jinwen; Chen, Aixia; Wang, Hongtao

2015-12-01

A novel method for energy recycling from sewage sludge was developed through biophysical drying coupled with fast pyrolysis. Thermal decomposition properties of biophysical-dried sludge (BDS) and thermal-dried sludge (TDS) were characterized through thermogravimetric (TG) coupled with mass spectrometry (MS) analysis. BDS exhibited typical peaks in each differential thermogravimetric (DTG) region and presented slower mass loss rates in H, C, and L regions (180-550°C) but remarkable weight loss in region I (>550°C) compared with TDS. The charring process centered at region I, was responsible for the prominent H2 emission from BDS. The pseudo multicomponent model showed that the Em values of BDS and TDS were 48.84 and 37.75 kJ/mol, respectively. Furthermore, fast pyrolysis of BDS was proven to facilitate syngas and char formation more than TDS. For the yielded syngas, the thermal conversion of BDS was characterized by high H2 and CH4 content beyond 700°C. Copyright © 2015. Published by Elsevier Ltd.

Inactivation of Indigenous Viruses in Raw Sludge by Air Drying

PubMed Central

Brashear, David A.; Ward, Richard L.

1983-01-01

Air drying of raw sludge caused inactivation of indigenous viruses. A gradual loss of infectivity occurred with the loss of water until the solids content reached about 80%. A more rapid decline of viral infectivity occurred with further dewatering. PMID:6309080

Inhibition of the de novo synthesis of PCDD/Fs on model fly ash by sludge drying gases.

PubMed

Chen, Tong; Zhan, Ming-Xiu; Lin, Xiao-Qing; Li, Xiao-Dong; Lu, Sheng-Yong; Yan, Jian-Hua; Buekens, Alfons; Cen, Ke-Fa

2014-11-01

Sludge drying gases (SDG), evolving from drying and mild thermal decomposition (<300°C) of raw sewage sludge contain NH3 and SO2 as well as other N- and S-compounds. All of these are potential PCDD/Fs suppressants. It is indeed observed that these SDG suppress 2,3,7,8-substitued PCDD/Fs formation on Model Fly Ash (MFA) with an efficiency up to 97.6% in wt. units and 96% in I-TEQ, respectively. This suppression is strong for (the bulk of) PCDD/Fs, adsorbed on the model fly ash; conversely, sludge drying gases enhance PCDD/Fs desorption from MFA. Moreover, TCDD/Fs are suppressed least, possibly following stepwise dechlorination of higher chlorinated PCDD/Fs. Characteristics, such as the type, origins and amount of sludge, its moisture-, nitrogen- and sulfur content and the nature of the thermal treatment applied are all expected to influence upon the suppression capabilities. In this study three types of dry sludge are tested and applied as suppressant in four different amounts or modes. The quality of the sludge drying gases is continuously monitored: the Gasmet results reveal that NH3 and SO2 are the most important components of SDG. The MFA reaction residue is scrutinized by Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analysis. A large number of particles attaching to the surface of model fly ash are observed by SEM. Moreover, EDS analysis reveals that part of the chlorine in MFA is carried away with the SDG and replaced by sulfur, so that eliminating chlorine may be part of the inhibition mechanism. However, further research is still needed to establish the optimum operating modes and to confirm the role of both inorganic and organic nitrogen and sulfur compounds in the suppression of PCDD/Fs formation on model fly ash. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dry co-digestion of sewage sludge and rice straw under mesophilic and thermophilic anaerobic conditions.

PubMed

Chu, Xiangqian; Wu, Guangxue; Wang, Jiaquan; Hu, Zhen-Hu

2015-12-01

Dry anaerobic digestion of sewage sludge can recover biogas as energy; however, its low C/N ratio limits it as a single substrate in the anaerobic digestion. Rice straw is an abundant agricultural residue in China, which is rich in carbon and can be used as carbon source. In the present study, the performance of dry co-digestion of sewage sludge and rice straw was investigated under mesophilic (35 °C) and thermophilic (55 °C) conditions. The operational factors impacting dry co-digestion of sewage sludge and rice straw such as C/N ratio, moisture content, and initial pH were explored under mesophilic conditions. The results show that low C/N ratios resulted in a higher biogas production rate, but a lower specific biogas yield; low moisture content of 65 % resulted in the instability of the digestion system and a low specific biogas yield. Initial pH ranging 7.0-9.0 did not affect the performance of the anaerobic digestion. The C/N ratio of 26-29:1, moisture content of 70-80 %, and pH 7.0-9.0 resulted in good performance in the dry mesophilic co-digestion of sewage sludge and rice straw. As compared with mesophilic digestion, thermophilic co-digestion of sewage sludge and rice straw significantly enhanced the degradation efficiency of the substrates and the specific biogas yield (p < 0.05) at the conditions of C/N ratio 26:1, moisture content 80 %, and natural initial pH. Although high concentrations of ammonia-nitrogen (NH4-N, 1500 mg/kg wet weight) were formed during thermophilic digestion, there was no obvious inhibition occurred. The results indicated that rice straw can be used as carbon source for the dry co-digestion of sewage sludge under mesophilic and thermophilic conditions.

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

Gaseous fuels production from dried sewage sludge via air gasification.

PubMed

Werle, Sebastian; Dudziak, Mariusz

2014-07-01

Gasification is a perspective alternative method of dried sewage sludge thermal treatment. For the purpose of experimental investigations, a laboratory fixed-bed gasifier installation was designed and built. Two sewage sludge (SS) feedstocks, taken from two typical Polish wastewater treatment systems, were analysed: SS1, from a mechanical-biological wastewater treatment system with anaerobic stabilization (fermentation) and high temperature drying; and (SS2) from a mechanical-biological-chemical wastewater treatment system with fermentation and low temperature drying. The gasification results show that greater oxygen content in sewage sludge has a strong influence on the properties of the produced gas. Increasing the air flow caused a decrease in the heating value of the produced gas. Higher hydrogen content in the sewage sludge (from SS1) affected the produced gas composition, which was characterized by high concentrations of combustible components. In the case of the SS1 gasification, ash, charcoal, and tar were produced as byproducts. In the case of SS2 gasification, only ash and tar were produced. SS1 and solid byproducts from its gasification (ash and charcoal) were characterized by lower toxicity in comparison to SS2. However, in all analysed cases, tar samples were toxic. © The Author(s) 2014.

Key variables analysis of a novel continuous biodrying process for drying mixed sludge.

PubMed

Navaee-Ardeh, Shahram; Bertrand, François; Stuart, Paul R

2010-05-01

A novel continuous biodrying process has been developed whose goal is to increase the dry solids content of the sludge to economic levels rendering it suitable for a safe and economic combustion operation in a biomass boiler. The sludge drying rates are enhanced by the metabolic bioheat produced in the matrix of mixed sludge. The goal of this study was to systematically analyze the continuous biodrying reactor. By performing a variable analysis, it was found that the outlet relative humidity profile was the key variable in the biodrying reactor. The influence of different outlet relative humidity profiles was then evaluated using biodrying efficiency index. It was found that by maintaining the air outlet relative humidity profile at 85/85/96/96% in the four compartments of the reactor, the highest biodrying efficiency index can be achieved, while economic dry solids level (>45%w/w) are guaranteed. Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.

Use of biogas for cogeneration of heat and electricity for local application: performance evaluation of an engine power generator and a sludge thermal dryer.

PubMed

Lobato, L C S; Chernicharo, C A L; Pujatti, F J P; Martins, O M; Melo, G C B; Recio, A A R

2013-01-01

A small unit of cogeneration of energy and heat was tested at the Centre for Research and Training on Sanitation UFMG/COPASA - CePTS, located at the Arrudas Sewage Treatment Plant, in Belo Horizonte, Minas Gerais, Brazil. The unit consisted of an engine power generator adapted to run on biogas, a thermal dryer prototype and other peripherals (compressor, biogas storage tank, air blower, etc.). The heat from engine power generator exhaust gases was directed towards the thermal dryer prototype to dry the sludge and disinfect it. The results showed that the experimental apparatus is self-sufficient in electricity, even producing a surplus, available for other uses. The tests of drying and disinfection of sludge lasted 7 h, leading to an increase in solids content from 4 to 8% (50% reduction in sludge volume). Although the drying of sludge was not possible (only thickening was achieved), the disinfection process proved very effective, enabling the complete inactivation of helminth eggs.

Winery waste recycling through anaerobic co-digestion with waste activated sludge.

PubMed

Da Ros, C; Cavinato, C; Pavan, P; Bolzonella, D

2014-11-01

In this study biogas and high quality digestate were recovered from winery waste (wine lees) through anaerobic co-digestion with waste activated sludge both in mesophilic and thermophilic conditions. The two conditions studied showed similar yields (0.40 m(3)/kgCODfed) but different biological process stability: in fact the mesophilic process was clearly more stable than the thermophilic one in terms of bioprocess parameters. The resulting digestates showed good characteristics for both the tested conditions: heavy metals, dioxins (PCDD/F), and dioxin like bi-phenyls (PCBs) were concentred in the effluent if compared with the influent because of the important reduction of the solid dry matter, but remained at levels acceptable for agricultural reuse. Pathogens in digestate decreased. Best reductions were observed in thermophilic condition, while at 37°C the concentration of Escherichia coli was at concentrations level as high as 1000 UFC/g. Dewatering properties of digestates were evaluated by means of the capillary suction time (CST) and specific resistance to filtration (SRF) tests and it was found that a good dewatering level was achievable only when high doses of polymer (more than 25 g per kg dry solids) were added to sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Analysis of sludge from Hanford K East Basin canisters

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

Makenas, B.J.; Welsh, T.L.; Baker, R.B.

1997-09-12

Sludge samples from the canisters in the Hanford K East Basin fuel storage pool have been retrieved and analyzed. Both chemical and physical properties have been determined. The results are to be used to determine the disposition of the bulk of the sludge and to assess the impact of residual sludge on dry storage of the associated intact metallic uranium fuel elements. This report is a summary and review of the data provided by various laboratories. Although raw chemistry data were originally reported on various bases (compositions for as-settled, centrifuged, or dry sludge) this report places all of the datamore » on a common comparable basis. Data were evaluated for internal consistency and consistency with respect to the governing sample analysis plan. Conclusions applicable to sludge disposition and spent fuel storage are drawn where possible.« less

Changes in microbiological composition of soils and soil contamination with drug-resistant bacteria caused by the use of sewage sludge in nature

NASA Astrophysics Data System (ADS)

Stanczyk-Mazanek, Ewa; Pasonl, Lukasz; Kepa, Urszula

2017-11-01

This study evaluated the effect of the use of sewage sludge in nature on biological soil parameters. The study was conducted is field experiment environment (small beds). The sandy soil was fertilized with sewage sludge dried naturally (in heaps) and in solar drying facilities. The fertilization was based on the doses of sewage sludge and manure with the amounts of 10, 20, 30 and 40 Mg/ha. The experiment duration was 3 years. The sanitary status of the soils fertilized with the sludge and manure was evaluated (coliform index, Clostridium perfrinens). Furthermore, the content of pathogenic bacteria was evaluated, with determination of its resistance to first-line antibiotics.

Effect of filter media thickness on the performance of sand drying beds used for faecal sludge management.

PubMed

Manga, M; Evans, B E; Camargo-Valero, M A; Horan, N J

2016-12-01

The effect of sand filter media thickness on the performance of faecal sludge (FS) drying beds was determined in terms of: dewatering time, contaminant load removal efficiency, solids generation rate, nutrient content and helminth eggs viability in the dried sludge. A mixture of ventilated improved pit latrine sludge and septage in the ratio 1:2 was dewatered using three pilot-scale sludge drying beds with sand media thicknesses of 150, 250 and 350 mm. Five dewatering cycles were conducted and monitored for each drying bed. Although the 150 mm filter had the shortest average dewatering time of 3.65 days followed by 250 mm and 350 mm filters with 3.83 and 4.02 days, respectively, there was no significant difference (p > 0.05) attributable to filter media thickness configurations. However, there was a significant difference for the percolate contaminant loads in the removal and recovery efficiency of suspended solids, total solids, total volatile solids, nitrogen species, total phosphorus, chemical oxygen demand, dissolved chemical oxygen demand and biochemical oxygen demand, with the highest removal efficiency for each parameter achieved by the 350 mm filter. There were also significant differences in the nutrient content (NPK) and helminth eggs viability of the solids generated by the tested filters. Filtering media configurations similar to 350 mm have the greatest potential for optimising nutrient recovery from FS.

Combined alkaline and ultrasonic pretreatment of sludge before aerobic digestion.

PubMed

Jin, Yiying; Li, Huan; Mahar, Rasool Bux; Wang, Zhiyu; Nie, Yongfeng

2009-01-01

Alkaline and ultrasonic sludge disintegration can be used as the pretreatment of waste activated sludge (WAS) to promote the subsequent anaerobic or aerobic digestion. In this study, different combinations of these two methods were investigated. The evaluation was based on the quantity of soluble chemical oxygen demand (SCOD) in the pretreated sludge as well as the degradation of organic matter in the subsequent aerobic digestion. For WAS samples with combined pretreatment, the released COD levels were higher than those with ultrasonic or alkaline pretreatment alone. When combined with the ultrasonic treatment, NaOH treatment was more efficient than Ca(OH)2 for WAS solubilization. The COD levels released in various sequential options of combined NaOH and ultrasonic treatments were in the the following descending order: simultaneous treatment > NaOH treatment followed by ultrasonic treatment > ultrasonic treatment followed by NaOH treatment. For simultaneous treatment, low NaOH dosage (100 g/kg dry solid), short duration (30 min) of NaOH treatment, and low ultrasonic specific energy (7500 kJ/kg dry solid) were suitable for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with optimal parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than that with ultrasonic (42.5%) or with NaOH pretreatment (43.5%) in the subsequent aerobic digestion at the same retention time.

Technology Assessment Report - Aqueous Sludge Gasification Technologies

EPA Science Inventory

Sludge production in the United States is increasing with an increase in population. An estimated 7.2 million dry tons of treated and tested sewage sludge was generated in 2004 and 4.1 million tons of paper mill sludge was produced in 1995. Consequently, there is an increased ne...

40 CFR 61.54 - Sludge sampling.

Code of Federal Regulations, 2012 CFR

2012-07-01

... maximum 24-hour period sludge incineration or drying rate shall be determined by use of a flow rate... 40 Protection of Environment 9 2012-07-01 2012-07-01 false Sludge sampling. 61.54 Section 61.54... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Mercury § 61.54 Sludge...

40 CFR 61.54 - Sludge sampling.

Code of Federal Regulations, 2013 CFR

2013-07-01

... maximum 24-hour period sludge incineration or drying rate shall be determined by use of a flow rate... 40 Protection of Environment 9 2013-07-01 2013-07-01 false Sludge sampling. 61.54 Section 61.54... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Mercury § 61.54 Sludge...

40 CFR 61.54 - Sludge sampling.

Code of Federal Regulations, 2014 CFR

2014-07-01

... maximum 24-hour period sludge incineration or drying rate shall be determined by use of a flow rate... 40 Protection of Environment 9 2014-07-01 2014-07-01 false Sludge sampling. 61.54 Section 61.54... EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS National Emission Standard for Mercury § 61.54 Sludge...

Fate of emerging and priority micropollutants during the sewage sludge treatment: Case study of Paris conurbation. Part 1: Contamination of the different types of sewage sludge.

PubMed

Mailler, R; Gasperi, J; Patureau, D; Vulliet, E; Delgenes, N; Danel, A; Deshayes, S; Eudes, V; Guerin, S; Moilleron, R; Chebbo, G; Rocher, V

2017-01-01

This article provides data on the contamination of different kinds of sludge (raw, centrifuged, digested, thermally dried sludge and sludge cake) from Paris conurbation by 71 various pollutants including pharmaceutical products (PHPs), hormones, perfluorinated acids (PFAs), linear alkylbenzene sulfonate (LAS), alkylphenols (APs), phthalates (PAEs), polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs). Very high contents of LAS (0.1-10g/kg dry matter - DM) compared to other compounds were found in all types of sludge followed by DEHP (10-100mg/kg DM) and fluoroquinolones (1-100mg/kg DM). APs were measured at intermediary contents in Parisian sludge, lying in the 2-20mg/kg DM range. Finally, hormones, PAHs, PCBs, PAEs, PFAs and the remaining PHPs were all found at contents lower than 1mg/kg DM. For most compounds (PHPs, PFOS, DEHP, PAHs), no significant differences in the micropollutant contents were found for similar types of sludge from different WWTP in Paris, highlighting the homogeneity of sludge contamination in downstream Paris catchment. The variability of concentration is rather high (coefficient of variation >100%) for several PHPs, PFAs or PCBs while it is moderate (<100%) or low (<50%) for fluoroquinolones, hormones, PAHs, APs or LAS. In addition, digestion seems to have a buffer effect as variabilities are lower in digested sludge for PHPs, PFAs, APs and PCBs. During sludge treatment (centrifugation, digestion, thermal drying, sludge conditioning+press filtration), the hormones, LAS, APs, PAHs, DEHP and PCBs concentrations increased, while those of PHPs and PFAs decreased. In the case of digestion, the increase of content can be explained by no pollutant removal or a lower removal than DM removal (concentration phenomenon) whereas the decrease underlines that the compound is more removed than the DM. In any case, these concentration variations presuppose the mechanisms of dissipation that could be attributed to volatilization, biotic or abiotic transformation (complete or with metabolites production), bound residues formation. In addition, data on sludge liquors - centrifuged (CW) and condensed (TDW) waters - from respectively centrifugation and thermal drying were collected. Several hormones, PHPs, PFAs, LAS, PAEs, APs, PCBs and PAHs were quantified in CW and TDW, displaying a transfer through the water removal. The concentrations observed are rather comparable to those found in wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Monitoring of sludge dewatering equipment by image classification

NASA Astrophysics Data System (ADS)

Maquine de Souza, Sandro; Grandvalet, Yves; Denoeux, Thierry

2004-11-01

Belt filter presses represent an economical means to dewater the residual sludge generated in wastewater treatment plants. In order to assure maximal water removal, the raw sludge is mixed with a chemical conditioner prior to being fed into the belt filter press. When the conditioner is properly dosed, the sludge acquires a coarse texture, with space between flocs. This information was exploited for the development of a software sensor, where digital images are the input signal, and the output is a numeric value proportional to the dewatered sludge dry content. Three families of features were used to characterize the textures. Gabor filtering, wavelet decomposition and co-occurrence matrix computation were the techniques used. A database of images, ordered by their corresponding dry contents, was used to calibrate the model that calculates the sensor output. The images were separated in groups that correspond to single experimental sessions. With the calibrated model, all images were correctly ranked within an experiment session. The results were very similar regardless of the family of features used. The output can be fed to a control system, or, in the case of fixed experiment conditions, it can be used to directly estimate the dewatered sludge dry content.

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.

Optimizing chemical conditioning for odour removal of undigested sewage sludge in drying processes.

PubMed

Vega, Esther; Monclús, Hèctor; Gonzalez-Olmos, Rafael; Martin, Maria J

2015-03-01

Emission of odours during the thermal drying in sludge handling processes is one of the main sources of odour problems in wastewater treatment plants. The objective of this work was to assess the use of the response surface methodology as a technique to optimize the chemical conditioning process of undigested sewage sludges, in order to improve the dewaterability, and to reduce the odour emissions during the thermal drying of the sludge. Synergistic effects between inorganic conditioners (iron chloride and calcium oxide) were observed in terms of sulphur emissions and odour reduction. The developed quadratic models indicated that optimizing the conditioners dosage is possible to increase a 70% the dewaterability, reducing a 50% and 54% the emission of odour and volatile sulphur compounds respectively. The optimization of the conditioning process was validated experimentally. Copyright © 2014 Elsevier Ltd. All rights reserved.

Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment.

PubMed

Olsson, Jesper; Feng, Xin Mei; Ascue, Johnny; Gentili, Francesco G; Shabiimam, M A; Nehrenheim, Emma; Thorin, Eva

2014-11-01

In this study two wet microalgae cultures and one dried microalgae culture were co-digested in different proportions with sewage sludge in mesophilic and thermophilic conditions. The aim was to evaluate if the co-digestion could lead to an increased efficiency of methane production compared to digestion of sewage sludge alone. The results showed that co-digestion with both wet and dried microalgae, in certain proportions, increased the biochemical methane potential (BMP) compared with digestion of sewage sludge alone in mesophilic conditions. The BMP was significantly higher than the calculated BMP in many of the mixtures. This synergetic effect was statistically significant in a mixture containing 63% (w/w VS based) undigested sewage sludge and 37% (w/w VS based) wet algae slurry, which produced 23% more methane than observed with undigested sewage sludge alone. The trend was that thermophilic co-digestion of microalgae and undigested sewage sludge did not give the same synergy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Re-use of drinking water treatment plant (DWTP) sludge: Characterization and technological behaviour of cement mortars with atomized sludge additions

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

Husillos Rodriguez, N., E-mail: nuriah@ietcc.csic.e; Martinez Ramirez, S.; Blanco Varela, M.T.

This paper aims to characterize spray-dried DWTP sludge and evaluate its possible use as an addition for the cement industry. It describes the physical, chemical and micro-structural characterization of the sludge as well as the effect of its addition to Portland cements on the hydration, water demand, setting and mechanical strength of standardized mortars. Spray drying DWTP sludge generates a readily handled powdery material whose particle size is similar to those of Portland cement. The atomized sludge contains 12-14% organic matter (mainly fatty acids), while its main mineral constituents are muscovite, quartz, calcite, dolomite and seraphinite (or clinoclor). Its amorphousmore » material content is 35%. The mortars were made with type CEM I Portland cement mixed with 10 to 30% atomized sludge exhibited lower mechanical strength than the control cement and a decline in slump. Setting was also altered in the blended cements with respect to the control.« less

Recent developments in the Sandia Laboratories' sewage sludge irradiation program

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

Sivinski, H.D.; Brandon, J.R.; Morris, M.E.

1977-11-01

Pathogen reduction studies have shown that a 1 Mrad treatment (or less at elevated temperatures) is very effective in eliminating pathogenic bacteria and viable parasite ova in liquid sludges. Heat is effective in reducing levels not only of pathogenic bacteria and Ascaris ova, but viruses as well. Ammonia has been shown to be virucidal to poliovirus and several other enteric viruses. Sludge processing costs are seen to be marginally competitive with heat treatment for liquid sludges and relatively economical for composted or dried sludges. Physical/chemical effects studies have shown that the effects of irradiation of sludges on dewatering properties aremore » not significant when compared to polymers, nor is the combined effect synergistic. Dried, irradiated undigested sludge has been shown to be of significant nutritional value when used as a feed supplement for sheep and cattle, as well as in agronomic uses. No significant harmful effects have been demonstrated in the feeding program thus far. Product enhancement studies are currently under way, including schemes for removing nitrogen from effluent streams for addition as ammonium salts to sludges.« less

Chitosan use in chemical conditioning for dewatering municipal-activated sludge.

PubMed

Zemmouri, H; Mameri, N; Lounici, H

2015-01-01

This work aims to evaluate the potential use of chitosan as an eco-friendly flocculant in chemical conditioning of municipal-activated sludge. Chitosan effectiveness was compared with synthetic cationic polyelectrolyte Sedipur CF802 (Sed CF802) and ferric chloride (FeCl₃). In this context, raw sludge samples from Beni-Messous wastewater treatment plant (WWTP) were tested. The classic jar test method was used to condition sludge samples. Capillary suction time (CST), specific resistance to filtration (SRF), cakes dry solid content and filtrate turbidity were analyzed to determine filterability, dewatering capacity of conditioned sludge and the optimum dose of each conditioner. Data exhibit that chitosan, FeCl₃and Sed CF802 improve sludge dewatering. Optimum dosages of chitosan, Sed CF802 and FeCl₃allowing CST values of 6, 5 and 9 s, were found, respectively, between 2-3, 1.5-3 and 6 kg/t ds. Both polymers have shown faster water removal with more permeable sludge. SRF values were 0.634 × 10¹², 0.932 × 10¹² and 2 × 10¹² m/kg for Sed CF802, chitosan and FeCl₃respectively. A reduction of 94.68 and 87.85% of the filtrate turbidity was obtained with optimal dosage of chitosan and Sed CF802, respectively. In contrast, 54.18% of turbidity abatement has been obtained using optimal dosage of FeCl₃.

Proof of concept for a new energy-positive wastewater treatment scheme.

PubMed

Remy, C; Boulestreau, M; Lesjean, B

2014-01-01

For improved exploitation of the energy content present in the organic matter of raw sewage, an innovative concept for treatment of municipal wastewater is tested in pilot trials and assessed in energy balance and operational costs. The concept is based on a maximum extraction of organic matter into the sludge via coagulation, flocculation and microsieving (100 μm mesh size) to increase the energy recovery in anaerobic sludge digestion and decrease aeration demand for carbon mineralisation. Pilot trials with real wastewater yield an extraction of 70-80% of total chemical oxygen demand into the sludge while dosing 15-20 mg/L Al and 5-7 mg/L polymer with stable operation of the microsieve and effluent limits below 2-3 mg/L total phosphorus. Anaerobic digestion of the microsieve sludge results in high biogas yields of 600 NL/kg organic dry matter input (oDMin) compared to 430 NL/kg oDMin for mixed sludge from a conventional activated sludge process. The overall energy balance for a 100,000 population equivalent (PE) treatment plant (including biofilter for post-treatment with full nitrification and denitrification with external carbon source) shows that the new concept is an energy-positive treatment process with comparable effluent quality than conventional processes, even when including energy demand for chemicals production. Estimated operating costs for electricity and chemicals are in the same range for conventional activated sludge processes and the new concept.

Gaseous emissions from sewage sludge combustion in a moving bed combustor.

PubMed

Batistella, Luciane; Silva, Valdemar; Suzin, Renato C; Virmond, Elaine; Althoff, Chrtistine A; Moreira, Regina F P M; José, Humberto J

2015-12-01

Substantial increase in sewage sludge generation in recent years requires suitable destination for this residue. This study evaluated the gaseous emissions generated during combustion of an aerobic sewage sludge in a pilot scale moving bed reactor. To utilize the heat generated during combustion, the exhaust gas was applied to the raw sludge drying process. The gaseous emissions were analyzed both after the combustion and drying steps. The results of the sewage sludge characterization showed the energy potential of this residue (LHV equal to 14.5 MJ kg(-1), db) and low concentration of metals, polycyclic aromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). The concentration of CO, NOx, BTEX (benzene, toluene, ethylbenzene and xylenes) emitted from the sludge combustion process were lower than the legal limits. The overall sludge combustion and drying process showed low emissions of PCDD/PCDF (0.42 ng I-TEQ N m(-3)). BTEX and PAH emissions were not detected. Even with the high nitrogen concentration in the raw feed (5.88% db), the sludge combustion process presented NOx emissions below the legal limit, which results from the combination of appropriate feed rate (A/F ratio), excess air, and mainly the low temperature kept inside the combustion chamber. It was found that the level of CO emissions from the overall sludge process depends on the dryer operating conditions, such as the oxygen content and the drying temperature, which have to be controlled throughout the process in order to achieve low CO levels. The aerobic sewage sludge combustion process generated high SO2 concentration due to the high sulfur content (0.67 wt%, db) and low calcium concentration (22.99 g kg(-1)) found in the sludge. The high concentration of SO2 in the flue gas (4776.77 mg N m(-3)) is the main factor inhibiting PCDD/PCDF formation. Further changes are needed in the pilot plant scheme to reduce SO2 and particulate matter emissions, such as the installation of exhaust gas-cleaning systems. According to previous studies, the efficient operation of such cleaning systems is also effective for metals emission control, which makes the combustion of sewage sludge a feasible treatment method from both energetic and environmental perspectives. Copyright © 2015 Elsevier Ltd. All rights reserved.

Who contributes more to N2O emission during sludge bio-drying with two different aeration strategies, nitrifiers or denitrifiers?

PubMed

Zhang, Junya; Wang, Yuanyue; Yu, Dawei; Tong, Juan; Chen, Meixue; Sui, Qianwen; ChuLu, BuHe; Wei, Yuansong

2017-04-01

Global warming effects have drawn more and more attention to studying all sources and sinks of nitrous oxide (N 2 O). Sludge bio-drying, as an effective sludge treatment technology, is being adopted worldwide. In this study, two aeration strategies (piles I and II) were compared to investigate the primary contributors to N 2 O emission during sludge bio-drying through studying the evolution of functional genes involved in nitrification (amoA, hao, and nxrA) and denitrification (narG, nirS, nirK, norB, and nosZ) by quantitative PCR (qPCR). Results showed that the profile of N 2 O emission can be divided into three stages, traditional denitrification contributed largely to N 2 O emission at stage I (days 1-5), but N 2 O emission mainly happened at stage II (days 5-14) due to nitrifier denitrification and NH 2 OH accumulation by ammonia-oxidizing bacteria (AOB), accounting for 51.4% and 58.2% of total N 2 O emission for piles I and II, respectively. At stage III (days 14-21), nitrifier denitrification was inhibited because sludge bio-drying proceeded mainly by the physical aeration, thus N 2 O emission decreased and changed little. The improved aeration strategy availed pile I to reduce N 2 O emission much especially at stages II and III, respectively. These results indicated that nitrifier denitrification by AOB and biological NH 2 OH oxidation due to AOB made more contribution to N 2 O emission, and aeration strategy was crucial to mitigate N 2 O emission during sludge bio-drying.

Effects of spring season solar drying process on sanitation indicators in sewage sludge and potential as a method for fertilizer production.

PubMed

Sypuła, Małgorzata; Paluszak, Zbigniew; Ligocka, Anna; Skowron, Krzysztof

2013-01-01

The agricultural use of sewage sludge is possible on condition of maintaining microbiological and parasitological standards, and one of the most modern methods improving its sanitary state is solar drying. In the presented study, the effect of this process on the elimination of indicator microorganisms (Escherichia coli, Salmonella Senftenberg W775, Enterococcus spp.) and eggs of Ascaris suum introduced into the biomass of sludge was examined. The experiment was carried out in the spring period with a maximal temperature of 18 °C inside the drying plant. Bacteria and parasite eggs were introduced into special carriers (cylinders filled with sewage sludge) and placed at selected points of the drier. The carriers were removed every 7 days and subject to a research procedure in order to estimate the number of bacteria and percentage of live eggs of Ascaris suum. Sanitization of the material was not obtained, since after 28 days of the process the final product contained a large concentration of Enterococcus spp. and S. Senftenberg W775 (10(5) -10(9) MPNg(-1)). Only the number of E. coli decreased by 6 log. During the process, the fastest decrease in the number of bacteria was observed in E. coli (ca 0.2 log/day), slower in enterococci (0.02-0.081 log/day), and the slowest in bacilli of the genus Salmonella (0.011-0.061 log/day). Sludge after drying also still contained 57-66% of live eggs of A. suum. The study proved that the solar drying of sludge in the spring period results in a product which poses a hazard for public and animal health and environmental sustainability, and should not be used as a fertilizer.

Effect of nonylphenol on volatile fatty acids accumulation during anaerobic fermentation of waste activated sludge.

PubMed

Duan, Xu; Wang, Xiao; Xie, Jing; Feng, Leiyu; Yan, Yuanyuan; Zhou, Qi

2016-11-15

Most of the reported studies on anaerobic fermentation of sludge focused on the influences of operating conditions, pretreatment methods, and its characteristics, and little attention was paid to those of persistent organic pollutants (POPs) which widespreadly appeared in sludge. In this study, the effect of nonylphenol, a typical POPs in waste activated sludge (WAS), on anaerobic fermentation for volatile fatty acids (VFAs) accumulation was investigated. The concentration of VFAs during WAS anaerobic fermentation was found to be affected positively from 2856 mg COD/L in the control (without NP) to 5620 mg COD/L with NP of 200 mg/kg dry sludge. Mechanism exploration exhibited that the main reason for the enhanced VFAs accumulation in the presence of NP was that more acetic acid was generated during the acidification of WAS, which was increased by almost three times (3790 versus 1310 mg COD/L). In WAS fermentation systems, the abundance of anaerobic functional microorganisms was advantageous to the accumulation of acetic acid. Further investigation by the pure acetogen revealed that both the viability and activity of Proteiniphilum acetatigenes were improved by NP during anaerobic fermentation, resulting in more production of acetic acid and showing good agreement with that in the real WAS fermentation systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Drying Beds. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.

ERIC Educational Resources Information Center

Klopping, Paul H.

Provided in this lesson is introductory material on sand and surfaced sludge drying beds. Typical construction and operation, proper maintenance, and safety procedures are considered. The lesson includes an instructor's guide and student workbook. The instructor's guide contains a description of the lesson, estimated presentation time,…

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.

Degradation of sulfamethazine in sewage sludge mixture by gamma irradiation

NASA Astrophysics Data System (ADS)

Chu, Libing; Wang, Jianlong; Liu, Yuankun

2015-03-01

The gamma-irradiation-induced degradation of antibiotics sulfamethazine (SMT) in sludge mixture was investigated. The results showed that gamma irradiation was effective in removing SMT from contaminated sludge mixture. With an initial SMT concentration of 10 mg/L, the SMT removal efficiency reached 65% at 1.0 kGy and increased to 98% at 2.5 kGy. The SMT degradation rate was lower in the sludge mixture than that in pure water. The pseudo first-order kinetic constant of SMT degradation in pure water was 2.3 times higher than that in the sludge mixture. Analysis of the SMT concentrations in the supernatant and sludge residue revealed that 93-97% of SMT was observed in the supernatant and the detected SMT in the sludge residue was 168±29, 147±4, and 87±9 μg/g dry weight following irradiation at doses of 0, 1.0 and 2.5 kGy, respectively. The sludge solubilization slowly increased from 1.5% to 3.5% with increasing dose from 1.0 to 5.0 kGy, while the sludge activity decreased by 85-98%. Addition of H2O2 exhibited a synergetic effect on the degradation of SMT, with the pseudo first-order kinetic constant k increasing by around 25%.

Effects of ultrasonic disintegration of excess sewage sludge.

PubMed

Zielewicz, Ewa

2016-10-01

Breaking down sludge floc (sonodyspergation effect) and destruction of the cell membranes of microorganisms forming floc is a direct effect of ultrasonic disintegration of sludge excess. This results in release of organic material by liquid sludge (the sonolysis effect). Desired technological effects of the disintegration are: to shorten the hydrolytic phase of fermentation, to increase the production of biogas (source of renewable energy) and an increased mineralization (stability) of fermented sludge. The presented study demonstrates research covering thickened excess sludge of various physicochemical properties, collected from nine municipal sewage treatment plants. The sludge was subjected to ultrasonic disintegration using three differently constructed disintegrators and different proportions of sonification area. Direct effects of disintegration were monitored and recorded using selected indicators describing changes in the properties of sludge and increase of substance dispersed and dissolved in the supernatant liquid to be filtered. Studies have demonstrated that those (direct) effects of ultrasonic disintegration depend on the physicochemical properties of the sludge (foremost the concentration of dry solids) that determine their variable susceptibility to the disintegration methods. The direct effects also depend on optimal process conditions (which consist of the construction of the ultrasonic disintegrator), the geometric proportions of the sonication area and the operating parameters of disintegration (which could be appropriately matched to the characteristics of sludge). The most preferable results were obtained for ultrasonic disintegration of sludge with a dry matter concentration C 0 < 4.2 %. The highest effect of sonolysis-an almost 30-fold increase in the COD dissolved in the supernatant-was obtained for the sludge of lowest dry matter (C 0 = 2.0 %), which was sonicated in a reactor with a short transducer of the largest radiating surface area, as well as the lowest ratio between this area and area of reactor. The best effects of disagglomeration of flocks have corresponded with the high value of power density U UD = 880-900 WL(-1).

Energy recovery from thermal treatment of dewatered sludge in wastewater treatment plants.

PubMed

Yang, Qingfeng; Dussan, Karla; Monaghan, Rory F D; Zhan, Xinmin

Sewage sludge is a by-product generated from municipal wastewater treatment (WWT) processes. This study examines the conversion of sludge via energy recovery from gasification/combustion for thermal treatment of dewatered sludge. The present analysis is based on a chemical equilibrium model of thermal conversion of previously dewatered sludge with moisture content of 60-80%. Prior to combustion/gasification, sludge is dried to a moisture content of 25-55% by two processes: (1) heat recovered from syngas/flue gas cooling and (2) heat recovered from syngas combustion. The electricity recovered from the combined heat and power process can be reused in syngas cleaning and in the WWT plant. Gas temperature, total heat and electricity recoverable are evaluated using the model. Results show that generation of electricity from dewatered sludge with low moisture content (≤ 70%) is feasible within a self-sufficient sludge treatment process. Optimal conditions for gasification correspond to an equivalence ratio of 2.3 and dried sludge moisture content of 25%. Net electricity generated from syngas combustion can account for 0.071 kWh/m(3) of wastewater treated, which is up to 25.4-28.4% of the WWT plant's total energy consumption.

Digestion of high rate activated sludge coupled to biochar formation for soil improvement in the tropics.

PubMed

Nansubuga, Irene; Banadda, Noble; Ronsse, Frederik; Verstraete, Willy; Rabaey, Korneel

2015-09-15

High rate activated sludge (HRAS) is well-biodegradable sludge enabling energy neutrality of wastewater treatment plants via anaerobic digestion. However, even through successful digestion a notable residue still remains. Here we investigated whether this residue can be converted to biochar, for its use as a fertilizer or as a solid fuel, and assessed its characteristics and overall process efficiency. In a first phase, HRAS was anaerobicaly digested under mesophilic conditions at a sludge retention time of 20 days. HRAS digested well (57.9 ± 6.2% VS degradation) producing on average 0.23 ± 0.04 L CH4 per gram VS fed. The digestate particulates were partially air-dried to mimic conditions used in developing countries, and subsequently converted to biochar by fixed-bed slow pyrolysis at a residence time of 15 min and at highest heating temperatures (HHT) of 300 °C, 400 °C and 600 °C. Subsequently, the produced chars were characterized by proximate analysis, CHN-elemental analysis, pH in solution and bomb calorimetry for higher heating value. The yield and volatile matter decreased with increasing HHT while ash content and fixed carbon increased with increasing HHT. The produced biochar showed properties optimal towards soil amendment when produced at a temperature of 600 °C with values of 5.91 wt%, 23.75 wt%, 70.35% on dry basis (db) and 0.44 for volatile matter, fixed carbon, ash content and H/C ratio, respectively. With regard to its use for energy purposes, the biochar represented a lower calorific value than the dried HRAS digestate likely due to high ash content. Based on these findings, it can be concluded that anaerobic digestion of HRAS and its subsequent biochar formation at HHT of 600 °C represents an attractive route for sludge management in tropic settings like in Uganda, coupling carbon capture to energy generation, carbon sequestration and nutrient recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sludge conditioning using the composite of a bioflocculant and PAC for enhancement in dewaterability.

PubMed

Guo, Junyuan; Chen, Cheng

2017-10-01

This study investigated the production of a bioflocculant by using rice stover and its potential in sludge dewatering. Production of the bioflocculant was positively associated with cell growth and highest value of 2.37 g L -1 was obtained with main backbone of polysaccharides. The bioflocculant showed good performances in sludge dewatering, after conditioned by this bioflocculant, dry solids (DS) and specific resistance to filtration (SRF) of typical wastewater activated sludge reached 19.3% and 4.8 × 10 12  m kg -1 , respectively, which were much better than the ones obtained with chemical flocculants. Sludge dewatering was further improved when the bioflocculant and polyaluminum chloride (PAC) were used simultaneously, and the optimized conditioning process by the composite was bioflocculant of 10.5 g kg -1 , PAC of 19.4 g kg -1 , and pH of 8.1. Under this optimal condition, DS and SRF of the sludge appeared as 24.1% and 3.0 × 10 12  m kg -1 , respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Sludge Lagoons. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.

ERIC Educational Resources Information Center

Sharman, Ronald M.

This lesson describes three different types of sludge lagoons: (1) drying lagoons; (2) facultative lagoons; and (3) anaerobic lagoons. Normal operating sequence and equipment are also described. The lesson is designed to be used in sequence with the complete Sludge Treatment and Disposal Course #166 or as an independent lesson. The instructor's…

Thermophilic Dry Methane Fermentation of Distillation Residue Eluted from Ethanol Fermentation of Kitchen Waste and Dynamics of Microbial Communities.

PubMed

Huang, Yu-Lian; Tan, Li; Wang, Ting-Ting; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji

2017-01-01

Thermophilic dry methane fermentation is advantageous for feedstock with high solid content. Distillation residue with 65.1 % moisture content was eluted from ethanol fermentation of kitchen waste and subjected to thermophilic dry methane fermentation, after adjusting the moisture content to 75 %. The effect of carbon to nitrogen (C/N) ratio on thermophilic dry methane fermentation was investigated. Results showed that thermophilic dry methane fermentation could not be stably performed for >10 weeks at a C/N ratio of 12.6 and a volatile total solid (VTS) loading rate of 1 g/kg sludge/d; however, it was stably performed at a C/N ratio of 19.8 and a VTS loading rate of 3 g/kg sludge/d with 83.4 % energy recovery efficiency. Quantitative PCR analysis revealed that the number of bacteria and archaea decreased by two orders of magnitude at a C/N ratio of 12.6, whereas they were not influenced at a C/N ratio of 19.8. Microbial community analysis revealed that the relative abundance of protein-degrading bacteria increased and that of organic acid-oxidizing bacteria and acetic acid-oxidizing bacteria decreased at a C/N ratio of 12.6. Therefore, there was accumulation of NH 4 + and acetic acid, which inhibited thermophilic dry methane fermentation.

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.

Inhibition of Anaerobic Phosphate Release by Nitric Oxide in Activated Sludge

PubMed Central

Van Niel, E. W. J.; Appeldoorn, K. J.; Zehnder, A. J. B.; Kortstee, G. J. J.

1998-01-01

Activated sludge not containing significant numbers of denitrifying, polyphosphate [poly(P)]-accumulating bacteria was grown in a fill-and-draw system and exposed to alternating anaerobic and aerobic periods. During the aerobic period, poly(P) accumulated up to 100 mg of P · g of (dry) weight. When portions of the sludge were incubated anaerobically in the presence of acetate, 80 to 90% of the intracellular poly(P) was degraded and released as orthophosphate. Degradation of poly(P) was mainly catalyzed by the concerted action of polyphosphate:AMP phosphotransferase and adenylate kinase, resulting in ATP formation. In the presence of 0.3 mM nitric oxide (NO) in the liquid-phase release of phosphate, uptake of acetate, formation of poly-β-hydroxybutyrate, utilization of glycogen, and formation of ATP were severely inhibited or completely abolished. In cell extracts of the sludge, adenylate kinase activity was completely inhibited by 0.15 mM NO. The nature of this inhibition was probably noncompetitive, similar to that with hog adenylate kinase. Activated sludge polyphosphate glucokinase was also completely inhibited by 0.15 mM NO. It is concluded that the inhibitory effect of NO on acetate-mediated phosphate release by the sludge used in this study is due to the inhibition of adenylate kinase in the phosphate-releasing organisms. The inhibitory effect of nitrate and nitrite on phosphate release is probably due to their conversion to NO. The lack of any inhibitory effect of NO on adenylate kinase of the poly(P)-accumulating Acinetobacter johnsonii 210A suggests that this type of organism is not involved in the enhanced biological phosphate removal by the sludges used. PMID:9687452

Applications for reuse of lime sludge from water softening.

DOT National Transportation Integrated Search

2005-07-15

Lime sludge, an inert material mostly composed of calcium carbonate, is the result of : softening hard water for distribution as drinking water. A large city such as Des Moines, : Iowa, produces about 30,700 tons of lime sludge (dry weight basis) ann...

40 CFR 60.152 - Standard for particulate matter.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Standard for particulate matter. 60.152... Plants § 60.152 Standard for particulate matter. (a) On and after the date on which the performance test...: (1) Particulate matter at a rate in excess of 0.65 g/kg dry sludge input (1.30 lb/ton dry sludge...

40 CFR 60.152 - Standard for particulate matter.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for particulate matter. 60.152... Plants § 60.152 Standard for particulate matter. (a) On and after the date on which the performance test...: (1) Particulate matter at a rate in excess of 0.65 g/kg dry sludge input (1.30 lb/ton dry sludge...

40 CFR 60.152 - Standard for particulate matter.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Standard for particulate matter. 60.152... Plants § 60.152 Standard for particulate matter. (a) On and after the date on which the performance test...: (1) Particulate matter at a rate in excess of 0.65 g/kg dry sludge input (1.30 lb/ton dry sludge...

40 CFR 60.152 - Standard for particulate matter.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Standard for particulate matter. 60.152... Plants § 60.152 Standard for particulate matter. (a) On and after the date on which the performance test...: (1) Particulate matter at a rate in excess of 0.65 g/kg dry sludge input (1.30 lb/ton dry sludge...

40 CFR 60.152 - Standard for particulate matter.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Standard for particulate matter. 60.152... Plants § 60.152 Standard for particulate matter. (a) On and after the date on which the performance test...: (1) Particulate matter at a rate in excess of 0.65 g/kg dry sludge input (1.30 lb/ton dry sludge...

Two Cases of Tsunami Dust Pneumonia: Organizing Pneumonia Caused by the Inhalation of Dried Tsunami Sludge after the 2011 Great East Japan Earthquake.

PubMed

Yamanda, Shinsuke; Kobayashi, Seiichi; Hanagama, Masakazu; Sato, Hikari; Suzuki, Satoshi; Ueda, Shinsaku; Takahashi, Toru; Yanai, Masaru

We report two cases of organizing pneumonia (OP) secondary to the inhalation of the dried tsunami sludge which formed during the 2011 Great East Japan Earthquake and the consequent tsunami. After the disaster, both of these patients had been engaged in the restoration work. About half a month later, they developed shortness of breath and pulmonary infiltrates. These patients were diagnosed with interstitial pneumonia. Their biopsy specimens revealed multifocal peribronchiolitis and OP. An electron probe microanalysis of these specimens demonstrated the presence of elements from the earth's crust in the inflammatory lesions. These two cases indicate that exposure to dried tsunami sludge can cause OP.

Indirect methods of dried sewage sludge contamination assessments.

PubMed

Werle, Sebastian; Dudziak, Mariusz; Grübel, Klaudiusz

2016-07-28

Thermal conversion (combustion, co-combustion, gasification and pyrolysis) appears to be the most promising alternative for sewage sludge management in the future. Nevertheless, safe and ecological usage of sewage sludge as a fuel requires information about their contamination. The aim of this paper is to present the photoacoustic spectroscopy (PAS) as a good method for contamination assessments of dried sewage sludge. Two types of granular sewage sludge: Sewage sludge 1 (SS1) taken from Polish wastewater treatment plant operating in the mechanical-biological system and sewage sludge 2 (SS2) taken from mechanical-biological-chemical wastewater treatment plant with phosphorus precipitation were analysed. The spectrophotometer FTIR Nicolet 6700 equipped with photoacoustic cell (Model 300, MTEC, USA) was used. The comparison with the most popular analytical methods (GC-MS) was also done. The results of PAS studies confirm the difference between the SS1 and SS2 which is in agreement with the GC-MS analysis. Higher absorbance was observed at each wavelength characteristics for the oscillator of chemical moieties for the SS1 with respect to the SS2.

Beneficial uses program. Progress report for period ending March 31, 1977

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

None

1977-07-01

Progress is reported in a program aimed at recovering radiation sources from radioactive wastes and using these sources, mainly /sup 137/Cs, for irradiating sewage sludge. Information is included on: development and cost of dried sludge irradiator; heat and radiation inactivation of sludge-contained viruses and bacteria; virucidal agents in sludge; use of thermoradiated sludge as animal feed; and a comparison of the efficiency of various source materials. (LCL)

Municipal wastewater sludge as a sustainable bioresource in the United States

DOE PAGES

Seiple, Timothy E.; Coleman, André M.; Skaggs, Richard L.

2017-04-20

Within the United States and Puerto Rico, publicly owned treatment works (POTWs) process 130.5 Gl/d (34.5 Bgal/d) of wastewater, producing sludge as a waste product. Emerging technologies offer novel waste-to-energy pathways through whole sludge conversion into biofuels. Assessing the feasibility, scalability and tradeoffs of various energy conversion pathways is difficult in the absence of highly spatially resolved estimates of sludge production. In this study, average wastewater solids concentrations and removal rates, and site specific daily average influent flow are used to estimate site specific annual sludge production on a dry weight basis for >15,000 POTWs. Current beneficial uses, regional productionmore » hotspots and feedstock aggregation potential are also assessed. Analyses indicate 1) POTWs capture 12.56 Tg/y (13.84 MT/y) of dry solids; 2) 50% are not beneficially utilized, and 3) POTWs can support seven regions that aggregate >910 Mg/d (1000 T/d) of sludge within a travel distance of 100 km.« less

Biodiesel production from wet municipal sludge: evaluation of in situ transesterification using xylene as a cosolvent.

PubMed

Choi, O K; Song, J S; Cha, D K; Lee, J W

2014-08-01

This study proposes a method to produce biodiesel from wet wastewater sludge. Xylene was used as an alternative cosolvent to hexane for transesterification in order to enhance the biodiesel yield from wet wastewater sludge. The water present in the sludge could be separated during transesterification by employing xylene, which has a higher boiling point than water. Xylene enhanced the biodiesel yield up to 8.12%, which was 2.5 times higher than hexane. It was comparable to the maximum biodiesel yield of 9.68% obtained from dried sludge. Xylene could reduce either the reaction time or methanol consumption, when compared to hexane for a similar yield. The fatty acid methyl esters (FAMEs) content of the biodiesel increased approximately two fold by changing the cosolvent from hexane to xylene. The transesterification method using xylene as a cosolvent can be applied effectively and economically for biodiesel recovery from wet wastewater sludge without drying process. Copyright © 2014 Elsevier Ltd. All rights reserved.

In situ biodiesel production from greasy sewage sludge using acid and enzymatic catalysts.

PubMed

Sangaletti-Gerhard, Naiane; Cea, Mara; Risco, Vicky; Navia, Rodrigo

2015-03-01

This study proposes to select the most appropriate sewage sludge (greasy, primary and secondary) for in situ transesterification and to compare the technical, economic and energetic performance of an enzymatic catalyst (Novozym®435) with sulfuric acid. Greasy sludge was selected as feedstock for biodiesel production due to its high lipid content (44.4%) and low unsaponifiable matter. Maximum methyl esters yield (61%) was reached when processing the wet sludge using sulfuric acid as catalyst and n-hexane, followed by dried-greasy sludge catalyzed by Novozym®435 (57% methyl esters). Considering the economic point of view, the process using acid catalyst was more favorable compared to Novozym®435 catalyst due to the high cost of lipase. In general, greasy sludge (wet or dried) showed high potential to produce biodiesel. However, further technical adjustments are needed to make biodiesel production by in situ transesterification using acid and enzymatic catalyst feasible. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioaccumulation of metals in ryegrass (Lolium perenne L.) following the application of lime stabilised, thermally dried and anaerobically digested sewage sludge.

PubMed

Healy, M G; Ryan, P C; Fenton, O; Peyton, D P; Wall, D P; Morrison, L

2016-08-01

The uptake and accumulation of metals in plants is a potential pathway for the transfer of environmental contaminants in the food chain, and poses potential health and environmental risks. In light of increased population growth and urbanisation, the safe disposal of sewage sludge, which can contain significant levels of toxic contaminants, remains an environmental challenge globally. The aims of this experiment were to apply municipal sludge, having undergone treatment by thermal drying, anaerobic digestion, and lime stabilisation, to permanent grassland in order to assess the bioaccumulation of metals (B, Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Nb, Mo, Sb, Ba, W, Pb, Fe, Cd) by perennial ryegrass over a period of up to 18 weeks after application. The legislation currently prohibits use of grassland for fodder or grazing for at least three weeks after application of treated sewage sludge (biosolids). Five treatments were used: thermally dried (TD), anaerobically digested (AD) and lime stabilised (LS) sludge all from one wastewater treatment plant (WWTP), AD sludge from another WWTP, and a study control (grassland only, without application of biosolids). In general, there was no significant difference in metal content of the ryegrass between micro-plots that received treated municipal sludge and the control over the study duration. The metal content of the ryegrass was below the levels at which phytotoxicity occurs and below the maximum levels specified for animal feeds. Copyright © 2016 Elsevier Inc. All rights reserved.

Use of life cycle assessment to evaluate environmental impacts associated with the management of sludge and biogas.

PubMed

do Amaral, Karina Cubas; Aisse, Miguel Mansur; Possetti, Gustavo Rafael Collere; Prado, Marcelo Real

2018-05-01

Upflow anaerobic sludge blanket (UASB) reactors used in sewage treatment generate two by-products that can be reused: sludge and biogas. At the present time in Brazil, most of this resulting sludge is disposed of in sanitary landfills, while biogas is commonly burned off in low-efficiency flares. The aim of the present study was to use life cycle assessment to evaluate the environmental impacts from four different treatment and final destination scenarios for the main by-products of wastewater treatment plants. The baseline scenario, in which the sludge was sanitized using prolonged alkaline stabilization and, subsequently, directed toward agricultural applications and the biogas destroyed in open burners, had the most impact in the categories of global warming, terrestrial ecotoxicity, and human non-carcinogenic toxicity. The scenario in which heat resulting from biogas combustion is used to dry the sludge showed significant improvements over the baseline scenario in all the evaluated impact categories. The recovery of heat from biogas combustion decreased significantly the environmental impact associated with global warming. The combustion of dried sludge is another alternative to improve the sludge management. Despite the reduction of sludge volume to ash, there are environmental impacts inherent to ozone formation and terrestrial acidification.

Dust recycling technology in Kimitsu Works

NASA Astrophysics Data System (ADS)

Oda, Hiroshi; Ibaraki, Tetsuharu

Dust recycling technology by the rotary hearth furnace has been applied at Nippon Steel‧s Kimitsu Works since 2000. The dust and sludge with iron oxide and carbon are agglomerated into shaped articles and the iron oxide is reduced in a high temperature atmosphere. Zinc and other impurities in the dust and sludge are expelled and exhausted into off gas. The DRI pellets made from the dust and sludge have 70% metallization and are strong enough for being recycled to the blast furnaces. No.1 plant, which was constructed in May 2000 and has an agglomeration method of pelletizing, recycles mainly dry dusts. No.2 plant, which was constructed in December 2002 and has an agglomeration method of extrusion, recycles mainly sludge. The combination of the two plants is a solution for recycling various kinds of dusts and sludge emitted in a large scale steel works as Kimitsu Works

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

Seiple, Timothy E.; Coleman, André M.; Skaggs, Richard L.

Within the United States and Puerto Rico, publicly owned treatment works (POTWs) process 130.5 Gl/d (34.5 Bgal/d) of wastewater, producing sludge as a waste product. Emerging technologies offer novel waste-to-energy pathways through whole sludge conversion into biofuels. Assessing the feasibility, scalability and tradeoffs of various energy conversion pathways is difficult in the absence of highly spatially resolved estimates of sludge production. In this study, average wastewater solids concentrations and removal rates, and site specific daily average influent flow are used to estimate site specific annual sludge production on a dry weight basis for >15,000 POTWs. Current beneficial uses, regional productionmore » hotspots and feedstock aggregation potential are also assessed. Analyses indicate 1) POTWs capture 12.56 Tg/y (13.84 MT/y) of dry solids; 2) 50% are not beneficially utilized, and 3) POTWs can support seven regions that aggregate >910 Mg/d (1000 T/d) of sludge within a travel distance of 100 km.« less

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.

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... municipal solid waste (not to exceed 30 percent of the dry weight of sewage sludge and auxiliary fuel... forces and water to remove pollutants in the exit gas from a sewage sludge incinerator stack. (r) Wet... 503.41 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SEWAGE SLUDGE STANDARDS...

Anaerobic digestion of ultrasonicated sludge at different solids concentrations - Computation of mass-energy balance and greenhouse gas emissions.

PubMed

Pilli, Sridhar; Yan, S; Tyagi, R D; Surampalli, R Y

2016-01-15

Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without pre-treatment, were assessed using mass-energy balance and the corresponding greenhouse gas (GHG) emissions. For a digestion period of 30 days, volatile solids degradation of the control sludge and the ultrasonicated secondary sludge was 51.4% and 60.1%, respectively. Mass balance revealed that the quantity of digestate required for dewatering, transport and land application was the lowest (20.2 × 10(6) g dry sludge/day) for ultrasonicated secondary sludge at 31.4 g TS/L. Furthermore, for ultrasonicated secondary sludge at 31.4 g TS/L, the maximum net energy (energy output - energy input) of total dry solids (TDS) was 7.89 × 10(-6) kWh/g and the energy ratio (output/input) was 1.0. GHG emissions were also reduced with an increase in the sludge solids concentration (i.e., 40.0 g TS/L < 30.0 g TS/L < 20.0 g TS/L). Ultrasonication pre-treatment proved to be efficient and beneficial for enhancing anaerobic digestion efficiency of the secondary sludge when compared to the primary and mixed sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

An adsorbent with a high adsorption capacity obtained from the cellulose sludge of industrial residues.

PubMed

Orlandi, Géssica; Cavasotto, Jéssica; Machado, Francisco R S; Colpani, Gustavo L; Magro, Jacir Dal; Dalcanton, Francieli; Mello, Josiane M M; Fiori, Márcio A

2017-02-01

One of the major problems in effluent treatment plants of the cellulose and paper industry is the large amount of residual sludge generated. Therefore, this industry is trying to develop new methods to treat such residues and to use them as new products, such as adsorbents. In this regard, the objective of this work was to develop an adsorbent using the raw activated sludge generated by the cellulose and paper industry. The activated cellulose sludge, after being dried, was chemically activated with 42.5% (v/v) phosphoric acid at 85 °C for 1 h and was charred at 500 °C, 600 °C and 700 °C for 2 h. The efficiency of the obtained adsorbent materials was evaluated using kinetic tests with methylene blue solutions. Using the adsorption kinetics, it was verified that the three adsorbents showed the capacity to adsorb dye, and the adsorbent obtained at a temperature of 600 °C showed the highest adsorption capacity of 107.1 mg g -1 . The kinetic model that best fit the experimental data was pseudo-second order. The Langmuir-Freudlich isotherm adequately described the experimental data. As a result, the cellulose sludge generated by the cellulose and paper industries could be used as an adsorbent. Copyright © 2016 Elsevier Ltd. All rights reserved.

Citric acid assisted Fenton-like process for enhanced dewaterability of waste activated sludge with in-situ generation of hydrogen peroxide.

PubMed

Xiao, Keke; Pei, Kangyue; Wang, Hui; Yu, Wenbo; Liang, Sha; Hu, Jingping; Hou, Huijie; Liu, Bingchuan; Yang, Jiakuan

2018-09-01

Fenton's reagent has been widely used to enhance sludge dewaterability. However, drawbacks associated with hydrogen peroxide (H 2 O 2 ) in Fenton's reagents exist, since it is a hazardous chemical and shows carcinogenicity, explosivity, instability, and corrosivity. Moreover, initial acidification and subsequent neutralization are needed as optimal conditions for homogeneous Fenton conditioning and final filtrate discharge. In this study, a Fenton-like process for the enhanced dewaterability of waste activated sludge with in-situ generation of H 2 O 2 and without extra pH adjustment was firstly proposed, namely citric acid (CA)-assisted oxygen activation in an air/nano zero-valent iron (nZVI) system and chemical re-coagulation with polydiallyldimethylammonium chloride (PDMDAAC). Using the response surface methodology (RSM), the optimal doses of CA, nZVI, and PDMDAAC were determined to be 13, 33, and 9 mg g -1 dry solids (DS), respectively. This composite conditioner showed a good dewatering capability compared with the raw sludge, e.g. the capillary suction time decreased from 130.0 to 9.5 s. The enhanced sludge dewaterability was further confirmed by laboratory-scale diaphragm filter press dewatering tests, which produced a lower cake moisture content compared with the raw sludge, and the final pH of the filtrate was close to neutrality. The citric acid promoted the production of H 2 O 2 and Fe(II)/Fe(III) species, the degradation of protein in tightly-bound extracellular polymeric substances, and the decomposition of protein-N in the solid phase of sludge, resulting a greater conversion of bound water to free water. The results of electron spin resonance indicated that the hydroxyl radicals were mainly responsible for the decomposition of proteinaceous compounds. The subsequent chemical re-coagulation with PDMDAAC can make the zeta potential of sludge samples less negative, reduce the repulsive electrostatic interactions, and agglomerate the smaller particles into larger aggregates, thus enhancing sludge dewaterability. Copyright © 2018 Elsevier Ltd. All rights reserved.

40 CFR 503.32 - Pathogens.

Code of Federal Regulations, 2013 CFR

2013-07-01

... determine whether the sewage sludge contains viable helminth ova. (B) When the density of viable helminth ova in the sewage sludge prior to pathogen treatment is less than one per four grams of total solids (dry weight basis), the sewage sludge is Class A with respect to viable helminth ova until the next...

40 CFR 503.32 - Pathogens.

Code of Federal Regulations, 2014 CFR

2014-07-01

... determine whether the sewage sludge contains viable helminth ova. (B) When the density of viable helminth ova in the sewage sludge prior to pathogen treatment is less than one per four grams of total solids (dry weight basis), the sewage sludge is Class A with respect to viable helminth ova until the next...

Polycyclic Aromatic Hydrocarbon Affects Acetic Acid Production during Anaerobic Fermentation of Waste Activated Sludge by Altering Activity and Viability of Acetogen.

PubMed

Luo, Jingyang; Chen, Yinguang; Feng, Leiyu

2016-07-05

Till now, almost all the studies on anaerobic fermentation of waste activated sludge (WAS) for bioproducts generation focused on the influences of operating conditions, pretreatment methods and sludge characteristics, and few considered those of widespread persistent organic pollutants (POPs) in sludge, for example, polycyclic aromatic hydrocarbons (PAHs). Herein, phenanthrene, which was a typical PAH and widespread in WAS, was selected as a model compound to investigate its effect on WAS anaerobic fermentation for short-chain fatty acids (SCFAs) accumulation. Experimental results showed that the concentration of SCFAs derived from WAS was increased in the presence of phenanthrene during anaerobic fermentation. The yield of acetic acid which was the predominant SCFA in the fermentation reactor with the concentration of 100 mg/kg dry sludge was 1.8 fold of that in the control. Mechanism exploration revealed that the present phenanthrene mainly affected the acidification process of anaerobic fermentation and caused the shift of the microbial community to benefit the accumulation of acetic acid. Further investigation showed that both the activities of key enzymes (phosphotransacetylase and acetate kinase) involved in acetic acid production and the quantities of their corresponding encoding genes were enhanced in the presence of phenanthrene. Viability tests by determining the adenosine 5'-triphosphate content and membrane potential confirmed that the acetogens were more viable in anaerobic fermentation systems with phenanthrene, which resulted in the increased production of acetic acid.

Extracellular polymeric substances (EPS) producing bacterial strains of municipal wastewater sludge: isolation, molecular identification, EPS characterization and performance for sludge settling and dewatering.

PubMed

Bala Subramanian, S; Yan, S; Tyagi, R D; Surampalli, R Y

2010-04-01

Wastewater treatment plants often face the problems of sludge settling mainly due to sludge bulking. Generally, synthetic organic polymer and/or inorganic coagulants (ferric chloride, alum and quick lime) are used for sludge settling. These chemicals are very expensive and further pollute the environment. Whereas, the bioflocculants are environment friendly and may be used to flocculate the sludge. Extracellular polymeric substances (EPS) produced by sludge microorganisms play a definite role in sludge flocculation. In this study, 25 EPS producing strains were isolated from municipal wastewater treatment plant. Microorganisms were selected based on EPS production properties on solid agar medium. Three types of EPS (slime, capsular and bacterial broth mixture of both slime and capsular) were harvested and their characteristics were studied. EPS concentration (dry weight), viscosity and their charge (using a Zetaphoremeter) were also measured. Bioflocculability of obtained EPS was evaluated by measuring the kaolin clay flocculation activity. Six bacterial strains (BS2, BS8, BS9, BS11, BS15 and BS25) were selected based on the kaolin clay flocculation. The slime EPS was better for bioflocculation than capsular EPS and bacterial broth. Therefore, extracted slime EPS (partially purified) from six bacterial strains was studied in terms of sludge settling [sludge volume index (SVI)] and dewatering [capillary suction time (CST)]. Biopolymers produced by individual strains substantially improved dewaterability. The extracted slime EPS from six different strains were partially characterized. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

40 CFR 61.52 - Emission standard.

Code of Federal Regulations, 2012 CFR

2012-07-01

... standard. (a) Emissions to the atmosphere from mercury ore processing facilities and mercury cell chlor... atmosphere from sludge incineration plants, sludge drying plants, or a combination of these that process...

40 CFR 61.52 - Emission standard.

Code of Federal Regulations, 2013 CFR

2013-07-01

... standard. (a) Emissions to the atmosphere from mercury ore processing facilities and mercury cell chlor... atmosphere from sludge incineration plants, sludge drying plants, or a combination of these that process...

40 CFR 61.52 - Emission standard.

Code of Federal Regulations, 2014 CFR

2014-07-01

... standard. (a) Emissions to the atmosphere from mercury ore processing facilities and mercury cell chlor... atmosphere from sludge incineration plants, sludge drying plants, or a combination of these that process...

40 CFR 61.52 - Emission standard.

Code of Federal Regulations, 2011 CFR

2011-07-01

... standard. (a) Emissions to the atmosphere from mercury ore processing facilities and mercury cell chlor... atmosphere from sludge incineration plants, sludge drying plants, or a combination of these that process...

Response of bacteria in wastewater sludge to moisture loss by evaporation and effect of moisture content on bacterial inactivation by ionizing radiation.

PubMed Central

Ward, R L; Yeager, J G; Ashley, C S

1981-01-01

Two studies were carried out to determine the influence of moisture content of the survival of bacteria in raw wastewater sludge. The first study involved the effect of water loss by evaporation on the bacterial population. The second used these dewatered samples to measure the effects of moisture content on the inactivation of bacteria sludge by ionizing radiation. Both studies involved survival measurements of six representative fecally associated bacteria grown separately in sterilized sludge as well as survival data on bacteria indigenous to sludge. Growth of bacteria was stimulated in sludge during the initial phase of moisture removal by evaporation, but the reduction of moisture content below about 50% by weight caused a proportional decrease in bacterial numbers. In comparison with the original sludge, this decrease reached about one-half to one order of magnitude in all dried samples except those containing Proteus mirabilis, which decreased about four orders of magnitude. The rates of inactivation of bacteria by ionizing radiation in sludge were usually modified to some degrees by variations in moisture content. Most bacteria were found to be somewhat protected from ionizing radiation at reduced moisture levels. The largest effect was found with Salmonella typhimurium, whose radiation resistance approximately doubled in dried sludge. However, no excessively large D10 values were found for any bacterial species tested. PMID:6789765

Immersion frying for the thermal drying of sewage sludge: an economic assessment.

PubMed

Peregrina, Carlos; Rudolph, Victor; Lecomte, Didier; Arlabosse, Patricia

2008-01-01

This paper presents an economic study of a novel thermal fry-drying technology which transforms sewage sludge and recycled cooking oil (RCO) into a solid fuel. The process is shown to have significant potential advantage in terms of capital costs (by factors of several times) and comparable operating costs. Three potential variants of the process have been simulated and costed in terms of both capital and operating requirements for a commercial scale of operation. The differences are in the energy recovery systems, which include a simple condensation of the evaporated water and two different heat pump configurations. Simple condensation provides the simplest process, but the energy efficiency gain of an open heat pump offset this, making it economically somewhat more attractive. In terms of operating costs, current sludge dryers are dominated by maintenance and energy requirements, while for fry-drying these are comparatively small. Fry-drying running costs are dominated by provision of makeup waste oil. Cost reduction could focus on cheaper waste oil, e.g. from grease trap waste.

Forest land application of municipal sludge.

Treesearch

D.G. Brockway

1988-01-01

In Michigan, 199 municipal and numerous industrial wastewater treatment facilities annually generate 222,750 dry tons of sludge, most of which is recycled on farmland. Substantial potential exists, however, to increase application on forest land in the northern two-thirds of the state (Brockway and Nguyen 1986). Although sludge application on agricultural land has...

Beneficial uses program. Progress report, period ending June 30, 1979

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

Not Available

1979-10-01

Progress in research on the irradiation of sewage sludge, the potential use of dried sewage sludge as animal feed or soil conditioners, the inactivation of rotavirus in sewage sludge, fruit fly control by the irradiation of citrus fruits, and the production of /sup 137/Cs source pellets is reported. (LCL)

Municipal wastewater sludge as a sustainable bioresource in the United States.

PubMed

Seiple, Timothy E; Coleman, André M; Skaggs, Richard L

2017-07-15

Within the United States and Puerto Rico, publicly owned treatment works (POTWs) process 130.5 Gl/d (34.5 Bgal/d) of wastewater, producing sludge as a waste product. Emerging technologies offer novel waste-to-energy pathways through whole sludge conversion into biofuels. Assessing the feasibility, scalability and tradeoffs of various energy conversion pathways is difficult in the absence of highly spatially resolved estimates of sludge production. In this study, average wastewater solids concentrations and removal rates, and site specific daily average influent flow are used to estimate site specific annual sludge production on a dry weight basis for >15,000 POTWs. Current beneficial uses, regional production hotspots and feedstock aggregation potential are also assessed. Analyses indicate 1) POTWs capture 12.56 Tg/y (13.84 MT/y) of dry solids; 2) 50% are not beneficially utilized, and 3) POTWs can support seven regions that aggregate >910 Mg/d (1000 T/d) of sludge within a travel distance of 100 km. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Reuse of de-inking sludge from wastepaper recycling in cement mortar products.

PubMed

Yan, Shiqin; Sagoe-Crentsil, Kwesi; Shapiro, Gretta

2011-08-01

This paper presents results of an investigation into the use of de-inking sludge from a paper recycling mill as feedstock material in the manufacture of cement mortar products, including masonry blocks and mortar renders. Both physical and mechanical properties of mortar specimens containing various amounts of de-inking sludge were investigated. It was observed that the addition of de-inking sludge to cement mortar at a fixed water-to-cement ratio significantly reduced flow properties and increased setting time. Water absorption and volume of permeable voids of cement mortar increased with increased dosage of de-inking sludge, with a corresponding reduction of bulk density. The 91-day compressive strength of mortar samples with 2.5 wt% and 20 wt% de-inking sludge loadings retained 83% and 62% respectively of the reference mortar strength. The corresponding drying shrinkage increased by up to 160% compared to reference samples. However, a de-inking sludge loading of up to 2.5 wt% did not significantly alter measured physical and mechanical properties. The results demonstrate that despite the high moisture absorbance of de-inking sludge due to its organic matter and residual cellulose fibre content, it serves as a potential supplementary additive and its cellulosic content proving to be an active set retardant to cementitious masonry products. Copyright © 2011 Elsevier Ltd. All rights reserved.

Two-dimensional CFD modeling of the heat and mass transfer process during sewage sludge drying in a solar dryer

NASA Astrophysics Data System (ADS)

Krawczyk, Piotr; Badyda, Krzysztof

2011-12-01

The paper presents key assumptions of the mathematical model which describes heat and mass transfer phenomena in a solar sewage drying process, as well as techniques used for solving this model with the Fluent computational fluid dynamics (CFD) software. Special attention was paid to implementation of boundary conditions on the sludge surface, which is a physical boundary between the gaseous phase - air, and solid phase - dried matter. Those conditions allow to model heat and mass transfer between the media during first and second drying stages. Selection of the computational geometry is also discussed - it is a fragment of the entire drying facility. Selected modelling results are presented in the final part of the paper.

The slag original from the process of sewage sludge incineration selected properties characteristic

NASA Astrophysics Data System (ADS)

Głowacka, Anna; Rucińska, Teresa; Kiper, Justyna

2017-11-01

This work characterizes the physical and chemical properties of slag from combustion of municipal sewage sludge in "Pomorzany" waste treatment plant in Szczecin. The technology of sludge management is based on drying the sludge in low-temperature belt driers, to a content level of at least 90%, dry mass., and then burning in a grate boiler with mobile grate. The research of the slag resulting from combustion of municipal sewage sludge was conducted using reference methods, presenting images from a scanning electron microscope. The tested waste contained from 16.300 to 23.150% P2O5 completely soluble in strong acids, pH 8.03, mineral substance 98.73% dry mass. The content of heavy metals did not exceed the permissible amount specified in the Regulation of the Minister of Agriculture and Rural Development of 18 June 2008 on the implementation of certain provisions of the Act on fertilizers and fertilization (Journal of Laws of 2008 No. 119, item. 765). The screening trials showed that 48.4% are fractions of 630 µm-1.25 mm. The results show that the waste code 19 01 12 may be used as: alternative source of phosphorus for direct application to soil treatment, for production of organic - mineral fertilizers and as construction aggregate for production of concrete mortars.

Self-heating of dried industrial tannery wastewater sludge induced by pyrophoric iron sulfides formation.

PubMed

Bertani, R; Biasin, A; Canu, P; Della Zassa, M; Refosco, D; Simionato, F; Zerlottin, M

2016-03-15

Similarly to many powders of solids, dried sludge originated from tannery wastewater may result in a self-heating process, under given circumstances. In most cases, it causes a moderate heating (reaching 70-90°C), but larger, off-design residence times in the drier, in a suboxic atmosphere, extremely reactive solids can be produced. Tannery waste contains several chemicals that mostly end up in the wastewater treatment sludge. Unexpected and uncontrolled self heating could lead to a combustion and even to environmental problems. Elaborating on previous studies, with the addition of several analytical determinations, before and after the self-heating, we attempted to formulate a mechanism for the onset of heating. We demonstrated that the system Fe/S/O has been involved in the process. We proved that the formation of small quantities of pyrophoric iron sulfides is the key. They are converted to sulfated by reaction with water and oxygen with exothermic processes. The pyrite/pyrrhotite production depends on the sludge drying process. The oxidation of sulfides to oxides and sulfates through exothermic steps, reasonably catalyzed by metals in the sludge, occurs preferentially in a moist environment. The mechanism has been proved by reproducing in the laboratory prolonged heating under anoxic/suboxic atmosphere. Copyright © 2015 Elsevier B.V. All rights reserved.

Aged refuse enhances anaerobic digestion of waste activated sludge.

PubMed

Zhao, Jianwei; Gui, Lin; Wang, Qilin; Liu, Yiwen; Wang, Dongbo; Ni, Bing-Jie; Li, Xiaoming; Xu, Rui; Zeng, Guangming; Yang, Qi

2017-10-15

In this work, a low-cost alternative approach (i.e., adding aged refuse (AR) into waste activated sludge) to significantly enhance anaerobic digestion of sludge was reported. Experimental results showed that with the addition dosage of AR increasing from 0 to 400 mg/g dry sludge soluble chemical oxygen demand (COD) increased from 1150 to 5240 mg/L at the digestion time of 5 d, while the maximal production of volatile fatty acids (VFA) increased from 82.6 to 183.9 mg COD/g volatile suspended solids. Although further increase of AR addition decreased the concentrations of both soluble COD and VFA, their contents in these systems with AR addition at any concentration investigated were still higher than those in the blank, which resulted in higher methane yields in these systems. Mechanism studies revealed that pertinent addition of AR promoted solubilization, hydrolysis, and acidogenesis processes and did not affect methanogenesis significantly. It was found that varieties of enzymes and anaerobes in AR were primary reason for the enhancement of anaerobic digestion. Humic substances in AR benefited hydrolysis and acidogenesis but inhibited methanogenesis. The effect of heavy metals in AR on sludge anaerobic digestion was dosage dependent. Sludge anaerobic digestion was enhanced by appropriate amounts of heavy metals but inhibited by excessive amounts of heavy metals. The relative abundances of microorganisms responsible for sludge hydrolysis and acidogenesis were also observed to be improved in the system with AR addition, which was consistent with the performance of anaerobic digestion. Copyright © 2017 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.

Detection of methoxylated and hydroxylated polychlorinated biphenyls in sewage sludge in China with evidence for their microbial transformation

PubMed Central

Sun, Jianteng; Zhu, Lizhong; Pan, Lili; Wei, Zi; Song, Yao; Zhang, Yuduo; Qu, Liping; Zhan, Yu

2016-01-01

The concentrations of methoxylated polychlorinated biphenyls (MeO-PCBs) and hydroxylated polychlorinated biphenyls (OH-PCBs) were measured in the sewage sludge samples collected from twelve wastewater treatment plants in China. Two MeO-PCB congeners, including 3′-MeO-CB-65 and 4′-MeO-CB-101, were detected in three sludge with mean concentrations of 0.58 and 0.52 ng/g dry weight, respectively. OH-PCBs were detected in eight sludge samples, with an average total concentration of 4.2 ng/g dry weight. Furthermore, laboratory exposure was conducted to determine the possible source of OH-PCBs and MeO-PCBs in the sewage sludge, and their metabolism by the microbes. Both 4′-OH-CB-101 and 4′-MeO-CB-101 were detected as metabolites of CB-101 at a limited conversion rate after 5 days. Importantly, microbial interconversion between OH-PCBs and MeO-PCBs was observed in sewage sludge. Demethylation of MeO-PCBs was favored over methylation of OH-PCBs. The abundant and diverse microbes in sludge play a key role in the transformation processes of the PCB analogues. To our knowledge, this is the first report on MeO-PCBs in environmental matrices and on OH-PCBs in sewage sludge. The findings are important to understand the environmental fate of PCBs. PMID:27417462

Detection of methoxylated and hydroxylated polychlorinated biphenyls in sewage sludge in China with evidence for their microbial transformation

NASA Astrophysics Data System (ADS)

Sun, Jianteng; Zhu, Lizhong; Pan, Lili; Wei, Zi; Song, Yao; Zhang, Yuduo; Qu, Liping; Zhan, Yu

2016-07-01

The concentrations of methoxylated polychlorinated biphenyls (MeO-PCBs) and hydroxylated polychlorinated biphenyls (OH-PCBs) were measured in the sewage sludge samples collected from twelve wastewater treatment plants in China. Two MeO-PCB congeners, including 3‧-MeO-CB-65 and 4‧-MeO-CB-101, were detected in three sludge with mean concentrations of 0.58 and 0.52 ng/g dry weight, respectively. OH-PCBs were detected in eight sludge samples, with an average total concentration of 4.2 ng/g dry weight. Furthermore, laboratory exposure was conducted to determine the possible source of OH-PCBs and MeO-PCBs in the sewage sludge, and their metabolism by the microbes. Both 4‧-OH-CB-101 and 4‧-MeO-CB-101 were detected as metabolites of CB-101 at a limited conversion rate after 5 days. Importantly, microbial interconversion between OH-PCBs and MeO-PCBs was observed in sewage sludge. Demethylation of MeO-PCBs was favored over methylation of OH-PCBs. The abundant and diverse microbes in sludge play a key role in the transformation processes of the PCB analogues. To our knowledge, this is the first report on MeO-PCBs in environmental matrices and on OH-PCBs in sewage sludge. The findings are important to understand the environmental fate of PCBs.

Microbial safety of air-dried and rewetted biosolids.

PubMed

Rouch, Duncan A; Mondal, Tania; Pai, Sneha; Glauche, Florian; Fleming, Vennessa A; Thurbon, Nerida; Blackbeard, Judy; Smith, Stephen R; Deighton, Margaret

2011-06-01

To assess microbial safety of treated sewage sludge (biosolids), we examined the inactivation of microbial indicators for potential bacterial, viral and protozoan pathogens. The levels of indicators were determined throughout the air-drying and storage phases of anaerobically digested sewage sludge. Samples were collected from two wastewater treatment plants (WWTPS) in Victoria, Australia. Established methods were applied for analysis of bacteria and coliphages, based on membrane filtration and layered plates, respectively. In the pan drying phase, the prevalence of Escherichia coli was reduced by >5 log10 compared with sludge entering the pan. Thus, after pan drying of 8-11 months at WWTP A and 15 months at WWTP B, the numbers of E. coli were reduced to below 10(2) cfu/g dry solids (DS). This level is acceptable for unrestricted use in agriculture in Australia (P1 treatment grade), the UK (enhanced treatment status) and the USA (Class A pathogen reduction). Coliphage numbers also decreased substantially during the air-drying phase, indicating that enteric viruses are also likely to be destroyed during this phase. Clostridium perfringens appeared to be an overly conservative indicator. Survival, but not regrowth, of E. coli or Salmonella was observed in rewetted biosolids (15-20% moisture content), after being seeded with these species, indicating a degree of safety of stored biosolids upon rewetting by rain.

The influence of biosolids treatment files on the mobility of metal trace elements.

PubMed

Maisonnave, V; Montrejaud-Vignoles, M; Bonnin, C; Revel, J C; Vignoles, C

2001-01-01

The production of sludge in France is estimated to be about 900,000 metric tons dry matter per year and 60% of this is recycled onto agricultural land. At present, the long term future of this procedure is open to question and among the different arguments being put forward are the levels of metallic trace elements and the risk of accumulation in soils. This study presents the behaviour of metallic trace elements in sludges from three different treatment procedures: thickened liquid sludges, dewatered sludges and dried sludges. These biosolids are mixed with a clay soil and then placed in a temperature and humidity controlled glasshouse. Several containers are seeded with ryegrass and compared with controls. For the three harvests, covering all the amendments studied (including non-amended soil), the differences are not really representative. Absorption by the ryegrass is low in all cases. For the cadmium, the chromium, the nickel and the lead, the roots are 5 to 10 times more concentrated than the leaves. The majority of these elements stay absorbed in the roots, regardless of the amendment used. The addition of the sludges has considerably reduced the uptake of water in ryegrass throughout its growth cycle. Quite apart from their fertilizing qualities, wastewater treatment plant sludges could offer important implications for irrigation.

Selective enrichment of a methanol-utilizing consortium using pulp & paper mill waste streams

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

Gregory R. Mockos; William A. Smith; Frank J. Loge

Efficient utilization of carbon inputs is critical to the economic viability of the current forest products sector. Input carbon losses occur in various locations within a pulp mill, including losses as volatile organics and wastewater . Opportunities exist to capture this carbon in the form of value-added products such as biodegradable polymers. Waste activated sludge from a pulp mill wastewater facility was enriched for 80 days for a methanol-utilizing consortium with the goal of using this consortium to produce biopolymers from methanol-rich pulp mill waste streams. Five enrichment conditions were utilized: three high-methanol streams from the kraft mill foul condensatemore » system, one methanol-amended stream from the mill wastewater plant, and one methanol-only enrichment. Enrichment reactors were operated aerobically in sequencing batch mode at neutral pH and 25°C with a hydraulic residence time and a solids retention time of four days. Non-enriched waste activated sludge did not consume methanol or reduce chemical oxygen demand. With enrichment, however, the chemical oxygen demand reduction over 24 hour feed/decant cycles ranged from 79 to 89 %, and methanol concentrations dropped below method detection limits. Neither the non-enriched waste activated sludge nor any of the enrichment cultures accumulated polyhydroxyalkanoates (PHAs) under conditions of nitrogen sufficiency. Similarly, the non-enriched waste activated sludge did not accumulate PHAs under nitrogen limited conditions. By contrast, enriched cultures accumulated PHAs to nearly 14% on a dry weight basis under nitrogen limited conditions. This indicates that selectively-enriched pulp mill waste activated sludge can serve as an inoculum for PHA production from methanol-rich pulp mill effluents.« less

Application of municipal sewage sludge in forest and degraded land

Treesearch

D.H. Marx; C.R. Berry; Paul P. Kormanik

1995-01-01

Nearly 8 million dry tons of municipal sewage sludge are produced each year in the USA by the more than 15,000 publicly owned treatment plants and the tonnage is increasing.For two decades, researchers in the USA have been studying the feasibility of land application of municipal sewage sludge. Research, large-scale practical projects, and commercial ventures have...

Use of Municipal Sewage Sludge for Improvement of Forest Sites in the Southeast

Treesearch

Charles R. Berry

1987-01-01

In eight field experiments dried municipal sewage sludge was applied to forest sites before planting of seedlings. In all cases, tree growth was faster on sludge-amended plots than on plots that received fertilizer and lime or no amendment. Deep subsoiling was beneficial regardless of Soil amendment. Where weeds were plentiful at the outset, they became serious...

[Effect of Aeration Strategies on Emissions of Nitrogenous Gases and Methane During Sludge Bio-Drying].

PubMed

Qi, Lu; Wei, Yuan-song; Zhang, Jun-ya; Zhao, Chen-yang; Cai, Xing; Zhang, Yuan-li; Shao, Chun-yan; Li, Hong-mei

2016-01-15

The data on nitrogen gas (NH3, N2O, NO) emissions during sludge bio-drying process in China is scarce, especially NO due to its unstable chemical property. In this study, effect of two aeration modes on emissions of methane and nitrogenous gas was compared during the continuous aerated turning pile sludge bio-drying process at full scale. In these two aeration strategies, the one currently used in the plant was set as the control, and the other was set as the test in which the aeration was used for oxygen supply, pile temperature control, and moisture removal in the start-up, middle and final stages, respectively. The results showed that the aeration strategy used in the test could not only obviously accelerate the rate of sludge drying (the moisture contents of the test and the control were 36.6% and 42% on day 11) , but also had a better drying performance (the final moisture contents of the test and the control were 33.6% and 37.6%, respectively) and decreased the ammonia cumulative emission by 5%, (ammonia cumulative emission of the test and the control were 208 mg x m(-3) and 219.8 mg x m(-3), respectively). Though a lower accumulated emission (eCO2) of greenhouse gas in the test at 3.61 kg x t(-1) was observed than that of the control (3.73 kg x t(-1) dry weight) , the cumulative emission of NO in the test at 1.9 g x m(-2) was 15. 9% higher than that of the control (1.6 g x m(-2)).

Influence of sewage sludge, as a substrate, in the plasticity of functional characteristics of plants.

PubMed

da Silva, Vicente Elício Porfiro Sales Gonçalves; Buarque, Patrícia Marques Carneiro; Ferreira, Wanessa Nepomuceno; Buarque, Hugo Leonardo de Brito; Silva, Maria Amanda Menezes

2018-04-24

This work aimed to evaluate the effect of sewage sludge application as fertilizer on the plasticity of functional characteristics of species commonly found in the Caatinga. The research was developed in the nursery of the Federal Institute of Education, Science and Technology of Ceará (IFCE), Quixadá campus, located in northeastern Brazil. Three treatments were applied: raw sludge, sanitized sludge, and no manipulation. In each treatment, five species were planted, each with five individuals, totaling 75 individuals, which were tagged, and 4 months after germination, they were destroyed to obtain dry matter content (TMSF) from leaf, stem (TMSC), fine root (TMSRF), and thick root (TMSRG); leaf area; height and diameter of the seedling; and length above and below the ground. The sanitized sludge was responsible for giving higher values for leaf area, height of the seedlings, and diameter and length of stem and root. However, the dry matter content of the fine roots was higher in the treatment without manipulation. At the community level, as TMSRG increased, TMSC also increased, the same occurred between TMSRG and TMSRF, TMSC and TMSRF, and stem length and leaf area. In the treatment without manipulation, there was a positive correlation between leaf area, height and plant diameter, and negative correlation between root length and plant diameter. Thus, it can be concluded that the use of sanitized sludge is a good tool to increase the availability of soil resources, conferring to individuals' greater dry matter content, greater leaf area, and higher height and diameter above the ground.

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

Strength, leachability and microstructure characteristics of cement-based solidified plating sludge

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

Asavapisit, Suwimol; Naksrichum, Siripat; Harnwajanawong, Naraporn

2005-06-01

The solidification of the stabilized zinc-cyanide plating sludge was carried out using ordinary Portland cement (OPC) and pulverized fuel ash (PFA) as solidification binders. The plating sludge were used at the level of 0%, 10%, 20% and 30% dry weight, and PFA was used to replace OPC at 0%, 10%, 20% and 30% dry weight, respectively. Experimental results showed that a significant reduction in strength was observed when the plating sludge was added to both the OPC and OPC/PFA binders, but the negative effect was minimized when PFA was used as part substitute for OPC. SEM observation reveals that themore » deposition of the plating sludge on the surface of the clinkers and PFA could be the cause for hydration retardation. In addition, calcium zinc hydroxide hydrate complex and the unreacted di- and tricalcium silicates were the major phases in X-ray diffraction (XRD) patterns of the solidified plating waste hydrated for 28 days, although the retardation effect on hydration reactions but Cr concentration in toxicity characteristic leaching procedure (TCLP) leachates was lower than the U.S. EPA regulatory limit.« less

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.

Fabrication of microfibrillated cellulose gel from waste pulp sludge via mild maceration combined with mechanical shearing

Treesearch

Nusheng Chen; Junyong Zhu; Zhaohui Tong

2016-01-01

This article describes a facile route, which combines mild maceration of waste pulp sludge and a mechanical shearing process, to prepare microfibrillated cellulose (MFC) with a high storage modulus. In the maceration, the mixture of glacial acetic acid and hydrogen peroxide was used to extract cellulose from never-dried waste pulp sludge. Then, two different mechanical...

Helminth eggs inactivation efficiency by faecal sludge dewatering and co-composting in tropical climates.

PubMed

Koné, Doulaye; Cofie, Olufunke; Zurbrügg, Christian; Gallizzi, Katharina; Moser, Daya; Drescher, Silke; Strauss, Martin

2007-11-01

This study investigates helminth eggs removal and inactivation efficiency in a treatment process combining faecal sludge (FS) dewatering and subsequent co-composting with organic solid waste as a function of windrow turning frequency. Fresh public toilet sludge and septage mixed at a 1:2 ratio were dewatered on a drying bed. Biosolids with initial loads of 25-83 helminth eggs/g total solids (TS) were mixed with solid waste as bulking material for co-composting at a 1:2 volume ratio. Two replicate sets of compost heaps were mounted in parallel and turned at different frequencies during the active composting period: (i) once every 3 days and (ii) once every 10 days. Turning frequency had no effect on helminth eggs removal efficiency. In both setups, helminth eggs were reduced to <1 viable egg/g TS, thereby complying with the WHO guidelines 2006 for the safe reuse of FS.

Selective Enrichment of a Methanol-Utilizing Consortium Using Pulp and Paper Mill Waste Streams

NASA Astrophysics Data System (ADS)

Mockos, Gregory R.; Smith, William A.; Loge, Frank J.; Thompson, David N.

Efficient utilization of carbon inputs is critical to the economic viability of the current forest products sector. Input carbon losses occur in various locations within a pulp mill, including losses as volatile organics and wastewater. Opportunities exist to capture this carbon in the form of value-added products such as biodegradable polymers. Wasteactivated sludge from a pulp mill wastewater facility was enriched for 80 days for a methanol-utilizing consortium with the goal of using this consortium to produce biopolymers from methanol-rich pulp mill waste streams. Five enrichment conditions were utilized: three high-methanol streams from the kraft mill foul condensate system, one methanol-amended stream from the mill wastewater plant, and one methanol-only enrichment. Enrichment reactors were operated aerobically in sequencing batch mode at neutral pH and 25°C with a hydraulic residence time and a solids retention time of 4 days. Non-enriched waste activated sludge did not consume methanol or reduce chemical oxygen demand. With enrichment, however, the chemical oxygen demand reduction over 24-h feed/ decant cycles ranged from 79 to 89%, and methanol concentrations dropped below method detection limits. Neither the non-enriched waste-activated sludge nor any of the enrichment cultures accumulated polyhydroxyalkanoates (PHAs) under conditions of nitrogen sufficiency. Similarly, the non-enriched waste activated sludge did not accumulate PHAs under nitrogen-limited conditions. By contrast, enriched cultures accumulated PHAs to nearly 14% on a dry weight basis under nitrogen-limited conditions. This indicates that selectively enriched pulp mill waste activated sludge can serve as an inoculum for PHA production from methanol-rich pulp mill effluents.

Utilization of municipal sewage sludge as additives for the production of eco-cement.

PubMed

Lin, Yiming; Zhou, Shaoqi; Li, Fuzhen; Lin, Yixiao

2012-04-30

The effects of using dried sewage sludge as additive on cement property in the process of clinker burning were investigated in this paper. The eco-cement samples were prepared by adding 0.50-15.0% of dried sewage sludge to unit raw meal, and then the mixtures were burned at 1450 °C for 2 h. The results indicated that the major components in the eco-cement clinkers were similar to those in ordinary Portland cement. Although the C(2)S phase formation increased with the increase of sewage sludge content, it was also found that the microstructure of the mixture containing 15.0% sewage sludge in raw meal was significantly different and that a larger amount of pores were distributed in the clinker. Moreover, all the eco-cement pastes had a longer initial setting time and final setting time than those of plain cement paste, which increased as the sewage sludge content in the raw meal increased. All the eco-cement pastes had lower early flexural strengths, which increased as the sewage sludge content increased, while the compressive strengths decreased slightly. However, this had no significant effect on all the strengths at later stages. Furthermore, the leaching concentrations of all the types of eco-cement clinkers met the standard of Chinese current regulatory thresholds. Copyright © 2012 Elsevier B.V. All rights reserved.

A new settling velocity model to describe secondary sedimentation.

PubMed

Ramin, Elham; Wágner, Dorottya S; Yde, Lars; Binning, Philip J; Rasmussen, Michael R; Mikkelsen, Peter Steen; Plósz, Benedek Gy

2014-12-01

Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM(ZS). In addition, correlations between the Herschel-Bulkley rheological model parameters and sludge concentration were identified with data from batch rheological experiments. A 2-D axisymmetric CFD model of a circular SST containing the new settling velocity and rheological model was validated with full-scale measurements. Finally, it was shown that the representation of compression settling in the CFD model can significantly influence the prediction of sludge distribution in the SSTs under dry- and wet-weather flow conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomass production and nutrient removal by Chlorella sp. as affected by sludge liquor concentration.

PubMed

Åkerström, Anette M; Mortensen, Leiv M; Rusten, Bjørn; Gislerød, Hans Ragnar

2014-11-01

The use of microalgae for biomass production and nutrient removal from the reject water produced in the dewatering process of anaerobically digested sludge, sludge liquor, was investigated. The sludge liquor was characterized by a high content of total suspended solids (1590 mg L(-1)), a high nitrogen concentration (1210 mg L(-1)), and a low phosphorus concentration (28 mg L(-1)). Chlorella sp. was grown in sludge liquor diluted with wastewater treatment plant effluent water to different concentrations (12, 25, 40, 50, 70, and 100%) using batch mode. The environmental conditions were 25 °C, a continuous lightning of 115 μmol m(-2) s(-1), and a CO2 concentration of 3.0%. The highest biomass production (0.42-0.45 g dry weight L(-1) Day(-1)) was achieved at 40-50% sludge liquor, which was comparable to the production of the control culture grown with an artificial fertilizer. The biomass production was 0.12 and 0.26 g dry weight L(-1) Day(-1) at 12% and 100% sludge liquor, respectively. The percentage of nitrogen in the algal biomass increased from 3.6% in 12% sludge liquor and reached a saturation of ∼10% in concentrations with 50% sludge liquor and higher. The phosphorus content in the biomass increased linearly from 0.2 to 1.5% with increasing sludge liquor concentrations. The highest nitrogen removal rates by algal biosynthesis were 33.6-42.6 mg TN L(-1) Day(-1) at 40-70% sludge liquor, while the highest phosphorus removal rates were 3.1-4.1 mg TP L(-1) Day(-1) at 50-100% sludge liquor. Published by Elsevier Ltd.

Anaerobic storage as a pretreatment for enhanced biodegradability of dewatered sewage sludge.

PubMed

Xu, Huacheng; He, Pinjing; Wang, Guanzhao; Shao, Liming; Lee, Duujong

2011-01-01

Dewatered sewage sludge is often stored still before further processing and final disposal. This study showed that anaerobic storage of dewatered sewage sludge could hydrolyze organic matter from the sludge matrix, and increase soluble organic acid content from 90 to 2400 mg/L and soluble organic carbon content from 220 to 1650 mg/L. Correspondingly, the contents of proteins, celluloses and hemicelluloses were reduced by 2-9%. Applying anaerobic storage markedly enhanced the efficiency of the subsequent bio-drying process on stored sludge. Correspondingly, biogas and odor gas were produced immediately after commencing the sludge storage. Anaerobic storage with odor control can be applied as a pretreatment process for dewatered sewage sludge in wastewater treatment plants. Copyright © 2010 Elsevier Ltd. All rights reserved.

Performance of a system with full- and pilot-scale sludge drying reed bed units treating septic tank sludge in Brazil.

PubMed

Calderón-Vallejo, Luisa Fernanda; Andrade, Cynthia Franco; Manjate, Elias Sete; Madera-Parra, Carlos Arturo; von Sperling, Marcos

2015-01-01

This study investigated the performance of sludge drying reed beds (SDRB) at full- and pilot-scale treating sludge from septic tanks in the city of Belo Horizonte, Brazil. The treatment units, planted with Cynodon spp., were based on an adaptation of the first-stage of the French vertical-flow constructed wetland, originally developed for treating sewage. Two different operational phases were investigated; in the first one, the full-scale unit was used together with six pilot-scale columns in order to test different feeding strategies. For the second phase, only the full-scale unit was used, including a recirculation of the filtered effluent (percolate) to one of the units of the French vertical wetland. Sludge application was done once a week emptying a full truck, during 25 weeks. The sludge was predominantly diluted, leading to low solids loading rates (median values of 18 kgTS m(-2) year(-1)). Chemical oxygen demand removal efficiency in the full-scale unit was reasonable (median of 71%), but the total solids removal was only moderate (median of 44%) in the full-scale unit without recirculation. Recirculation did not bring substantial improvements in the overall performance. The other loading conditions implemented in the pilot columns also did not show statistically different performances.

Occurrence and estrogenic potency of eight bisphenol analogs in sewage sludge from the U.S. EPA targeted national sewage sludge survey.

PubMed

Yu, Xiaohua; Xue, Jingchuan; Yao, Hong; Wu, Qian; Venkatesan, Arjun K; Halden, Rolf U; Kannan, Kurunthachalam

2015-12-15

As health concerns over bisphenol A (BPA) in consumer products are mounting, this weak estrogen mimicking compound is gradually being replaced with structural analogs, whose environmental occurrence and estrogen risks are not well understood yet. We used high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to determine the concentrations of eight bisphenol analogs in 76 sewage sludge samples collected by the U.S. Environmental Protection Agency (EPA) in 2006/2007 from 74 wastewater treatment plants (WWTPs) in 35 states. Bisphenols were detected at the following concentration ranges (ng/g dry weight) and detection frequencies: BPA (6.5-4700; 100%); bisphenol S (BPS; <1.79-1480; 84%); bisphenol F (BPF; <1.79-242; 68%); bisphenol AF (BPAF; <1.79-72.2; 46%); bisphenol P (BPP; <1.79-6.42; <5%), bisphenol B (BPB; <1.79-5.60; <5%), and bisphenol Z (BPZ; <1.79--66.7; <5%). Bisphenol AP (BPAP) was not detected in any of the samples (<1.79 ng/g dw). Concentrations of BPA in sewage sludge were an order of magnitude higher than those reported in China but similar to those in Germany. The calculated 17β-estradiol equivalents (E2EQ) of bisphenols present in sludge samples were 7.74 (0.26-90.5) pg/g dw, which were three orders of magnitude lower than the estrogenic activity contributed by natural estrogens present in the sludge. The calculated mass loading of bisphenols through the disposal of sludge and wastewater was <0.02% of the total U.S. production. As the usage of BPA is expected to decline further, environmental emissions of BPS, BPF, and BPAF are likely to increase in the future. This study establishes baseline levels and estrogenic activity of diverse bisphenol analogs in sewage sludge. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of airflow rates and aeration mode on the respiration activity of four organic wastes: Implications on the composting process.

PubMed

Mejias, Laura; Komilis, Dimitrios; Gea, Teresa; Sánchez, Antoni

2017-07-01

The aim of this study was to assess the effect of the airflow and of the aeration mode on the composting process of non-urban organic wastes that are found in large quantities worldwide, namely: (i) a fresh, non-digested, sewage sludge (FSS), (ii) an anaerobically digested sewage sludge (ADSS), (iii) cow manure (CM) and (iv) pig sludge (PS). This assessment was done using respirometric indices. Two aeration modes were tested, namely: (a) a constant air flowrate set at three different initial fixed airflow rates, and (b) an oxygen uptake rate (OUR)-controlled airflow rate. The four wastes displayed the same behaviour namely a limited biological activity at low aeration, while, beyond a threshold value, the increase of the airflow did not significantly increase the dynamic respiration indices (DRI 1 max , DRI 24 max and AT 4 ). The threshold airflow rate varied among wastes and ranged from 42NL air kg -1 DMh -1 for CM and from 67 to 77NL air kg -1 DMh -1 for FSS, ADSS and PS. Comparing the two aeration modes tested (constant air flow, OUR controlled air flow), no statistically significant differences were calculated between the respiration activity indices obtained at those two aeration modes. The results can be considered representative for urban and non-urban organic wastes and establish a general procedure to measure the respiration activity without limitations by airflow. This will permit other researchers to provide consistent results during the measurement of the respiration activity. Results indicate that high airflows are not required to establish the maximum respiration activity. This can result in energy savings and the prevention of off-gas treatment problems due to the excessive aeration rate in full scale composting plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thin Layer Drying Kinetics of By-Products from Olive Oil Processing

PubMed Central

Montero, Irene; Miranda, Teresa; Arranz, Jose Ignacio; Rojas, Carmen Victoria

2011-01-01

The thin-layer behavior of by-products from olive oil production was determined in a solar dryer in passive and active operation modes for a temperature range of 20–50 °C. The increase in the air temperature reduced the drying time of olive pomace, sludge and olive mill wastewater. Moisture ratio was analyzed to obtain effective diffusivity values, varying in the oil mill by-products from 9.136 × 10−11 to 1.406 × 10−9 m2/s in forced convection (ma = 0.22 kg/s), and from 9.296 × 10−11 to 6.277 × 10−10 m2/s in natural convection (ma = 0.042 kg/s). Diffusivity values at each temperature were obtained using the Fick’s diffusion model and, regardless of the convection, they increased with the air temperature. The temperature dependence on the effective diffusivity was determined by an Arrhenius type relationship. The activation energies were found to be 38.64 kJ/mol, 30.44 kJ/mol and 47.64 kJ/mol for the olive pomace, the sludge and the olive mill wastewater in active mode, respectively, and 91.35 kJ/mol, 14.04 kJ/mol and 77.15 kJ/mol in natural mode, in that order. PMID:22174639

Migration and transformation of sulfur in the municipal sewage sludge during disposal in cement kiln.

PubMed

Huang, Yuyan; Li, Haoxin; Jiang, Zhengwu; Yang, Xiaojie; Chen, Qing

2018-05-07

The aim of this work was to investigate the migration and transformation of sulfur in the municipal sewage sludge during disposal in cement kiln, and better understand the emission of the sulfur related pollutants in this process. In consideration of the temperature conditions in the practical operation, municipal sewage sludge was pre-dried at 105 °C, and then dried at 210, 260 and 310 °C, co-combusted with cement raw mill at 800, 900 and 1000 °C, and 1350, 1400 and 1450 °C respectively in the laboratory. X-ray photoelectron spectroscopy (XPS) was used to determine the S2p spectral lines of the municipal sewage sludge treated in the different process. Besides, The Thermal Analysis-Thermogravimetry (DTA-TG), Back Scattered Electron (BSE) and Energy Dispersive Spectrometer (EDS) were also employed to explore the mechanism of sulfur subsistence at 1450 °C. The results indicate that sulfide, thiophene, sulfone and sulfate are mainly sulfur compound in the municipal sewage sludge dried at 105 °C. Sulfoxide, a new sulfur compound, appears after it is further dried at 210 °C. The relative contents of sulfide and thiophene are continuously declined as the drying temperature increases due to their evaporation, decomposition and transformation in this process. The transformation of sulfide and thiophene makes the relative contents of sulfoxide and sulfate accordingly increased. However, the relative content of sulfone experiences an elevating-lowering process while the dry temperature elevated from 210 to 310 °C. This case is related to its evaporation and decomposition, as well as its production for the transformation of sulfide and thiophene. In the co-combustion process, sulfide, thiophene and sulfone are entirely vanished for their evaporation, decomposition and transformation. Sulfone is still contained at 800 °C, but when the temperature unceasingly rises, it is completely decomposed or evaporated and sulfate is the only sulfur compound. The microstructures left by the gas release are also observed in the mixtures sintered at 1450 °C, however sulfate still exists even at 1450 °C. The BSE and EDS results show that the melt phase is the important contribution to the appearance of sulfate at the high temperature. These results will sever as a theoretically reference for the pollution control of the sulfur related pollutants in the disposal process of the municipal sewage sludge in cement kiln. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impact of drying and composting procedures on the concentrations of 4-nonylphenols, di-(2-ethylhexyl)phthalate and polychlorinated biphenyls in anaerobically digested sewage sludge.

PubMed

Gibson, Richard W; Wang, Min-Jian; Padgett, Emma; Lopez-Real, Joe M; Beck, Angus J

2007-07-01

Enhanced treatments of sewage sludge produce a more manageable product for agricultural use by stabilizing the material, removing water, and reducing the possibility of pathogen transfer. We investigated the impact of pilot-scale composting and drying of sludge on physicochemical characteristics and on the concentrations of some organic contaminants. During the 143 day composting procedure, organic matter fell 22% and moisture by half. Concentrations of 4-nonylphenols (4-NPs) fell by 88% and di-(2-ethylhexyl) phthalate (DEHP) by 60%; losses continued throughout the procedure. Losses of total polychlorinated biphenyls (PCBs) were 11%, mostly from the lower molecular weight congeners, suggesting volatilization as the most likely loss mechanism. The drying process was much shorter, 40 days, yet organic matter content decreased by 27% and moisture by 85%. Losses of 4-NPs (39%) and DEHP (22%) were less than in composting and stopped when moisture content became constant. There were no losses of PCBs. Both treatments are simple, practical procedures that reduce the volume of waste and are applicable in situ on farms. Composting would be the method of choice for reducing organic contaminants but requires much longer times than drying.

Utilization of alum sludge as chromium removal

NASA Astrophysics Data System (ADS)

Zahari, Nazirul Mubin; Sidek, Lariyah Mohd; Zulkifli, Muhammad Azmeer Asyraf; Hua, Chua Kok; Jalil, Nurulhidayah Abdul

2017-09-01

The amount of alum sludge produced at water treatment plant has become a problem where it is highly costly in order to dispose them. Various research was conducted to find the most suitable and economic alternative to recycle and reused of alum sludge. In this study, alum sludge was retrieved from Waterworks where it was dewatered, dried, grounded and sieved to obtain smallest particle sizes of alum sludge. The synthetic water was prepared at the laboratory in as it was used to imitate the properties of real water contaminated with chromium. This study was conducted to determine the percentage reduction of chromium concentration in synthetic water by using alum sludge as absorbent. The percentage reduction of chromium was observed under the effect of initial concentration of chromium and the height of alum sludge. The result indicates that chromium concentration reduction was the highest at the lowest initial concentration and at the highest height of alum sludge and vice versa.

Studies find more alternatives to soil cover

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

Not Available

1984-02-01

Researchers from Southern Illinois University at Carbondale have experimented with planting forage grasses on acid coal refuse after deeply incorporating sewage sludge and limestone. Studies were conducted at Peabody Coal Co.'s Will Scarlet Mine, two miles north of Stonefort, IL. Digested liquid sewage sludge was hauled from the Chicago Sanitation District and deposited one meter deep into holding basins adjacent to the study site. The material was then dried in these basins for two years. In 1979, a specially modified cable trencher opened trenches 8 cm wide to depths of 30 cm and 60 cm for various treatments. Researchers depositedmore » the dried sludge using a silage wagon and spread the limestone by hand. Eleven different treatments of sludge and limestone were deposited at the two different incorporation depths. In March 1981 three grasses--reed canary grass, red top, and tall fescue--were seeded in a randomized complete block design within each of the eleven treatments. The deep incorporation of sewage sludge and/or limestone improved the physical and chemical properties of the coal refuse sufficiently to establish and maintain good stands of these forage grasses. Also, in spite of the high concentration of heavy metals in coal refuse amended with sewage sludge, the plant uptake was less than the maximum suggested level for feed. Analysis showed that the sewage sludge increased the organic matter of the coal refuse and decreased the bulk density. Water retention was higher in the sewage sludge amended treatments, but there were no differences in the availability of water. The pH of coal refuse increased from 2.5 to 5.0 at higher rates of sludge or limestone.« less

Estimating the Health Risk Associated with the Use of Ecological Sanitation Toilets in Malawi.

PubMed

Kumwenda, Save; Msefula, Chisomo; Kadewa, Wilfred; Ngwira, Bagrey; Morse, Tracy

2017-01-01

Use of Ecological Sanitation (EcoSan) sludge is becoming popular due to increasing price of organic fertilizers in Malawi; however, there is little evidence on the associated risks. Quantitative microbiological risk assessment (QMRA) was done to determine health risks associated with use of EcoSan. Pathogens considered included Escherichia coli (E. coli) , Salmonella, and soil transmitted helminths (STHs). Exponential and Beta Poisson models were used to estimate the risk from helminthic and bacterial pathogens, respectively. Main exposure pathways were through poor storage of sludge, contamination of foods during drying, walking barefoot on the ground contaminated with sludge, pit emptying without protection, and application of sludge in the fields. Estimated annual risk for Ascaris lumbricoides, Taenia, and hookworms was approximately over 5.6 × 10 -1 for both Fossa Alternas (FAs) and Urine Diverting Dry Toilet (UDDTs). Risk from E. coli and Salmonella was 8.9 × 10 -2 and above. The risks were higher than WHO acceptable risk for use of faecal sludge in crops of 10 -4 infections per year. Promoters and users of EcoSan latrines need to consider advocating for strict guidelines to reduce the risk.

Investigation of sewage sludge treatment using air plasma assisted gasification.

PubMed

Striūgas, Nerijus; Valinčius, Vitas; Pedišius, Nerijus; Poškas, Robertas; Zakarauskas, Kęstutis

2017-06-01

This study presents an experimental investigation of downdraft gasification process coupled with a secondary thermal plasma reactor in order to perform experimental investigations of sewage sludge gasification, and compare process parameters running the system with and without the secondary thermal plasma reactor. The experimental investigation were performed with non-pelletized mixture of dried sewage sludge and wood pellets. To estimate the process performance, the composition of the producer gas, tars, particle matter, producer gas and char yield were measured at the exit of the gasification and plasma reactor. The research revealed the distribution of selected metals and chlorine in the process products and examined a possible formation of hexachlorobenzene. It determined that the plasma assisted processing of gaseous products changes the composition of the tars and the producer gas, mostly by destruction of hydrocarbon species, such as methane, acetylene, ethane or propane. Plasma processing of the producer gas reduces their calorific value but increases the gas yield and the total produced energy amount. The presented technology demonstrated capability both for applying to reduce the accumulation of the sewage sludge and production of substitute gas for drying of sewage sludge and electrical power. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimating the Health Risk Associated with the Use of Ecological Sanitation Toilets in Malawi

PubMed Central

Msefula, Chisomo; Kadewa, Wilfred; Ngwira, Bagrey; Morse, Tracy

2017-01-01

Use of Ecological Sanitation (EcoSan) sludge is becoming popular due to increasing price of organic fertilizers in Malawi; however, there is little evidence on the associated risks. Quantitative microbiological risk assessment (QMRA) was done to determine health risks associated with use of EcoSan. Pathogens considered included Escherichia coli (E. coli), Salmonella, and soil transmitted helminths (STHs). Exponential and Beta Poisson models were used to estimate the risk from helminthic and bacterial pathogens, respectively. Main exposure pathways were through poor storage of sludge, contamination of foods during drying, walking barefoot on the ground contaminated with sludge, pit emptying without protection, and application of sludge in the fields. Estimated annual risk for Ascaris lumbricoides, Taenia, and hookworms was approximately over 5.6 × 10−1 for both Fossa Alternas (FAs) and Urine Diverting Dry Toilet (UDDTs). Risk from E. coli and Salmonella was 8.9 × 10−2 and above. The risks were higher than WHO acceptable risk for use of faecal sludge in crops of 10−4 infections per year. Promoters and users of EcoSan latrines need to consider advocating for strict guidelines to reduce the risk. PMID:29250122

Similar PAH Fate in Anaerobic Digesters Inoculated with Three Microbial Communities Accumulating Either Volatile Fatty Acids or Methane

PubMed Central

Braun, Florence; Hamelin, Jérôme; Bonnafous, Anaïs; Delgenès, Nadine; Steyer, Jean-Philippe; Patureau, Dominique

2015-01-01

Urban sludge produced on wastewater treatment plants are often contaminated by organic pollutants such as polycyclic aromatic hydrocarbons (PAH). Their removal under methanogenic conditions was already reported, but the factors influencing this removal remain unclear. Here, we determined the influence of microbial communities on PAH removal under controlled physico-chemical conditions. Twelve mesophilic anaerobic digesters were inoculated with three microbial communities extracted from ecosystems with contrasting pollution histories: a PAH contaminated soil, a PCB contaminated sediment and a low contaminated anaerobic sludge. These anaerobic digesters were operated during 100 days in continuous mode. A sterilised activated sludge, spiked with 13 PAH at concentrations usually encountered in full-scale wastewater treatment plants, was used as substrate. The dry matter and volatile solid degradation, the biogas production rate and composition, the volatile fatty acids (VFA) production and the PAH removals were monitored. Bacterial and archaeal communities were compared in abundance (qPCR), in community structure (SSCP fingerprinting) and in dominant microbial species (454-pyrosequencing). The bioreactors inoculated with the community extracted from low contaminated anaerobic sludge showed the greater methane production. The PAH removals ranged from 10 % to 30 %, respectively, for high and low molecular weight PAH, whatever the inoculums tested, and were highly correlated with the dry matter and volatile solid removals. The microbial community structure and diversity differed with the inoculum source; this difference was maintained after the 100 days of digestion. However, the PAH removal was not correlated to these diverse structures and diversities. We hence obtained three functional stable consortia with two contrasted metabolic activities, and three different pictures of microbial diversity, but similar PAH and matter removals. These results confirm that PAH removal depends on the molecule type and on the solid matter removal. But, as PAH elimination is similar whether the solid substrate is degraded into VFA or into methane, it seems that the fermentative communities are responsible for their elimination. PMID:25874750

Similar PAH fate in anaerobic digesters inoculated with three microbial communities accumulating either volatile fatty acids or methane.

PubMed

Braun, Florence; Hamelin, Jérôme; Bonnafous, Anaïs; Delgenès, Nadine; Steyer, Jean-Philippe; Patureau, Dominique

2015-01-01

Urban sludge produced on wastewater treatment plants are often contaminated by organic pollutants such as polycyclic aromatic hydrocarbons (PAH). Their removal under methanogenic conditions was already reported, but the factors influencing this removal remain unclear. Here, we determined the influence of microbial communities on PAH removal under controlled physico-chemical conditions. Twelve mesophilic anaerobic digesters were inoculated with three microbial communities extracted from ecosystems with contrasting pollution histories: a PAH contaminated soil, a PCB contaminated sediment and a low contaminated anaerobic sludge. These anaerobic digesters were operated during 100 days in continuous mode. A sterilised activated sludge, spiked with 13 PAH at concentrations usually encountered in full-scale wastewater treatment plants, was used as substrate. The dry matter and volatile solid degradation, the biogas production rate and composition, the volatile fatty acids (VFA) production and the PAH removals were monitored. Bacterial and archaeal communities were compared in abundance (qPCR), in community structure (SSCP fingerprinting) and in dominant microbial species (454-pyrosequencing). The bioreactors inoculated with the community extracted from low contaminated anaerobic sludge showed the greater methane production. The PAH removals ranged from 10% to 30%, respectively, for high and low molecular weight PAH, whatever the inoculums tested, and were highly correlated with the dry matter and volatile solid removals. The microbial community structure and diversity differed with the inoculum source; this difference was maintained after the 100 days of digestion. However, the PAH removal was not correlated to these diverse structures and diversities. We hence obtained three functional stable consortia with two contrasted metabolic activities, and three different pictures of microbial diversity, but similar PAH and matter removals. These results confirm that PAH removal depends on the molecule type and on the solid matter removal. But, as PAH elimination is similar whether the solid substrate is degraded into VFA or into methane, it seems that the fermentative communities are responsible for their elimination.

Effective water content reduction in sewage wastewater sludge using magnetic nanoparticles.

PubMed

Lakshmanan, Ramnath; Kuttuva Rajarao, Gunaratna

2014-02-01

The present work compares the use of three flocculants for sedimentation of sludge and sludge water content from sewage wastewater i.e. magnetic iron oxide nanoparticles (MION), ferrous sulfate (chemical) and Moringa crude extract (protein). Sludge water content, wet/dry weight, turbidity and color were performed for, time kinetics and large-scale experiment. A 30% reduction of the sludge water content was observed when the wastewater was treated with either protein or chemical coagulant. The separation of sludge from wastewater treated with MION was achieved in less than 5min using an external magnet, resulted in 95% reduction of sludge water content. Furthermore, MION formed denser flocs and more than 80% reduction of microbial content was observed in large volume experiments. The results revealed that MION is efficient in rapid separation of sludge with very low water content, and thus could be a suitable alternative for sludge sedimentation and dewatering in wastewater treatment processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of water treatment sludges toxicity using the Daphnia bioassay.

PubMed

Sotero-Santos, Rosana B; Rocha, Odete; Povinelli, Jurandyr

2005-10-01

Alum and ferric chloride sludges from two water treatment plants (WTPs) were analyzed regarding their physicochemical characteristics and toxicity to Daphnia similis. Experiments were carried out in the dry and rainy seasons. Acute and chronic toxicity was measured using survival and reproduction as measurement endpoints. No acute toxicity of the sludge was observed in 48 h exposure. Ferric chloride sludge caused chronic toxicity, demonstrated by low fecundity and some mortality, while alum sludge caused chronic toxicity characterized by low fecundity. Some sludge characteristics varied between samplings, including turbidity, solids contents, N, P and metal (Al and Fe) concentrations. These variables and the increase of chemical oxygen demand (COD) were identified as the main cause of degradation of the receiving waters. However, no relationship was observed between these variables and degree of toxicity. It is apparent from these results that water treatment sludges may be toxic and therefore may impair receiving waters. Alum sludge was less toxic than ferric chloride sludge.

Biodiesel production from municipal secondary sludge.

PubMed

Kumar, Manish; Ghosh, Pooja; Khosla, Khushboo; Thakur, Indu Shekhar

2016-09-01

In the present study, feasibility of biodiesel production from freeze dried sewage sludge was studied and its yield was enhanced by optimization of the in situ transesterification conditions (temperature, catalyst and concentration of sludge solids). Optimized conditions (45°C, 5% catalyst and 0.16g/mL sludge solids) resulted in a 20.76±0.04% biodiesel yield. The purity of biodiesel was ascertained by GC-MS, FT-IR and NMR ((1)H and (13)C) spectroscopy. The biodiesel profile obtained revealed the predominance of methyl esters of fatty acids such as oleic, palmitic, myristic, stearic, lauric, palmitoleic and linoleic acids indicating potential use of sludge as a biodiesel feedstock. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacterial communities and their association with the bio-drying of sewage sludge.

PubMed

Cai, Lu; Chen, Tong-Bin; Gao, Ding; Yu, Jie

2016-03-01

Bio-drying is a technology that aims to remove water from a material using the microbial heat originating from organic matter degradation. However, the evolution of bacterial communities that are associated with the drying process has not been researched systematically. This study was performed to investigate the variations of bacterial communities and the relationships among bacterial communities, water evaporation, water generation, and organic matter degradation during the bio-drying of sewage sludge. High-throughput pyrosequencing was used to analyze the bacterial communities, while water evaporation and water generation were determined based on an in situ water vapor monitoring device. The values of water evaporation, water generation, and volatile solids degradation were 412.9 g kg(-1) sewage sludge bio-drying material (SSBM), 65.0 g kg(-1) SSBM, and 70.2 g kg(-1) SSBM, respectively. Rarefaction curves and diversity indices showed that bacterial diversity plummeted after the temperature of the bio-drying pile dramatically increased on d 2, which coincided with a remarkable increase of water evaporation on d 2. Bacterial diversity increased when the pile cooled. During the thermophilic phase, in which Acinetobacter and Bacillus were the dominant genera, the rates of water evaporation, water generation, and VS degradation peaked. These results implied that the elevated temperature reshaped the bacterial communities, which played a key role in water evaporation, and the high temperature also contributed to the effective elimination of pathogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

Environmental and economic life cycle assessment for sewage sludge treatment processes in Japan.

PubMed

Hong, Jinglan; Hong, Jingmin; Otaki, Masahiro; Jolliet, Olivier

2009-02-01

Life cycle assessment for sewage sludge treatment was carried out by estimating the environmental and economic impacts of the six alternative scenarios most often used in Japan: dewatering, composting, drying, incineration, incinerated ash melting and dewatered sludge melting, each with or without digestion. Three end-of-life treatments were also studied: landfilling, agricultural application and building material application. The results demonstrate that sewage sludge digestion can reduce the environmental load and cost through reduced dry matter volume. The global warming potential (GWP) generated from incineration and melting processes can be significantly reduced through the reuse of waste heat for electricity and/or heat generation. Equipment production in scenarios except dewatering has an important effect on GWP, whereas the contribution of construction is negligible. In addition, the results show that the dewatering scenario has the highest impact on land use and cost, the drying scenario has the highest impact on GWP and acidification, and the incinerated ash melting scenario has the highest impact on human toxicity due to re-emissions of heavy metals from incinerated ash in the melting unit process. On the contrary, the dewatering, composting and incineration scenarios generate the lowest impact on human toxicity, land use and acidification, respectively, and the incinerated ash melting scenario has the lowest impact on GWP and cost. Heavy metals released from atmospheric effluents generated the highest human toxicity impact, with the effect of dioxin emissions being significantly lower. This study proved that the dewatered sludge melting scenario is an environmentally optimal and economically affordable method.

Comparative study of the methods used for treatment and final disposal of sewage sludge in European countries.

PubMed

Kelessidis, Alexandros; Stasinakis, Athanasios S

2012-06-01

Municipal wastewater treatment results to the production of large quantities of sewage sludge, which requires proper and environmentally accepted management before final disposal. In European Union, sludge management remains an open and challenging issue for the Member States as the relative European legislation is fragmentary and quite old, while the published data concerning sludge treatment and disposal in different European countries are often incomplete and inhomogeneous. The main objective of the current study was to outline the current situation and discuss future perspectives for sludge treatment and disposal in EU countries. According to the results, specific sludge production is differentiated significantly between European countries, ranging from 0.1 kg per population equivalent (p.e.) and year (Malta) to 30.8 kg per p.e. and year (Austria). More stringent legislations comparing to European Directive 86/278/EC have been adopted for sludge disposal in soil by several European countries, setting lower limit values for heavy metals as well as limit values for pathogens and organic micropollutants. A great variety of sludge treatment technologies are used in EU countries, while differences are observed between Member States. Anaerobic and aerobic digestion seems to be the most popular stabilization methods, applying in 24 and 20 countries, respectively. Mechanical sludge dewatering is preferred comparing to the use of drying beds, while thermal drying is mainly applied in EU-15 countries (old Member States) and especially in Germany, Italy, France and UK. Regarding sludge final disposal, sludge reuse (including direct agricultural application and composting) seems to be the predominant choice for sludge management in EU-15 (53% of produced sludge), following by incineration (21% of produced sludge). On the other hand, the most common disposal method in EU-12 countries (new Member States that joined EU after 2004) is still landfilling. Due to the obligations set by Directive 91/271/EC, a temporary increase of sludge amounts that are disposed in landfills is expected during the following years in EU-12 countries. Beside the above, sludge reuse in land and sludge incineration seem to be the main practices further adopted in EU-27 (all Member States) up to 2020. The reinforcement of these disposal practices will probably result to adoption of advanced sludge treatment technologies in order to achieve higher pathogens removal, odors control and removal of toxic compounds and ensure human health and environmental protection. Copyright © 2012 Elsevier Ltd. All rights reserved.

Experimental rheological procedure adapted to pasty dewatered sludge up to 45 % dry matter.

PubMed

Mouzaoui, M; Baudez, J C; Sauceau, M; Arlabosse, P

2018-04-15

Wastewater sludge are characterized by complex rheological properties, strongly dependent on solids concentration and temperature. These properties are required for process hydrodynamic modelling but their correct measurement is often challenging at high solids concentrations. This is especially true to model the hydrodynamic of dewatered sludge during drying process where solids content (TS) increases with residence time. Indeed, until now, the literature mostly focused on the rheological characterization of sludge at low and moderate TS (between 4 and 8%). Limited attention was paid to pasty and highly concentrated sludge mainly because of the difficulties to carry out the measurements. Results reproducibility appeared to be poor and thus may not be always fully representative of the effective material properties. This work demonstrates that reproducible results can be obtained by controlling cracks and fractures which always take place in classical rotational rheometry. In that purpose, a well-controlled experimental procedure has been developed, allowing the exact determination of the surface effectively sheared. This surface is calculated by scattering a classical stress sweep with measurements at a reference strain value. The implementation of this procedure allows the correct determination of solid-like characteristics from 20 to 45% TS but also shows that pasty and highly concentrated sludge highlight normal forces caused by dilatancy. Moreover the surface correction appears to be independent of TS in the studied range. Copyright © 2018 Elsevier Ltd. All rights reserved.

Eucalyptus development in degraded soil fertilized with sewage sludge and mineral fertilizer

NASA Astrophysics Data System (ADS)

Rodrigues, R. A. F.; Santos, E. B.; Alves, M. C.; Arruda, O. G.

2012-04-01

The aim of this study was to compare the development of eucalyptus in a degraded Oxisol with mineral fertilizer and sewage sludge. The study was conducted in Selviria, Mato Grosso do Sul, Brasil. The culture of eucalyptus was planted in 2003 at 2.0 m x 1.5 m spacing, with application of 60 Mg ha-1 of sewage sludge (dry basis) and mineral fertilizer. After five years (2008) the area received biosolids and mineral fertilizer, and after five months, were evaluated for height and diameter at breast height of Eucalyptus. The experimental design was randomized blocks with four treatments: T1 - control (without addition of inputs), T2 - Mineral fertilization (30 kg ha-1 N, 90 kg ha-1 of P2O5 and 60 kg ha-1 K2O), T3 - Reapplication of 4.64 Mg ha-1 of sewage sludge, dry basis, T4 - Reapplication of 9.28 Mg ha-1 of sewage sludge, dry basis. Before reapplication the biosolids plant height was higher in the eucalyptus with treatment 9.28 Mg ha-1 of sewage sludge (8.03 m) compared to control (5.75 m) and mineral fertilizer (5.91 m) and that treatment 4.64 Mg ha-1 of sewage sludge (6.34 m) did not differ from the previous three. For the diameter at breast height was the highest value for treatment with 9.28 Mg ha-1 (7.78 cm) compared to control (5.23 cm) and 4.64 Mg ha-1 (5.03 cm), and that of mineral fertilizer (5.96 cm) did not differ from all treatments. After reapplication of sludge plant height was higher in the eucalyptus treatment with 9.28 Mg ha-1 of sewage sludge (11.21 m) compared with control (7.51 m), mineral fertilizer (7.77 m) and 4 64 Mg ha-1 (8.07 m), which did not differ. The diameter at breast height had the same behavior before the application of biosolids in the highest value observed being 9.28 Mg ha-1 (8.46 cm) compared with control (5.75 cm) and 4.64 Mg ha-1 (5.03 cm) and that of mineral fertilizer (6.34 cm) did not differ from the others. Reapplication of the dose of 9.28 Mg ha-1 of sewage sludge in degraded Oxisol provided greater height and diameter at breast height from eucalyptus trees.

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.

Utilization of sewage sludge in the manufacture of lightweight aggregate.

PubMed

Franus, Małgorzata; Barnat-Hunek, Danuta; Wdowin, Magdalena

2016-01-01

This paper presents a comprehensive study on the possibility of sewage sludge management in a sintered ceramic material such as a lightweight aggregate. Made from clay and sludge lightweight aggregates were sintered at two temperatures: 1100 °C (name of sample LWA1) and 1150 °C (name of sample LWA2). Physical and mechanical properties indicate that the resulting expanded clay aggregate containing sludge meets the basic requirements for lightweight aggregates. The presence of sludge supports the swelling of the raw material, thereby causing an increase in the porosity of aggregates. The LWA2 has a lower value of bulk particle density (0.414 g/cm(3)), apparent particle density (0.87 g/cm(3)), and dry particle density (2.59 g/cm(3)) than it is in the case of LWA1 where these parameters were as follows: bulk particle density 0.685 g/cm(3), apparent particle density 1.05 g/cm(3), and dry particle density 2.69 g/cm(3). Water absorption and porosity of LWA1 (WA = 14.4 %, P = 60 %) are lower than the LWA2 (WA = 16.2 % and P = 66 %). This is due to the higher heating temperature of granules which make the waste gases, liberating them from the decomposition of organic sewage sludge. The compressive strength of LWA2 aggregate is 4.64 MPa and for LWA1 is 0.79 MPa. Results of leaching tests of heavy metals from examined aggregates have shown that insoluble metal compounds are placed in silicate and aluminosilicate structure of the starting materials (clays and sludges), whereas soluble substances formed crystalline skeleton of the aggregates. The thermal synthesis of lightweight aggregates from clay and sludge mixture is a waste-free method of their development.

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.

Utilization of urban sewage sludge: Chinese perspectives.

PubMed

Chen, H; Yan, S-H; Ye, Z-L; Meng, H-J; Zhu, Y-G

2012-06-01

Urbanization and industrialization in China has resulted in a dramatic increase in the volume of wastewater and sewage sludge produced from wastewater treatment plants. Problems associated with sewage sludge have attracted increasing attention from the public and urban planners. How to manage sludge in an economically and environmentally acceptable manner is one of the critical issues that modern societies are facing. Sludge treatment systems consist of thickening, dewatering, and several different alternative main treatments (anaerobic digestion, aerobic digestion, drying, composting, and incineration). Agricultural application, landfill, and incineration are the principal disposal methods for sewage sludge in China. However, sewage sludge disposal in the future should focus on resource recovery, reducing environmental impacts and saving economic costs. The reuse of biosolids in all scenarios can be environmentally beneficial and cost-effective. Anaerobic digestion followed by land application is the preferable options due to low economic and energy costs and material reuse. It is necessary to formulate a standard suitable for the utilization of sewage sludge in China.

Enhancing methane production from waste activated sludge using a novel indigenous iron activated peroxidation pre-treatment process.

PubMed

Zhou, Xu; Wang, Qilin; Jiang, Guangming

2015-04-01

Methane production from anaerobic digestion of waste activated sludge (WAS) is limited by the slow hydrolysis rate and/or poor methane potential of WAS. This study presents a novel pre-treatment strategy based on indigenous iron (in WAS) activated peroxidation to enhance methane production from WAS. Pre-treatment of WAS for 30 min at 50mg H2O2/g total solids (dry weight) and pH 2.0 (iron concentration in WAS was 7 mg/g TS) substantially enhanced WAS solubilization. Biochemical methane potential tests demonstrated that methane production was improved by 10% at a digestion time of 16d after incorporating the indigenous iron activated peroxidation pre-treatment. Model-based analysis indicated that indigenous iron activated peroxidation pre-treatment improved the methane potential by 13%, whereas the hydrolysis rate was not significantly affected. The economic analysis showed that the proposed pre-treatment method can save the cost by $112,000 per year in a treatment plant with a population equivalent of 300,000. Copyright © 2015 Elsevier Ltd. All rights reserved.

Environmental assessment of different dewatering and drying methods on the basis of life cycle assessment.

PubMed

Stefaniak, J; Zelazna, A; Pawłowski, A

2014-01-01

Sewage sludge is an inevitable product of wastewater treatment in municipal wastewater plants and its amount has increased dramatically due to the growing number of sewage systems users. This sludge needs to be adequately treated in order to decrease its hazardous properties and any negative influence on the environment. In this paper, gate to gate analysis, on the basis of life cycle assessment (LCA), was carried out in order to compare the environmental impact of alternative ways of sludge processing employing a dewatering press and three different kinds of dryers - belt dryer, container dryer and batch dryer. SimaPro 7.2 software and Ecoinvent 2.2 database were used to estimate the carbon footprint and energy balance of these processes. The main energy consumption in the scenarios analyzed is caused by the drying process. The solution based on application of the batch dryer allows a saving of 39.6% of energy compared with the most energy-consuming solution using a belt dryer. Sludge processing using belt and container dryers cause greater environmental burdens.

Conversion of paper sludge to ethanol, II: process design and economic analysis.

PubMed

Fan, Zhiliang; Lynd, Lee R

2007-01-01

Process design and economics are considered for conversion of paper sludge to ethanol. A particular site, a bleached kraft mill operated in Gorham, NH by Fraser Papers (15 tons dry sludge processed per day), is considered. In addition, profitability is examined for a larger plant (50 dry tons per day) and sensitivity analysis is carried out with respect to capacity, tipping fee, and ethanol price. Conversion based on simultaneous saccharification and fermentation with intermittent feeding is examined, with ethanol recovery provided by distillation and molecular sieve adsorption. It was found that the Fraser plant achieves positive cash flow with or without xylose conversion and mineral recovery. Sensitivity analysis indicates economics are very sensitive to ethanol selling price and scale; significant but less sensitive to the tipping fee, and rather insensitive to the prices of cellulase and power. Internal rates of return exceeding 15% are projected for larger plants at most combinations of scale, tipping fee, and ethanol price. Our analysis lends support to the proposition that paper sludge is a leading point-of-entry and proving ground for emergent industrial processes featuring enzymatic hydrolysis of cellulosic biomass.

Microplastics in Sewage Sludge: Effects of Treatment.

PubMed

Mahon, A M; O'Connell, B; Healy, M G; O'Connor, I; Officer, R; Nash, R; Morrison, L

2017-01-17

Waste water treatment plants (WWTPs) are receptors for the cumulative loading of microplastics (MPs) derived from industry, landfill, domestic wastewater and stormwater. The partitioning of MPs through the settlement processes of wastewater treatment results in the majority becoming entrained in the sewage sludge. This study characterized MPs in sludge samples from seven WWTPs in Ireland which use anaerobic digestion (AD), thermal drying (TD), or lime stabilization (LS) treatment processes. Abundances ranged from 4196 to 15 385 particles kg -1 (dry weight). Results of a general linear mixed model (GLMM) showed significantly higher abundances of MPs in smaller size classes in the LS samples, suggesting that the treatment process of LS shears MP particles. In contrast, lower abundances of MPs found in the AD samples suggests that this process may reduce MP abundances. Surface morphologies examined using scanning electron microscopy (SEM) showed characteristics of melting and blistering of TD MPs and shredding and flaking of LS MPs. This study highlights the potential for sewage sludge treatment processes to affect the risk of MP pollution prior to land spreading and may have implications for legislation governing the application of biosolids to agricultural land.

Parasite contamination (helminth eggs) in sludge treatment plants: definition of a sampling strategy.

PubMed

Gaspard, Philippe G; Schwartzbrod, Janine

2003-03-01

The use of sludge in agriculture must be carried out according to many guidelines, especially regarding a precise knowledge of the pathogenic microorganisms it contains. The control of the produced sludge requires a sampling strategy that is representative of the contamination present in the sludge. Thus, we evaluated the distribution of helminth eggs in sludge to determine how to sample and at what frequency. Two plants were studied, firstly we studied sludge that was undergoing biological treatment (anaerobic digestion, prolonged aeration), secondly we evaluated the dehydration step (centrifugation and filter press). The helminth egg concentrations were measured over short periods (between 5 minutes and 7 hours) and for periods of over 24 hours (7 to 28 days). The results showed that there was much homogeneity in periods of less than 7 hours, thus it was advisable to take grab samples. An appropriate sample weight was 30 g dry matter, because this allowed an analysis in triplicate when testing treatment processes according to standards of France, (less than 3 viable eggs/10 g dry matter). Determination of the egg concentration in the plants during periods of over 24 hours showed that the parasite flow was stable. In some cases, large variations were due to the treatment processes (storage or thickening, mixing of different sludges). These results have been confirmed with the study of 6 other plants during a one year period. Thus, the recommended sampling frequency can be limited to every 3 to 6 months, by adapting the sampling methods to the characteristics of the plant.

Effect of Pseudomonas sp. HF-1 inoculum on construction of a bioaugmented system for tobacco wastewater treatment: analysis from quorum sensing.

PubMed

Wang, Mei-Zhen; He, Hong-Zhen; Zheng, Xin; Feng, Hua-Jun; Lv, Zhen-Mei; Shen, Dong-Sheng

2014-01-01

To better construct a bioaugmented system for tobacco wastewater treatment, activated sludge was inoculated with different concentrations of the nicotine-degrading bacterium Pseudomonas sp. HF-1. The results showed that inoculum concentrations of 0.55 ± 0.01 and 1.10 ± 0.03 mg/g (dry weight of strain HF-1/dry weight of activated sludge) were best to ensure strain HF-1 survival and successful bioaugmentation. The release pattern of autoinducer (AI) for quorum sensing in the bioaugmented system was also investigated. During the period of HF-1 inoculation, compared with failed bioaugmented systems, AI-2 was significantly increased in the successful systems, suggesting that AI-2-mediated bacterial communication played an important role in the colonization of HF-1. When inoculation of strain HF-1 was stopped, the amount of AI-2 decreased and leveled out in all systems. Notably, there was a greater than threefold increase of short-chain AHLs in failed bioaugmented systems, but no increase in successful ones, implying that the fluctuation of short-chain AHLs could be an indicator of the failure of bioaugmentation. Thus, AI-2-mediated quorum sensing could be implemented to facilitate HF-1 colonization.

PCDD/F, PAH and heavy metals in the sewage sludge from six wastewater treatment plants in Beijing, China.

PubMed

Dai, Jiayin; Xu, Muqi; Chen, Jiping; Yang, Xiangping; Ke, Zhenshan

2007-01-01

In order to better understand land application of sewage sludge, the characterization of heavy metals, PCDD/F and PAHs in sewage sludge was investigated from six different wastewater treatment plants (WWTP) in Beijing City, China. It was found that the total concentrations of Zn in Wujiacun (WJC) sewage sludge, and Cd and Hg in sewage sludge generated from all of the six different places are higher than Chinese regulation limit of pollutants for sludge to be used for agriculture (GB18918-2002). The levels of 16 PAHs that have been categorized as priority pollutants by US EPA in the sewage sludge samples varied from 2467 to 25923 microg/kg (dry weight), the highest values of 25923 microg/kg being found in WJC WWTP. The concentrations of Benzo[a]pyrene were as high as 6.1mg/kg dry weight in WJC sewage sludge, exceeding the maximum permitted content by GB18918-2002. Individual PAH content varies considerably with sewage samples. The ratios of anthracene to anthracene plus phenanthrene (An/178), benz[a]anthracene to benz[a]anthracene plus chrysene (BaA/228), indene[1,2,3-cd]pyrene to indene[1,2,3-cd]pyrene plus benzo[g,h,i]perylene (In/In+BP), and fluoranthene to fluoranthene plus pyrene (Fl/Fl+Py) suggest that petroleum and combustion of fossil fuel were the dominant contributions for the PAHs in sewage sludge. The concentrations of total PCDD/F in the sewage sludge ranged from 330 to 4245 pg/g d.w. The toxicity equivalent concentrations is between 3.47-88.24 pg I-TEQ according to NATO/CCMS, which is below Chinese legislation limit value proposed for land application. The PCDD/F congener/homologue profiles found in the Beijing samples indicated that the high chlorinated PCDD/F contamination might originate mainly from PCP-related source and depositional sources while the low chlorinated PCDD/F homologues could be originating from incineration or coal combustion. The major source of PCDD/Fs in Beijing sludge is still unclear.

Alternative fuels for multiple-hearth furnaces

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

Bracken, B.D.; Lawson, T.U.

1980-04-01

A study of alternative procedures for reducing the consumption of No. 2 fuel oil at the Lower Molonglo Water Quality Control Centre near Canberra, Aust., indicated that in comparison with the present system of incineration with heat supplied by burning fuel oil, the installation of a sludge drying operation, consisting of a rotary dryer heated by furnace exhaust gases with the dried sludge used to fuel the furnace, would become economically desirable by 1985 if afterburning is not required, and would be justified immediately if afterburning is required to meet air pollution control regulations. The substitution of any of fourmore » waste fuels (refuse-derived fuel, waste paper, wood waste, or waste oil) or of coal for the No. 2 fuel oil would not be cost-effective through 1989. The furnace system, including afterburning and fuel oil requirements, the envisioned alternative fuel use systems, sludge processing alternatives, heat balance results, and economics are discussed.« less

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.

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.

Monitoring of growth and physiological activities of biofilm during succession on polystyrene from activated sludge under aerobic and anaerobic conditions.

PubMed

Naz, Iffat; Batool, Syeda Ain-ul; Ali, Naeem; Khatoon, Nazia; Atiq, Niama; Hameed, Abdul; Ahmed, Safia

2013-08-01

The present research work monitored the successive biofilm development and its catabolic role in the degradation of polystyrene (PS). PS material was artificially colonized with biofilm by incubating it with activated sludge under aerobic and anaerobic conditions. Biofilm formation was monitored by gravimetric weight analysis, spectrophotometric absorbance technique, heterotrophic plate count, and scanning electron microscopy under aerobic and anaerobic conditions. The wet weight (1.59 and 1.17 g) and dry weight (0.41 and 0.08 g) of a biofilm showed a significant constant increase under aerobic and anaerobic conditions, respectively, from first till 9 weeks of incubation. Plate count of the selected bacteria (Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Pseudomonas aeruginosa) considerably declined (90-99 %) in the biofilm after seventh and fifth weeks of incubation under aerobic and anaerobic conditions, respectively, indicating a positive shift from pathogenic to beneficial microbial community. While most probable number index of fecal coliforms and E. coli in the sludge showed more reduction (98 and 99 %) under aerobic as compare to anaerobic conditions (86 and 91 %) after 9 weeks of biofilm formation on PS cubes. Correspondingly, the decreasing levels of chemical oxygen demand and biochemical oxygen demand (up to 73 %) showed signs of sludge digestion. Scanning electron microscope coupled with energy dispersive X-ray spectroscope revealed nature of PS media containing high carbon content. However, biofilm development proved to be involved in the biochemical transformation of the PS medium as indicated by Fourier transform infrared spectroscopy.

Transformation of phosphorus during drying and roasting of sewage sludge.

PubMed

Li, Rundong; Yin, Jing; Wang, Weiyun; Li, Yanlong; Zhang, Ziheng

2014-07-01

Sewage sludge (SS), a by-product of wastewater treatment, consists of highly concentrated organic and inorganic pollutants, including phosphorus (P). In this study, P with different chemical fractions in SS under different drying and roasting temperatures was investigated with the use of appropriate standards, measurements, and testing protocol. The drying and roasting treatment of SS was conducted in a laboratory-scale furnace. Two types of SS samples under different treatment temperatures were analyzed by (31)P NMR spectroscopy. These samples were dried by a vacuum freeze dryer at -50°C and a thermoelectric thermostat drying box at 105°C. Results show that the inorganic P (IP) content increased as the organic P content decreased, and the bio-availability of P increased because IP is a form of phosphorousthat can be directly absorbed by plants. (31)P NMR analysis results indicate the change in P fractions at different temperatures. Non-apatite P was the dominant form of P under low-temperature drying and roasting, whereas apatite P was the major one under high-temperature drying and roasting. Results indicate that temperature affects the transformation of P. Copyright © 2014 Elsevier Ltd. All rights reserved.

40 CFR Table 5 to Subpart Llll of... - Summary of Reporting Requirements for New Sewage Sludge Incineration Units a

Code of Federal Regulations, 2013 CFR

2013-07-01

.... Documentation for siting requirements. 4. Anticipated date of initial startup. § 60.4915(a). Notification of initial startup Prior to initial startup 1. Maximum design dry sewage sludge burning capacity2.... 4. Anticipated date of initial startup. 5. Site-specific monitoring plan. 6. The site-specific...

40 CFR Table 5 to Subpart Llll of... - Summary of Reporting Requirements for New Sewage Sludge Incineration Units a

Code of Federal Regulations, 2014 CFR

2014-07-01

.... Documentation for siting requirements. 4. Anticipated date of initial startup. § 60.4915(a). Notification of initial startup Prior to initial startup 1. Maximum design dry sewage sludge burning capacity2.... 4. Anticipated date of initial startup. 5. Site-specific monitoring plan. 6. The site-specific...

Production of extracellular polymeric substances (EPS) by Serratia sp.1 using wastewater sludge as raw material and flocculation activity of the EPS produced.

PubMed

Bezawada, J; Hoang, N V; More, T T; Yan, S; Tyagi, N; Tyagi, R D; Surampalli, R Y

2013-10-15

Growth profile and extracellular polymeric substances (EPS) production of Serratia sp.1 was studied in shake flask fermentation for 72 h using wastewater sludge as raw material. Maximum cell concentration of 6.7 × 10(9) cfu/mL was obtained at 48 h fermentation time. EPS dry weight, flocculation activity and dewaterability of different EPS (tightly bound or TB-EPS, loosely bound or LB-EPS and broth-EPS or B-EPS) were also measured. The highest concentration of LB-EPS (2.45 g/L) and TB-EPS (0.99 g/L) were attained at 48 h of fermentation. Maximum flocculation activity and dewaterability (ΔCST) of TB-EPS (76.4%, 14.5s and 76.5%, 15.5s), LB-EPS (67.8%, 8.1s and 64.7%, 7.6s) and broth EPS (61%, 6.1s and 70.4%, 6.8s) were obtained at 36 and 48 h of growth. Higher flocculation activity and dewaterability were achieved with TB-EPS than with the two other EPS. Characterization of TB-EPS and LB-EPS was done in terms of their protein and carbohydrate content. Protein content was much higher in TB-EPS where as carbohydrate content was only slightly higher in TB-EPS than LB-EPS. Morphology of the Serratia strain after fermentation in sludge and TSB was observed under a scanning electron microscope and the cell size was found to be bigger in the sludge medium than the TSB medium. Copyright © 2013 Elsevier Ltd. All rights reserved.

Behavior, fate, and mass loading of short chain chlorinated paraffins in an advanced municipal sewage treatment plant.

PubMed

Zeng, Lixi; Li, Huijuan; Wang, Thanh; Gao, Yan; Xiao, Ke; Du, Yuguo; Wang, Yawei; Jiang, Guibin

2013-01-15

Sewage treatment plants (STP) are an important source of short chain chlorinated paraffins (SCCPs) to the ambient environment through discharge of effluent and application of sludge. In this work, a field study was conducted to determine the behavior and possible removal of SCCPs during the sewage treatment process in an advanced municipal STP in Beijing, China. SCCPs were detected in all sewage water and sludge samples, and 97% of the initial mass loading in raw sewage was found to be associated with suspended matter. The total concentrations in raw influent, tertiary effluent, and dewatered sludge were 184 ± 19 ng/L, 27 ± 6 ng/L, and 15.6 ± 1.4 μg/g dry weight (d.w.), respectively. The dissolved concentrations of total SCCPs (∑SCCPs) significantly decreased during mechanical, biological, and chemical treatments. SCCP homologue profiles in aqueous phase were distinctly different from those in solid phase. Along the treatment process, the relative abundance of shorter chain and lower chlorinated congeners gradually increased in sewage water, but no obvious variations of homologue profiles were found in sludge. Mass flow analysis indicated, the removal efficiency in aqueous phase for ∑SCCPs was 82.2%, and the congener-specific removal efficiencies were positively related to their solid-water partition coefficients (K(d)). Mass balance results indicated that 0.8% and 72.6% of the initial SCCP mass loading were ultimately found in the effluents and dewatered sludge, respectively, while the remaining 26.6% was lost mainly due to biodegradation/biotransformation. It was suggested that the activated sludge system including basic anaerobic-anoxic-aerobic processes played an effective role in removing SCCPs from the wastewater, while the sorption to sludge by hydrophobic interactions was an important fate of SCCPs during the sewage treatment.

Analysis of the combustion and pyrolysis of dried sewage sludge by TGA and MS.

PubMed

Magdziarz, Aneta; Werle, Sebastian

2014-01-01

In this study, the combustion and pyrolysis processes of three sewage sludge were investigated. The sewage sludge came from three wastewater treatment plants. Proximate and ultimate analyses were performed. The thermal behaviour of studied sewage sludge was investigated by thermogravimetric analysis with mass spectrometry (TGA-MS). The samples were heated from ambient temperature to 800 °C at a constant rate 10 °C/min in air (combustion process) and argon flows (pyrolysis process). The thermal profiles presented in form of TG/DTG curves were comparable for studied sludges. All TG/DTG curves were divided into three stages. The main decomposition of sewage sludge during the combustion process took place in the range 180-580 °C with c.a. 70% mass loss. The pyrolysis process occurred in lower temperature but with less mass loss. The evolved gaseous products (H2, CH4, CO2, H2O) from the decomposition of sewage sludge were identified on-line. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparing the use of sewage sludge ash and glass powder in cement mortars.

PubMed

Chen, Zhen; Poon, Chi Sun

2017-06-01

This study explored the suitability of using sewage sludge ash (SSA) and mixed-colored glass powder (MGP) as construction materials in cement mortars. Positive findings from this study may help promote the recycling of waste SSA and MGP in construction works. The results indicated that the SSA decreased while MGP improved the mortar workability. The SSA exhibited very low pozzolanic activity, but the cement mortar prepared with 20% SSA yielded strength values slightly superior to those of the glass mortars due to its water absorption ability. MGP can serve as a pozzolan and when 20% of cement was replaced by MGP, apparent compressive strength gains were found at later curing ages. The SSA could be used to mitigate ASR expansion while the MGP was superior in resisting drying shrinkage.

Presence and fate of coliphages and enteric viruses in three wastewater treatment plants effluents and activated sludge from Tunisia.

PubMed

Jebri, Sihem; Jofre, Juan; Barkallah, Insaf; Saidi, Mouldi; Hmaied, Fatma

2012-07-01

The role of water in the transmission of infectious diseases is well defined; it may act as a reservoir of different types of pathogens. Enteric viruses can survive and persist for a long time in water, maintaining infectivity in many instances. This suggests the need to include virus detection in the evaluation of the microbiological quality of waters. In this study, enteric viruses (enteroviruses and hepatitis A virus (HAV)) were investigated by RT-PCR and coliphages (known as indicators of viral contamination) were enumerated with the double-layer technique agar in effluents and sewage sludge from three Tunisian wastewater treatment plants. The molecular detection of enteric viruses revealed 7.7% of positive activated sludge samples for enteroviruses. None of the samples was positive for HAV. Molecular virus detection threshold was estimated to be 10(3) PFU/100 ml. All samples contained high concentrations of coliphages except those of dry sludge. Reductions in the concentrations of bacteriophages attained by the wastewater treatment plants are of the order of magnitude as reductions described elsewhere. Peak concentrations in raw wastewater were associated with winter rains and suspended materials rate in analysed samples. Our data which is the first in North Africa showed that similar trends of coliphages distribution to other studies in other countries. No clear correlation between studied enteric viruses and coliphages concentration was proved. Coliphages abundance in collected samples should raise concerns about human enteric viruses transmission as these residues are reused in agricultural fields.

Hydraulic conductivity of fly ash-sewage sludge mixes for use in landfill cover liners.

PubMed

Herrmann, Inga; Svensson, Malin; Ecke, Holger; Kumpiene, Jurate; Maurice, Christian; Andreas, Lale; Lagerkvist, Anders

2009-08-01

Secondary materials could help meeting the increasing demand of landfill cover liner materials. In this study, the effect of compaction energy, water content, ash ratio, freezing, drying and biological activity on the hydraulic conductivity of two fly ash-sewage sludge mixes was investigated using a 2(7-1) fractional factorial design. The aim was to identify the factors that influence hydraulic conductivity, to quantify their effects and to assess how a sufficiently low hydraulic conductivity can be achieved. The factors compaction energy and drying, as well as the factor interactions material x ash ratio and ash ratio x compaction energy affected hydraulic conductivity significantly (alpha=0.05). Freezing on five freeze-thaw cycles did not affect hydraulic conductivity. Water content affected hydraulic conductivity only initially. The hydraulic conductivity data were modelled using multiple linear regression. The derived models were reliable as indicated by R(adjusted)(2) values between 0.75 and 0.86. Independent on the ash ratio and the material, hydraulic conductivity was predicted to be between 1.7 x 10(-11)m s(-1) and 8.9 x 10(-10)m s(-1) if the compaction energy was 2.4 J cm(-3), the ash ratio between 20% and 75% and drying did not occur. Thus, the investigated materials met the limit value for non-hazardous waste landfills of 10(-9)m s(-1).

Relative effectiveness of sewage sludge as a nitrogen fertilizer for tall fescue

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

Kiemnec, G.L.; Jackson, T.L.; Hemphill, D.D. Jr.

Sewage sludge application rates on grasses are mainly determined by N availability and concentration of toxic metals in sludge. The exact availability of N in sludge is difficult to predict. A 3-yr study was conducted to determine which sludge rates would give yields of tall fescue (Festuca arundinacea Shreb. Alta) comparable to yields obtained from inorganic N application. Sludge and NH/sub 4/NO/sub 3/ were surface applied at annual rates of 0, 110, 220, 440, and 880 (sludge only) kg N/ha. Dry matter yield of tall fescue from sludge-treated soils was 36, 56, and 50% of that on NH/sub 4/NO/sub 3/-treatedmore » soils for 1976, 1977, and 1978, respectively. Sludge was 27, 41, and 44% as effective as NH/sub 4/NO/sub 3/ as a source of available N in 1976, 1977, and 1978, respectively. Ammonium-N in the sewage sludge apparently provided most of the available N for fescue growth. Concentrations of Zn, Cd, and Cu were higher and Mn lower in tall fescue grown on sludge-treated soil with NH/sub 4/NO/sub 3/ and usually increased toward the end of the growing season. However, plant concentrations of these heavy metals never reached toxic levels at any time. Sewage sludge was an effective and safe nutrient source for tall fescue.« less

SOURCES OF PCBS TO THE ATMOSPHERE IN CHICAGO

EPA Science Inventory

The project will obtain additional short-term PCB samples in southwestern Chicago to determine the amount of PCB emissions to the air from a sludge drying facility. Four different types of samples will be collected: (1) short-term ambient air samples surrounding the drying beds,...

Occurrence and fate of perfluorinated acids in two wastewater treatment plants in Shanghai, China.

PubMed

Zhang, Chaojie; Yan, Hong; Li, Fei; Zhou, Qi

2015-02-01

Perfluorinated acids (PFAs) have drawn much attention due to their environmental persistence, ubiquitous existence, and bioaccumulation potential. The discharge of wastewater effluent from municipal wastewater treatment plants (WWTPs) is a significant source of PFAs to the environment. In this study, wastewater and sludge samples were collected from two WWTPs in Shanghai, China, to investigate the contamination level and fate of PFAs in different stages of processing. The total concentrations of PFAs (∑PFAs) in influent from plants A and B were 2,452 and 292 ng L(-1), respectively. Perfluoropentanoic acid (1,520 ± 80 ng L(-1) in plant A and 89.2 ± 12.1 ng L(-1) in plant B) was the predominant PFA in influent waters, followed by perfluorooctanoic acid. The concentration of ∑PFAs ranged from 75.0 to 126.0 ng g(-1) dry weight in sludge samples from plant B, with perfluorooctanesulfonic acid as the predominant contaminant. The concentrations and fate of PFAs in different WWTPs vary. The ∑PFAs entering plant A decreased significantly in the final effluent of activated sludge process, while that in plant B increased significantly in the final effluent of sequencing batch reactor system. The concentration changes could be due to the sorption onto sludge, or the degradation of PFAs precursors.

Palmarosa [Cymbopogon martinii (Roxb.) Wats.] as a putative crop for phytoremediation, in tannery sludge polluted soil.

PubMed

Pandey, Janhvi; Chand, Sukhmal; Pandey, Shipra; Rajkumari; Patra, D D

2015-12-01

A field experiment using tannery sludge as a soil amendment material and palmarosa (Cymbopogon martinii) as a potential phytostabilizer was conducted to investigate their synergistic effect in relation to the improvement in soil quality/property. Three consecutive harvests of two cultivars of palmarosa-PRC-1 and Trishna, were examined to find out the influence of different tannery sludge doses on their herb, dry matter, essential oil yield and heavy metal accumulation. Soil fertility parameters (N, P, K, Organic carbon) were markedly affected by different doses of sludge. Enhanced soil nitrogen was positively correlated with herb yield (0.719*) and plant height (0.797*). The highest dose of tannery sludge (100 t ha(-1)) exhibited best performance than other treatments with respect to herb, dry matter and oil yield in all three harvests. Trishna was found to be superior to PRC-1 in relation to same studied traits. Quality of oil varied, but was insignificant statistically. Uptake of heavy metals followed same order (Cr>Ni>Pb>Cd) in roots and shoots. Translocation factor <1 for all trace elements and Bioconcentration factor >1 was observed in case of all heavy metals. Overall, tannery sludge enhanced the productivity of crop and metal accumulation occurred in roots with a meager translocation to shoots, hence it can be used as a phytostabiliser. The major advantage of taking palmarosa in metal polluted soil is that unlike food and agricultural crops, the product (essential oil) is extracted by hydro-distillation and there is no chance of oil contamination, thus is commercially acceptable. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of olive mill wastewaters on the oxygen consumption by activated sludge microorganisms: an acute toxicity test method.

PubMed

Paixão, S M; Anselmo, A M

2002-01-01

The test for inhibition of oxygen consumption by activated sludge (ISO 8192-1986 (E)) was evaluated as a tool for assessing, the acute toxicity of olive mill wastewaters (OMW). According to the ISO test, information generated by this method may be helpful in estimating the effect of a test material on bacterial communities in the aquatic environment, especially in aerobic biological treatment systems. However, the lack of standardized bioassay methodology for effluents imposed that the test conditions were modified and adapted. The experiments were conducted in the presence or absence of an easily biodegradable carbon source (glucose) with different contact times (20 min and 24 h). The results obtained showed a remarkable stimulatory effect of this effluent to the activated sludge microorganisms. In fact, the oxygen uptake rate values increase with increasing effluent concentrations and contact times up to 0.98 microl O(2) h(-1) mg(-1) dry weight for a 100% OMW sample, 24 h contact time, with blanks exhibiting an oxygen uptake rate of ca. 1/10 of this value (0.07-0.10). It seems that the application of the ISO test as an acute toxicity test for effluents should be reconsidered, with convenient adaptation for its utilization as a method of estimating the effect on bacterial communities present in aerobic biological treatment systems. Copyright 2002 John Wiley & Sons, Ltd.

Beneficial reuse of precast concrete industry sludge to produce alkaline stabilized biosolids.

PubMed

Gowda, C; Seth, R; Biswas, N

2008-01-01

The precast concrete industry generates waste called concrete sludge during routine mixer tank washing. It is highly alkaline and hazardous, and typically disposed of by landfilling. This study examined the stabilization of municipal sewage sludge using concrete sludge as an alkaline agent. Sewage sludge was amended with 10 to 40% of concrete sludge by wet weight, and 10 and 20% of lime by dry weight of the sludge mix. Mixes containing 30 and 40% of concrete sludge with 20% lime fulfilled the primary requirements of Category 1 and 2 (Canada) biosolids of maintaining a pH of 12 for at least 72 hours. The heavy metals were below Category 1 regulatory limits. The 40% concrete sludge mix was incubated at 52 degrees C for 12 of the 72 hours to achieve the Category 1 and 2 regulations of less than 1000 fecal coliform/g solids. The nutrient content of the biosolids was 8.2, 10 and 0.6 g/kg of nitrogen, phosphorus and potassium respectively. It can be used as a top soil or augmented with potassium for use as fertilizer. The study demonstrates that concrete sludge waste can be beneficially reused to produce biosolids, providing a long-term sustainable waste management solution for the concrete industry.

Production of polyhydroxyalkanoates (PHA) by bacterial consortium from excess sludge fermentation liquid at laboratory and pilot scales.

PubMed

Jia, Qianqian; Xiong, Huilei; Wang, Hui; Shi, Hanchang; Sheng, Xinying; Sun, Run; Chen, Guoqiang

2014-11-01

The generation of polyhydroxyalkanoates (PHA) from excess sludge fermentation liquid (SFL) was studied at lab and pilot scale. A PHA-accumulated bacterial consortium (S-150) was isolated from activated sludge using simulated SFL (S-SFL) contained high concentration volatile fatty acids (VFA) and nitrogen. The maximal PHA content accounted for 59.18% in S-SFL and dropped to 23.47% in actual SFL (L-SFL) of the dry cell weight (DCW) at lab scale. The pilot-scale integrated system comprised an anaerobic fermentation reactor (AFR), a ceramic membrane system (CMS) and a PHA production bio-reactor (PHAR). The PHA content from pilot-scale SFL (P-SFL) finally reached to 59.47% DCW with the maximal PHA yield coefficient (YP/S) of 0.17 g PHA/g COD. The results indicated that VFA-containing SFL was suitable for PHA production. The adverse impact of excess nitrogen and non-VFAs in SFL might be eliminated by pilot-scale domestication, which might resulted in community structure optimization and substrate selective ability improvement of S-150. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of heavy metals contained in soil irrigated with a mixture of sewage sludge and effluent for thirty years on soil microbial biomass and plant growth

NASA Astrophysics Data System (ADS)

Katanda, Y.; Mushonga, C.; Banganayi, F.; Nyamangara, J.

The use of sewage effluent as a source of nutrients and water in peri-urban crop production is widespread in developing countries. A study was conducted in 2005 at Crowborough and Firle farms (near Harare) to assess effect of Cd on microbial biomass and activity, effect of sewage sludge and effluent on soybean (Glycine max L (Merr)) nodulation, and uptake of Zn and Cu by lettuce ( Lactuca sativa L.), mustard rape ( Brassica juncea L.), covo ( Brassica napus) and star grass ( Cynodon nlemfuensis). The soil that was used had been irrigated with sewage sludge and effluent for 30 years. Soil collected from Crowborough farm was enriched with Cd to different concentrations (0.4-5 mg Cd kg -1 soil) using Cd(NO 3) 2 and microbial biomass C and N (chloroform-incubation extraction) and respiration rates (CO 2 evolution) determined. A similar experiment to determine the effect of repeated addition of small amounts of Cd to soil over time on the same parameters was conducted. Three vegetables and star grass were grown in a pot experiment and harvested at six weeks after transplanting for the determination of above ground dry matter yield, and Zn and Cu, uptake. In another pot experiment, two soybean varieties, Magoye and Solitaire, were harvested after eight weeks and nodule number and effectiveness, and above ground dry matter yield were then determined. Cd significantly decreased biomass C (68%) and N (73%). Microbial respiration also significantly decreased. It was concluded that long-term application of sewage sludge and effluent to soil has negative effects on soil micro organisms, including Rhizobia. These micro organisms are essential for N-fixation. The damage to Rhizobia, caused diminished nodulation of soybean. Mustard rape and lettuce can accumulate Zn and Cu beyond toxic limits without apparent reduction in growth thereby posing a serious concern to the food chain. The consumption of mustard rape and lettuce grown on soil amended with sewage sludge and effluent at Crowborough and Firle farms poses a health risk to people who consume vegetables grown in this area.

PROCESS DESIGN MANUAL: LAND APPLICATION OF ...

EPA Pesticide Factsheets

Land application of sewage sludge generated by domestic sewage treatment is performed in an environmentally safe and cost–effective manner in many communities. Land application involves taking advantage of the fertilizing and soil conditioning properties of sewage sludge by spreading the sewage sludge on the soil surface, incorporating or injecting the sewage sludge into soil, or spraying the sewage sludge. Because sewage sludge disposal practices (e.g., landfilling) are becoming less available and more costly, and because of the increasing desire to beneficially reuse waste residuals whenever possible, land application is increasingly chosen as a sewage sludge use or disposal practice. Approximately 33 percent of the 5.4 million dry metric tons of sewage sludge generated annually in the United States at publicly owned treatment works (POTWs) is land applied. Of the sewage sludge that is land applied, approximately 67% is land applied on agricultural lands, 3% on forest lands, approximately 9% on reclamation sites, and 9% on public contact sites; 12% is sold or given away in a bag or other container for application to the land (Federal Register, Vol. 58, No. 32, February 19, 1993). In addition, approximately 8.6 billion gallons of domestic septage is generated annually. Land application of sewage sludge has been practiced in many countries for centuries so that the nutrients (e.g., nitrogen, phosphorus) and organic matter in sewage sludge can be beneficia

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.

Life cycle assessment of two emerging sewage sludge-to-energy systems: evaluating energy and greenhouse gas emissions implications.

PubMed

Cao, Yucheng; Pawłowski, Artur

2013-01-01

A "cradle-to-grave" life cycle assessment was conducted to examine the energy and greenhouse gas (GHG) emission footprints of two emerging sludge-to-energy systems. One system employs a combination of anaerobic digestion (AD) and fast pyrolysis for bioenergy conversion, while the other excludes AD. Each system was divided into five process phases: plant construction, sludge pretreatment, sludge-to-bioenergy conversion, bioenergy utilizations and biochar management. Both systems achieved energy and GHG emission benefits, and the AD-involving system performed better than the AD-excluding system (5.30 vs. 0.63 GJ/t sludge in net energy gain and 0.63 vs. 0.47 t CO(2)eq/t sludge in emission credit for base case). Detailed contribution and sensitivity analyses were conducted to identify how and to what degree the different life-cycle phases are responsible for the energy and emission impacts. The energy and emission performances were significantly affected by variations in bioenergy production, energy requirement for sludge drying and end use of bioenergy. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of Surfactants on the Improvement of Sludge Dewaterability Using Cationic Flocculants

PubMed Central

Zhai, Jun; Teng, Houkai; Zhao, Chun; Zhao, Chuanliang; Liao, Yong

2014-01-01

The effects of the cationic surfactant (cationic cetyl trimethyl ammonium bromide, CTAB) on the improvement of the sludge dewaterability using the cationic flocculant (cationic polyacrylamide, CPAM) were analyzed. Residual turbidity of supernatant, dry solid (DS) content, extracellular polymeric substances (EPS), specific resistance to filtration (SRF), zeta potential, floc size, and settling rate were investigated, respectively. The result showed that the CTAB positively affected the sludge conditioning and dewatering. Compared to not using surfactant, the DS and the settling rate increased by 8%–21.2% and 9.2%–15.1%, respectively, at 40 mg·L−1 CPAM, 10×10−3 mg·L−1 CTAB, and pH 3. The residual turbidities of the supernatant and SRF were reduced by 14.6%–31.1% and 6.9%–7.8% compared with turbidities and SRF without surfactant. Furthermore, the release of sludge EPS, the increases in size of the sludge flocs, and the sludge settling rate were found to be the main reasons for the CTAB improvement of sludge dewatering performance. PMID:25347394

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…

Sewage sludge drying by energy recovery from OFMSW composting: Preliminary feasibility evaluation

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

Rada, Elena Cristina; Ragazzi, Marco; Villotti, Stefano

2014-05-01

Highlights: • The aim is to support the drying of sewage sludge, using a solar greenhouse. • The system allows the exploitation of heat available from OFMSW aerobic process. • Another aim is to face the problem of OFMSW treatment, in particular food waste. • Energy and mass balances are presented for a case study. - Abstract: In this paper an original energy recovery method from composting is analyzed. The integrated system exploits the heat available from the aerobic biochemical process in order to support the drying of sewage sludge, using a specific solar greenhouse. The aim is to tacklemore » the problem of organic waste treatment, with specific regard to food waste. This is done by optimizing the energy consumption of the aerobic process of composting, using the heat produced to solve a second important waste management problem such as the sewage waste treatment. Energy and mass balances are presented in a preliminary feasibility study. Referring to a composting plant with a capacity of 15,000 t/y of food waste, the estimation of the power from recovered heat for the entire plant resulted about 42 kW. The results demonstrated that the energy recoverable can cover part of the heat necessary for the treatment of sludge generated by the population served by the composting plant (in terms of food waste and green waste collection). The addition of a renewable source such as solar energy could cover the residual energy demand. The approach is presented in detail in order for it to be replicated in other case studies or at full scale applications.« less

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.

Impacts of tilling and covering treatments on the biosolids solar drying conversion from Class B to Class A

USDA-ARS?s Scientific Manuscript database

The objective of this study was to evaluate the effects of tillage and cover treatments of solar drying on the conversion of Class B treated sewage sludge to a Class A product. The experiments were performed over two years at Green Valley, Arizona in steel-constructed sand-filled drying beds of 1.0m...

Anaerobic digestion of thermal pre-treated sludge at different solids concentrations--Computation of mass-energy balance and greenhouse gas emissions.

PubMed

Pilli, Sridhar; More, Tanaji; Yan, Song; Tyagi, Rajeshwar Dayal; Surampalli, Rao Y

2015-07-01

The effect of thermal pre-treatment on sludge anaerobic digestion (AD) efficiency was studied at different total solids (TS) concentrations (20.0, 30.0 and 40.0 g TS/L) and digestion times (0, 5, 10, 15, 20 and 30 days) for primary, secondary and mixed wastewater sludge. Moreover, sludge pre-treatment, AD and disposal processes were evaluated based on a mass-energy balance and corresponding greenhouse gas (GHG) emissions. Mass balance revealed that the least quantity of digestate was generated by thermal pre-treated secondary sludge at 30.0 g TS/L. The net energy (energy output-energy input) and energy ratio (energy output/energy input) for thermal pre-treated sludge was greater than control in all cases. The reduced GHG emissions of 73.8 × 10(-3) g CO2/g of total dry solids were observed for the thermal pre-treated secondary sludge at 30.0 g TS/L. Thermal pre-treatment of sludge is energetically beneficial and required less retention time compared to control. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation of phthalate and di-(2-ethylhexyl)phthalate by indigenous and inoculated microorganisms in sludge-amended soil

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

Roslev, P.; Madsen, P.L.; Thyme, J.B.

The metabolism of phthalic acid (PA) and di-(2-ethylhexyl) (DEHP) in sludge-amended agricultural soil was studied with radiotracer techniques. The initial rates of metabolism of PA and DEHP were estimated to be 731.8 and 25.6 pmol/g (dry weight) per day, respectively. Indigenous microorganisms assimilated 28 and 17% of the carbon in [{sup 14}C]PA and [{sup 14}C]DEHP, respectively, into microbial biomass. The rates of DEHP metabolism were much greater in sludge assays without soil than in assays with sludge-amended soil. Mineralization of [{sup 14}C]DEHP to {sup 14}CO{sub 2} increased fourfold after inoculation of sludge and soil samples with DEHP-degrading strain SDE 2.more » The elevated mineralization potential was maintained for more than 27 days. Experiments performed with strain SDE 2 suggested that the bioavailability and mineralization of DEHP decreased substantially in the presence of soil and sludge components. The microorganisms metabolizing PA and DEHP in sludge and sludge-amended soil were characterized by substrate-specific radiolabelling, followed by analysis of {sup 14}C-labelled phospholipid ester-linked fatty acids ({sup 14}C-PLFAs).« less

Concentrations and speciation of heavy metals in sludge from nine textile dyeing plants.

PubMed

Liang, Xin; Ning, Xun-an; Chen, Guoxin; Lin, Meiqing; Liu, Jingyong; Wang, Yujie

2013-12-01

The safe disposal of sludge from textile dyeing industry requires research on bioavailability and concentration of heavy metals. In this study, concentrations and chemical speciation of heavy metals (Cd, Cr, Cu, Ni, Zn, Pb) in sludge from nine different textile dyeing plants were examined. Some physiochemical features of sludge from textile dyeing industry were determined, and a sequential extraction procedure recommended by the Community Bureau of Reference (BCR) was used to study the metal speciation. Cluster analysis (CA) and principal component analysis (PCA) were applied to provide additional information regarding differences in sludge composition. The results showed that Zn and Cu contents were the highest, followed by Ni, Cr, Cd and Pb. The concentration of Cd and Ni in some sludge samples exceeded the standard suggested for acidic soils in China (GB18918-2002). In sludge from textile dyeing plants, Pb, Cd and Cr were principally distributed in the oxidizable and residual fraction, Cu in the oxidizable fraction, Ni in all four fractions and Zn in the acid soluble/exchangeable and reducible fractions. The pH and heat-drying method affected the fractionation of heavy metals in sludge. © 2013 Elsevier Inc. All rights reserved.

Full-scale phosphorus recovery from digested waste water sludge in Belgium - part I: technical achievements and challenges.

PubMed

Marchi, A; Geerts, S; Weemaes, M; Schiettecatte, W; Wim, S; Vanhoof, C; Christine, V

2015-01-01

To date, phosphorus recovery as struvite in wastewater treatment plants has been mainly implemented on water phases resulting from dewatering processes of the sludge line. However, it is possible to recover struvite directly from sludge phases. Besides minimising the return loads of phosphorus from the sludge line to the water line, placing such a process within the sludge line is claimed to offer advantages such as a higher recovery potential, enhanced dewaterability of the treated sludge, and reduced speed of scaling in pipes and dewatering devices. In the wastewater treatment plant at Leuven (Belgium), a full-scale struvite recovery process from digested sludge has been tested for 1 year. Several monitoring campaigns and experiments provided indications of the efficiency of the process for recovery. The load of phosphorus from the sludge line returning to the water line as centrate accounted for 15% of the P-load of the plant in the reference situation. Data indicated that the process divides this phosphorus load by two. An improved dewaterability of 1.5% of dry solids content was achieved, provided a proper tuning of the installation. Quality analyses showed that the formed struvite was quite pure.

Scale-up and economic analysis of biodiesel production from municipal primary sewage sludge.

PubMed

Olkiewicz, Magdalena; Torres, Carmen M; Jiménez, Laureano; Font, Josep; Bengoa, Christophe

2016-08-01

Municipal wastewater sludge is a promising lipid feedstock for biodiesel production, but the need to eliminate the high water content before lipid extraction is the main limitation for scaling up. This study evaluates the economic feasibility of biodiesel production directly from liquid primary sludge based on experimental data at laboratory scale. Computational tools were used for the modelling of the process scale-up and the different configurations of lipid extraction to optimise this step, as it is the most expensive. The operational variables with a major influence in the cost were the extraction time and the amount of solvent. The optimised extraction process had a break-even price of biodiesel of 1232 $/t, being economically competitive with the current cost of fossil diesel. The proposed biodiesel production process from waste sludge eliminates the expensive step of sludge drying, lowering the biodiesel price. Copyright © 2016 Elsevier Ltd. All rights reserved.

Feasibility Study on Manufacturing Lightweight Aggregates from Water Purification Sludge

NASA Astrophysics Data System (ADS)

Peng, Ching-Fang; Chen, How-Ji

2018-02-01

This study mainly discussed the feasibility of manufacturing lightweight aggregates from water purification sludge in Taiwan. They were analysed for the physical and chemical composition before the sintering test for lightweight aggregates in a laboratory. Then the physical and mechanical properties of the synthesized aggregates were assessed. The result showed that the chemical composition of sludge in the water purification plants was within the appropriate range for manufacturing lightweight aggregate as proposed in the literature. The sintering test demonstrated that the particle density of aggregates from the ten types of water purification sludge were mostly less than 1.8 g/cm3. In addition, the dry unit weight, the organic impurity, the ignition loss, and other characteristics of synthesized aggregates met the requirement of CNS standards, while its water absorption and crushing strength also fulfilled the general commercial specifications. Therefore, reclamation of water purification sludge for production of lightweight aggregate is indeed feasible.

Effect of water treatment sludge on growth and elemental composition of tomato (Lycopersicon esculentum) shoots

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

Elliott, H.A.; Singer, L.M.

The impact of a water treatment sludge on the fertility of a silt loam soil was assessed by monitoring the yield and elemental composition of tomato (Lycopersicon esculentum) shoots in a greenhouse study. Application of sludge at rates from 2-10% (air dry weight basis) raised the soil pH from 5.3 to 8.0 which enhanced plant growth. A substantial reduction in metal (Cd, Zn, Cu, Ni) uptake was observed with sludge amendments, even at the highest rates. The alkaline nature of this sludge (pH=9.3, calcium carbonate equivalence=53%) suggest its potential use as a liming material for agricultural soils. Overly alkaline conditionsmore » should be avoided however, as high application rates combined with ammonia fertilization had an antagonistic effect on plant growth, possibly from P deficiency induced by struvite (MgNH{sub 4}PO{sub 4}) formation.« less

Improvement of growth of Eucalyptus globulus and soil biological parameters by amendment with sewage sludge and inoculation with arbuscular mycorrhizal and saprobe fungi.

PubMed

Arriagada, C; Sampedro, I; Garcia-Romera, I; Ocampo, J

2009-08-15

Sewage sludge is widely used as an organic soil amendment to improve soil fertility. We investigated the effects of sewage sludge (SS) application on certain biological parameters of Eucalyptus globulus Labill. The plant was either uninoculated or inoculated with saprobe fungi (Coriolopsis rigida and Trichoderma harzianum) or arbuscular mycorrhizal (AM) fungi (Glomus deserticola and Gigaspora rosea). Sewage sludge was applied to the surface of experimental plots at rates of 0, 2, 4, 6 and 8 g 100 g(-1) of soil. Inoculation with both AM and saprobe fungi in the presence of SS was essential for the promotion of plant growth. The AM, saprobe fungi and SS significantly increased dry shoot weight. The AM fungi induced a significant increase in Fluorescein diacetate (FDA) activity but did not increase beta-glucosidase activity. Addition of SS to AM-inoculated soil did not affect either FDA or alpha-glucosidase activities in plants from soil that was either uninoculated or inoculated with the saprobe fungi. SS increased beta-glucosidase activity when it was applied at 4 g 100 g(-1). SS negatively affected AM colonization as well as the mycelium SDH activity for both mycorrhizal fungi. SS increased Eucalyptus shoot biomass and enhanced its nutrient status. Inoculation of the soil with G. deserticola stimulated significant E. globulus growth and increases in shoot tissue content of N, P, K, Ca, Mg and Fe. Dual inoculation with G. deserticola and either of the saprobe fungi had positive effects on K, Ca, Mg and Fe contents. The application of 8 g 100 g(-1) of SS had no positive effects on plant nutrition. The experimental setup provided a suitable tool for evaluating SS in combination with saprobe and AM fungi as a biological fertiliser for its beneficial effects on E. globulus plant growth.

Preliminary Study of Thermal Treatment of Coke Wastewater Sludge Using Plasma Torch

NASA Astrophysics Data System (ADS)

Li, Mingshu; Li, Shengli; Sun, Demao; Liu, Xin; Feng, Qiubao

2016-10-01

Thermal plasma was applied for the treatment of coke wastewater sludge derived from the steel industry in order to investigate the feasibility of the safe treatment and energy recovery of the sludge. A 30 kW plasma torch system was applied to study the vitrification and gas production of coke wastewater sludge. Toxicity leaching results indicated that the sludge treated via the thermal plasma process converted into a vitrified slag which resisted the leaching of heavy metals. CO2 was utilized as working gas to study the production and heat energy of the syngas. The heating value of the gas products by thermal plasma achieved 8.43 kJ/L, indicating the further utilization of the gas products. Considering the utilization of the syngas and recovery heat from the gas products, the estimated treatment cost of coke wastewater sludge via plasma torch was about 0.98 CNY/kg sludge in the experiment. By preliminary economic analysis, the dehydration cost takes an important part of the total sludge treatment cost. The treatment cost of the coke wastewater sludge with 50 wt.% moisture was calculated to be about 1.45 CNY/kg sludge dry basis. The treatment cost of the coke wastewater sludge could be effectively controlled by decreasing the water content of the sludge. These findings suggest that an economic dewatering pretreatment method could be combined to cut the total treatment cost in an actual treatment process.

Key issues to consider when using alum sludge as substrate in constructed wetland.

PubMed

Zhao, Xiaohong; Zhao, Yaqian; Wang, Wenke; Yang, Yongzhe; Babatunde, Akintunde; Hu, Yuansheng; Kumar, Lordwin

2015-01-01

Globally, alum sludge is an easily, locally and largely available by-product from water treatment plants where aluminium sulphate is used as the coagulant for raw water purification. Owing to the high content of Al ions (29.7±13.3% dry weight) in alum sludge and the strong affinity of Al ions to adsorb various pollutants especially phosphorus (P), alum sludge (in the form of dewatered cakes) has been investigated in recent years as a low-cost alternative substrate in constructed wetland (CW) systems to enhance the treatment efficiency especially for high strength P-containing wastewater. Long-term trials in different scales have demonstrated that the alum sludge-based CW is a promising technique with a two-pronged feature of using 'waste' for wastewater treatment. Alum sludge cakes in CW can serve as a medium for wetland plant growth, as a carrier for biofilm development and as a porous material for wastewater infiltration. After the intensive studies of the alum sludge-based CW system, this paper aims to address the key issues and concerns pertaining to this kind of CW system. These include: (1) Is alum sludge suitable for reuse in CWs? (2) Is Al released from the sludge a concern? (3) What is the lifespan of the alum sludge in CWs? (4) How can P be recovered from the used alum sludge? (5) Does clogging happen in alum sludge-based CW systems and what is the solution?

The Ruhrverband sewage sludge disposal concept in the conflict between European and German standards and regulations.

PubMed

Evers, P; Schmitt, F; Albrecht, D R; Jardin, N

2005-01-01

The Ruhrverband, acting as a water association responsible for integrated water resources management within the entire natural river basin of the Ruhr, operates a network of 83 wastewater treatment plants (WWTPs) and connected sludge disposal facilities. According to German regulations, the disposal of sewage sludge containing more than 5% of organic dry solids will be prohibited as of 1 June 2005. In Germany, the only future alternative to incineration will be the agricultural utilization of sludge. However, this way of sludge disposal is presently the subject of critical discussions in Germany because of the organic and inorganic toxic substances, which may be contained in sewage sludge, despite the fact that very stringent standards are to be met by agricultural uses. On the other hand, application of sewage sludge to agricultural land is explicitly supported by the European Sewage Sludge Directive 86/278/EEC. In the face of this controversial situation the Ruhrverband has initiated, in 2000, the development of a comprehensive and sustainable sludge and waste disposal concept for all wastewater facilities it operates in the entire Ruhr River Basin. The concept includes de-central sludge digestion and dewatering and subsequent transport to two central sludge incineration plants. It is expected that in future not more than 5% of all sludges produced in Ruhrverband's WWTPs will be used in agriculture. That means, the major part of 95% will have to be incinerated.

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

Transformation products and human metabolites of triclocarban and tricllosan in sewage sludge across the United States

USGS Publications Warehouse

Pycke, Benny F.G.; Roll, Isaac B.; Brownawell, Bruce J.; Kinney, Chad A.; Furlong, Edward T.; Kolpin, Dana W.; Halden, Rolf U.

2014-01-01

Removal of triclocarban (TCC) and triclosan (TCS) from wastewater is a function of adsorption, abiotic degradation, and microbial mineralization or transformation, reactions that are not currently controlled or optimized in the pollution control infrastructure of standard wastewater treatment. Here, we report on the levels of eight transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in raw and treated sewage sludge. Two sample sets were studied: samples collected once from 14 wastewater treatment plants (WWTPs) representing nine states, and multiple samples collected from one WWTP monitored for 12 months. Time-course analysis of significant mass fluxes (α = 0.01) indicate that transformation of TCC (dechlorination) and TCS (methylation) occurred during sewage conveyance and treatment. Strong linear correlations were found between TCC and the human metabolite 2′-hydroxy-TCC (r = 0.84), and between the TCC-dechlorination products dichlorocarbanilide (DCC) and monochlorocarbanilide (r = 0.99). Mass ratios of DCC-to-TCC and of methyl-triclosan (MeTCS)-to-TCS, serving as indicators of transformation activity, revealed that transformation was widespread under different treatment regimes across the WWTPs sampled, though the degree of transformation varied significantly among study sites (α = 0.01). The analysis of sludge sampled before and after different unit operation steps (i.e., anaerobic digestion, sludge heat treatment, and sludge drying) yielded insights into the extent and location of TCC and TCS transformation. Results showed anaerobic digestion to be important for MeTCS transformation (37–74%), whereas its contribution to partial TCC dechlorination was limited (0.4–2.1%). This longitudinal and nationwide survey is the first to report the occurrence of transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in sewage sludge.

Transformation products and human metabolites of triclocarban and triclosan in sewage sludge across the United States.

PubMed

Pycke, Benny F G; Roll, Isaac B; Brownawell, Bruce J; Kinney, Chad A; Furlong, Edward T; Kolpin, Dana W; Halden, Rolf U

2014-07-15

Removal of triclocarban (TCC) and triclosan (TCS) from wastewater is a function of adsorption, abiotic degradation, and microbial mineralization or transformation, reactions that are not currently controlled or optimized in the pollution control infrastructure of standard wastewater treatment. Here, we report on the levels of eight transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in raw and treated sewage sludge. Two sample sets were studied: samples collected once from 14 wastewater treatment plants (WWTPs) representing nine states, and multiple samples collected from one WWTP monitored for 12 months. Time-course analysis of significant mass fluxes (α=0.01) indicate that transformation of TCC (dechlorination) and TCS (methylation) occurred during sewage conveyance and treatment. Strong linear correlations were found between TCC and the human metabolite 2'-hydroxy-TCC (r=0.84), and between the TCC-dechlorination products dichlorocarbanilide (DCC) and monochlorocarbanilide (r=0.99). Mass ratios of DCC-to-TCC and of methyl-triclosan (MeTCS)-to-TCS, serving as indicators of transformation activity, revealed that transformation was widespread under different treatment regimes across the WWTPs sampled, though the degree of transformation varied significantly among study sites (α=0.01). The analysis of sludge sampled before and after different unit operation steps (i.e., anaerobic digestion, sludge heat treatment, and sludge drying) yielded insights into the extent and location of TCC and TCS transformation. Results showed anaerobic digestion to be important for MeTCS transformation (37-74%), whereas its contribution to partial TCC dechlorination was limited (0.4-2.1%). This longitudinal and nationwide survey is the first to report the occurrence of transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in sewage sludge.

Transformation Products and Human Metabolites of Triclocarban and Triclosan in Sewage Sludge Across the United States

PubMed Central

2015-01-01

Removal of triclocarban (TCC) and triclosan (TCS) from wastewater is a function of adsorption, abiotic degradation, and microbial mineralization or transformation, reactions that are not currently controlled or optimized in the pollution control infrastructure of standard wastewater treatment. Here, we report on the levels of eight transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in raw and treated sewage sludge. Two sample sets were studied: samples collected once from 14 wastewater treatment plants (WWTPs) representing nine states, and multiple samples collected from one WWTP monitored for 12 months. Time-course analysis of significant mass fluxes (α = 0.01) indicate that transformation of TCC (dechlorination) and TCS (methylation) occurred during sewage conveyance and treatment. Strong linear correlations were found between TCC and the human metabolite 2′-hydroxy-TCC (r = 0.84), and between the TCC-dechlorination products dichlorocarbanilide (DCC) and monochlorocarbanilide (r = 0.99). Mass ratios of DCC-to-TCC and of methyl-triclosan (MeTCS)-to-TCS, serving as indicators of transformation activity, revealed that transformation was widespread under different treatment regimes across the WWTPs sampled, though the degree of transformation varied significantly among study sites (α = 0.01). The analysis of sludge sampled before and after different unit operation steps (i.e., anaerobic digestion, sludge heat treatment, and sludge drying) yielded insights into the extent and location of TCC and TCS transformation. Results showed anaerobic digestion to be important for MeTCS transformation (37–74%), whereas its contribution to partial TCC dechlorination was limited (0.4–2.1%). This longitudinal and nationwide survey is the first to report the occurrence of transformation products, human metabolites, and manufacturing byproducts of TCC and TCS in sewage sludge. PMID:24932693

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.

[Effects of stabilization treatment on migration and transformation of heavy metals in mineral waste residues].

PubMed

Zhao, Shu-Hua; Chen, Zhi-Liang; Zhang, Tai-Ping; Pan, Wei-Bin; Peng, Xiao-Chun; Che, Rong; Ou, Ying-Juan; Lei, Guo-Jian; Zhou, Ding

2014-04-01

Different forms of heavy metals in soil will produce different environmental effects, and will directly influence the toxicity, migration and bioavailability of heavy metals. This study used lime, fly ash, dried sludge, peanut shells as stabilizers in the treatment of heavy metals in mineral waste residues. Morphological analyses of heavy metal, leaching experiments, potted plant experiments were carried out to analyze the migration and transformation of heavy metals. The results showed that after adding stabilizers, the pH of the acidic mineral waste residues increased to more than neutral, and the organic matter content increased significantly. The main existing forms of As, Pb, and Zn in the mineral waste residues were the residual. The contents of exchangeable and organic matter-bound As decreased by 65.6% and 87.7% respectively after adding fly ash, dried sludge and peanut shells. Adding lime, fly ash and peanut shells promoted the transformation of As from the Fe-Mn oxide-bound to the carbonate-bound, and adding lime and fly ash promoted the transformation of Pb and Zn from the exchangeable, Fe-Mn oxide-bound, organic matter-bound to the residual. After the early stage of the stabilization treatment, the contents of As, Pb and Zn in the leachate had varying degrees of decline, and adding peanut shells could reduce the contents of As, Pb and Zn in the leachate further. Among them, the content of As decreased most significantly after treatment with fly ash, dried sludge and peanut shells, with a decline of 57.4%. After treatment with lime, fly ash and peanut shells, the content of Zn decreased most significantly, by 24.9%. The addition of stabilizers was advantageous to the germination and growth of plants. The combination of fly ash, dried sludge and peanut shell produced the best effect, and the Vetiveria zizanioides germination rate reached 76% in the treated wasted mineral residues.

[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.

Investigation of bacterial community in activated sludge with an anaerobic side-stream reactor (ASSR) to decrease the generation of excess sludge.

PubMed

Kim, Young Mo; Chon, Dong-Hyun; Kim, Hee-Sik; Park, Chul

2012-09-01

The goal of this study was to investigate the bacterial community in activated sludge with an anaerobic side-stream reactor (ASSR), a process permitting significant decrease in sludge production during wastewater treatment. The study operated five activated sludge systems with different sludge treatment schemes serving as various controls for the activated sludge with ASSR. Bacterial communities were analyzed by denaturing gradient gel electrophoresis (DGGE), sequencing and construction of phylogenetic relationships of the identified bacteria. The DGGE data showed that activated sludge incorporating ASSR contained higher diversity of bacteria, resulting from long solids retention time and recirculation of sludge under aerobic and anaerobic conditions. The similarity of DGGE profiles between ASSR and separate anaerobic digester (control) was high indicating that ASSR is primarily related to conventional anaerobic digesters. Nevertheless, there was also unique bacteria community appearing in ASSR. Interestingly, sludge in the main system and in ASSR showed considerably different bacterial composition indicating that ASSR allowed enriching its own bacterial community different than that from the aeration basin, although two reactors were connected via sludge recirculation. In activated sludge with ASSR, sequences represented by predominant DGGE bands were affiliated with Proteobacteria. The remaining groups were composed of Spirochaetes, Clostridiales, Chloroflexi, and Actinobacteria. Their putative role in the activated sludge with ASSR is also discussed in this study. Copyright © 2012 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

Pathogen reduction in septic tank sludge through vermicomposting using Eisenia fetida.

PubMed

Rodríguez-Canché, L G; Cardoso Vigueros, L; Maldonado-Montiel, T; Martínez-Sanmiguel, M

2010-05-01

This study evaluated the potential of earthworms (Eisenia fetida) to remove pathogens from the sludge from septic tanks. Three earthworm population densities, equivalent to 1, 2, and 2.5kgm(-2), were tested for pathogen removal from sludge. The experimental phase lasted 60days, starting from the initial earthworm inoculation. After 60days, it was found that earthworms reduced concentrations of fecal coliforms, Salmonella spp., and helminth ova to permissible levels (<1000MPN/g, <3MPN/g, and <1viable ova/g on a dry weight basis, respectively) in accordance with Official Mexican Standard of environmental protection (NOM-004-SEMARNAT-2002) (SEMARNAT, 2002). Thus, sludge treatment with earthworms generated Class A biosolids, useful for forest, agricultural, and soil improvement. Copyright 2009 Elsevier Ltd. All rights reserved.

Fermentative hydrogen gas production using biosolids pellets as the inoculum source.

PubMed

Kalogo, Youssouf; Bagley, David M

2008-02-01

Biosolids pellets produced from anaerobically digested municipal wastewater sludge by drying to greater than 90% total solids at 110-115 degrees C for at least 75 min, were tested for their suitability as an inoculum source for fermentative hydrogen production. The hydrogen recoveries (mg gaseous H(2) produced as COD/mg added substrate COD) for glucose-fed batch systems were equal, 20.2-21.5%, between biosolids pellets and boiled anaerobic digester sludge as inoculum sources. Hydrogen recoveries from primary sludge were 2.4% and 3.5% using biosolids pellets and boiled sludge, respectively, and only 0.2% and 0.8% for municipal wastewater. Biosolids pellets should be a practical inoculum source for fermentative hydrogen reactors, although the effectiveness will depend on the wastewater treated.

Evaluation of Pathogen Removal in a Solar Sludge Drying Facility Using Microbial Indicators

PubMed Central

Shanahan, Emily F.; Roiko, Anne; Tindale, Neil W.; Thomas, Michael P.; Walpole, Ronald; Kurtböke, D. İpek

2010-01-01

South East Queensland is one of the fastest growing regions in Australia with a correspondingly rapid increase in sewage production. In response, local councils are investing in more effective and sustainable options for the treatment and reuse of domestic and industrial effluents. A novel, evaporative solar dryer system has been installed on the Sunshine Coast to convert sewage sludge into a drier, usable form of biosolids through solar radiation exposure resulting in decreased moisture concentration and pathogen reduction. Solar-dried biosolids were analyzed for selected pathogenic microbial, metal and organic contaminants at the end of different drying cycles in a collaborative study conducted with the Regional Council. Although fecal coliforms were found to be present, enteroviruses, parasites, E. coli, and Salmonella sp. were not detected in the final product. However, elevated levels of zinc and copper were still present which restricted public use of the biosolids. Dilution of the dried biosolids with green waste as well as composting of the biosolids is likely to lead to the production of an environmentally safe, Class A end-product. PMID:20616991

Removal of endocrine-disrupting chemicals and conventional pollutants in a continuous-operating activated sludge process integrated with ozonation for excess sludge reduction.

PubMed

Nie, Yafeng; Qiang, Zhimin; Ben, Weiwei; Liu, Junxin

2014-06-01

Sludge ozonation is considered as a promising technology to achieve a complete reduction of excess sludge, but as yet its effects on the removal of endocrine-disrupting chemicals (EDCs) and conventional pollutants (i.e., COD, N and P) in the activated sludge process are still unclear. In this study, two lab-scale continuous-operating activated sludge treatment systems were established: one was operated in conjunction with ozonation for excess sludge reduction, and the other was operated under normal conditions as control. The results indicate that an ozone dose of 100 mg O₃ g(-1)SS led to a zero yield of excess sludge in the sludge-reduction system during a continuous-operating period of 45d. Although ozonation gave a relatively lower specific oxygen uptake rate of activated sludge, it had little effect on the system's removal performance of COD and nitrogen substances. As a plus, sludge ozonation contributed a little more removal of target EDCs (estrone, 17β-estrodiol, estriol, 17α-ethinylestradiol, bisphenol A, and 4-nonylphenol). However, the total phosphorus removal declined notably due to its accumulation in the sludge-reduction system, which necessitates phosphorus recovery for the activated sludge process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Recovery of hazardous semiconductor-industry sludge as a useful resource.

PubMed

Lee, Tzen-Chin; Liu, Feng-Jiin

2009-06-15

Sludge, a solid waste recovered from wastewater of semiconductor-industries composes of agglomerates of nano-particles like SiO(2) and CaF(2). This sludge deflocculates in acidic and alkaline aqueous solutions into nano-particles smaller than 100 nm. Thus, this sludge is potentially hazardous to water resources when improperly dumped. It can cause considerable air-pollution when fed into rotary-kilns as a raw material for cement production. In this study, dried and pulverized sludge was used to replace 5-20 wt.% Portland cement in cement mortar. The compressive strength of the modified mortar was higher than that of plain cement mortar after curing for 3 days and more. In particular, the strength of mortar with 10 wt.% substitution improved by 25-35% after curing for 7-90 days. TCLP studies reveal no detectable release of heavy metals. Preliminary studies showed that nano-particles deflocculated from the sludge, when cured for up to 3 days retain in the modified mortar their nano-size, which become large-sized hydration compounds that contribute to the final mortar strength. Semiconductor sludge can thus be utilized as a useful resource to replace portion of cement in cement mortar, thereby avoiding their potential hazard on the environment.

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

Korcak, R.F.

Open pollinated York Imperial apple (Malus domestica Borkh.) seeds were germinated and grown for a period of 7 months in: (1) sand with complete nutrient solutions added; (2) limed and unlimed soil, (3) limed and unlimed soil amended with two different sewage sludges at rates of 25, 50 or 100 dry kg ha/sup -1/. A third composted, lime stabilized sludge was added either sieved or non-sieved at the same rates. The sludge materials used were: (1) a high metal, composted sludge from Baltimore, MD (BALT); (2) a high Cd sewage sludge (CITY) and (3) a low metal, composted sewage sludgemore » from Washington, D.C. (DC). Germination was unaffected by treatments. After 7 months, the best growth was obtained from the sand plus nutrient solution media. Two of the three sludge materials increased seedling growth over that of the soil, either limed or unlimed. The BALT compost treated soils produced the lowest growth, particularly when unlimed. Elevated tissue metal levels indicated that Mn, Zn, Cu and Ni were the probable causes of reduced growth noted from the BALT compost treatment. The use of soil with or without low metal sludges as media for early apple seedling growth when compared to standard sand culture is not recommended.« less

Elementary analysis and energetic potential of the municipal sewage sludges from the Gdańsk and Kościerzyna WWTPs

NASA Astrophysics Data System (ADS)

Ostojski, Arkadiusz

2018-01-01

This paper aims to present municipal sewage sludge (MSS) elementary analysis and energetic potential based on measurement of heat of combustion (higher heating value HHV) and calculation of calorific values (lower heating value LHV). The analysis takes into the consideration water content in sewage sludge, at different utilization stages, in wastewater treatment plants in Gdańsk Wschód and Kościerzyna - Pomeranian Voivodeship. The study yielded the following results (in % dry matter): ash 19÷31 %, C - 31÷36 %, H - 5÷6 %, N - 4÷6 %, O - 28÷32 %, S - 1 %. Calorific value of stabilized sludges in Gdańsk was on average 13.8÷15 MJ/kg. In case of sludges not undergoing digestion from Kościerzyna WWTP, the calorific value was at the level of 17.5 MJ/kg. Thus, sewage sludges are good energy carriers. High water content though is the problem, as it lowers the useful effect of heat. There is no alternative for thermal sewage sludge neutralization, which is in conformity with valid Polish National Waste Management Plan (KPGO 2022).

The physical state of finely dispersed soil-like systems with drilling sludge as an example

NASA Astrophysics Data System (ADS)

Smagin, A. V.; Kol'Tsov, I. N.; Pepelov, I. L.; Kirichenko, A. V.; Sadovnikova, N. B.; Kinzhaev, R. R.

2011-02-01

The physical state and its dynamics were studied at the quantitative level for drilling sludge (finely dispersed waste of the oil industry). Using original methodological approaches, the main hydrophysical and technological properties of sludge samples were assessed for the first time, including the water retention curve, the specific surface, the water conductivity, the electrical conductivity, the porosity dynamics during shrinkage, the water yield, etc., which are used in the current models of water transfer and the behavior of these soil-like objects under real thermodynamic conditions. The technologically unfavorable phenomenon of the spontaneous swelling of sludge during the storage of drilling waste was theoretically explained. The water regime of the homogeneous 0.5-m thick drilling sludge layer under the free gravity outflow and permanent evaporation of water from the surface was analyzed using the HYDRUS-1D model. The high water retention capacity and the low water conductivity and water yield of sludge do not allow their drying to the three-phase state (with the entry of air) acceptable for terrestrial plants under humid climatic conditions, which explains the spontaneous transformation of sludge pits to only hydromorphic ecosystems.

Functional Diversity of Microbial Communities in Sludge-Amended Soils

NASA Astrophysics Data System (ADS)

Sun, Y. H.; Yang, Z. H.; Zhao, J. J.; Li, Q.

The BIOLOG method was applied to exploration of functional diversity of soil microbial communities in sludge-amended soils sampled from the Yangtze River Delta. Results indicated that metabolic profile, functional diversity indexes and Kinetic parameters of the soil microbial communities changed following soil amendment with sewage sludge, suggesting that the changes occurred in population of the microbes capable of exploiting carbon substrates and in this capability as well. The kinetic study of the functional diversity revealed that the metabolic profile of the soil microbial communities exhibited non-linear correlation with the incubation time, showing a curse of sigmoid that fits the dynamic model of growth of the soil microbial communities. In all the treatments, except for treatments of coastal fluvo-aquic soil amended with fresh sludge and dried sludge from Hangzhou, kinetic parameters K and r of the functional diversity of the soil microbial communities decreased significantly and parameter S increased. Changes in characteristics of the functional diversity well reflected differences in C utilizing capacity and model of the soil microbial communities in the sludge-amended soils, and changes in functional diversity of the soil microbial communities in a particular eco-environment, like soil amended with sewage sludge.

Medium-Chain Chlorinated Paraffins (CPs) Dominate in Australian Sewage Sludge.

PubMed

Brandsma, Sicco H; van Mourik, Louise; O'Brien, Jake W; Eaglesham, Geoff; Leonards, Pim E G; de Boer, Jacob; Gallen, Christie; Mueller, Jochen; Gaus, Caroline; Bogdal, Christian

2017-03-21

To simultaneously quantify and profile the complex mixture of short-, median-, and long-chain CPs (SCCPs, MCCPs, and LCCPs) in Australian sewage sludge, we applied and further validated a recently developed novel instrumental technique, using quadrupole time-of-flight high resolution mass spectrometry running in the negative atmospheric pressure chemical ionization mode (APCI-qTOF-HRMS). Without using an analytical column the cleaned extracts were directly injected into the qTOF-HRMS followed by quantification of the CPs by a mathematical algorithm. The recoveries of the four SCCP, MCCP and LCCP-spiked sewage sludge samples ranged from 86 to 123%. This APCI-qTOF-HRMS method is a fast and promising technique for routinely measuring SCCPs, MCCPs, and LCCPs in sewage sludge. Australian sewage sludge was dominated by MCCPs with concentrations ranging from 542 to 3645 ng/g dry weight (dw). Lower SCCPs concentrations (<57-1421 ng/g dw) were detected in the Australian sewage sludge, which were comparable with the LCCPs concentrations (116-960 ng/g dw). This is the first time that CPs were reported in Australian sewage sludge. The results of this study gives a first impression on the distribution of the SCCPs, MCCPs, and LCCPs in Australia wastewater treatment plants (WWTPs).

New quality-control materials for the determination of alkylphenols and alkylphenol ethoxylates in sewage sludge.

PubMed

Fernández-Sanjuan, María; Lacorte, Silvia; Rigol, Anna; Sahuquillo, Angels

2012-11-01

The determination of alkylphenols in sewage sludge is still hindered by the complexity of the matrix and of the analytes, some of which are a mixture of isomers. Most of the methods published in the literature have not been validated, due to the lack of reference materials for the determination of alkylphenols in sludge. Given this situation, the objectives of the present study were to develop a new quality-control material for determining octylphenol, nonylphenol and nonylphenol monoethoxylate in sludge. The material was prepared from an anaerobically digested sewage sludge, which was thermally dried, sieved, homogenized and bottled after checking for the bulk homogeneity of the processed material. Together with the sewage sludge, an extract was also prepared, in order to provide a quality-control material for allowing laboratories to test the measuring step. The homogeneity and 1-year stability of the two materials were evaluated. Statistical analysis proved that the materials were homogeneous and stable for at least 1 year stored at different temperatures. These materials are intended to assist in the quality control of the determination of alkylphenols and alkylphenol ethoxylates in sewage sludge.

Phytoextraction of heavy metals from municipal sewage sludge by Rosa multiflora and Sida hermaphrodita.

PubMed

Antonkiewicz, Jacek; Kołodziej, Barbara; Bielińska, Elżbieta Jolanta

2017-04-03

The aim of the study was to evaluate the efficacy of the multiflora rose var. "Jatar" (Rosa multiflora Thunb. ex Murray) and the Virginia fanpetals (Sida hermaphrodita Rusby) to phytoextract heavy metals from municipal sewage sludge. The 6-year field experiment involved four levels of fertilization with sewage sludge at doses of 0, 10, 20, 40, and 60 Mg DM (Dry Mass) sludge ha -1 . The increasing doses of sewage sludge were found to significantly increase the yield of multiflora rose and Virginia fanpetals biomass. They also significantly increased the content of heavy metals in these plants. The highest uptake of heavy metals by the multiflora rose and Virginia fanpetals crops was recorded at the fertilization dose of 60 Mg DM ⋅ ha -1 . Our investigations show that the Virginia fanpetals was more efficient in the phytoextraction of Cr, Ni, Cu, Zn, and Cd from the sewage sludge than the multiflora rose, due to the greater yields and higher heavy metal uptake by the former plant. In turn, the multiflora rose phytoextracted greater amounts of Pb from the sewage sludge. The analyses indicate that the Virginia fanpetals can be used for phytoremediation (phytoextraction) of heavy metals contained in sewage sludge.

Thermal processing of paper sludge and characterisation of its pyrolysis products.

PubMed

Strezov, Vladimir; Evans, Tim J

2009-05-01

Paper sludge is a waste product from the paper and pulp manufacturing industry that is generally disposed of in landfills. Pyrolysis of paper sludge can potentially provide an option for managing this waste by thermal conversion to higher calorific value fuels, bio-gas, bio-oils and charcoal. This work investigates the properties of paper sludge during pyrolysis and energy required to perform thermal conversion. The products of paper sludge pyrolysis were also investigated to determine their properties and potential energy value. The dominant volatile species of paper sludge pyrolysis at 10 degrees C/min were found to be CO and CO(2), contributing to almost 25% of the paper sludge dry weight loss at 500 degrees C. The hydrocarbons (CH(4), C(2)H(4), C(2)H(6)) and hydrogen contributed to only 1% of the total weight loss. The bio-oils collected at 500 degrees C were primarily comprised of organic acids with the major contribution being linoleic acid, 2,4-decadienal acid and oleic acid. The high acidic content indicates that in order to convert the paper sludge bio-oil to bio-diesel or petrochemicals, further upgrading would be necessary. The charcoal produced at 500 degrees C had a calorific value of 13.3MJ/kg.

Characteristics of carbonized sludge for co-combustion in pulverized coal power plants

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

Park, Sang-Woo; Jang, Cheol-Hyeon, E-mail: jangch@hanbat.ac.kr

2011-03-15

Co-combustion of sewage sludge can destabilize its combustion profile due to high volatility, which results in unstable flame. We carried out fuel reforming for sewage sludge by way of carbonization at pyrolysis temperature of 300-500 deg. C. Fuel characteristics of carbonized sludge at each temperature were analyzed. As carbonization temperature increased, fuel ratio increased, volatile content reduced, and atomic ratio relation of H/C and O/C was similar to that of lignite. The analysis result of FT-IR showed the decrease of aliphatic C-H bond and O-C bond in carbonization. In the analysis result of TG-DTG, the thermogravimetry reduction temperature of carbonizedmore » sludge (CS400) was proven to be higher than that of dried sludge, but lower than that of sub-bituminous coal. Hardgrove grindability index increased in proportion to fuel ratio increase, where the carbonized sludge value of 43-110 was similar or higher than the coal value of 49-63. As for ash deposits, slagging and fouling index were higher than that of coal. When carbonized sludge (CS400) and coal were co-combusted in 1-10% according to calorific value, slagging tendency was low in all conditions, and fouling tendency was medium or high according to the compositions of coal.« less

Occurrence and distribution of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in industrial and domestic sewage sludge.

PubMed

Balasubramani, Aparna; Rifai, Hanadi S

2015-10-01

Sewage sludge samples collected from 43 different domestic and industrial wastewater treatment plants and petrochemical industries that discharge to the Houston Ship Channel (HSC) were analyzed for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), which are highly toxic and carcinogenic towards humans and animals. The measured total PCDD/F toxic equivalency (TEQ) ranged between 0.73 and 7348.40 pg/g dry weight. The mean TEQ of PCDD/Fs in industrial sludge was approximately 40 times higher than that in sewage sludge. The PCDD homolog concentrations in the industrial samples were higher than those observed at the wastewater treatment plants by a factor of 10, with total heptachlorodibenzodioxin (HpCDD) exhibiting the maximum concentration in most of the samples. Among the PCDF homologs, total heptadichlorodibenzofuran (HpCDF) dominated the total homolog concentration in sludge from the wastewater treatment plants, whereas total tetradichlorodibenzofuran (TeCDF) dominated the industrial sludge samples. Overall, the total PCDD/F TEQ in sludge samples was much higher than that in effluent samples from the same facility. A linear correlation (R (2) = 0.62, p value < 0.068) was found indicating that sludge sampling can be used as a surrogate for effluent concentrations in wastewater treatment plants but not for industrial discharges.

Characteristics of carbonized sludge for co-combustion in pulverized coal power plants.

PubMed

Park, Sang-Woo; Jang, Cheol-Hyeon

2011-03-01

Co-combustion of sewage sludge can destabilize its combustion profile due to high volatility, which results in unstable flame. We carried out fuel reforming for sewage sludge by way of carbonization at pyrolysis temperature of 300-500°C. Fuel characteristics of carbonized sludge at each temperature were analyzed. As carbonization temperature increased, fuel ratio increased, volatile content reduced, and atomic ratio relation of H/C and O/C was similar to that of lignite. The analysis result of FT-IR showed the decrease of aliphatic C-H bond and O-C bond in carbonization. In the analysis result of TG-DTG, the thermogravimetry reduction temperature of carbonized sludge (CS400) was proven to be higher than that of dried sludge, but lower than that of sub-bituminous coal. Hardgrove grindability index increased in proportion to fuel ratio increase, where the carbonized sludge value of 43-110 was similar or higher than the coal value of 49-63. As for ash deposits, slagging and fouling index were higher than that of coal. When carbonized sludge (CS400) and coal were co-combusted in 1-10% according to calorific value, slagging tendency was low in all conditions, and fouling tendency was medium or high according to the compositions of coal. Copyright © 2010 Elsevier Ltd. All rights reserved.

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

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.

Physicochemistry, morphology and leachability of selected metals from post-galvanized sewage sludge from screw factory in Łańcut, SE Poland

NASA Astrophysics Data System (ADS)

Galas, Dagmara; Kalembkiewicz, Jan; Sitarz-Palczak, Elżbieta

2016-12-01

Morphology, physicochemical properties, chemical composition of post-galvanized sewage sludge from Screw Factory in Łańcut, leachability and mobility of metals has been analyzed. The analyses with the use of scanning electron microscope with an adapter to perform chemical analysis of microsites (EDS) showed that the material is characterized by a high fragmentation and a predominant number of irregularly shaped grains. The sewage sludge is alkaline with a large loss of ignition (34.6%) and small bulk density (< 1 g/cm3). The EDS analyses evidenced presence of oxygen, silicon, calcium, chromium, iron and zinc in all examined areas, and presence of manganese and copper in selected areas indicating a non-uniform distribution of metals in the sewage sludge. Within one-stage mineralization and FAAS technique a predominant share of calcium, zinc and iron in terms of dry matter was recorded in the sewage sludge. The contents of Co, Cr, Cu, K, Mn, Ni and Pb in sewage sludge are below 1%. Evaluation of mobility and leaching of metals in sewage sludge was carried out by means of two parameters: accumulation coefficient of mobile fractions and leaching level related to the mass solubility of sewage sludge. The results indicate that the short-term or long-term storage of not inactivated post-galvanized sewage sludge can result in release of metals.

Occurrence of hexabromocyclododecane (HBCD) in sewage sludge from Shanghai: implications for source and environmental burden.

PubMed

Xiang, Nan; Chen, Ling; Meng, Xiang-Zhou; Dai, Xiaohu

2015-01-01

Sewage sludge is regarded as one important sink for hydrophobic pollutants, including hexabromocyclododecane (HBCD), but the current pollution situation of HBCD in sludge from China is unknown, despite that many studies have reported its occurrence in other environmental compartments across China. In this study, we collected 27 sludge samples from Shanghai to investigate the occurrence and distribution, to examine the diastereoisomer profile and sources, and to provide advice for future pollution control. HBCD is ubiquitous in sludge with a mean concentration of 4.7ngg(-1) dry weight (dw) (range: 0.10-37.2ngg(-1) dw), lower than data from European countries and the United States. Sludge from wastewater treatment plants (WWTPs) treating industrial wastewater contained high levels of HBCD. However, no significant relationships were found between HBCD and four parameters (total organic carbon, the percentage of industrial wastewater, capacity and sludge production of WWTPs). α- and γ-HBCD were two main components with the corresponding contributions of 47.9% and 48.0%. Comparing with the annual production of HBCD in China, its storage in sewage sludge is extremely low (less than 0.002%), indicating future release of HBCD from waste polystyrene foam will be significant, and careful considerations should be taken during waste disposal. To our knowledge, this is the first report on HBCD in sewage sludge from China. Copyright © 2014 Elsevier Ltd. All rights reserved.

Toxicity assessment of soil amended with tannery sludge, trivalent chromium and hexavalent chromium, using wheat, oat and sorghum plants.

PubMed

López-Luna, J; González-Chávez, M C; Esparza-García, F J; Rodríguez-Vázquez, R

2009-04-30

This work assessed the effect of soil amended with tannery sludge (0, 500, 1000, 2000, 4000 and 8000 mg Cr kg(-1)soil), Cr(3+) as CrCl(3).6H(2)O (0, 100, 250, 500, 1000 and 2000 mg Cr kg(-1)soil), and Cr(6+) as K(2)Cr(2)O(7) (0, 25, 50, 100, 200 and 500 mg Cr kg(-1)soil) on wheat, oat and sorghum plants. Seed germination, seedling growth (root and shoot) and Cr accumulation in dry tissue were measured. Toxicological parameters; medium effective concentration, no observed adverse effect concentration and low observed adverse effect concentration were determined. Root growth was the most sensitive assessment of Cr toxicity (P<0.05). There was a significant correlation (P<0.0001) between Cr accumulation in dry tissue and toxic effects on seedling growth. The three Cr sources had different accumulation and mobility patterns; tannery sludge was less toxic for all three plant species, followed by CrCl(3).6H(2)O and K(2)Cr(2)O(7).

Influence of operating conditions on the air gasification of dry refinery sludge in updraft gasifier

NASA Astrophysics Data System (ADS)

Ahmed, R.; Sinnathambi, C. M.

2013-06-01

In the present work, details of the equilibrium modeling of dry refinery sludge (DRS) are presented using ASPEN PLUS Simulator in updraft gasifier. Due to lack of available information in the open journal on refinery sludge gasification using updraft gasifier, an evaluate for its optimum conditions on gasification is presented in this paper. For this purpose a Taguchi Orthogonal array design, statistical software is applied to find optimum conditions for DRS gasification. The goal is to identify the most significant process variable in DRS gasification conditions. The process variables include; oxidation zone temperature, equivalent ratio, operating pressure will be simulated and examined. Attention was focused on the effect of optimum operating conditions on the gas composition of H2 and CO (desirable) and CO2 (undesirable) in terms of mass fraction. From our results and finding it can be concluded that the syngas (H2 & CO) yield in term of mass fraction favors high oxidation zone temperature and at atmospheric pressure while CO2 acid gas favor at a high level of equivalent ratio as well as air flow rate favoring towards complete combustion.

Determination of sedative hypnotics in sewage sludge by pressurized liquid extraction with high-performance liquid chromatography and tandem mass spectrometry.

PubMed

Arbeláez, Paula; Granados, Judith; Borrull, Francesc; Marcé, Rosa Maria; Pocurull, Eva

2014-12-01

This paper describes a method for the determination of eight sedative hypnotics (benzodiazepines and barbiturates) in sewage sludge using pressurized liquid extraction and liquid chromatography with tandem mass spectrometry. Pressurized liquid extraction operating conditions were optimized and maximum recoveries were reached using methanol under the following operational conditions: 100ºC, 1500 psi, extraction time of 5 min, one extraction cycle, flush volume of 60% and purge time of 120 s. Pressurized liquid extraction recoveries were higher than 88% for all the compounds except for carbamazepine (55%). The repeatability and reproducibility between days, expressed as relative standard deviation (n = 5), were lower than 6 and 10%, respectively. The detection limits for all compounds were lower than 12.5 μg/kg of dry weight. The method was applied to determine benzodiazepines and barbiturates in sewage sludge from urban sewage treatment plants, and carbamazepine showed the highest concentration (7.9-18.9 μg/kg dry weight). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

The use of sewage sludge and horticultural waste to develop artificial soil for plant cultivation in Singapore.

PubMed

Stabnikova, O; Goh, W-K; Ding, H-B; Tay, J-H; Wang, J-Y

2005-06-01

Greenhouse pot experiments were performed with Ipomoea aquatica (Kang Kong) to evaluate artificial soil produced from poor fertility subsoil, horticultural compost, and sewage sludge. The addition of horticultural compost and sewage sludge to subsoil substantially improved plant growth, improved the physical properties of subsoil and enriched subsoil by essential nutrients for plants. The effect was enhanced when the two ingredients were added to subsoil together. The highest yield of biomass of I. aquatica was observed in artificial soil prepared by mixing subsoil with 4% (wet weight/wet weight) of horticultural compost and 2% (dry weight/wet weight) of sewage sludge. The contents of heavy metals in plants, grown in the artificial soil, were significantly lower than toxic levels. The artificial soil could be recommended for urban landscaping and gardening in Singapore.

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.

Digital image processing and analysis for activated sludge wastewater treatment.

PubMed

Khan, Muhammad Burhan; Lee, Xue Yong; Nisar, Humaira; Ng, Choon Aun; Yeap, Kim Ho; Malik, Aamir Saeed

2015-01-01

Activated sludge system is generally used in wastewater treatment plants for processing domestic influent. Conventionally the activated sludge wastewater treatment is monitored by measuring physico-chemical parameters like total suspended solids (TSSol), sludge volume index (SVI) and chemical oxygen demand (COD) etc. For the measurement, tests are conducted in the laboratory, which take many hours to give the final measurement. Digital image processing and analysis offers a better alternative not only to monitor and characterize the current state of activated sludge but also to predict the future state. The characterization by image processing and analysis is done by correlating the time evolution of parameters extracted by image analysis of floc and filaments with the physico-chemical parameters. This chapter briefly reviews the activated sludge wastewater treatment; and, procedures of image acquisition, preprocessing, segmentation and analysis in the specific context of activated sludge wastewater treatment. In the latter part additional procedures like z-stacking, image stitching are introduced for wastewater image preprocessing, which are not previously used in the context of activated sludge. Different preprocessing and segmentation techniques are proposed, along with the survey of imaging procedures reported in the literature. Finally the image analysis based morphological parameters and correlation of the parameters with regard to monitoring and prediction of activated sludge are discussed. Hence it is observed that image analysis can play a very useful role in the monitoring of activated sludge wastewater treatment plants.

Lipid-enhancement of activated sludges obtained from conventional activated sludge and oxidation ditch processes.

PubMed

Revellame, Emmanuel D; Hernandez, Rafael; French, W Todd; Holmes, William E; Forks, Allison; Callahan, Robert

2013-11-01

Lipid-enhancement of activated sludges was conducted to increase the amount of saponifiable lipids in the sludges. The sludges were obtained from a conventional activated sludge (CAS) and an oxidation ditch process (ODP). Results showed 59-222% and 150-250% increase in saponifiable lipid content of the sludges from CAS and ODP, respectively. The fatty acid methyl ester (FAMEs) obtained from triacylglycerides was 57-67% (of total FAMEs) for enhanced CAS and 55-73% for enhanced ODP, a very significant improvement from 6% to 10% (CAS) and 4% to 8% (ODP). Regardless of the source, the enhancement resulted in sludges with similar fatty acid profile indicating homogenization of the lipids in the sludges. This study provides a potential strategy to utilize existing wastewater treatment facilities as source of significant amount of lipids for biofuel applications. Published by Elsevier Ltd.

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.

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.

40 CFR 61.50 - Applicability.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ore to recover mercury, use mercury chlor-alkali cells to produce chlorine gas and alkali metal hydroxide, and incinerate or dry wastewater treatment plant sludge. [40 FR 48302, Oct. 14, 1975] ...

[Treatment of Flue Gas from Sludge Drying Process by A Thermophilic Biofilter].

PubMed

Chen, Wen-he; Deng, Ming-jia; Luo, Hui; Ding, Wen-iie; Li, Lin; Lin, Jian; Liu, Jun-xin

2016-01-15

A thermophilic biofilter was employed to treat the flue gas generated from sludge drying process, and the performance in both the start period and the stationary phase was studied under the gas flow rate of 2 700-3 100 m3 x h(-1) and retention time of 21.88-25.10 s. The results showed that the thermophilic biofilter could effectively treat gases containing sulfur dioxide, ammonia and volatile organic compounds (VOC). The removal efficiencies could reach 100%, 93.61% and 87.01%, respectively. Microbial analysis indicated that most of the population belonged to thermophilic bacteria. Paenibacillus sp., Chelatococcus sp., Bacillus sp., Clostridium thermosuccinogenes, Pseudoxanthomonas sp. and Geobacillus debilis which were abundant in the thermophilic biofilter, had the abilities of denitrification, desulfurization and degradation of volatile organic compounds.

Enhancing sewage sludge dewaterability by bioleaching approach with comparison to other physical and chemical conditioning methods.

PubMed

Liu, Fenwu; Zhou, Jun; Wang, Dianzhan; Zhou, Lixiang

2012-01-01

The sewage sludge conditioning process is critical to improve the sludge dewaterability prior to mechanical dewatering. Traditionally, sludge is conditioned by physical or chemical approaches, mostly with the addition of inorganic or organic chemicals. Here we report that bioleaching, an efficient and economical microbial method for the removal of sludge-borne heavy metals, also plays a significant role in enhancing sludge dewaterability. The effects of bioleaching and physical or chemical approaches on sludge dewaterability were compared. The conditioning result of bioleaching by Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans on sludge dewatering was investigated and compared with the effects of hydrothermal (121 degrees C for 2 hr), microwave (1050 W for 50 sec), ultrasonic (250 W for 2 min), and chemical conditioning (24% ferric chloride and 68% calcium oxide; dry basis). The results show that the specific resistance to filtration (SRF) or capillary suction time (CST) of sludge is decreased by 93.1% or 74.1%, respectively, after fresh sludge is conditioned by bioleaching, which is similar to chemical conditioning treatment with ferric chloride and calcium oxide but much more effective than other conditioning approaches including hydrothermal, microwave, and ultrasonic conditioning. Furthermore, after sludge dewatering, bioleached sludge filtrate contains the lowest concentrations of chroma (18 times), COD (542 mg/L), total N (TN, 300 mg/L), NH4(+)-N (208 mg/L), and total P (TP, 2 mg/L) while the hydrothermal process resulted in the highest concentration of chroma (660 times), COD (18,155 mg/L), TN (472 mg/L), NH4(+)-N (381 mg/L), and TP (191 mg/L) among these selected conditioning methods. Moreover, unlike chemical conditioning, sludge bioleaching does not result in a significant reduction of organic matter, TN, and TP in the resulting dewatered sludge cake. Therefore, considering sludge dewaterability and the chemical properties of sludge filtrate and resulting dewatered sludge cakes, bioleaching has potential as an approach for improving sludge dewaterability and reducing the cost of subsequent reutilization or disposal of dewatered sludge.

Waste treatment by bacterial additions

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

Deutsch, D.J.; Stigall, E.; Barth, E.

1979-04-23

Companies such as General Environmental Science Corp. and Polybac Corp., which market specialized bacterial cultures for treating industrial wastes, claim that the cultures improve the operation of activated-sludge, trickling-filter, and lagoon-treatment plants, and provide faster system response to startups, variable and shock loads, and cold weather. The effectiveness of the special cultures is difficult to verify and has been questioned by environmental experts, including R. L. Raymond (Suntech Inc.) and E. Barth (EPA), although E. Stigall (EPA) believes they may aid plant recovery after upsets. A study by Business Communications Co. has predicted that the market for such additives willmore » reach $50 million by 1987, from $5 million in 1979. The use of such cultures in Exxon Corp.'s 1 million gal/day activated sludge system at the Benicia, Calif., oil refinery improved the system's performance by 32Vertical Bar3<, resulted in faster unit startups and more stable operation, and reduced foaming. J. T. Baker Co. has used successfully two broad-spectrum dried additives for ammonia removal and hydrocarbon degradation at its 3 million gal/day secondary treatment plant at Phillipsburg, N.J.« less

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.

SLUDGE TREATMENT PROJECT KOP DISPOSITION - THERMAL AND GAS ANALYSIS FOR THE COLD VACUUM DRYING FACILITY

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

SWENSON JA; CROWE RD; APTHORPE R

2010-03-09

The purpose of this document is to present conceptual design phase thermal process calculations that support the process design and process safety basis for the cold vacuum drying of K Basin KOP material. This document is intended to demonstrate that the conceptual approach: (1) Represents a workable process design that is suitable for development in preliminary design; and (2) Will support formal safety documentation to be prepared during the definitive design phase to establish an acceptable safety basis. The Sludge Treatment Project (STP) is responsible for the disposition of Knock Out Pot (KOP) sludge within the 105-K West (KW) Basin.more » KOP sludge consists of size segregated material (primarily canister particulate) from the fuel and scrap cleaning process used in the Spent Nuclear Fuel process at K Basin. The KOP sludge will be pre-treated to remove fines and some of the constituents containing chemically bound water, after which it is referred to as KOP material. The KOP material will then be loaded into a Multi-Canister Overpack (MCO), dried at the Cold Vacuum Drying Facility (CVDF) and stored in the Canister Storage Building (CSB). This process is patterned after the successful drying of 2100 metric tons of spent fuel, and uses the same facilities and much of the same equipment that was used for drying fuel and scrap. Table ES-l present similarities and differences between KOP material and fuel and between MCOs loaded with these materials. The potential content of bound water bearing constituents limits the mass ofKOP material in an MCO load to a fraction of that in an MCO containing fuel and scrap; however, the small particle size of the KOP material causes the surface area to be significantly higher. This relatively large reactive surface area represents an input to the KOP thermal calculations that is significantly different from the calculations for fuel MCOs. The conceptual design provides for a copper insert block that limits the volume available to receive KOP material, enhances heat conduction, and functions as a heat source and sink during drying operations. This use of the copper insert represents a significant change to the thermal model compared to that used for the fuel calculations. A number of cases were run representing a spectrum of normal and upset conditions for the drying process. Dozens of cases have been run on cold vacuum drying of fuel MCOs. Analysis of these previous calculations identified four cases that provide a solid basis for judgments on the behavior of MCO in drying operations. These four cases are: (1) Normal Process; (2) Degraded vacuum pumping; (3) Open MCO with loss of annulus water; and (4) Cool down after vacuum drying. The four cases were run for two sets of input parameters for KOP MCOs: (1) a set of parameters drawn from safety basis values from the technical data book and (2) a sensitivity set using parameters selected to evaluate the impact of lower void volume and smaller particle size on MCO behavior. Results of the calculations for the drying phase cases are shown in Table ES-2. Cases using data book safety basis values showed dry out in 9.7 hours and heat rejection sufficient to hold temperature rise to less than 25 C. Sensitivity cases which included unrealistically small particle sizes and corresponding high reactive surface area showed higher temperature increases that were limited by water consumption. In this document and in the attachment (Apthorpe, R. and M.G. Plys, 2010) cases using Technical Databook safety basis values are referred to as nominal cases. In future calculations such cases will be called safety basis cases. Also in these documents cases using parameters that are less favorable to acceptable performance than databook safety values are referred to as safety cases. In future calculations such cases will be called sensitivity cases or sensitivity evaluations Calculations to be performed in support of the detailed design and formal safety basis documentation will expand the calculations presented in this document to include: additional features of the drying cycle, more realistic treatment of uranium metal consumption during oxidation, larger water inventory, longer time scales, and graphing of results of hydrogen gas concentration.« less

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.

Agricultural recycling of treatment-plant sludge: a case study for a vegetable-processing factory.

PubMed

Dolgen, Deniz; Alpaslan, M Necdet; Delen, Nafiz

2007-08-01

The present study evaluated the possibility of using the sludge produced by a vegetable-processing factory in agriculture. The sludge was amended with a soil mixture (i.e., a mixture of sand, soil, and manure) and was applied at 0, 165, 330, 495 and 660 t/ha to promote the growth of cucumbers. The effects of various sludge loadings on plant growth were assessed by counting plants and leaves, measuring stem lengths, and weighing the green parts and roots of the plants. We also compared heavy metal uptake by the plants for sludge loadings of 330, 495, and 660 t/ha with various recommended standards for vegetables. Our results showed that plant growth patterns were influenced to some extent by the sludge loadings. In general, the number of leaves, stem length, and dry weight of green parts exhibited a pronounced positive growth response compared with an unfertilized control, and root growth showed a lesser but still significant response at sludge loadings of 165 and 330 t/ha. The sludge application caused no significant increase in heavy metal concentrations in the leaves, though zinc (Zn) and iron (Fe) were found at elevated concentrations. However, despite the Zn and Fe accumulation, we observed no toxicity symptoms in the plants. This may be a result of cucumber's tolerance of high metal levels.

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.

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.

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.

Medium-Chain Chlorinated Paraffins (CPs) Dominate in Australian Sewage Sludge

PubMed Central

2017-01-01

To simultaneously quantify and profile the complex mixture of short-, median-, and long-chain CPs (SCCPs, MCCPs, and LCCPs) in Australian sewage sludge, we applied and further validated a recently developed novel instrumental technique, using quadrupole time-of-flight high resolution mass spectrometry running in the negative atmospheric pressure chemical ionization mode (APCI-qTOF-HRMS). Without using an analytical column the cleaned extracts were directly injected into the qTOF-HRMS followed by quantification of the CPs by a mathematical algorithm. The recoveries of the four SCCP, MCCP and LCCP-spiked sewage sludge samples ranged from 86 to 123%. This APCI-qTOF-HRMS method is a fast and promising technique for routinely measuring SCCPs, MCCPs, and LCCPs in sewage sludge. Australian sewage sludge was dominated by MCCPs with concentrations ranging from 542 to 3645 ng/g dry weight (dw). Lower SCCPs concentrations (<57–1421 ng/g dw) were detected in the Australian sewage sludge, which were comparable with the LCCPs concentrations (116–960 ng/g dw). This is the first time that CPs were reported in Australian sewage sludge. The results of this study gives a first impression on the distribution of the SCCPs, MCCPs, and LCCPs in Australia wastewater treatment plants (WWTPs). PMID:28218842

Technical, economic and environmental assessment of sludge treatment wetlands.

PubMed

Uggetti, Enrica; Ferrer, Ivet; Molist, Jordi; García, Joan

2011-01-01

Sludge treatment wetlands (STW) emerge as a promising sustainable technology with low energy requirements and operational costs. In this study, technical, economic and environmental aspects of STW are investigated and compared with other alternatives for sludge management in small communities (<2000 population equivalent). The performance of full-scale STW was characterised during 2 years. Sludge dewatering increased total solids (TS) concentration by 25%, while sludge biodegradation lead to volatile solids around 45% TS and DRI(24h) between 1.1 and 1.4 gO(2)/kgTS h, suggesting a partial stabilisation of biosolids. In the economic and environmental assessment, four scenarios were considered for comparison: 1) STW with direct land application of biosolids, 2) STW with compost post-treatment, 3) centrifuge with compost post-treatment and 4) sludge transport to an intensive wastewater treatment plant. According to the results, STW with direct land application is the most cost-effective scenario, which is also characterised by the lowest environmental impact. The life cycle assessment highlights that global warming is a significant impact category in all scenarios, which is attributed to fossil fuel and electricity consumption; while greenhouse gas emissions from STW are insignificant. As a conclusion, STW are the most appropriate alternative for decentralised sludge management in small communities. Copyright © 2010 Elsevier Ltd. All rights reserved.

Estrogenic compounds in Tunisian urban sewage treatment plant: occurrence, removal and ecotoxicological impact of sewage discharge and sludge disposal.

PubMed

Belhaj, Dalel; Athmouni, Khaled; Jerbi, Bouthaina; Kallel, Monem; Ayadi, Habib; Zhou, John L

2016-12-01

The occurrence, fate and ecotoxicological assessment of selected estrogenic compounds were investigated at Tunisian urban sewage treatment plant. The influents, effluents, as well as primary, secondary and dehydrated sludge, were sampled and analyzed for the target estrogens to evaluate their fate. All target compounds were detected in both sewage and sludge with mean concentrations from 0.062 to 0.993 μg L -1 and from 11.8 to 792.9 μg kg -1 dry weight, respectively. A wide range of removal efficiencies during the treatment processes were observed, from 6.3 % for estrone to 76.8 % for estriol. Ecotoxicological risk assessment revealed that the highest ecotoxicological risk in sewage effluent and dehydrated sludge was due to 17β-estradiol with a risk quotient (RQ) of 4.6 and 181.9, respectively, and 17α-ethinylestradiol with RQ of 9.8 and 14.85, respectively. Ecotoxicological risk after sewage discharge and sludge disposal was limited to the presence of 17β-estradiol in dehydrated-sludge amended soil with RQ of 1.38. Further control of estrogenic hormones in sewage effluent and sludge is essential before their discharge and application in order to prevent their introduction into the natural environment.

Chromium precipitation from tanning spent liquors using industrial alkaline residues: A comparative study

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

Fonseca Almeida, M.A.; Boaventura, R.A.R.

1998-07-01

Chromium precipitation from spent tanning liquors using industrial alkaline tailings is described and removal efficiencies are compared with those obtained with traditional chemicals as NaOH, CaO and MgO: (1) using steelmaking dusts at dosages up to 70 g/l residual Cr remains {ge} 3.7 mg/l. Moreover Cr and mainly Pb are partially leached by the spent tanning liquor, therefore limiting the use of this industrial residue as Cr precipitant; (2) a dosage of 80 g/l (dry basis) of chemical sludge from a water treatment plant results in a removal efficiency of 99.97% Cr and residual Cr {le} 2 mg/l under experimentalmore » conditions that include stirring at 100 rpm for 1 h and settling for 23 h. Sedimentation time may be reduced to 2 h if stirring is extended to 2 h. Resulting sludge volume is about 400 ml/l. However, during Cr precipitation, Al is leached form the added product up to about 40 mg Al per liter of supernatant; (3) precipitation using acetylene production sludge only requires a dosage of 16 g/l (dry basis) to remove 99.96% Cr after stirring for 1 h and settling for 2 h. The soluble Cr concentration in the clarified effluent is {le} 2 mg/l and the sludge volume about 500 ml/l. This Cr level can also be achieved at a dosage of 14 g/l, provided the stirring time is increased to 3 h; (4) these results are comparable with those using either CaO or MgO at similar dosages; and (5) NaOH at dosages between 6.4 and 14 g/l proved to be not sufficiently effective for Cr precipitation. Although removal efficiencies up to 99.9% are achieved, residual Cr is always above 8.7 mg/l. Additionally, the resulting sludge is not very dense, thus leading to high sludge volume production.« less

Electro-dewatering of wastewater sludge: influence of the operating conditions and their interactions effects.

PubMed

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

2011-04-01

Electric field-assisted dewatering, also called electro-dewatering (EDW), 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. The application of these additional fields can be applied to either or both dewatering stages (filtration and/or compression), or as a pre-or post-treatment of the dewatering process. In this study, the performance of the EDW on wastewater sludge was investigated. Experiments were carried out on a laboratory filtration/compression cell, provided with electrodes, in order to apply an electrical field. The chosen operating conditions pressure (200-1200 kPa) and voltage (10-50 V) are sufficient to remove a significant proportion of the water that cannot be removed using mechanical dewatering technologies alone. A response surface methodology (RSM) was used to evaluate the effects of the processing parameters of EDW on (i) the final dry solids content, which is a fundamental dewatering parameter and an excellent indicator of the extent of EDW and (ii) the energy consumption calculated for each additional mass of water removed. A two-factor central composite design was used to establish the optimum conditions for the EDW of wastewater sludge. Experiments showed that the use of an electric field combined with mechanical compression requires less than 10 and 25% of the theoretical thermal drying energy for the low and moderate voltages cases, respectively. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Stable thermophilic anaerobic digestion of dissolved air flotation (DAF) sludge by co-digestion with swine manure.

PubMed

Creamer, K S; Chen, Y; Williams, C M; Cheng, J J

2010-05-01

Environmentally sound treatment of by-products in a value-adding process is an ongoing challenge in animal agriculture. The sludge produced as a result of the dissolved air flotation (DAF) wastewater treatment process in swine processing facilities is one such low-value residue. The objective of this study was to determine the fundamental performance parameters for thermophilic anaerobic digestion of DAF sludge. Testing in a semi-continuous stirred tank reactor and in batch reactors was conducted to determine the kinetics of degradation and biogas yield. Stable operation could not be achieved using pure DAF sludge as a substrate, possibly due to inhibition by long-chain fatty acids or to nutrient deficiencies. However, in a 1:1 ratio (w/w, dry basis) with swine manure, operation was both stable and productive. In the semi-continuous stirred reactor at 54.5 degrees Celsius, a hydraulic residence time of 10 days, and an organic loading rate of 4.68 gVS/day/L, the methane production rate was 2.19 L/L/day and the specific methane production rate was 0.47 L/gVS (fed). Maximum specific methanogenic activity (SMA) in batch testing was 0.15 mmoles CH(4) h(-1) gVS(-1) at a substrate concentration of 6.9 gVS L(-1). Higher substrate concentrations cause an initial lag in methane production, possibly due to long-chain fatty acid or nitrogen inhibition. Copyright 2009 Elsevier Ltd. All rights reserved.

Soil microbial biomass and community structure affected by repeated additions of sewage sludge in four Swedish long-term field experiments

NASA Astrophysics Data System (ADS)

Börjesson, G.; Kätterer, T.; Kirchmann, H.

2012-04-01

Soil organic matter is a key attribute of soil fertility. The pool of soil organic C can be increased, either by mineral fertilisers or by adding organic amendments such as sewage sludge. Sewage sludge has positive effects on agricultural soils through the supply of organic matter and essential plant nutrients, but sludge may also contain unwanted heavy metals, xenobiotic substances and pathogens. One obvious effect of long-term sewage sludge addition is a decrease in soil pH, caused by N mineralisation followed by nitrification, sulphate formation and presence of organic acids with the organic matter added. The objective of this study was to investigate the effect of sewage sludge on the microbial biomass and community structure. Materials and methods We analysed soil samples from four sites where sewage sludge has been repeatedly applied in long-term field experiments situated in different parts of Sweden; Ultuna (59°49'N, 17°39'E, started 1956), Lanna (58°21'N, 13°06'E, started 1997-98), Petersborg (55°32'N, 13°00'E, started 1981) and Igelösa (55°45'N, 13°18'E, started 1981). In these four experiments, at least one sewage sludge treatment is included in the experimental design. In the Ultuna experiment, all organic fertilisers, including sewage sludge, are applied every second year, corresponding to 4 ton C ha-1. The Lanna experiment has a similar design, with 8 ton dry matter ha-1 applied every second year. Lanna also has an additional treatment in which metal salts (Cd, Cu, Ni and Zn) are added together with sewage sludge. At Petersborg and Igelösa, two levels of sewage sludge (4 or 12 ton dry matter ha-1 every 4th year) are compared with three levels of NPK fertiliser (0 N, ½ normal N and normal N). Topsoil samples (0-20 cm depth) from the four sites were analysed for total C, total N, pH and PLFAs (phospholipid fatty acids). In addition, crop yields were recorded. Results At all four sites, sewage sludge has had a positive effect on crop yields and soil organic matter levels. Correlations between soil organic matter and total PLFA contents showed highly positive correlations at all sites (with R-values between 0.72 and 0.88). To find out whether sewage sludge through its metal impurities could impose stress on the microbial biomass, we compared the correlations between all different fertilisers used and PLFAs. The slopes of these comparisons revealed that sludge did not differ from other fertiliser treatments, which means that our results contrast earlier reports on negative effects of metals in sludge on soil microbes. The microbial community structure, studied with principal component analysis of individual PLFAs, was strongly affected by changes in soil pH, and at those sites where sewage sludge had caused a low pH, Gram-positive bacteria were more dominant than in the other treatments. However, differences in community structure were larger between sites than between the treatments investigated in this study, thus indicating that the original soil properties were more important for the microbial community structure than the fertiliser treatments.

Evaluation of sludge from paper recycling as bedding material for broilers.

PubMed

Villagrá, A; Olivas, I; Benitez, V; Lainez, M

2011-05-01

Several materials have been used as bedding substrates in broiler production. In this work, the sludge from paper recycling was tested for its potential use as litter material and was compared with wood shavings. Moisture content, apparent density, and water-holding capacity were measured and characterized in both materials. Later, 192 male broiler chickens were distributed among 16 experimental pens, 8 of which contained wood shavings as bedding material and 8 of which contained the sludge. Growth rate, consumption, tonic immobility, gait score, breast lesions, foot pad dermatitis, hock burn, tibial dyschondroplasia, and metatarsal thickness were determined in the birds. Although the moisture content of the sludge was high, it decreased strongly after 7 d of drying, reaching lower values than those of wood shavings. In general, few differences were found between the materials in terms of bird performance and welfare and only the incidence of hock burn was higher in the sludge than in the wood shavings. Although further research is needed, sludge from paper recycling is a possible alternative to traditional bedding materials because it achieves most of the requirements for broiler bedding materials and does not show negative effects on the birds.

Simultaneous sonication-assisted extraction, and determination by gas chromatography-mass spectrometry, of di-(2-ethylhexyl)phthalate, nonylphenol, nonylphenol ethoxylates and polychlorinated biphenyls in sludge from wastewater treatment plants.

PubMed

Aparicio, I; Santos, J L; Alonso, E

2007-02-19

Di-(2-ethyl-hexyl)phthalate (DEHP), nonylphenol, nonylphenol mono- and diethoxylates (NPEs) and polychlorinated biphenyls (PCBs) are organic pollutants in sewage sludge which have to be monitored in the European Union according to a future Sludge Directive. In the present work, an analytical method for the simultaneous extraction and determination of DEHP, NPEs and PCBs is proposed for the routine analysis of these compounds in sludge from wastewater treatment plants. All the compounds were simultaneously extracted by sonication with hexane and analysed by gas chromatography-mass spectrometry (GC-MS) in electronic impact mode. Recoveries achieved were 105% for DEHP, 61.4-88.6% for NPEs and 55.8-108.3% for PCBs with relative standard deviation bellow 10%. Limits of quantification were 65 microg kg(-1) for DEHP, from 630 to 2504 microg kg(-1) for NPEs and from 5.4 to 10.6 microg kg(-1) for PCBs in dried sludge. The applicability of the proposed method was evaluated by the determination of these compounds in sludge from wastewater treatment plants in Seville (South Spain).

Dynamics of Cd, Cu and Pb added to soil through different kinds of sewage sludge.

PubMed

Torri, S I; Lavado, R S

2008-01-01

A greenhouse experiment was set up to study the distribution of Cd, Cu and Pb in three typical soils of the Pampas Region amended with sewage sludge. A sequential extraction procedure was used to obtain four operationally defined geochemical species: exchangeable, bound to organic matter, bound to carbonates, and residual. Two kinds of sewage sludge were used: pure sewage sludge and sewage sludge containing 30% DM of its own incinerated ash, at rates equivalent to a field application of 150 t DM ha(-1). Pots were maintained at 80% of field capacity through daily irrigation with distilled water. Soil samples were obtained on days 1, 60, 270 and 360, and then air-dried and passed through a 2 mm sieve for analysis. Results showed that sludge application increased the less available forms of Cd, Cu and Pb. The inorganic forms became the most prevalent forms for Cu and Pb, whereas Cd was only found in the residual fraction. The concentrations of OM-Cu and INOR-Cu in the amended soil samples were closely correlated with soil pH, whereas the chemical behavior of Cd and Pb did not depend on soil physico-chemical characteristics.

Preliminary results of lab-scale investigations of products of incomplete combustion during incineration of primary and mixed digested sludge.

PubMed

Braguglia, C M; Bagnuolo, G; Gianico, A; Mininni, G; Pastore, C; Mascolo, G

2016-03-01

Separation between primary and secondary sludge treatment could be a valuable solution for sludge management. According to this approach, secondary sludge can be conveniently used in agriculture while primary sludge could be easily dried and incinerated. It follows that some concern may arise from incinerating primary sludge with respect to the current practice to incinerate mixed digested sludge. Incineration of primary and mixed digested municipal sludge was investigated with a lab-scale equipment in terms of emissions of products of incomplete combustion (PICs) during incineration failure modes. PICs can be grouped in three sub-categories, namely aliphatic hydrocarbons (alkanes and alkenes), compounds with a single aromatic ring, and polycyclic aromatic hydrocarbons (PAHs). After-burning temperature was the most important parameter to be controlled in order to minimize emissions of alkanes and alkenes. As for mono-aromatic compounds, benzene and toluene are the most thermally resistant compounds, and in some cases, an after-burning temperature of 1100 °C was not enough to get the complete destruction of benzene leading to a residual emission of 18 mg/kgsludge. PAHs showed an opposite trend with respect to aliphatic and mono-aromatic hydrocarbons being the thermal failure mode the main responsible of PIC emissions. A proper oxygen concentration is more important than elevated temperature thus reflecting the high thermal stability of PAHs. Overall, obtained results, even though obtained under flameless conditions that are different from those of the industrial plants, demonstrated that separation of primary and secondary sludge does not pose any drawbacks or concern regarding primary sludge being disposed of by incineration even though it is more contaminated than mixed digested sludge in terms of organic pollutants.

The investigation of solid slag obtained by neutralization of sewage sludge.

PubMed

Kavaliauskas, Zydrunas; Valincius, Vitas; Stravinskas, Giedrius; Milieska, Mindaugas; Striugas, Nerijus

2015-11-01

The purpose of this research is to investigate the feasibility of utilizing the slag collected after gasification of organic fuel combined with sewage sludge. The residue left after gasification process is likely usable as raw material for production of supercondensers. The sewage sludge neutralization system consists of a dosing system (fuel tank), gasifier, plasma reactor, electrostatic filter, and heat exchangers. For the gasification process, dried solid sewage is supplied in proportion of 70% to biomass 30% by weight. The slag is collected in a specially designed chamber beneath the gasifier. A scanning electron microscope (SEM) was used to evaluate surface morphology of the samples. Elemental analysis of the sewage sludge slag was performed using the energy-dispersive spectroscopy (EDS) method, which showed different solid-state elements contained in the porous structure of the solid phase: carbon 29%, aluminum 26%, potassium 20%, chlorine 1%, and others. The specific surface area of the sewage sludge slag is 6.15 m(2)/g as the BET analysis shows. In order to use the slag as a secondary raw material, detailed analysis of the structure and properties is necessary for a decision on whether the slag left after gasification of sewage sludge is suitable for any further usages. Initial results indicate that the slag may be used for production of electrodes for supercapacitors. Every year thousands of tons of sewage sludge are formed in Lithuania. Sewage sludge consists of organic and inorganic compounds. Partial combustion, plasma decomposition, and other methods are used to neutralize the sewage sludge. The incineration of sewage sludge results in generation of solid-phase slag. In this paper the material structure and composition of a solid slag (formed during neutralization of sewage sludge) is considered. Also, the impact the ambient temperature on structure and composition of solid slag is analyzed.

Non-slag co-gasification of biomass and coal in entrained-bed furnace

NASA Astrophysics Data System (ADS)

Itaya, Yoshinori; Suami, Akira; Kobayashi, Nobusuke

2018-02-01

Gasification is a promising candidate of processes to upgrade biomass and to yield clean gaseous fuel for utilization of renewable energy resources. However, a sufficient amount of biomass is not always available to operate a large scale of the plant. Co-gasification of biomass with coal is proposed as a solution of the problem. Tar emission is another subject during operation in shaft or kiln type of gasifiers employed conventionally for biomass. The present authors proposed co-gasification of biomass and coal in entrained-bed furnace, which is a representative process without tar emission under high temperature, but operated so to collect dust as flyash without molten slag formation. This paper presents the works performed on co-gasification performance of biomass and pulverized coal to apply to entrained-bed type of furnaces. At first, co-gasification of woody powder and pulverized coal examined using the lab-scale test furnace of the down-flow entrained bed showed that the maximum temperatures in the furnace was over 1500 K and the carbon conversion to gas achieved at higher efficiency than 80-90 percent although the residence time in the furnace was as short as a few seconds. Non-slag co-gasification was carried out successfully without slag formation in the furnace if coal containing ash with high fusion temperature was employed. The trend suggesting the effect of reaction rate enhancement of co-gasification was also observed. Secondary, an innovative sewage sludge upgrading system consisting of self-energy recovery processes was proposed to yield bio-dried sludge and to sequentially produce char without adding auxiliary fuel. Carbonization behavior of bio-dried sludge was evaluated through pyrolysis examination in a lab-scale quartz tube reactor. The thermal treatment of pyrolysis of sludge contributed to decomposition and removal of contaminant components such as nitrogen and sulfur. The gasification kinetics of sludge and coal was also determined by a thermogravimetric analysis. It was revealed that co-gasification rate of sludge and coal chars was influenced negatively due to high ash content in sludge.

Contribution of precursor compounds to the release of per- and polyfluoroalkyl substances (PFASs) from waste water treatment plants (WWTPs).

PubMed

Eriksson, Ulrika; Haglund, Peter; Kärrman, Anna

2017-11-01

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous in sludge and water from waste water treatment plants, as a result of their incorporation in everyday products and industrial processes. In this study, we measured several classes of persistent PFASs, precursors, transformation intermediates, and newly identified PFASs in influent and effluent sewage water and sludge from three municipal waste water treatment plants in Sweden, sampled in 2015. For sludge, samples from 2012 and 2014 were analyzed as well. Levels of precursors in sludge exceeded those of perfluoroalkyl acids and sulfonic acids (PFCAs and PFSAs), in 2015 the sum of polyfluoroalkyl phosphoric acid esters (PAPs) were 15-20ng/g dry weight, the sum of fluorotelomer sulfonic acids (FTSAs) was 0.8-1.3ng/g, and the sum of perfluorooctane sulfonamides and ethanols ranged from non-detected to 3.2ng/g. Persistent PFSAs and PFCAs were detected at 1.9-3.9ng/g and 2.4-7.3ng/g dry weight, respectively. The influence of precursor compounds was further demonstrated by an observed substantial increase for a majority of the persistent PFCAs and PFSAs in water after waste water treatment. Perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS) had a net mass increase in all WWTPs, with mean values of 83%, 28%, 37% and 58%, respectively. The load of precursors and intermediates in influent water and sludge combined with net mass increase support the hypothesis that degradation of precursor compounds is a significant contributor to PFAS contamination in the environment. Copyright © 2017. Published by Elsevier B.V.

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.

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.

Bromine and Chlorine in Aerosols and Fly Ash when Co-Firing Solid Recovered Fuel, Spruce Bark and Paper Mill Sludge in a 80MWth BFB Boiler

NASA Astrophysics Data System (ADS)

Vainikka, P.; Silvennoinen, J.; Yrjas, P.; Frantsi, A.; Hietanen, L.; Hupa, M.; Taipale, R.

Aerosol and fly ash sampling was carried out at a 80MWth bubbling fluidised bed (BFB) boiler plant co-firing solid recovered fuel (SRF), spruce bark and paper mill wastewater sludge in two experimental conditions. The SRF-Bark ratio in the fuel mix was kept constant at 50%-50% on dry mass basis in both experiments but two sludge proportions were used: 15% and 4% on dry mass basis. Aerosol samples were collected from the superheater region of the boiler furnace and fly ash from the electrostatic precipitator (ESP). Na, K, Cl and S were found to be in mainly water soluble compounds in the aerosols sampled by means of a Dekati type Low Pressure Impactor (DLPI). Bromine was found in several weight percentages in aerosols and it was amongst the main elements in some of the samples collected. Bromine is assumed to mainly originate from flame retarded plastics and textiles in the SRF. According to the measurements, the fate of Br seems to be analogous to the other main halogen, Cl, and its conversion from fuel to aerosols was high, indicating a strong tendency to form bromine salts.

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 accumulation pattern inside oxidation ditch case study.

PubMed

Fouad, Moharram; El-Morsy, Ahmed

2014-01-01

The sludge accumulation pattern of an oxidation ditch (OD) plant treating municipal wastewater was observed under dry and wet weather conditions, during 3 years of operation. The accumulation patterns along the ditches and their rates were revealed. In addition, the composition of the accumulation was investigated. Finally, the ratio of sand and volatile particles, mixed liquor suspended solids (MLSS), and mixed liquor volatile suspended solids, as well as the removal efficiency were also observed against the accumulated sludge. Further, a laboratory-scale channel was used to investigate the settleability of grit after mixing with variable values of MLSS. The observed results indicated that the economical design and operation of ODs using a velocity value between 0.3-0.35 m/s is not recommended, to avoid the settling of all solids. High values of MLSS and sludge age need high horizontal velocity (more than 0.35 m/s) and more power to avoid settling problems and system failure. The influence of flow velocity on the sludge settleability was studied, enabling better planning of future ditch design and operation.

Mechanical and wear characteristics of epoxy composites filled with industrial wastes: A comparative study

NASA Astrophysics Data System (ADS)

Purohit, A.; Satapathy, A.

2017-02-01

Use of industrial wastes, such as slag and sludge particles, as filler in polymers is not very common in the field of composite research. Therefore in this paper, a comparison of mechanical characteristics of epoxy based composites filled with LD sludge, BF slag and LD slag (wastes generated in iron and steel industries) were presented. A comparative study among these composites in regard to their dry sliding wear characteristics under similar test conditions was also included. Composites with different weight proportions (0, 5, 10, 15 and 20 wt.%) of LD sludge were fabricated by solution casting technique. Mechanical properties were evaluated as per ASTM test standards and sliding wear test was performed following a design of experiment approach based on Taguchi’s orthogonal array. The test results for epoxy-LD sludge composites were compared with those of epoxy-BF slag and epoxy-LD slag composites reported by previous investigators. The comparison reveals that epoxy filled with LD sludge exhibits superior mechanical and wear characteristics among the three types of composites considered in this study.

Concentrations and environmental fate of Ra in cation-exchange regeneration brine waste disposed to septic tanks and accumulation in sludge, New Jersey Coastal Plain, USA.

PubMed

Szabo, Zoltan; Jacobsen, Eric; Kraemer, Thomas F; Parsa, Bahman

2008-06-01

Concentrations of Ra in liquid and solid wastes generated from 15 softeners treating domestic well waters from New Jersey Coastal Plain aquifers (where combined Ra ((226)Ra plus (228)Ra) concentrations commonly exceed 0.185 Bq L(-1)) were determined. Softeners, when maintained, reduced combined Ra about 10-fold (<0.024 Bq L(-1)). Combined Ra exceeded 0.185 Bq L(-1) at 1 non-maintained system. Combined Ra was enriched in regeneration brine waste (maximum, 81.2 Bq L(-1)), but concentrations in septic-tank effluents receiving brine waste were less than in the untreated ground waters. The maximum combined Ra concentration in aquifer sands (40.7 Bq kg(-1) dry weight) was less than that in sludge from the septic tanks (range, 84-363 Bq kg(-1)), indicating Ra accumulation in sludge from effluent. The combined Ra concentration in sludge from the homeowners' septic systems falls within the range reported for sludge samples from publicly owned treatment works within the region.

Concentrations and environmental fate of Ra in cation-exchange regeneration brine waste disposed to septic tanks and accumulation in sludge, New Jersey Coastal Plain, USA

USGS Publications Warehouse

Szabo, Z.; Jacobsen, E.; Kraemer, T.F.; Parsa, B.

2008-01-01

Concentrations of Ra in liquid and solid wastes generated from 15 softeners treating domestic well waters from New Jersey Coastal Plain aquifers (where combined Ra (226Ra plus 228Ra) concentrations commonly exceed 0.185 Bq L-1) were determined. Softeners, when maintained, reduced combined Ra about 10-fold (<0.024 Bq L-1). Combined Ra exceeded 0.185 Bq L-1 at 1 non-maintained system. Combined Ra was enriched in regeneration brine waste (maximum, 81.2 Bq L-1), but concentrations in septic-tank effluents receiving brine waste were less than in the untreated ground waters. The maximum combined Ra concentration in aquifer sands (40.7 Bq kg-1 dry weight) was less than that in sludge from the septic tanks (range, 84-363 Bq kg-1), indicating Ra accumulation in sludge from effluent. The combined Ra concentration in sludge from the homeowners' septic systems falls within the range reported for sludge samples from publicly owned treatment works within the region.

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

Hydrothermal Liquefaction and Upgrading of Municipal Wastewater Treatment Plant Sludge: A Preliminary Techno-Economic Analysis

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

Snowden-Swan, Lesley J.; Zhu, Yunhua; Jones, Susanne B.

A preliminary process model and techno-economic analysis (TEA) was completed for fuel produced from hydrothermal liquefaction (HTL) of sludge waste from a municipal wastewater treatment plant (WWTP) and subsequent biocrude upgrading. The model is adapted from previous work by Jones et al. (2014) for algae HTL, using experimental data generated in fiscal year 2015 (FY15) bench-scale HTL testing of sludge waste streams. Testing was performed on sludge samples received from MetroVancouver’s Annacis Island WWTP (Vancouver, B.C.) as part of a collaborative project with the Water Environment and Reuse Foundation (WERF). The full set of sludge HTL testing data from thismore » effort will be documented in a separate report to be issued by WERF. This analysis is based on limited testing data and therefore should be considered preliminary. Future refinements are necessary to improve the robustness of the model, including a cross-check of modeled biocrude components with the experimental GCMS data and investigation of equipment costs most appropriate at the smaller scales used here. Environmental sustainability metrics analysis is also needed to understand the broader impact of this technology pathway. The base case scenario for the analysis consists of 10 HTL plants, each processing 100 dry U.S. ton/day (92.4 ton/day on a dry, ash-free basis) of sludge waste and producing 234 barrel per stream day (BPSD) biocrude, feeding into a centralized biocrude upgrading facility that produces 2,020 barrel per standard day of final fuel. This scale was chosen based upon initial wastewater treatment plant data collected by the resource assessment team from the EPA’s Clean Watersheds Needs Survey database (EPA 2015a) and a rough estimate of what the potential sludge availability might be within a 100-mile radius. In addition, we received valuable feedback from the wastewater treatment industry as part of the WERF collaboration that helped form the basis for the selected HTL and upgrading plant scales and feedstock credit (current cost of disposal). It is assumed that the sludge is currently disposed of at $16.20/wet ton ($46/dry ton at 35% solids; $50/ton dry, ash-free basis) and this is included as a feedstock credit in the operating costs. The base case assumptions result in a minimum biocrude selling price of $3.8/gge and a minimum final upgraded fuel selling price of $4.9/gge. Several areas of process improvement and refinements to the analysis have the potential to significantly improve economics relative to the base case: • Optimization of HTL sludge feed solids content • Optimization of HTL biocrude yield • Optimization of HTL reactor liquid hourly space velocity (LHSV) • Optimization of fuel yield from hydrotreating • Combined large and small HTL scales specific to regions (e.g., metropolitan and suburban plants) Combined improvements believed to be achievable in these areas can potentially reduce the minimum selling price of biocrude and final upgraded fuel by about 50%. Further improvements may be possible through recovery of higher value components from the HTL aqueous phase, as being investigated under separate PNNL projects. Upgrading the biocrude at an existing petroleum refinery could also reduce the MFSP, although this option requires further testing to ensure compatibility and mitigate risks to a refinery. And finally, recycling the HTL aqueous phase product stream back to the headworks of the WWTP (with no catalytic hydrothermal gasification treatment) can significantly reduce cost. This option is uniquely appropriate for application at a water treatment facility but also requires further investigation to determine any technical and economic challenges related to the extra chemical oxygen demand (COD) associated with the recycled water.« less

Hydrothermal Liquefaction and Upgrading of Municipal Wastewater Treatment Plant Sludge: A Preliminary Techno-Economic Analysis, Rev.1

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

Snowden-Swan, Lesley J.; Zhu, Yunhua; Jones, Susanne B.

A preliminary process model and techno-economic analysis (TEA) was completed for fuel produced from hydrothermal liquefaction (HTL) of sludge waste from a municipal wastewater treatment plant (WWTP) and subsequent biocrude upgrading. The model is adapted from previous work by Jones et al. (2014) for algae HTL, using experimental data generated in fiscal year 2015 (FY15) bench-scale HTL testing of sludge waste streams. Testing was performed on sludge samples received from Metro Vancouver’s Annacis Island WWTP (Vancouver, B.C.) as part of a collaborative project with the Water Environment and Reuse Foundation (WERF). The full set of sludge HTL testing data frommore » this effort will be documented in a separate report to be issued by WERF. This analysis is based on limited testing data and therefore should be considered preliminary. In addition, the testing was conducted with the goal of successful operation, and therefore does not represent an optimized process. Future refinements are necessary to improve the robustness of the model, including a cross-check of modeled biocrude components with the experimental GCMS data and investigation of equipment costs most appropriate at the relatively small scales used here. Environmental sustainability metrics analysis is also needed to understand the broader impact of this technology pathway. The base case scenario for the analysis consists of 10 HTL plants, each processing 100 dry U.S. ton/day (92.4 ton/day on a dry, ash-free basis) of sludge waste and producing 234 barrel per stream day (BPSD) biocrude, feeding into a centralized biocrude upgrading facility that produces 2,020 barrel per standard day of final fuel. This scale was chosen based upon initial wastewater treatment plant data collected by PNNL’s resource assessment team from the EPA’s Clean Watersheds Needs Survey database (EPA 2015a) and a rough estimate of what the potential sludge availability might be within a 100-mile radius. In addition, we received valuable feedback from the wastewater treatment industry as part of the WERF collaboration that helped form the basis for the selected HTL and upgrading plant scales and feedstock credit (current cost of disposal). It is assumed that the sludge is currently disposed of at $16.20/wet ton ($46/dry ton at 35% solids; $50/ton dry, ash-free basis) and this is included as a feedstock credit in the operating costs. The base case assumptions result in a minimum biocrude selling price of $3.8/gge and a minimum final upgraded fuel selling price of $4.9/gge. Several areas of process improvement and refinements to the analysis have the potential to significantly improve economics relative to the base case: •Optimization of HTL sludge feed solids content •Optimization of HTL biocrude yield •Optimization of HTL reactor liquid hourly space velocity (LHSV) •Optimization of fuel yield from hydrotreating •Combined large and small HTL scales specific to regions (e.g., metropolitan and suburban plants) Combined improvements believed to be achievable in these areas can potentially reduce the minimum selling price of biocrude and final upgraded fuel by about 50%. Further improvements may be possible through recovery of higher value components from the HTL aqueous phase, as being investigated under separate PNNL projects. Upgrading the biocrude at an existing petroleum refinery could also reduce the MFSP, although this option requires further testing to ensure compatibility and mitigation of risks to a refinery. And finally, recycling the HTL aqueous phase product stream back to the headworks of the WWTP (with no catalytic hydrothermal gasification treatment) can significantly reduce cost. This option is uniquely appropriate for application at a water treatment facility but also requires further investigation to determine any technical and economic challenges related to the extra chemical oxygen demand (COD) associated with the recycled water.« less

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.

Occurrence and Fate of Trace Contaminants during Aerobic and Anaerobic Sludge Digestion and Dewatering.

PubMed

Guerra, Paula; Kleywegt, Sonya; Payne, Michael; Svoboda, M Lewina; Lee, Hing-Biu; Reiner, Eric; Kolic, Terry; Metcalfe, Chris; Smyth, Shirley Anne

2015-07-01

Digestion of municipal wastewater biosolids is a necessary prerequisite to their beneficial use in land application, in order to protect public health and the receiving environment. In this study, 13 pharmaceuticals and personal care products (PPCPs), 11 musks, and 17 polybrominated diphenyl ethers were analyzed in 84 samples including primary sludge, waste activated sludge, digested biosolids, dewatered biosolids, and dewatering centrate or filtrate collected from five wastewater treatment plants with aerobic or anaerobic digestion. Aerobic digestion processes were sampled during both warm and cold temperatures to analyze seasonal differences. Among the studied compounds, triclosan, triclocarban, galaxolide, and BDE-209 were the substances most frequently detected under different treatment processes at levels up to 30,000 ng/g dry weight. Comparing aerobic and anaerobic digestion, it was observed that the levels of certain PPCPs and musks were significantly higher in anaerobically digested biosolids, relative to the residues from aerobic digestion. Therefore, aerobic digestion has the potential advantage of reducing levels of PPCPs and musks. On the other hand, anaerobic digestion has the advantage of recovering energy from the biosolids in the form of combustible gases while retaining the nutrient and soil conditioning value of this resource. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

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...

Effect of dewatering and composting on helminth eggs removal from lagooning sludge under semi-arid climate.

PubMed

El Hayany, Bouchra; El Glaoui, Ghizlen El Mezouari; Rihanni, Mohammed; Ezzariai, Amine; El Faiz, Abdelouahed; El Gharous, Mohamed; Hafidi, Mohamed; El Fels, Loubna

2018-04-01

In this work, we assessed the drying and composting effectiveness of helminth eggs removal from sewage sludge of a lagoon wastewater treatment plant located in Chichaoua city. The composting was run after mixing sludge with green waste in different proportions: M1 (½ sludge + ½ green waste), M2 ([Formula: see text] sludge + [Formula: see text] green waste), and M3 ([Formula: see text] sludge + [Formula: see text] green waste) for 105 days. The analysis of the dewatered sewage sludge showed a load of 8-24 helminth eggs/g of fresh matter identified as Ascaris spp. eggs (5-19 eggs/g) followed by Toxocara spp. (0.2 to 2.4 eggs/g); Hookworm spp. and Capillaria spp. (0.4-1 egg/g); Trichuris spp., Taenia spp., and Shistosoma spp. (< 1 egg/g) in the untreated sludge. After 105 days of treatment by composting, we noted a total reduction of helminth eggs in the order of 97.5, 97.83, and 98.37% for mixtures M1, M2, and M3, respectively. The Ascaris spp. eggs were reduced by 98% for M1 and M3 treatments and by 97% for M 2 Treatment. Toxocara spp., Hookworm spp., Trichuris spp., Capillaria spp., and Shistosoma spp. eggs were totally eliminated (100% decrease) and the Taenia spp. was absent from the first stage of composting. These results confirm the effectiveness of both dehydrating and composting processes on the removal of helminth eggs.

Life cycle GHG emissions of sewage sludge treatment and disposal options in Tai Lake Watershed, China.

PubMed

Liu, Beibei; Wei, Qi; Zhang, Bing; Bi, Jun

2013-03-01

The treatment and disposal of sewage sludge generate considerable amounts of greenhouse gases (GHGs) and pose environmental and economic challenges to wastewater treatment in China. To achieve a more informed and sustainable sludge management, this study conducts a life cycle inventory to investigate the GHG performances of six scenarios involving various sludge treatment technologies and disposal strategies. These scenarios are landfilling (S1), mono-incineration (S2), co-incineration (S3), brick manufacturing (S4), cement manufacturing (S5), and fertilizer for urban greening (S6). In terms of GHG emissions, S2 demonstrates the best performance with its large offset from sludge incineration energy recovery, followed by S4 and S6, whereas S1 demonstrates the poorest performance primarily because of its large quantity of methane leaks. The scenario rankings are affected by the assumptions of GHG offset calculation. In most scenarios, GHG performance could be improved by using waste gas or steam from existing facilities for drying sludge. Furthermore, considering the GHG performance along with economic, health, and other concerns, S6 is recommended. We thus suggest that local governments promote the use of composted sludge as urban greening fertilizers. In addition, the use of sludge with 60% water content, in place of the current standard of 80%, in wastewater treatment plants is proposed to be the new standard for Tai Lake Watershed in China. Copyright © 2013 Elsevier B.V. All rights reserved.

Removing freon gas from hydraulic fluid

NASA Technical Reports Server (NTRS)

Williams, B. B.; Mitchell, S. M.; State, T. S.

1981-01-01

Dissolved freon gas is removed from hydraulic fluid by raising temperature to 150 F and bubbling dry nitrogen gas through it, even while fluid circulates through hydraulic system. Procedure reduces parts corrosion, sludge formation, and contamination.

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.

Hydrogen-Rich Syngas Production from Gasification and Pyrolysis of Solar Dried Sewage Sludge: Experimental and Modeling Investigations

PubMed Central

Ghrib, Amina; Friaa, Athar; Ouerghi, Aymen; Naoui, Slim; Belayouni, Habib

2017-01-01

Solar dried sewage sludge (SS) conversion by pyrolysis and gasification processes has been performed, separately, using two laboratory-scale reactors, a fixed-bed pyrolyzer and a downdraft gasifier, to produce mainly hydrogen-rich syngas. Prior to SS conversion, solar drying has been conducted in order to reduce moisture content (up to 10%). SS characterization reveals that these biosolids could be appropriate materials for gaseous products production. The released gases from SS pyrolysis and gasification present relatively high heating values (up to 9.96 MJ/kg for pyrolysis and 8.02  9.96 MJ/kg for gasification) due to their high contents of H2 (up to 11 and 7 wt%, resp.) and CH4 (up to 17 and 5 wt%, resp.). The yields of combustible gases (H2 and CH4) show further increase with pyrolysis. Stoichiometric models of both pyrolysis and gasification reactions were determined based on the global biomass formula, CαHβOγNδSε, in order to assist in the products yields optimization. PMID:28856162

Reduction of excess sludge production using mechanical disintegration devices.

PubMed

Strünkmann, G W; Müller, J A; Albert, F; Schwedes, J

2006-01-01

The usability of mechanical disintegration techniques for the reduction of excess sludge production in the activated sludge process was investigated. Using three different disintegration devices (ultrasonic homogeniser, stirred media mill, high pressure homogeniser) and different operational parameters of the disintegration, the effect of mechanical disintegration on the excess sludge production and on the effluent quality was studied within a continuously operated, laboratory scale wastewater treatment system with pre-denitrification. Depending on the operational conditions and the disintegration device used, a reduction of excess sludge production of up to 70% was achieved. A combination of mechanical disintegration with a membrane bioreactor process with high sludge age is more energy effective concerning reduction of sludge production than with a conventional activated sludge process at lower sludge ages. Depending on the disintegration parameters, the disintegration has no, or only minor, negative effect on the soluble effluent COD and on the COD-removal capacity of the activated sludge process. Nitrogen-removal was slightly deteriorated by the disintegration, whereas the system used was not optimised for nitrogen removal before disintegration was implemented.

Removal of metals in leachate from sewage sludge using electrochemical technology.

PubMed

Meunier, N; Drogui, P; Gourvenec, C; Mercier, G; Hausler, R; Blais, J F

2004-02-01

Heavy metals in acidic leachates from sewage sludge are usually removed by chemical precipitation, which often requires high concentration of chemicals and induces high metallic sludge production. Electrochemical technique has been explored as an alternative method in a laboratory pilot scale reactor for heavy metals (Cu and Zn) removal from sludge leachate. Three electrolytic cell arrangements using different electrodes materials were tested: mild steel or aluminium bipolar electrode (EC cell), Graphite/stainless steel monopolar electrodes (ER cell) and iron-monopolar electrodes (EC-ER cell). Results showed that the best performances of metal removal were obtained with EC and EC-ER cells using mild steel electrodes operated respectively at current intensities of 0.8 and 2.0 A through 30 and 60 min of treatment. The yields of Cu and Zn removal from leachate varied respectively from 92.4 to 98.9% and from 69.8 to 76.6%. The amounts of 55 and 44 kg tds(-1) of metallic sludge were respectively produced using EC and EC-ER cells. EC and EC-ER systems involved respectively a total cost of 21.2 and 13.1 CAN dollars per ton of dry sludge treated including only energy consumption and metallic sludge disposal. The treatment using EC-ER system was found to be effective and more economical than the traditional metal precipitation using either Ca(OH)2 and/or NaOH.

Influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochars derived from municipal sewage sludge.

PubMed

Jin, Junwei; Li, Yanan; Zhang, Jianyun; Wu, Shengchun; Cao, Yucheng; Liang, Peng; Zhang, Jin; Wong, Ming Hung; Wang, Minyan; Shan, Shengdao; Christie, Peter

2016-12-15

Dried raw sludge was pyrolyzed at temperatures ranging from 400 to 600°C at the increase of 50°C intervals to investigate the influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochar derived from municipal sewage sludge. The sludge biochar yield decreased significantly with increasing pyrolysis temperature but the pH, ash content and specific surface area increased. Conversion of sludge to biochar markedly decreased the H/C and N/C ratios. FT-IR analysis confirmed a dramatic depletion of H and N and a higher degree of aromatic condensation in process of biochar formation at higher temperatures. The total concentrations of Cu, Zn, Pb, Cr, Mn, and Ni increased with conversion of sludge to biochar and increasing pyrolysis temperature. However, using BCR sequential extraction and analysis, it was found that most of the heavy metals existed in the oxizable and residual forms after pyrolysis, especially at 600°C, resulting in a significant reduction in their bioavailability, leading to a very low environmental risk of the biochar. The present study indicates pyrolysis is a promising sludge treatment method for heavy metals immobilization in biochar, and highlights the potential to minimize the harmful effects of biochar by controlling pyrolysis temperature. Copyright © 2016 Elsevier B.V. All rights reserved.

Restoration of acidic mine spoils with sewage sludge: II measurement of solids applied

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

Stucky, D.J.; Zoeller, A.L.

1980-01-01

Sewage sludge was incorporated in acidic strip mine spoils at rates equivalent to 0, 224, 336, and 448 dry metric tons (dmt)/ha and placed in pots in a greenhouse. Spoil parameters were determined 48 hours after sludge incorporation, Time Planting (P), and five months after orchardgrass (Dactylis glomerata L.) was planted, Time Harvest (H), in the pots. Parameters measured were: pH, organic matter content (OM), cation exchange capacity (CEC), electrical conductivity (EC) and yield. Values for each parameter were significantly different at the two sampling times. Correlation coefficient values were calculated for all parameters versus rates of applied sewage sludgemore » and all parameters versus each other. Multiple regressions were performed, stepwise, for all parameters versus rates of applied sewage sludge. Equations to predict amounts of sewage sludge incorporated in spoils were derived for individual and multiple parameters. Generally, measurements made at Time P achieved the highest correlation coefficient and multiple correlation coefficient values; therefore, the authors concluded data from Time P had the greatest predictability value. The most important value measured to predict rate of applied sewage sludge was pH and some additional accuracy was obtained by including CEC in equation. This experiment indicated that soil properties can be used to estimate amounts of sewage sludge solids required to reclaim acidic mine spoils and to estimate quantities incorporated.« less

A modified oxic-settling-anaerobic activated sludge process using gravity thickening for excess sludge reduction

NASA Astrophysics Data System (ADS)

Wang, Jun; Li, Shi-Yu; Jiang, Feng; Wu, Ke; Liu, Guang-Li; Lu, Hui; Chen, Guang-Hao

2015-09-01

Oxic-settling-anaerobic process (OSA) was known as a cost-effective way to reduce the excess sludge production with simple upgrade of conventional activated sludge process (CAS). A low oxidation-reduction potential (ORP) level was the key factor to sludge decay and lysis in the sludge holding tank of the OSA process. However, the ORP control with nitrogen purge or chemical dosing in the OSA process would induce extra expense and complicate the operation. Hence, in this study, a sludge holding tank using gravity thickening was applied to OSA process to reduce the excess sludge production without any ORP control. Results showed that the modified OSA process not only reduced the excess sludge production effectively but also improved the sludge settleability without affected the treatment capacity. The reduction of the excess sludge production in the modified OSA process resulted from interactions among lots of factors. The key element of the process was the gravity thickening sludge holding tank.

Pharmaceuticals and personal care products in untreated and treated sewage sludge: Occurrence and environmental risk in the case of application on soil - A critical review.

PubMed

Verlicchi, P; Zambello, E

2015-12-15

This review is based on 59 papers published between 2002 and 2015, referring to about 450 treatment trains providing data regarding sludge concentrations for 169 compounds, specifically 152 pharmaceuticals and 17 personal care products, grouped into 28 different classes. The rationale of the study is to provide data to evaluate the environmental risk posed by the spreading of treated sludge in agriculture. Following discussion of the legislative scenario governing the final disposal of treated sludge in European countries and the USA, the study provides a snapshot of the occurrence of selected compounds in primary, secondary, mixed, digested, conditioned, composted and dried sludge originating in municipal wastewater treatment plants fed mainly with urban wastewater as well as in sludge-amended soil. Not only are measured values reported, but also predicted concentrations based on Kd values are reported. It emerges that in secondary sludge, the highest concentrations were found for fragrances, antiseptics and antibiotics and an attenuation in their concentrations occurs during treatment, in particular anaerobic digestion and composting. An in-depth literature survey of the (measured and predicted) Kd values for the different compounds and treated sludge are reported and an analysis of the influence of pH, redox conditions, sludge type was carried out. The data regarding measured and predicted concentrations of selected compounds in sludge-amended soil is then analyzed. Finally an environmental risk assessment posed by their occurrence in soil in the case of land application of sludge is examined, and the results obtained by different authors are compared. The most critical compounds found in the sludge-amended soil are estradiol, ciprofloxacin, ofloxacin, tetracycline, caffeine, triclosan and triclocarban. The study concludes with a focus on the main issues that should be further investigated in order to refine the environmental risk assessment. Copyright © 2015 Elsevier B.V. All rights reserved.

Overall effect of carbon production and nutrient release in sludge holding tank on mainstream biological nutrient removal efficiency.

PubMed

Jabari, Pouria; Yuan, Qiuyan; Oleszkiewicz, Jan A

2017-09-11

The potential of hydrolysis/fermentation of activated sludge in sludge holding tank (SHT) to produce additional carbon for the biological nutrient removal (BNR) process was investigated. The study was conducted in anaerobic batch tests using the BNR sludge (from a full-scale Westside process) and the mixture of BNR sludge with conventional non-BNR activated sludge (to have higher biodegradable particulate chemical oxygen demand (bpCOD) in sludge). The BioWin 4.1 was used to simulate the anaerobic batch test of the BNR sludge. Also, the overall effect of FCOD production and nutrient release on BNR efficiency of the Westside process was estimated. The experimental results showed that the phosphorous uptake of sludge increased during hydrolysis/ fermentation condition up to the point when poly-P was completely utilized; afterwards, it decreased significantly. The BioWin simulation could not predict the loss of aerobic phosphorous uptake after poly-P was depleted. The results showed that in the case of activated sludge with relatively higher bpCOD (originating from plants with short sludge retention time or without primary sedimentation), beneficial effect of SHT on BNR performance is feasible. In order to increase the potential of SHT to enhance BNR efficiency, a relatively low retention time and high sludge load is recommended.

Effects of dissolved oxygen on performance and microbial community structure in a micro-aerobic hydrolysis sludge in situ reduction process.

PubMed

Niu, Tianhao; Zhou, Zhen; Shen, Xuelian; Qiao, Weimin; Jiang, Lu-Man; Pan, Wei; Zhou, Jijun

2016-03-01

A sludge process reduction activated sludge (SPRAS), with a sludge process reduction module composed of a micro-aerobic tank and a settler positioned before conventional activated sludge process, showed good performance of pollutant removal and sludge reduction. Two SPRAS systems were operated to investigate effects of micro-aeration on sludge reduction performance and microbial community structure. When dissolved oxygen (DO) concentration in the micro-aerobic tank decreased from 2.5 (SPH) to 0.5 (SPL) mg/L, the sludge reduction efficiency increased from 42.9% to 68.3%. Compared to SPH, activated sludge in SPL showed higher contents of extracellular polymeric substances and dissolved organic matter. Destabilization of floc structure in the settler, and cell lysis in the sludge process reduction module were two major reasons for sludge reduction. Illumina-MiSeq sequencing showed that microbial diversity decreased under high DO concentration. Proteobacteria, Bacteroidetes and Chloroflexi were the most abundant phyla in the SPRAS. Specific comparisons down to the class and genus level showed that fermentative, predatory and slow-growing bacteria in SPL community were more abundant than in SPH. The results revealed that micro-aeration in the SPRAS improved hydrolysis efficiency and enriched fermentative and predatory bacteria responsible for sludge reduction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of dried wastewater-treatment sludge application on ground-water quality in South Dade County, Florida

USGS Publications Warehouse

Howie, Barbara

1992-01-01

Four test fields in the south Dade agricultural area were studied to determine the effects of sludge application on ground-water quality. Two fields had been cultivated for 10 years or more, and two had not been farmed for at least 10 years. The fields were representative of the area's two soil types (Rockdale and Perrine marl) and two major crop types (row crops and groves). Before the application of sludge, wells upgradient of, within, and downgradient of each field were sampled for possible sludge contaminants at the end of wet and dry seasons. Municipal wastewater treatment sludge from the Dade County Water and Sewe Authority Department was then applied to the fields at varying application rates. The wells at each field were sampled over a 2-year period under different hydrologic conditions for possible sludge-related constituents (specific conductance, pH, alkalinity, nitrogen, phosphorus, total organic carbon, copper, iron, magnesium, manganese, potassium, zinc, arsenic, cadmium, chloride, chromium, lead, mercury, nickel, and sodium). Comparisons were made between water quality in the vicinity of the test fields and Florida Department of Environmental Regulation primary and secondary drinking-water regulations, an between water quality upgradient of, beneath, and downgradient of the fields. Comparisons between presludge and postsludge water quality did not indicate any improvement because of retention of agrichemicals by the sludge nor did they indicate any deterioration because of leaching from the sludge. Comparisons of water quality upgradient of the fields to water quality beneath and downgradient of the fields also did not indicate any changes related to sludge. Florida Department of Environmental Regulation primary and secondary drinking-water regulations wer exceeded at the Rockdale maximum-application field by mercury (9.5 ug/L (micrograms per liter)), and the Perrine marl maximum-application field by manganese (60 ug/L) and lead (85 ug/L), and at the Perrine marl row-crop field by mercury (5.2 ug/L). All other exceedances were either in presludge or upgradient samples, or they were for constituents or properties, such as iron and color, which typically exceed standards in native ground water. Acid-extractable and base-neutral compounds, volatile organic compounds, chlorophenoxy herbicides, organophosphorus insecticides, and organochlorine compounds were analyzed for one shallow well at each field twice annually. Those compounds that equaled or exceeded the detection limit after sludge was applied included benzene (0.3 and 1.2 ug/L), chloroform (0.2 and 0.3 ug/L), bis(2-Ethylhexyl)phthalate (29 and 42 ug/L), methylene chloride (14 ug/L), tolulene (0.2, 0.4, 0.5, 1.3, and 4.4 ug/L), 1, 1,1-trichloroethana (0.6 ug/L), trichloroethylene (0.3 ug/L), 2.4-D (0.01 ug/L), and xylene (0.3 ug/L). It ws not possible to ascertain the origin of these compounds becuase they are available from sources other than sludge.

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

Mercury emissions and species during combustion of coal and waste

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

Hong Yao; Guangqian Luo; Minghou Xu

2006-10-15

The behaviors of mercury evolution for three types of coal and three types of dried sewage sludge are studied using a thermogravimetric (TG) analyzer. The mercury speciations in the flue gas from coal and sludge combustion are also analyzed by implementing a horizontal electrically heated tube furnace. Furthermore, the kinetic calculations of mercury oxidizing processes are carried out using the software package CHEMKIN in order to interpret the homogeneous mechanism of mercury oxidization. The results obtained show that the sulfur content in the sludge inhibits the evolution of mercury at low temperature if the Cl concentration is high enough. Chlorinemore » enhances mercury evolution in the coal combustion, whereas there is no relationship when the Cl concentration is high. Fixed carbon content plays a role in depression of the mercury evolution. Formation of oxidized mercury (HgCl{sub 2}) does not relate to the chlorine concentration in the raw coal and sludge. Whereas the ash and sulfur content in the sludge affects the Hg oxidization, kinetic calculations show that HgCl, Cl{sub 2}, and HOCl formation is important in producing the oxidized mercury during combustion of coal and sludge at 873 K. A suitable temperature for Hg oxidization when Cl{sub 2} is the oxidization resource is 700-1200 K. 32 refs., 10 figs., 5 tabs.« less

Parasite ova in anaerobically digested sludge

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

Arther, R.G.; Fitzgerald, P.R.; Fox, J.C.

The Metropolitan Sanitary District of Greater Chicago produces anaerobically digested wastewater sludge from a 14-day continuous-flow process maintained at 35 degrees Celcius. Some of the sludge is ultimately applied to strip-mined lands in Central Illinois (Fulton County) as a soil conditioner and fertilizer. Parasitic nematode ova were isolated from freshly processed samples, as well as from samples collected from storage lagoons, using a system of continuous sucrose solution gradients. The mean number of ova per 100 g of dry sludge was 203 Ascaris spp., 173 Toxocara spp., 48 Toxascaris leonina, and 36 Trichuris spp. An assessment of the viability ofmore » these ova was determined by subjecting the ova to conditions favorable for embryonation. Recovered ova were placed in 1.5% formalin and aerated at 22 degrees Celcius for 21 to 28 days. Development of ova isolated from freshly digested sludge occurred in 64% of the Ascaris spp., 53% of the Toxocara, 63% of the Toxascaris leonina, and 20% of the Trichuris spp. Viability was also demonstrated in ova recovered from sludge samples held in storage lagoons for a period of up to 5 years; embryonation occurred in 24% of the Ascaris spp., 10% of the Toxocara spp., 43% of the Toxascaris leonina, and 6% of the Trichuris spp. (Refs. 24).« less

Application of Heavy Metal Rich Tannery Sludge on Sustainable Growth, Yield and Metal Accumulation by Clarysage (Salvia sclarea L.).

PubMed

Chand, Sukhmal; Yaseen, M; Rajkumari; Patra, D D

2015-01-01

A field experiment was conducted to evaluate the effective utilization of tannery sludge for cultivation of clarysage (Salvia sclarea) at CIMAP research farm, Lucknow, India during the year 2012-2013. Six doses (0, 20, 40, 60, 80, 100 tha(-1)) of processed tannery sludge were tested in randomised block design with four replications. Results revealed that maximum shoot, root, dry matter and oil yield were obtained with application of 80 tha(-1)of tannery sludge and these were 94, 113 and 61% higher respectively, over control. Accumulation of heavy metals (Cr, Ni, Fe, Pb) were relatively high in shoot portion of the plant than root. Among heavy metals, magnitude of chromium accumulation was higher than nickel, iron and lead in shoot as well as in root. Linalool, linalyl acetate and sclareol content in oil increased by 13,8 and 27% respectively over control, with tannery sludge application at 80 tha(-1). Heavy metals such as chromium, cadmium and lead content reduced in postharvest soil when compared to initial status. Results indicated that clarysage (Salvia sclarea) can be grown in soil amended with 80 tha(-1)sludge and this can be a suitable accumulator of heavy metals for phytoremediation of metal polluted soils.

Ground-water flow and effects of agricultural application of sewage sludge and other fertilizers on the chemical quality of sediments in the unsaturated zone and ground water near Platteville, Colorado, 1985-89

USGS Publications Warehouse

Gaggiani, N.G.

1995-01-01

From fall 1985 through 1989, 6,431 dry tons of anaerobic, digested, sewage sludge were applied as a fertilizer on about 1 square mile of sandy farm- land near Platteville, Colorado. Mean nitrite plus nitrate as nitrogen concentrations in the surficial aquifer increased during the period of sewage- sludge application. However, the effects of municipal sewage sludge applied to the soil in section 16 are difficult to ascertain because anhydrous ammonia and cattle and chicken manure were applied to section 16 prior to sewage-sludge application and anhydrous ammonia was applied during the period of sewage-sludge application. Mostly ammonia plus organic nitrogen was detected in the unsaturated zone while nitrite plus nitrate as nitrogen predominated in the surficial aquifer. The areas of largest concentrations of nitrite plus nitrate as nitrogen were in the northeastern and southwestern quarter sections os section 16. Changes in nitrite plus nitrate as nitrogen concentrations with depth and time were detected in water samples from the multilevel ground-water sampling devices in the surficial aquifer. Nitrogen probably entered the saturated zone in the irrigated areas and low temporarily ponded areas and moved to the northeast with water in the surficial aquifer.

Gasification of yeast industry treatment plant sludge using downdraft Gasifier.

PubMed

Ayol, Azize; Tezer, Ozgun; Gurgen, Alim

2018-01-01

Sludges produced in biological wastewater treatment plants have rich organic materials in their characteristics. Recent research studies have focused on the energy recovery from sludge due to its high organic content. The gasification process is a thermal conversion technology transforming the chemical energy contained in a solid fuel into thermal energy and electricity. The produced syngas as a mixture of CO, CH 4 , H 2 and other gases can be used to generate electrical energy. The gasification of yeast industry sludge has been experimentally evaluated in a pilot scale downdraft-type gasifier as a route towards the energy recovery. The gasifier has 20 kg biomass/h fuel capacity. During gasification, the temperature achieved was more than 1,000°C in the gasifier, and then the syngas was transferred to the gas engine to yield the electricity. A load was connected to the grid box and approximately 1 kWh electrical power generation for 1 kg dry sludge was determined. The characteristics of residuals - ash, glassy material - were also analyzed. It was found that most of the heavy metals were fixed in the glassy material. Experimental results showed that the yeast industry sludge was an appropriate material for gasification studies and remarkable energy recovery was obtained in terms of power production by using syngas.

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.

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.

Odorants and malodors associated with land application of biosolids stabilized with lime and coal fly ash.

PubMed

Laor, Yael; Naor, Moshe; Ravid, Uzi; Fine, Pinchas; Halachmi, Ilan; Chen, Yona; Baybikov, Rima

2011-01-01

Malodor emissions limit public acceptance of using municipal biosolids as natural organic resources in agricultural production. We aimed to identify major odorants and to evaluate odor concentrations associated with land application of anaerobically digested sewage sludges (Class B) and their alkaline (lime and coal fly ash)-stabilized products (Class A). These two types of biosolids were applied at 12.6 tonnes ha(-1) (dry weight) to microplots of very fine clayey Vertisol in the Jezreel Valley, northern Israel. The volatile organic compounds (VOCs) emitted from the biosolids before and during alkaline stabilization and after incorporation into the soil were analyzed by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry. Odor concentrations at the plots were evaluated on site with a Nasal Ranger field olfactometer that sniffed over a defined land surface area through a static chamber. The odors emitted by anaerobically digested sewage sludges from three activated sludge water treatment plants had one characteristic chemical fingerprint. Alkaline stabilization emitted substantial odors associated with high concentrations of ammonia and release of nitrogen-containing VOCs and did not effectively reduce the potential odor annoyance. Odorous VOCs could be generated within the soil after biosolids incorporation, presumably because of anaerobic conditions within soil-biosolids aggregates. We propose that dimethyl disulfide and dimethyl trisulfide, which seem to be most related to the odor concentrations of biosolids-treated soil, be used as potential chemical markers for the odor annoyance associated with incorporation of anaerobically digested sewage sludges. by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

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.

Plant uptake of pentachlorophenol from sludge-amended soils

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

Bellin, C.A.; O'Connor, G.A.

A greenhouse study was conducted to determine the effects of sludge on plant uptake of {sup 14}C-pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal {sup 14}C. The GC/MS analysis of soil extracts at harvest suggests a half-life of PCP of about 10 d independent ofmore » sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were <0.01 for all crops, suggesting little PCP uptake. Thus, food-chain crop PCP uptake in these alkaline soils should not limit land application of sludge.« less

Plant uptake of pentachlorophenol from sludge-amended soils

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

Bellin, C.A.; O'Connor, G.A.

A greenhouse study was conducted to determine the effects of sludge on plant uptake of {sup 14}C-pentachlorophenol (PCP). Plants included tall fescue (Festuca arundinacea Schreb.), lettuce (Latuca sativa L.), carrot (Daucus carota L.), and chile pepper (Capsicum annum L.). Minimal intact PCP was detected in the fescue and lettuce by gas chromatography/mass spectrometry (GC/MS) analysis. No intact PCP was detected in the carrot tissue extracts. Chile pepper was not analyzed for intact PCP because methylene chloride extracts contained minimal {sup 14}C. The GC/MS analysis of soil extracts at harvest suggests a half-life of PCP of about 10 d independent ofmore » sludge rate or PCP loading rate. Rapid degradation of PCP in the soil apparently limited PCP availability to the plant. Bioconcentration factors (dry plant wt./initial soil PCP concentration) based on intact PCP were < 0.01 for all crops, suggesting little PCP uptake. Thus, food-chain crop PCP uptake in these alkaline soils should not limit land application of sludge.« less

The effect of mixing ratio variation of sludge and organic solid waste on biodrying process

NASA Astrophysics Data System (ADS)

Nasution, A. C.; Kristanto, G. A.

2018-01-01

In this study, organic waste was co-biodried with sludge cake to determine which mixing ratio gave the best result. The organic waste was consisted of dried leaves and green leaves, while the sludge cake was obtained from a waste water treatment plant in Bekasi. The experiment was performed on 3 lab-scale reactors with same specifications. After 21 days of experiment, it was found that the reactor with the lowest mixing fraction of sludge (5:1) has the best temperature profile and highest moisture content depletion compared with others. Initial moisture content and initial volatile solid content of this reactor’s feedstock was 52.25% and 82.4% respectively. The airflow rate was 10 lpm. After biodrying was done, the final moisture content of the feedstock from Reactor C was 22.0% and the final volatile solid content was 75.9%.The final calorific value after biodrying process was 3179,28kcal/kg.

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.

Supercritical water gasification of sewage sludge: gas production and phosphorus recovery.

PubMed

Acelas, Nancy Y; López, Diana P; Brilman, D W F Wim; Kersten, Sascha R A; Kootstra, A Maarten J

2014-12-01

In this study, the feasibility of the gasification of dewatered sewage sludge in supercritical water (SCW) for energy recovery combined with P-recovery from the solid residue generated in this process was investigated. SCWG temperature (400°C, 500°C, 600°C) and residence time (15min, 30min, 60min) were varied to investigate their effects on gas production and the P recovery by acid leaching. The results show that the dry gas composition for this uncatalyzed gasification of sewage sludge in SCW mainly comprised of CO2, CO, CH4, H2, and some C2-C3 compounds. Higher temperatures and longer residence times favored the production of H2 and CH4. After SCWG, more than 95% of the P could be recovered from the solid residue by leaching with acids. SCWG combined with acid leaching seems an effective method for both energy recovery and high P recovery from sewage sludge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effects of pyrolysis temperature, time and leaf litter and powder coal ash addition on sludge-derived adsorbents for nitrogen oxide.

PubMed

Ren, Xiaoli; Liang, Baohong; Liu, Min; Xu, Xiaoyuan; Cui, Meihua

2012-12-01

The objective of this research was to seek a cost effective solution to prepare adsorbents for nitrogen oxide from surplus sludge. Leaf litter and powder coal ash were used as cheap and easily available additives. An adsorbent for nitrogen oxide was prepared by pyrolysis of dried sludge mixed with zinc chloride. Under optimum pyrolysis conditions of 375°C for 90 min and a zinc chloride content of 30%, the surface area of the adsorbent with leaf litter was 514.41 m(2)/g, the surface area of the adsorbent with powder coal ash was 432.34 m(2)/g, respectively, corresponding to an increase of 90.70% and 60.27% when compared to the adsorbent without the additives. The saturated adsorption quantity of the adsorbent with leaf litter reached 271 mg/g at 20°C. The results indicated that the sludge-derived adsorbent was quite promising for nitrogen oxide removal. Copyright © 2012 Elsevier Ltd. All rights reserved.

Aerobic biodegradation of sludge with high hydrocarbon content generated by a Mexican natural gas processing facility.

PubMed

Roldán-Carrillo, T; Castorena-Cortés, G; Zapata-Peñasco, I; Reyes-Avila, J; Olguín-Lora, P

2012-03-01

The biodegradation of oil sludge from Mexican sour gas and petrochemical facilities contaminated with a high content of hydrocarbons, 334.7 ± 7.0 g kg(-1) dry matter (dm), was evaluated. Studies in microcosm systems were carried out in order to determine the capacity of the native microbiota in the sludge to reduce hydrocarbon levels under aerobic conditions. Different carbon/nitrogen/phosphorous (C/N/P) nutrient ratios were tested. The systems were incubated at 30 °C and shaken at 100 rpm. Hydrocarbon removals from 32 to 51% were achieved in the assays after 30 days of incubation. The best assay had C/N/P ratio of 100/1.74/0.5. The results of the Microtox(®) and Ames tests indicated that the original sludge was highly toxic and mutagenic, whereas the best assay gave a final product that did not show toxicity or mutagenicity. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

Effect of dissolved oxygen and temperature on macromolecular composition and PHB storage of activated sludge.

PubMed

Reyes, Paula; Urtubia, Alejandra; Schiappacasse, María C; Chamy, Rolando; Montalvo, Silvio; Borja, Rafael

2014-01-01

The macromolecular composition of activated sludge (lipids, intracellular proteins and intracellular polysaccharides) was studied together with its capacity to store macromolecules such as polyhydroxybutyrate (PHB) in a conventional activated sludge system fed with synthetic sewage water at an organic load rate of 1.0 kg COD/(m(3)·d), varying the dissolved oxygen (DO) and temperature. Six DO concentrations (0.8, 1.0, 1.5, 2.0, 2.5 and 8 mg/L) were studied at 20°C with a sludge retention time (SRT) of 6 days. In addition, four temperatures (10ºC, 15ºC, 20ºC and 30ºC) were assessed at constant DO (2 mg/L) with 2 days SRT in a second experimental run. The highest lipid content in the activated sludge was 95.6 mg/g VSS, obtained at 30°C, 2 mg/L of DO and a SRT of 2 days. The highest content of intracellular proteins in the activated sludge was 87.8 mg/g VSS, obtained at 20°C, 8 mg/L of DO and a SRT of 6 days. The highest content of intracellular polysaccharides in the activated sludge was 76.6 mg/g VSS, which was achieved at 20°C, a SRT of 6 days and a wide range of DO. The activated sludge PHB storage was very low for all the conditions studied.

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

Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine and its mononitroso derivative hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine by Klebsiella pneumoniae strain SCZ-1 isolated from an anaerobic sludge.

PubMed

Zhao, Jian-Shen; Halasz, Annamaria; Paquet, Louise; Beaulieu, Chantale; Hawari, Jalal

2002-11-01

In previous work, we found that an anaerobic sludge efficiently degraded hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), but the role of isolates in the degradation process was unknown. Recently, we isolated a facultatively anaerobic bacterium, identified as Klebsiella pneumoniae strain SCZ-1, using MIDI and the 16S rRNA method from this sludge and employed it to degrade RDX. Strain SCZ-1 degraded RDX to formaldehyde (HCHO), methanol (CH3OH) (12% of total C), carbon dioxide (CO(2)) (72% of total C), and nitrous oxide (N2O) (60% of total N) through intermediary formation of methylenedinitramine (O(2)NNHCH(2)NHNO(2)). Likewise, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX) was degraded to HCHO, CH3OH, and N2O (16.5%) with a removal rate (0.39 micromol. h(-1). g [dry weight] of cells(-1)) similar to that of RDX (0.41 micromol. h(-1). g [dry weight] of cells(-1)) (biomass, 0.91 g [dry weight] of cells. liter(-1)). These findings suggested the possible involvement of a common initial reaction, possibly denitration, followed by ring cleavage and decomposition in water. The trace amounts of MNX detected during RDX degradation and the trace amounts of hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine detected during MNX degradation suggested that another minor degradation pathway was also present that reduced -NO2 groups to the corresponding -NO groups.

Effects and risk assessment of linear alkylbenzene sulfonates in agricultural soil. 1. Short-term effects on soil microbiology.

PubMed

Elsgaard, L; Petersen, S O; Debosz, K

2001-08-01

Linear alkylbenzene sulfonates (LAS) may occur in sewage sludge that is applied to agricultural soil, in which LAS can be inhibitory to biological activity. As a part of a broader risk assessment of LAS in the terrestrial environment, we tested the short-term effects of aqueous LAS on microbial parameters in a sandy agricultural soil that was incubated for up to 11 d. The assays included 10 microbial soil parameters; ethylene degradation; potential ammonium oxidation; potential dehydrogenase activity; beta-glucosidase activity; iron reduction; the populations of cellulolytic bacteria, fungi and actinomycetes; the basal soil respiration; and the phospholipid fatty acid (PLFA) content. Except for beta-glucosidase activity, basal respiration, and total PLFA content, all soil parameters were sensitive to LAS, with EC10 values in the range of less than 8 to 22 mg/kg dry weight. This probably reflected a similar mode of LAS toxicity, ascribed to cell membrane interactions, and showed that sensitivity to LAS was common for various soil microorganisms. The extracellular beta-glucosidase activity was rather insensitive to LAS (ECI10, 47 mg/kg dry wt), whereas the basal soil respiration was not inhibited even at 793 mg/kg dry weight. This was interpreted as a combined response of inhibited and stimulated compartments of the microbial community. The PLFA content, surprisingly, showed no decrease even at 488 mg/kg. In conclusion, LAS inhibited specific microbial activities, although this could not be deduced from the basal respiration or the total PLFA content. The lowest EC10 values for microbial soil parameters were slightly higher than the predicted no-effect concentrations recently derived for plants and soil fauna (approximately 5 mg/kg dry wt).

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...

Growth, physiology and yield of durum wheat (Triticum durum) treated with sewage sludge under water stress conditions

PubMed Central

Boudjabi, Sonia; Kribaa, Mohammed; Chenchouni, Haroun

2015-01-01

In arid and semi-arid areas, low soil fertility and water deficit considerably limit crop production. The use of sewage sludge as an organic amendment could contribute to the improvement of soil fertility and hence the agronomic production. The study aims to highlight the behaviour of durum wheat to the application of sewage sludge associated with water stress. The assessment focused on morphophysiological parameters of the wheat plant and yield. Under greenhouse conditions, the variety Mohamed Ben Bachir was treated by four water stress levels (100 %, 80 %, 50 % and 30 %). Each stress level comprised five fertilizer treatments: 20, 50 and 100 t/ha of dry sludge, 35 kg/ha of urea, and a control with no fertilization. Results revealed a significant loss in water content and chlorophyll a in leaves. Water stress negatively affected the development of wheat plants by reducing significantly seed yield, leaf area and biomass produced. Plant’s responses to water stress manifested by an accumulation of proline and a decrease in total phosphorus. However, the increasing doses of sewage sludge limited the effect of water stress. Our findings showed an increase in the amount of chlorophyll pigments, leaf area, total phosphorus, biomass and yield. In addition, excessive accumulation of proline (1.11 ± 1.03 µg/g DM) was recorded as a result of the high concentration of sludge (100 t/ha DM). The application of sewage sludge is beneficial for the wheat crop, but the high accumulation of proline in plants treated with high dose of sludge suggests to properly consider this fact. The application of sludge should be used with caution in soils where water is limited. Because the combined effect of these two factors could result in a fatal osmotic stress to crop development. PMID:26417365

Feedstock and process influence on biodiesel produced from waste sewage sludge.

PubMed

Capodaglio, Andrea G; Callegari, Arianna

2018-06-15

Disposal of sewage sludge is one of the most important issues in wastewater treatment throughout Europe, as EU sludge production, estimated at 9.5 million tons dry weight in 2005, is expected to approach 13 million tons in 2020. While sludge disposal costs may constitute 30-50% of the total operation costs of wastewater treatment processes, waste sewage sludge still contains resources that may be put to use, like nutrients and energy, that can be recovered through a variety of approaches. Research has shown that waste sewage sludge can be a valuable and very productive feedstock for biodiesel generation, containing lipids (the fats from which biofuels are extracted) in amounts that would require large areas cultivated with typical biodiesel feedstock, to produce, and at a much lower final cost. Several methods have been tested for the production of biodiesel from sewage sludge. To date, among the most efficient such process is pyrolysis, and in particular Microwave-Assisted Pyrolysis (MAP), under which process conditions are more favorable in energetic and economic terms. Sludge characteristics are very variable, depending on the characteristics of the wastewater-generating service area and on the wastewater treatment process itself. Each sludge can be considered a unique case, and as such experimental determination of the optimal biodiesel yields must be conducted on a case-by-case basis. In addition to biodiesel, other pyrolysis products can add to the energetic yield of the process (and not only). This paper discusses how feedstock properties and process characteristics may influence biodiesel (and other products) yield from pyrolytic (and in particular, MAP) processes, and discusses future possible technological developments. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

ALTERNATIVES FOR CLASS A BIOSOLIDS

EPA Science Inventory

The presentation reviews the pathogenic microorganisms that may be found in sewage sludge and commonly employed Class A processes for controlling them including advanced digestion, alkaline treatment and heat drying. How extensively the processes are used as well as issues and co...

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.

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.

Pharmaceutical load in sewage sludge and biochar produced by hydrothermal carbonization.

PubMed

vom Eyser, C; Palmu, K; Schmidt, T C; Tuerk, J

2015-12-15

We investigated the removal of twelve pharmaceuticals in sewage sludge by hydrothermal carbonization (HTC), which has emerged as a technology for improving the quality of organic waste materials producing a valuable biochar material. In this study, the HTC converted sewage sludge samples to a biochar product within 4h at a temperature of 210 °C and a resulting pressure of about 15 bar. Initial pharmaceutical load of the sewage sludge was investigated as well as the residual concentrations in biochar produced from spiked and eight native sewage sludge samples from three waste water treatment plants. Additionally, the solid contents of source material and product were compared, which showed a considerable increase of the solid content after filtration by HTC. All pharmaceuticals except sulfamethoxazole, which remained below the limit of quantification, frequently occurred in the investigated sewage sludges in the μg/kg dry matter (DM) range. Diclofenac, carbamazepine, metoprolol and propranolol were detected in all sludge samples with a maximum concentration of 800 μg/kgDM for metoprolol. HTC was investigated regarding its contaminant removal efficiency using spiked sewage sludge. Pharmaceutical concentrations were reduced for seven compounds by 39% (metoprolol) to≥97% (carbamazepine). In native biochar samples the four compounds phenazone, carbamazepine, metoprolol and propranolol were detected, which confirmed that the HTC process can reduce the load of micropollutants. In contrast to the other investigated compounds phenazone concentration increased, which was further addressed in thermal behaviour studies including three structurally similar potential precursors. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of Autothermal Thermophilic Aerobic Digester Performance for the Stabilization of Municipal Wastewater Sludge.

PubMed

Shokoohi, Reza; Rahmani, Alireza; Asgari, Ghorban; Dargahi, Abdollah; Vaziri, Yaser; Abbasi, Mohammad Attar

2017-01-01

Sludge stabilization process in terms of operational, environmental and economic indexes is the most important stage of treatment and its disposal. This study was aimed to determine the performance of Autothermal Thermophilic Aerobic Digestion (ATAD) system as one of the low-cost and biocompatible methods of sludge treatment. This study has been done using a laboratory scale Autothermal Thermophilic Aerobic Digestion (ATAD). The reactor was consisted of two polyethylene tanks with a final capacity of 100 L for each tank. Both tanks with all fittings were installed on a metal frame. The variables of study were temperature, dissolved oxygen, pH, volatile organic compounds, total solids, COD and the number of Ascaris eggs and fecal coliforms per gram of dry matter of the sludge. The temperature was measured hourly and the pH and dissolved oxygen were measured and controlled twice per day. One-way ANNOVA was applied to analyze reasults. According to the results, the temperature of sludge increased from 11.7-61.2°C by biological reactions. Pathogen organisms were reduced from 80×106 to 503 in number during 72 h. After 6 days pathogen organisms and Ascaris eggs were removed completely. Volatile organic compounds and COD were reduced 42 and 38.3% respectively during the 6 days. It is concluded that the performance of ATAD in removing organic compounds from wastewater sludge were desirable. Resulted sludge from stabilization process were appropriate for use in agriculture as a soil supplement and met the indexes of class A sludge according to EPA's standards (CFR 40 Part 503).

Co-application of sewage sludge with biochar increases disappearance of polycyclic aromatic hydrocarbons from fertilized soil in long term field experiment.

PubMed

Stefaniuk, Magdalena; Oleszczuk, Patryk; Różyło, Krzysztof

2017-12-01

The application of sewage sludge with biochar as fertilizer may be a new method improves soil properties. Biochar increases of the crops productivity and reduction of bioavailability of contaminants. In the present study the persistence of sum of 16 (Σ16) PAHs (US EPA 16 PAHs) in a sewage sludge-amended soil (11t/h) and in a sewage sludge-amended soil with the addition of biochar (at a rate of 2.5, 5 or 10% of sewage sludge (dry weight basis)) was determined. This study was carried out as a plot experiment over a period of 18months. Samples for analysis were taken at the beginning of the study and after 6, 12 and 18months from the beginning of the experiment. Application of sewage sludge as a soil amendment did not cause a significant change (P≥0.05) in the soil content of Σ16 PAHs. In turn, the addition of biochar with sewage sludge to the soil, regardless of the contribution of biochar in the sewage sludge, resulted in a significant decrease in PAH content already at the beginning of the experiment. Throughout the experiment, in all treatments the PAH content varied, predominantly showing a decreasing trend. Ultimately, after 18months the content of Σ16 PAHs decreased by 19% in the experiment with sewage sludge alone and by 45, 35 and 28% in the experiment with sewage sludge and the 2.5%, 5.0% and 10% biochar rates, respectively. After 18months of the study, the largest losses in the sewage sludge-amended soil were observed for 2- and 3-ring PAHs. In the sewage sludge- and biochar-amended soil, compared to the beginning of the study and the sewage sludge-amended soil, the highest losses were found for 5- and 6-ring PAHs (2.5 and 5.0% rates) as well as for 5- and 2-ring PAHs (10% rate). Copyright © 2017 Elsevier B.V. All rights reserved.

Freeze Technology for Nuclear Applications - 13590

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

Rostmark, Susanne C.; Knutsson, Sven; Lindberg, Maria

2013-07-01

Freezing of soil materials is a complicated process of a number of physical processes: - freezing of pore water in a thermal gradient, - cryogenic suction causing water migration and - ice formation expanding pores inducing frost heave. Structural changes due to increase of effective stress during freezing also take place. The over consolidation gives a powerful dewatering/drying effect and the freeze process causes separation of contaminates. Artificial ground freezing (AGF is a well established technique first practiced in south Wales, as early as 1862. AGF is mostly used to stabilize tunnels and excavations. During the last ten years underwatermore » applications of freeze technologies based on the AGF have been explored in Sweden. The technology can, and has been, used in many different steps in a remediation action. Freeze Sampling where undisturbed samples are removed in both soft and hard sediment/sludge, Freeze Dredging; retrieval of sediment with good precision and minimal redistribution, and Freeze Drying; volume reduction of contaminated sludge/sediment. The application of these technologies in a nuclear or radioactive environment provides several advantages. Sampling by freezing gives for example an advantage of an undisturbed sample taken at a specified depth, salvaging objects by freezing or removal of sludges is other applications of this, for the nuclear industry, novel technology. (authors)« less

Sewage sludge drying by energy recovery from OFMSW composting: preliminary feasibility evaluation.

PubMed

Rada, Elena Cristina; Ragazzi, Marco; Villotti, Stefano; Torretta, Vincenzo

2014-05-01

In this paper an original energy recovery method from composting is analyzed. The integrated system exploits the heat available from the aerobic biochemical process in order to support the drying of sewage sludge, using a specific solar greenhouse. The aim is to tackle the problem of organic waste treatment, with specific regard to food waste. This is done by optimizing the energy consumption of the aerobic process of composting, using the heat produced to solve a second important waste management problem such as the sewage waste treatment. Energy and mass balances are presented in a preliminary feasibility study. Referring to a composting plant with a capacity of 15,000 t/y of food waste, the estimation of the power from recovered heat for the entire plant resulted about 42 kW. The results demonstrated that the energy recoverable can cover part of the heat necessary for the treatment of sludge generated by the population served by the composting plant (in terms of food waste and green waste collection). The addition of a renewable source such as solar energy could cover the residual energy demand. The approach is presented in detail in order for it to be replicated in other case studies or at full scale applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

Utilization of lime-dried sludge for eco-cement clinker production: effects of different feeding points.

PubMed

Cao, Haihua; Liu, Wei; Xu, Jingcheng; Liu, Jia; Huang, Juwen; Huang, Xiangfeng; Li, Guangming

2018-02-01

Co-processing lime-dried sludge (LDS) in cement kilns is an appropriate technique to solve the problem of LDS disposal and promote the sustainable development for cement industry. However, there were limited studies that investigated the effects of feeding points on product quality and cement kiln emissions. In this study, simulated experiments were conducted by dividing the feeding points into high-temperature zones (HTZs) and raw mill (RM). Cement quality and major cement kiln emission characteristics were comprehensively investigated. The results showed that in terms of burnability, compressive strength and microstructure, the optimum co-processing amount of LDS were 9 wt% when feeding at RM, while 6% when feeding at HTZs. Meanwhile, the organic emissions of RM samples were mainly low environmental risk compounds of amides and nitrogenous heterocyclic compounds. Inorganic gaseous pollutions of NO X and SO 2 , respectively, were 8.11 mg/g DS and 12.89 mg/g DS, compared with 7.61 mg/g DS and 4.44 mg/g DS for HTZs. However, all the cement kiln emissions concentration were still much lower than standard requirements. Overall, RM had a bigger LDS co-processing capacity and higher, but acceptable, cement kiln emissions. Feeding LDS via RM could dispose larger amounts of sludge and provide more alternative materials for cement manufacturing.

Septage unit treatment by sludge treatment reed beds for easy management and reuse: performance and design considerations.

PubMed

Kim, Boram; Bel, Thomas; Bourdoncle, Pascal; Dimare, Jocelyne; Troesch, Stéphane; Molle, Pascal

2018-01-01

Sustainable treatment and management of fecal sludge in rural areas require adapted solutions. Rustic and simple operating processes such as sludge treatment reed beds (STRB) have been increasingly considered for this purpose. The biggest full scale (2,600 m 2 of STRB) septage treatment unit in France had been built in Nègrepelisse with the final objectives of reusing treated sludge and leachates for agriculture spreading and tree irrigation, respectively. The aim of this investigation was to validate the treatment chain of this installation. The obtained field data showed firstly that the overall removal efficiencies of STRB were satisfactory and stable. Removal rates higher than 98% for chemical oxygen demand and suspended solids and a 95% for Kjeldahl nitrogen represented so far a beneficial septage treatment by STRB. The highlighted necessity of a suitable complementary leachate treatment (before tree irrigation) justified the presence of the second stage of vertical flow constructed wetland. The sludge deposit drying and mineralization efficiencies were on the right track. According to hydrotextural diagram analysis, surface deposit was however found to have high deformability probably due to the youth of the installation. An in-depth understanding of STRB system needs continuous long-term studies.

Effects of carbonization and solvent-extraction on change in fuel characteristics of sewage sludge.

PubMed

Park, Sang-Woo; Jang, Cheol-Hyeon

2011-09-01

Urban sewage sludge was carbonized at 300-500°C for 1h, and combustible components were extracted through the solvent-extraction process. N-methyl-2-pyrrolidinone (NMP) was used as the solvent for extraction, and the extraction temperature was fixed at 360°C. The atomic ratios of the solvent-extracted sludge of CS300 (ECS300) were shown to be 1.04 for H/C and 0.11 for O/C, which represented the characteristics of its coal band. Thus, its coal band was similar to that of a high-rank fuel such as bituminous coal. FT-IR analysis showed that the absorbance band of ECS300 was considerably different from that of dried sludge (RS) or the carbonized sludge at 300°C (CS300) but similar to that of coal, although the ash content absorbance band of 800-1200 cm(-1) was of very low intensity. The combustion profile showed that combustion of ESC300 occurred at a temperature higher than the ignition temperature (T(i)) or maximum weight loss rate (DTG(max)) of coal. Copyright © 2011 Elsevier Ltd. All rights reserved.

Microcosm assays and Taguchi experimental design for treatment of oil sludge containing high concentration of hydrocarbons.

PubMed

Castorena-Cortés, G; Roldán-Carrillo, T; Zapata-Peñasco, I; Reyes-Avila, J; Quej-Aké, L; Marín-Cruz, J; Olguín-Lora, P

2009-12-01

Microcosm assays and Taguchi experimental design was used to assess the biodegradation of an oil sludge produced by a gas processing unit. The study showed that the biodegradation of the sludge sample is feasible despite the high level of pollutants and complexity involved in the sludge. The physicochemical and microbiological characterization of the sludge revealed a high concentration of hydrocarbons (334,766+/-7001 mg kg(-1) dry matter, d.m.) containing a variety of compounds between 6 and 73 carbon atoms in their structure, whereas the concentration of Fe was 60,000 mg kg(-1) d.m. and 26,800 mg kg(-1) d.m. of sulfide. A Taguchi L(9) experimental design comprising 4 variables and 3 levels moisture, nitrogen source, surfactant concentration and oxidant agent was performed, proving that moisture and nitrogen source are the major variables that affect CO(2) production and total petroleum hydrocarbons (TPH) degradation. The best experimental treatment yielded a TPH removal of 56,092 mg kg(-1) d.m. The treatment was carried out under the following conditions: 70% moisture, no oxidant agent, 0.5% of surfactant and NH(4)Cl as nitrogen source.

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.

Data quality objectives for the initial fuel conditioning examinations

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

Lawrence, L.A.

The Data Quality Objectives (DQOs) were established for the response of the first group of fuel samples shipped from the K West Basin to the Hanford 327 Building hot cells for examinations to the proposed Path Forward conditioning process. Controlled temperature and atmosphere furnace testing testing will establish performance parameters using the conditioning process (drying, sludge drying, hydride decomposition passivation) proposed by the Independent Technical Assessment (ITA) Team as the baseline.

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.

Migration and distribution of sodium ions and organic matters during electro-dewatering of waste activated sludge at different dosages of sodium sulfate.

PubMed

Xiao, Jun; Wu, Xu; Yu, Wenbo; Liang, Sha; Yu, Jiangwei; Gu, Yueyuan; Deng, Huali; Hu, Jiukun; Xiao, Keke; Yang, Jiakuan

2017-12-01

In this study, the influence of Na 2 SO 4 on electro-dewatering (EDW) of waste activated sludge (WAS) was investigated. The highest water removal efficiency of 42.5% was achieved at the optimum Na 2 SO 4 dosage of 12.5 g kg -1 DS during EDW process at a constant voltage of 20 V. The migration and distribution of water, organic matters and Na + at different Na 2 SO 4 dosages were investigated through layered experiments. The results indicated the entire EDW process followed the S curve model, and it can be divided into three stages: (1) initial desalination stage: at the initial few min of EDW process, the rate of electroosmosis was extremely slow while electromigration of ions like Na + was intense, and the electromigration was more obvious with increased Na 2 SO 4 dosage; (2) dewatering stage: the dewatering efficiency increased dramatically via electroosmosis; (3) the dewaterability limit stage: the maximum value of dewatering efficiency has been achieved, while the water removal efficiency and dry solids content remained constant. During the EDW process, the possible electrolysis resulted in a pH gradient in the sludge cake. With the addition of Na 2 SO 4 in the EDW, the pH gradient was intensified, and the migration rate of organic matters moving from cathode to anode increased while compared with the raw WAS. This study provided insights into the mechanism of EDW process at different dosages of Na 2 SO 4 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Reed beds receiving industrial sludge containing nitroaromatic compounds. Effects of outgoing water and bed material extracts in the umu-c genotoxicity assay, DR-CALUX assay and on early life stage development in zebrafish (Danio rerio).

PubMed

Gustavsson, Lillemor; Hollert, Henner; Jonsson, Sofie; van Bavel, Bert; Engwall, Magnus

2007-05-01

Sweden has prohibited the deposition of organic waste since January, 2005. Since 1 million tons of sludge is produced every year in Sweden and the capacity for incineration does not fill the demands, other methods of sludge management have to be introduced to a larger degree. One common method in the USA and parts of Europe is the use of wetlands to treat wastewater and sewage sludge. The capacity of reed beds to affect the toxicity of a complex mixture of nitroaromatics in sludge, however, is not fully elucidated. In this study, an industrial sludge containing explosives and pharmaceutical residues was therefore treated in artificial reed beds and the change in toxicity was studied. Nitroaromatic compounds, which are the main ingredients of many pharmaceuticals and explosives, are well known to cause cytotoxicity and genotoxicity. Recently performed studies have also showed that embryos of zebrafish (Danio rerio) are sensitive to nitroaromatic compounds. Therefore, we tested the sludge passing through constructed wetlands in order to detect any changes in levels of embryotoxicity, genotoxicity and dioxin-like activity (AhR-agonists). We also compared unplanted and planted systems in order to examine the impact of the root system on the fate of the toxicants. An industrial sludge containing a complex mixture of nitroaromatics was added daily to small-scale constructed wetlands (vertical flow), both unplanted and planted with Phragmites australis. Sludge with an average dry weight of 1.25%, was added with an average hydraulic loading rate of 1.2 L/day. Outgoing water was collected daily and stored at -20 degrees C. The artificial wetland sediment was Soxhlet extracted, followed by clean-up with multi-layer silica, or extracted by ultrasonic treatment, yielding one organic extract and one water extract of the same sample. Genotoxicity of the extracts was measured according to the ISO protocol for the umu-C genotoxicity assay (ISO/TC 147/SC 5/ WG9 N8), using Salmonella typhimurium TA1535/pSK1002 as test organism. Embryotoxicity and teratogenicity were studied using the fish egg assay with zebrafish (Danio rerio) and the dioxin-like activity was measured using the DR-CALUX assay. Chemical analyses of nitroaromatic compounds were performed using Solid Phase Micro Extraction (SPME) and GC-MS. Organic extracts of the bed material showed toxic potential in all three toxicity tests after two years of sludge loading. There was a difference between the planted and the unplanted beds, where the toxicity of organic extracts overall was higher in the bed material from the planted beds. The higher toxicity of the planted beds could have been caused by the higher levels of total carbon in the planted beds, which binds organic toxicants, and by enrichment caused by lower volumes of outgoing water from the planted beds. Developmental disorders were observed in zebrafish exposed directly in contact to bed material from unplanted beds, but not in fish exposed to bed material from planted beds. Hatching rates were slightly lower in zebrafish exposed to outgoing water from unplanted beds than in embryos exposed to outgoing water from planted beds. Genotoxicity in the outgoing water was below detection limit for both planted and unplanted beds. Most of the added toxicants via the sludge were unaccounted for in the outgoing water, suggesting that the beds had toxicant removal potential, although the mechanisms behind this remain unknown. During the experimental period, the beds received a sludge volume (dry weight) of around three times their own volume. In spite of this, the toxicity in the bed material was lower than in the sludge. Thus, the beds were probably able to actually decrease the toxicity of the added, sludge-associated toxicants. When testing the acetone extracts of the bed material, the planted bed showed a higher toxicity than the unplanted beds in all three toxicity tests. The toxicity of water extracts from the unplanted beds, detected by the fish egg assay, were higher than the water extracts from the planted beds. No genotoxicity was detected in outgoing water from either planted or unplanted beds. All this together indicates that the planted reed beds retained semi-lipophilic acetone-soluble toxic compounds from the sludge better than the unplanted beds, which tended to leak out more of the water soluble toxic compounds in the outgoing water. The compounds identified by SPME/GC in the outgoing water were not in sufficient concentrations to have caused induction in the genotoxicity test. This study has pointed out the benefits of using constructed wetlands receiving an industrial sludge containing a complex mixture of nitroaromatics to reduce toxicity in the outgoing water. The water from planted, constructed wetlands could therefore be directed to a recipient without further cleaning. The bed material should be investigated over a longer period of time in order to evaluate potential accumulation and leakage prior to proper usage or storage. The plants should be investigated in order to examine uptake and possible release when the plant biomass is degraded.

40 CFR 503.43 - Pollutant limits.

Code of Federal Regulations, 2010 CFR

2010-07-01

....43 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SEWAGE SLUDGE STANDARDS FOR... in micrograms per cubic meter per gram per second. RSC = Risk specific concentration for arsenic... per day (dry weight basis). (2) The risk specific concentrations for arsenic, cadmium, and nickel used...

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.

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.

[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.

[Ultrasonic sludge treatment and its application on aerobic digestion].

PubMed

Li, Huan; Jin, Yi-ying; Nie, Yong-feng; Li, Lei; Yang, Hai-ying

2007-07-01

In order to enhance the degradation efficiency of waste activated sludge (WAS) in conventional aerobic digestion, various ultrasonic assisted treatment methods were investigated including ultrasonic disintegration of influent sludge, ultrasonic improvement of influent sludge activity and ultrasonic disintegration of return sludge. Firstly the effects of ultrasonic sludge treatment were studied to choose appropriate ultrasonic parameters, and then the experiments of aerobic digestion with different ultrasonic treatments were carried out. The results show that 1.0 W/mL, 10 minutes ultrasonic treatment can increase soluble chemical oxygen demand (SCOD) in the supernatant phase of sludge sample by 5.4 times and decrease total suspended solid (TSS) by 16%; 0.05 W/mL, 10 min ultrasonic treatment can increase the specific oxygen uptake rate (SOUR) of sludge sample by 29%. The two kinds of ultrasonic influent sludge pretreatment can't improve aerobic digestion effectively. Ultrasonic return sludge disintegration can enhance the volatile suspended solid (VSS) degradation ratio by 15%. Furthermore, the settlement performance of digested sludge is still good and the pollutant concentrations of supernatant phase increase slightly. So ultrasonic return sludge disintegration is considered as the most appropriate assisted treatment mode for aerobic digestion.

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.

Capital and operating costs of full-scale fecal sludge management and wastewater treatment systems in Dakar, Senegal.

PubMed

Dodane, Pierre-Henri; Mbéguéré, Mbaye; Sow, Ousmane; Strande, Linda

2012-04-03

A financial comparison of a parallel sewer based (SB) system with activated sludge, and a fecal sludge management (FSM) system with onsite septic tanks, collection and transport (C&T) trucks, and drying beds was conducted. The annualized capital for the SB ($42.66 capita(-1) year(-1)) was ten times higher than the FSM ($4.05 capita(-1) year(-1)), the annual operating cost for the SB ($11.98 capita(-1) year(-1)) was 1.5 times higher than the FSM ($7.58 capita(-1) year(-1)), and the combined capital and operating for the SB ($54.64 capita(-1) year(-1)) was five times higher than FSM ($11.63 capita(-1) year(-1)). In Dakar, costs for SB are almost entirely borne by the sanitation utility, with only 6% of the annualized cost borne by users of the system. In addition to costing less overall, FSM operates with a different business model, with costs spread among households, private companies, and the utility. Hence, SB was 40 times more expensive to implement for the utility than FSM. However, the majority of FSM costs are borne at the household level and are inequitable. The results of the study illustrate that in low-income countries, vast improvements in sanitation can be affordable when employing FSM, whereas SB systems are prohibitively expensive.

Capital and Operating Costs of Full-Scale Fecal Sludge Management and Wastewater Treatment Systems in Dakar, Senegal

PubMed Central

2012-01-01

A financial comparison of a parallel sewer based (SB) system with activated sludge, and a fecal sludge management (FSM) system with onsite septic tanks, collection and transport (C&T) trucks, and drying beds was conducted. The annualized capital for the SB ($42.66 capita–1 year–1) was ten times higher than the FSM ($4.05 capita–1 year–1), the annual operating cost for the SB ($11.98 capita–1 year–1) was 1.5 times higher than the FSM ($7.58 capita–1 year–1), and the combined capital and operating for the SB ($54.64 capita–1 year–1) was five times higher than FSM ($11.63 capita–1 year–1). In Dakar, costs for SB are almost entirely borne by the sanitation utility, with only 6% of the annualized cost borne by users of the system. In addition to costing less overall, FSM operates with a different business model, with costs spread among households, private companies, and the utility. Hence, SB was 40 times more expensive to implement for the utility than FSM. However, the majority of FSM costs are borne at the household level and are inequitable. The results of the study illustrate that in low-income countries, vast improvements in sanitation can be affordable when employing FSM, whereas SB systems are prohibitively expensive. PMID:22413875

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.

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.

STP K Basin Sludge Sample Archive at the Pacific Northwest National Laboratory FY2014

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

Fiskum, Sandra K.; Smoot, Margaret R.; Schmidt, Andrew J.

2014-06-01

The Pacific Northwest National Laboratory (PNNL) currently houses 88 samples (~10.5 kg) of K Basin sludge (81 wet and seven dry samples) on behalf of the Sludge Treatment Project (STP), which is managed for the U.S. Department of Energy (DOE) by the CH2M Hill Plateau Remediation Company (CHPRC). Selected samples are intended to serve, in part, as sentinels to enhance understanding of sludge properties after long-term storage, and thus enhance understanding of sludge behavior following transfer to sludge transfer and storage containers (STSCs) and storage at the Hanford 200 Area central plateau. In addition, remaining samples serve in contingency formore » future testing requirements. At PNNL, the samples are tracked and maintained under a prescriptive and disciplined monthly sample-monitoring program implemented by PNNL staff. This report updates the status of the K Basin archive sludge sample inventory to April 2014. The previous inventory status report, PNNL 22245 (Fiskum et al. 2013, limited distribution report), was issued in February of 2013. This update incorporates changes in the inventory related to repackaging of 17 samples under test instructions 52578 TI052, K Basin Sludge Sample Repackaging for Continued Long Term Storage, and 52578 TI053, K Basin Sludge Sample Repackaging Post-2014 Shear Strength Measurements. Note that shear strength measurement results acquired in 2014 are provided separately. Specifically, this report provides the following: • a description of the K Basin sludge sample archive program and the sample inventory • a summary and images of the samples that were repackaged in April 2014 • up-to-date images and plots of the settled density and water loss from all applicable samples in the inventory • updated sample pedigree charts, which provide a roadmap of the genesis and processing history of each sample in the inventory • occurrence and deficiency reports associated with sample storage and repackaging« less

A uniaxial cyclic compression method for characterizing the rheological and textural behaviors of mechanically dewatered sewage sludge.

PubMed

Liang, Fenglin; Sauceau, Martial; Dusserre, Gilles; Arlabosse, Patricia

2017-04-15

The mechanically dewatered sewage sludge with total solid content around 20% on a weight basis is very similar to yield stress fluid, its complex transition between solid and fluid states is not perfectly reversible and especially challenging in terms of pumping, land spreading and drying. To characterize the rheological and textural properties of highly concentrated sludge, a specific methodology based on uniaxial single and cyclic compression tests is developed. Three types of sludge samples (fresh original, fresh premixed and aged original ones) are extruded into cylinders and pressed between two parallel plates using a material testing machine. In single compression, the bioyield point beyond which the sludge fractures is around 7.3 kPa with true strain equal to 0.21. The cyclic compression tests reveal that the sludge behaves as a viscoelastic body when the true strain is smaller than 0.05 and as a visco-elasto-plastic once exceeding the yield stress. The elastic module is around 78 kPa; the viscosity is deduced, in the order of magnitude 10 4 -10 5  Pa·s and the yield stress is estimated about 4 kPa. In the unloading phase, the sludge behaves again as a viscoelastic body with clear hysteresis. With the increase of compression speed, the viscosity declines, which confirms that the sludge is a shear-thinning material. The yield stress and the bioyield increase with compression speed, but it does not induce extra internal damage in the samples since the resilience and the cohesiveness are unaltered. The reliability and sensitivity of the method is justified by highlighting the changes of sludge behavior due to aging and premixing effects: both decrease the strain energy density, but do aggravate the adhesiveness of the sludge; the aging makes the sludge less cohesive, while the premixing does not modify its cohesiveness. In spite of changes in test conditions, the elastic module of sludge samples remains unchanged. Copyright © 2017 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.

Reducing the startup time of aerobic granular sludge reactors through seeding floccular sludge with crushed aerobic granules.

PubMed

Pijuan, Maite; Werner, Ursula; Yuan, Zhiguo

2011-10-15

One of the main challenging issues for the aerobic granular sludge technology is the long startup time when dealing with real wastewaters. This study presents a novel strategy to reduce the time required for granulation while ensuring a high level of nutrient removal. This new approach consists of seeding the reactor with a mixture of crushed aerobic granules and floccular sludge. The effectiveness of the strategy was demonstrated using abattoir wastewater, containing nitrogen and phosphorus at approximately 250 mgN/L and 30 mgP/L, respectively. Seven different mixtures of crushed granules and floccular sludge at granular sludge fractions (w/w in dry mass) of 0%, 5%, 10%, 15%, 25%, 30% and 50% were used to start eight granulation processes. The granulation time (defined as the time when the 10th percentile bacterial aggregate size is larger than 200 μm) displayed a strong dependency on the fraction of granular sludge. The shortest granulation time of 18 days was obtained with 50% crushed granules, in comparison with 133 days with 5% crushed granules. Full granulation was not achieved in the two trials without seeding with crushed granules. In contrast to the 100% floccular sludge cases, where a substantial loss of biomass occurred during granulation, the biomass concentration in all other trails did not decrease during granulation. This allowed that good nitrogen removal was maintained in all the reactors during the granulation process. However, enhanced biological phosphorus removal was achieved in only one of the eight trials. This was likely due to the temporary accumulation of nitrite, a strong inhibitor of polyphosphate accumulating organisms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Microbiological hazards resulting from application of dairy sewage sludge: effects on occurrence of pathogenic microorganisms in soil.

PubMed

Jezierska-Tys, Stefania; Frac, Magdalena; Tys, Jerzy

2010-01-01

The aims of this study were to (1) examine the extent of bacterial contamination of soils subjected to exposure to dairy sewage sludge applied to soils as measured by determination of number of bacteria from the Escherichia coli family and (2) determine the effects of dairy sewage sludge and straw on populations of other microbial species present in gray-brown podzolic soil. The gray-brown podzolic soil was formed from heavy loamy sand, which is characterized by the following granulometric composition: a sand fraction, 65%; a silt fraction, 19%; and a silt and clay fraction; 16%. The brown soil was formed from silt-loam and characterized by the following granulometric composition of silty-clay deposit: sand fraction, 8%; silt fraction, 48%; and clay and silt fraction, 46%. In dairy sewage sludge the total bacteria number as defined by Alef and Nannipieri (1995) was 51 x 10(4) colony-forming units (cfu)/ kg dry matter (dm), fungi total number 10 x 10(3) cfu/ kg dm, and E. coli bacteria 9.5 x 10(3) most probable number (MPN)/kg dm. In dairy sewage sludge mixed with straw, total number of bacteria and total number of fungi decreased to 10(3) and 10(2), respectively. Competition for nitrogen, glucose, and lactose and organic acids such as acetic and succinic with soil microorganisms, as well as soil conditions such as lack of oxygen, lower soil pH, and temperature, may account for the reduction in the number of E. coli bacteria in soils to which dairy sewage sludge was applied. Dairy sewage sludge may provide a beneficial impact on soil environment and adversely affect microorganisms such that dairy sewage sludge may be used as a safe organic fertilizer.

Heavy metal speciation and toxicity characteristics of tannery sludge

NASA Astrophysics Data System (ADS)

Juel, Md. Ariful Islam; Chowdhury, Zia Uddin Md.; Ahmed, Tanvir

2016-07-01

Heavy metals present in tannery sludge can get mobilized in the environment in various forms and can be a cause for concern for the natural ecosystem and human health. The speciation of metals in sludge provides valuable information regarding their toxicity in the environment and determines their suitability for land application or disposal in landfills. Concentrations of seven heavy metals (Cr, Pb, Cd, Ni, Zn, As and Cu) in tannery sludge were determined to evaluate their toxicity levels. Metal contents ranged over the following intervals: As: 1.52-2.07 mg/kg; Pb: 57.5-67 mg/kg; Cr: 15339-26501 mg/kg; Cu: 261.3-579.5 mg/kg; Zn: 210.2-329.1 mg/kg and Ni: 137.5-141.3 mg/kg (dry weight basis). The concentrations of all heavy metals in the sludge samples were lower compared to EPA guidelines except chromium which was found to be several orders of magnitude higher than the guideline value. Toxicity Characteristics Leaching Procedure (TCLP) test indicated that the leaching potential of chromium was higher compared to the other heavy metals and exceeded the EPA land disposal restriction limits. To quantitatively assess the environmental burden of the chromium associated with tannery sludge, the IMPACT 2002+ methodology was adopted under the SimaPro software environment. Considering the USEPA limit for chromium as the baseline scenario, it was found that chromium in the tannery sludge had 6.41 times higher impact than the baseline in the categories of aquatic ecotoxicity, terrestrial ecotoxicity and non-carcinogens. Chromium has the highest contribution to toxicity in the category of aquatic ecotoxicity while copper is the major contributor to the category of terrestrial ecotoxicity in the tannery sludge.

Problematic issues of air protection during thermal processes related to the energetic uses of sewage sludge and other waste. Case study: Co-combustion in peaking power plant.

PubMed

Hroncová, Emília; Ladomerský, Juraj; Musil, Juraj

2018-03-01

Currently, it is necessary to deal with issues related to the emissions as there is a constantly increasing interest in combusting sludge from sewage treatment plants in the boilers for wood. An analysis of the energetic importance of the combustion of sewage sludge has already been carried out, but the effects of various treatments of the sludge are not always clear, e.g. composting and subsequent combustion to the air pollution. Investments in other thermal processes of energetic utilisation of sewage sludge and organic waste are not always successfully implemented. The objective of this paper is to point out some problematic cases for acceptance of thermal processes related to energetic use of waste in terms of the air protection. The other aim is to mention the experience with solutions of such issues in Slovakia. There are mentioned first results of the operational validation experiments during the energy generation in circulating fluidized bed boiler in peaking power plant (Power 110MW) with the addition of the so-called alternative fuel based on wood and sewage sludge to the main fuel - black coal (anthracite). And there has already been achieved the highest share of 12.4%w. (dry matter) of sewage sludge in form of compost in blend with black coal, which is technologically viable. Moreover analyzed the problems of the authorization and operation of the co-combustion of sewage sludge and of combustion of products of various kinds of pyrolysis waste - pyrolysis gas and pyrolysis oil are analyzed. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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.

Locally produced natural conditioners for dewatering of faecal sludge

PubMed Central

Gold, Moritz; Dayer, Pauline; Faye, Marie Christine Amie Sene; Clair, Guillaume; Seck, Alsane; Niang, Seydou; Morgenroth, Eberhard; Strande, Linda

2016-01-01

ABSTRACT In urban areas of low-income countries, treatment of faecal sludge (FS) is insufficient or non-existent. This results in large amounts of FS being dumped into the environment. Existing treatment technologies for FS, such as settling-thickening tanks and drying beds, are land intensive which is limiting in urban areas. Enhanced settling and dewatering by conditioning was evaluated in order to reduce the treatment footprint (or increase treatment capacity). Conventional wastewater conditioners, such as commercially available lime and polymers, are expensive, and commonly rely on complex supply chains for use in low-income countries. Therefore, the treatment performance of five conditioners which could be produced locally was evaluated: Moringa oleifera seeds and press cake, Jatropha curcas seeds, Jatropha Calotropis leaves and chitosan. M. oleifera seeds and press cake, and chitosan improved settling and dewatering and had a similar performance compared to lime and polymers. Optimal dosages were 400–500 kg M. oleifera/t TS, 300–800 kg lime/t TS and 25–50 kg polymer solution/t TS. In comparison, chitosan required 1.5–3.75 kg/t TS. These dosages are comparable to those recommended for wastewater (sludge). The results indicate that conditioning of FS can reduce total suspended solids (TSS) in the effluent of settling-thickening tanks by 22–81% and reduce dewatering time with drying beds by 59–97%. This means that the area of drying beds could be reduced by 59–97% with end-use as soil conditioner, or 9–26% as solid fuel. Least expensive options and availability will depend on the local context. In Dakar, Senegal, chitosan produced from shrimp waste appears to be most promising. PMID:26984372

Locally produced natural conditioners for dewatering of faecal sludge.

PubMed

Gold, Moritz; Dayer, Pauline; Faye, Marie Christine Amie Sene; Clair, Guillaume; Seck, Alsane; Niang, Seydou; Morgenroth, Eberhard; Strande, Linda

2016-11-01

In urban areas of low-income countries, treatment of faecal sludge (FS) is insufficient or non-existent. This results in large amounts of FS being dumped into the environment. Existing treatment technologies for FS, such as settling-thickening tanks and drying beds, are land intensive which is limiting in urban areas. Enhanced settling and dewatering by conditioning was evaluated in order to reduce the treatment footprint (or increase treatment capacity). Conventional wastewater conditioners, such as commercially available lime and polymers, are expensive, and commonly rely on complex supply chains for use in low-income countries. Therefore, the treatment performance of five conditioners which could be produced locally was evaluated: Moringa oleifera seeds and press cake, Jatropha curcas seeds, Jatropha Calotropis leaves and chitosan. M. oleifera seeds and press cake, and chitosan improved settling and dewatering and had a similar performance compared to lime and polymers. Optimal dosages were 400-500 kg M. oleifera/t TS, 300-800 kg lime/t TS and 25-50 kg polymer solution/t TS. In comparison, chitosan required 1.5-3.75 kg/t TS. These dosages are comparable to those recommended for wastewater (sludge). The results indicate that conditioning of FS can reduce total suspended solids (TSS) in the effluent of settling-thickening tanks by 22-81% and reduce dewatering time with drying beds by 59-97%. This means that the area of drying beds could be reduced by 59-97% with end-use as soil conditioner, or 9-26% as solid fuel. Least expensive options and availability will depend on the local context. In Dakar, Senegal, chitosan produced from shrimp waste appears to be most promising.

Presence and destruction of tubercle bacilli in sewage*

PubMed Central

Jensen, K. Erik

1954-01-01

The author examined the sewage from 5 towns with tuberculosis sanatoria and from one institution for the care of the feeble-minded, which had a tuberculosis ward, for the presence of tubercle bacilli. The 6 effluents were treated in biological-purification plants and average samples taken. These were centrifuged, and the sediment treated for 1 hour at 37°C with 4% NaOH before inoculation into guinea-pigs. Tubercle bacilli were demonstrated in the influent to all the plants and in the digested sludge of all those operating on sewage where the ratio of infective patients to all persons connected with the plant was up to 1:600. Experiments with cultivated tubercle bacilli showed that centrifuging of sewage resulted in only an insignificant loss of bacilli, but that NaOH treatment caused a loss of over 99%. After consideration of the risk of infection to both man and cattle from the sewage of tuberculosis institutions, the author reports on his own studies on the killing of tubercle bacilli in sewage. It took about 11½-15 months before tubercle bacilli could no longer be demonstrated in sludge that had been kept on the drying beds. The addition of 10 mg of chlorine per litre of biologically purified effluent from an activated-sludge plant was found effectively to destroy tubercle bacilli. Disinfection of sludge was also carried out with 0.5% lysol and 0.1%-0.2% formol; 3.1% copper sulfate proved ineffective. The author concludes that the disinfection of sewage from tuberculosis institutions presents no special difficulties, but that work on this subject in different countries should be co-ordinated in an effort to improve plant and reduce costs. PMID:13160757

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.

Assessment of two carrier materials for phosphate solubilizing biofertilizers and their effect on growth of wheat (Triticum aestivum L.).

PubMed

Mukhtar, Salma; Shahid, Izzah; Mehnaz, Samina; Malik, Kauser A

2017-12-01

Biofertilizers are usually carrier-based inoculants containing beneficial microorganisms. Incorporation of microorganisms in carrier material enables easy-handling, long-term storage and high effectiveness of biofertilizers. Objective of the present study was to assess enriched biogas sludge and soil as biofertilizer carriers on growth and yield of wheat. Six phosphate solubilizing strains were used in this study. Three phosphate solubilizing strains, 77-NS2 (Bacillus endophyticus), 77-CS-S1 (Bacillus sphaericus) and 77-NS5 (Enterobacter aerogenes) were isolated from the rhizosphere of sugarcane, two strains, PSB5 (Bacillus safensis) and PSB12 (Bacillus megaterium) from the rhizosphere of wheat and one halophilic phosphate solubilizing strain AT2RP3 (Virgibacillus sp.) from the rhizosphere of Atriplex amnicola, were used as bioinoculants. Phosphate solubilization ability of these strains was checked in vitro in Pikovskaya medium, containing rock phosphate (RP) as insoluble P source, individually supplemented with three different carbon sources, i.e., glucose, sucrose and maltose. Maximum phosphate solubilization; 305.6μg/ml, 217.2μg/ml and 148.1μg/ml was observed in Bacillus strain PSB12 in Pikovskaya medium containing sucrose, maltose and glucose respectively. A field experiment and pot experiments in climate control room were conducted to study the effects of biogas sludge and enriched soil based phosphorous biofertilizers on growth of wheat. Bacillus strain PSB12 significantly increased root and shoot dry weights and lengths using biogas sludge as carrier material in climate control room experiments. While in field conditions, significant increase in root and shoot dry weights, lengths and seed weights was seen by PSB12 and PSB5 (Bacillus) and Enterobacter strain 77-NS5 using biogas sludge as carrier. PSB12 also significantly increased both root and shoot dry weights and lengths in field conditions when used as enriched soil based inoculum. These results indicated that bacterial isolates having plant beneficial traits such as P solubilization are more promising candidates as biofertilizer when used with carrier materials. Copyright © 2017 Elsevier GmbH. All rights reserved.

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.

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.

A critical review of nitrogen mineralization in biosolids-amended soil, the associated fertilizer value for crop production and potential for emissions to the environment.

PubMed

Rigby, Hannah; Clarke, Bradley O; Pritchard, Deborah L; Meehan, Barry; Beshah, Firew; Smith, Stephen R; Porter, Nichola A

2016-01-15

International controls for biosolids application to agricultural land ensure the protection of human health and the environment, that it is performed in accordance with good agricultural practice and that nitrogen (N) inputs do not exceed crop requirements. Data from the scientific literature on the total, mineral and mineralizable N contents of biosolids applied to agricultural land under a wide range of climatic and experimental conditions were collated. The mean concentrations of total N (TN) in the dry solids (DS) of different biosolids types ranged from 1.5% (air-dried lime-treated (LT) biosolids) to 7.5% (liquid mesophilic anaerobic digestion (LMAD) biosolids). The overall mean values of mineralizable N, as a proportion of the organic N content, were 47% for aerobic digestion (AeD) biosolids, 40% for thermally dried (TD) biosolids, 34% for LT biosolids, 30% for mesophilic anaerobic digestion (MAD) biosolids, and 7% for composted (Com) biosolids. Biosolids air-dried or stored for extended periods had smaller total and mineralizable N values compared to mechanically dewatered types. For example, for biosolids treated by MAD, the mean TN (% DS) and mineralizable N (% organic N) contents of air-dried materials were 3% and 20%, respectively, compared to 5% and 30% with mechanical dewatering. Thus, mineralizable N declined with the extent of biological stabilization during sewage sludge treatment; nevertheless, overall plant available N (PAN=readily available inorganic N plus mineralizable N) was broadly consistent across several major biosolids categories within climatic regions. However, mineralizable N often varied significantly between climatic regions for similar biosolids types, influencing the overall PAN. This may be partly attributed to the increased rate, and also the greater extent of soil microbial mineralization of more stable, residual organic N fractions in biosolids applied to soil in warmer climatic zones, which also raised the overall PAN, compared to cooler temperate areas. It is also probably influenced by differences in upstream wastewater treatment processes that affect the balance of primary and secondary, biological sludges in the final combined sludge output from wastewater treatment, as well as the relative effectiveness of sludge stabilization treatments at specific sites. Better characterization of biosolids used in N release and mineralization investigations is therefore necessary to improve comparison of system conditions. Furthermore, the review suggested that some international fertilizer recommendations may underestimate mineralizable N in biosolids, and the N fertilizer value. Consequently, greater inputs of supplementary mineral fertilizer N may be supplied than are required for crop production, potentially increasing the risk of fertilizer N emissions to the environment. Thus greater economic and environmental savings in mineral N fertilizer application are potentially possible than are currently realized from biosolids recycling programmes. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Pyrolysis and oxy-fuel combustion characteristics and kinetics of petrochemical wastewater sludge using thermogravimetric analysis.

PubMed

Chen, Jianbiao; Mu, Lin; Cai, Jingcheng; Yao, Pikai; Song, Xigeng; Yin, Hongchao; Li, Aimin

2015-12-01

The pyrolysis and oxy-fuel combustion characteristics of petrochemical wastewater sludge (PS) were studied in air (O2/N2) and oxy-fuel (O2/CO2) atmospheres using non-isothermal thermogravimetric analysis (TGA). Pyrolysis experiments showed that the weight loss profiles were almost similar up to 1050K in both N2 and CO2 atmospheres, while further weight loss took place in CO2 atmosphere at higher temperatures due to char-CO2 gasification. Compared with 20%O2/80%N2, the drying and devolatilization stage of PS were delayed in 20%O2/80%CO2 due to the differences in properties of the diluting gases. In oxy-fuel combustion experiments, with O2 concentration increasing, characteristic temperatures decreased, while characteristic combustion rates and combustion performance indexes increased. Kinetic analysis of PS decomposition under various atmospheres was performed using Coats-Redfern approach. The results indicated that, with O2 concentration increasing, the activation energies of Step 1 almost kept constant, while the values of subsequent three steps increased. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Potential in Bioethanol Production From Waste Fiber Sludges in Pulp Mill-Based Biorefineries

NASA Astrophysics Data System (ADS)

Sjöde, Anders; Alriksson, Björn; Jönsson, Leif J.; Nilvebrant, Nils-Olof

Industrial production of bioethanol from fibers that are unusable for pulp production in pulp mills offers an approach to product diversification and more efficient exploitation of the raw material. In an attempt to utilize fibers flowing to the biological waste treatment, selected fiber sludges from three different pulp mills were collected, chemically analyzed, enzymatically hydrolyzed, and fermented for bioethanol production. Another aim was to produce solid residues with higher heat values than those of the original fiber sludges to gain a better fuel for combustion. The glucan content ranged between 32 and 66% of the dry matter. The lignin content varied considerably (1-25%), as did the content of wood extractives (0.2-5.8%). Hydrolysates obtained using enzymatic hydrolysis were found to be readily fermentable using Saccharomyces cerevisiae. Hydrolysis resulted in improved heat values compared with corresponding untreated fiber sludges. Oligomeric xylan fragments in the solid residue obtained after enzymatic hydrolysis were identified using matrix-assisted laser desorption ionization-time of flight and their potential as a new product of a pulp mill-based biorefinery is discussed.

The potential in bioethanol production from waste fiber sludges in pulp mill-based biorefineries.

PubMed

Sjöde, Anders; Alriksson, Björn; Jönsson, Leif J; Nilvebrant, Nils-Olof

2007-04-01

Industrial production of bioethanol from fibers that are unusable for pulp production in pulp mills offers an approach to product diversification and more efficient exploitation of the raw material. In an attempt to utilize fibers flowing to the biological waste treatment, selected fiber sludges from three different pulp mills were collected, chemically analyzed, enzymatically hydrolyzed, and fermented for bioethanol production. Another aim was to produce solid residues with higher heat values than those of the original fiber sludges to gain a better fuel for combustion. The glucan content ranged between 32 and 66% of the dry matter. The lignin content varied considerably (1-25%), as did the content of wood extractives (0.2-5.8%). Hydrolysates obtained using enzymatic hydrolysis were found to be readily fermentable using Saccharomyces cerevisiae. Hydrolysis resulted in improved heat values compared with corresponding untreated fiber sludges. Oligomeric xylan fragments in the solid residue obtained after enzymatic hydrolysis were identified using matrix-assisted laser desorption ionization-time of flight and their potential as a new product of a pulp mill-based biorefinery is discussed.

Evaluation of Dewatering Performance and Fractal Characteristics of Alum Sludge

PubMed Central

Sun, Yongjun; Fan, Wei; Zheng, Huaili; Zhang, Yuxin; Li, Fengting; Chen, Wei

2015-01-01

The dewatering performance and fractal characteristics of alum sludge from a drinking-water treatment plant were investigated in this study. Variations in residual turbidity of supernatant, dry solid content (DS), specific resistance to filtration (SRF), floc size, fractal dimension, and zeta potential were analyzed. Sludge dewatering efficiency was evaluated by measuring both DS and SRF. Results showed that the optimum sludge dewatering efficiency was achieved at 16 mg∙L-1 flocculant dosage and pH 7. Under these conditions, the maximum DS was 54.6%, and the minimum SRF was 0.61 × 1010 m∙kg-1. Floc-size measurements demonstrated that high flocculant dosage significantly improved floc size. Correlation analysis further revealed a strong correlation between fractal dimension and floc size after flocculation. A strong correlation also existed between floc size and zeta potential, and flocculants with a higher cationic degree had a larger correlation coefficient between floc size and zeta potential. In the flocculation process, the main flocculation mechanisms involved adsorption bridging under an acidic condition, and a combination between charge neutralization and adsorption-bridging interaction under neutral and alkaline conditions. PMID:26121132

PLANNING AND ASSESSMENT MEASURES TO UPDATING RESOURCES RECYCLING EQUIPMENTS IN COLLABORATION WITH SEWAGE TREATMENT PLANTS AND WASTE INCINERATION PLANTS

NASA Astrophysics Data System (ADS)

Nakakubo, Toyohiko; Tokai, Akihiro; Ohno, Koichi

This study aims to assess two biomass utilization policies: the integration of food waste treatment in a sewerage treatment plant with an anaerobic digestion tank, and the pruned branch usage as heat source for drying sludge. We focused on two points in our analysis that the impact of the increase of dewatered sludge on sludge treatment processes after digestion and the improvement of the efficiency of waste power generation plants. A developed model was applied to the case study in Kobe city and evaluated the impact until 2030 by four indicators: energy consumption, greenhouse gas (GHG) emission, phosphorus-recovery, and cost. The results showed that case 3-C, which introducing the combined sludge and food waste digestion system, pyrolysis gasification with gas engine and wood-chip boiler, could supply additional 452 TJ/y of energy, recovery 93 t-P/y of phosphorus, and reduce 38 kt-CO2eq./y of GHG while shrinking the cost by 88 million yen/y compared to business as usual types-update case.

Element accumulation in tall fescue and alfalfa

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

Stucky, D.J.; Newman, T.S.

This study was initiated to examine the effect of three application rates of dried anaerobically digested sludge on two different soil media on the establishment, yield, duration, and element accumulation in tall fescue and alfalfa. In a greenhouse study, acid strip-mine spoil and agricultural soil were used to compare plant growth in sewage-amended and untreated media. Sludge was applied at 0, 314, and 627 metric tons/hectare to the agricultural soil control and the strip mine spoil. Plant yields were significantly higher for strip-mine spoil amended with 627 metric tons/ha and for agricultural soil amended with 314 and 627 metric tons/ha.more » Concentrations of Mn, Ni, Cd, Zn, and Cu were measured in plants and soils. Concentrations of Mn, Zn, Ni, and Cd in tall fescue and alfalfa grown in strip-mine spoils were higher at higher sludge application rates. Sludge application rate did not affect Cu uptake. Concentrations of Mn, Zn, Ni, and Cd in tall fescue were highest during the 180 toese is the fluctuation in nutrient salt concentrations:agreement of experimental and calculated data is obtton beam.« less

Oxisol decapitated recovery with green manure and sewage sludge: Effect on growth of Astronium fraxinifolium

NASA Astrophysics Data System (ADS)

Souto Filho, S. N.; Marchini, D. C.; de Arruda, O. G.; Giácomo, R. G.; Alves, M. C.

2012-04-01

Incorrect use of land and large buildings in rural areas are causing changes to it, making them less productive and thus increasing the degraded areas. Techniques aimed at ecological restoration of degraded soils have been investigated. In recovery planning a degraded area, the great challenge to be achieved is the establishment of a A horizon, so that from then on, the process is catalyzed by the biosphere, and there may be other horizons, as the natural conditioning. In this sense the positive changes were investigated in an environment of decapitated Savannah Oxisol, which was removed a layer 8.5 m thick to build a hydroelectric power plant. For recovery, we used a native tree species, green manure, sewage sludge and grass. The studied soil is under human intervention techniques for recovery for seven years. The experimental design was randomized blocks with five treatments and five replications. The treatments were: 1-Control- bare soil (without management), 2-Astronium fraxinifolium Schott; 3-A. fraxinifolium + Canavalia ensiformis; 4- A. fraxinifolium + Raphanus sativus by 2005 was replaced in 2006 by Crotalaria juncea; 5- A. fraxinifolium + Brachiaria decumbens + sewage sludge (60 t ha-1, dry basis). We studied in 2010 and 2011 the development of tree species (stem diameter and plant height), the fresh and dry matter of green manures and B. decumbens. The results were analyzed by performing the variance analysis and Tukey test at 5% probability to compare averages. The rate of plant growth during the periods studied in the treatment with sewage sludge was higher than other treatments, so this is the most appropriate management for the recovery of degraded soil under study.

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 ...

The effect of low-temperature transformation of mixtures of sewage sludge and plant materials on content, leachability and toxicity of heavy metals.

PubMed

Gondek, Krzysztof; Baran, Agnieszka; Kopeć, Michał

2014-12-01

The aim of the study was to determine the influence of the process of low-temperature transformation and the addition of plant material to sewage sludge diversifying the content of mobile forms of heavy metals and their ecotoxicity. The experimental design included: sewage sludge+rape straw, sewage sludge+wheat straw, sewage sludge+sawdust, sewage sludge+bark and sewage sludge with no addition. The mixtures were subjected to thermal transformation in a chamber furnace, under conditions without air. The procedure consisted of two stages: the first stage (130°C for 40 min) focused on drying the material, whereas in the second stage (200°C for 30 min) proper thermal transformation of materials took place. Thermal transformation of the materials, caused an increase in total contents of heavy metals in comparison to the material before transformation. From among elements, the cadmium content changed the most in materials after thermal transformation. As a result of thermal transformation, the content of water soluble form of the heavy metals decreased significantly in all the prepared mixtures. Low toxicity of the extracts from materials for Vibrio fischeri and Lepidium sativum was found in the research, regardless of transformation process. L. sativum showed higher sensitivity to heavy metals occurring in the studied extracts from materials than V. fischeri, evidence of which are the positive significant correlations between the content of metals and the inhibition of root growth of L. sativum. Copyright © 2014 Elsevier Ltd. All rights reserved.

Gaseous emissions during the solid state fermentation of different wastes for enzyme production at pilot scale.

PubMed

Maulini-Duran, Caterina; Abraham, Juliana; Rodríguez-Pérez, Sheila; Cerda, Alejandra; Jiménez-Peñalver, Pedro; Gea, Teresa; Barrena, Raquel; Artola, Adriana; Font, Xavier; Sánchez, Antoni

2015-03-01

The emissions of volatile organic compounds (VOC), CH4, N2O and NH3 during the solid state fermentation process of some selected wastes to obtain different enzymes have been determined at pilot scale. Orange peel+compost (OP), hair wastes+raw sludge (HW) and winterization residue+raw sludge (WR) have been processed in duplicate in 50 L reactors to provide emission factors and to identify the different VOC families present in exhaust gaseous emissions. Ammonia emission from HW fermentation (3.2±0.5 kg Mg(-1) dry matter) and VOC emission during OP processes (18±6 kg Mg(-1) dry matter) should be considered in an industrial application of these processes. Terpenes have been the most emitted VOC family during all the processes although the emission of sulphide molecules during HW SSF is notable. The most emitted compound was dimethyl disulfide in HW and WR processes, and limonene in the SSF of OP. Copyright © 2014 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.

Characterization, Recovery Opportunities, and Valuation of Metals in Municipal Sludges from U.S. Wastewater Treatment Plants Nationwide.

PubMed

Westerhoff, Paul; Lee, Sungyun; Yang, Yu; Gordon, Gwyneth W; Hristovski, Kiril; Halden, Rolf U; Herckes, Pierre

2015-08-18

U.S. sewage sludges were analyzed for 58 regulated and nonregulated elements by ICP-MS and electron microscopy to explore opportunities for removal and recovery. Sludge/water distribution coefficients (KD, L/kg dry weight) spanned 5 orders of magnitude, indicating significant metal accumulation in biosolids. Rare-earth elements and minor metals (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) detected in sludges showed enrichment factors (EFs) near unity, suggesting dust or soils as likely dominant sources. In contrast, most platinum group elements (i.e., Ru, Rh, Pd, Pt) showed high EF and KD values, indicating anthropogenic sources. Numerous metallic and metal oxide colloids (<100-500 nm diameter) were detected; the morphology of abundant aggregates of primary particles measuring <100 nm provided clues to their origin. For a community of 1 million people, metals in biosolids were valued at up to US$13 million annually. A model incorporating a parameter (KD × EF × $Value) to capture the relative potential for economic value from biosolids revealed the identity of the 13 most lucrative elements (Ag, Cu, Au, P, Fe, Pd, Mn, Zn, Ir, Al, Cd, Ti, Ga, and Cr) with a combined value of US $280/ton of sludge.

Removal of polycyclic aromatic hydrocarbons (PAHs) from industrial sludges in the ambient air conditions: automotive industry.

PubMed

Karaca, Gizem; Tasdemir, Yucel

2013-01-01

Removal of polycyclic aromatic hydrocarbons (PAHs) existed in automotive industry treatment sludge was examined by considering the effects of temperature, UV, titanium dioxide (TiO2) and diethyl amine (DEA) in different dosages (i.e., 5% and 20%) in this study. Application of TiO2 and DEA to the sludge samples in ambient environment was studied. Ten PAH (Σ10 PAH) compounds were targeted and their average value in the sludge was found to be 4480 ± 1450 ng/g dry matter (DM). Total PAH content of the sludge was reduced by 25% in the ambient air environment. Meteorological conditions, atmospheric deposition, evaporation and sunlight irradiation played an effective role in the variations in PAH levels during the tests carried out in ambient air environment. Moreover, it was observed that when the ring numbers of PAHs increased, their removal rates also increased. Total PAH level did not change with the addition of 5% DEA and only 10% decreased with 5% TiO2 addition. PAH removal ratios were 8% and 32% when DEA (20%) and TiO2 (20%) were added, respectively. It was concluded that DEA was a weak photo-sensitizer yet TiO2 was effective only at 20% dosage.

Significance of various soil amendments to borrow pit reclamation with loblolly pine and fescue

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

Berry, C.R.; Marx, D.H.

Loblolly pine seedlings with ectomycorrhizae formed by Pisolithus tinctorius (Pt) or naturally occurring Thelephora terrestris (Tt) were planted on a borrow pit in South Carolina in plots with no amendment; with fertilizer plus dolomitic limestone alone and with pine bark or bottom ash or bark and ash together; or with dried sewage sludge alone and with bark or ash or bark and ash together. All plots were subsoiled, disked, and seeded to fescue grass before planting pine seedlings. Naturally occurring Pt formed abundant ectomycorrhizae on all Tt seedlings by the end of the first season, precluding any specific ectomycorrhizal fungusmore » effect for the duration of the study. Sewage sludge alone or with bark or ash amendments dramatically improved pine seedling growth and grass biomass in comparison with other soil treatments. Mean seedling volume (D/sup 2/H) was 28 times greater and grass biomass was five times greater in the sludge plots than on nonsludge plots. Generally, soil amended with sludge contained more N, P, organic matter, and had a higher cation exchange capacity than soil of other treatments. Foliage of pine seedlings in sludge-amended soil also contained more N and less Ca than other seedlings. The significance of these results to reclamation of borrow pits is discussed.« less

Identifying energy and carbon footprint optimization potentials of a sludge treatment line with Life Cycle Assessment.

PubMed

Remy, C; Lesjean, B; Waschnewski, J

2013-01-01

This study exemplifies the use of Life Cycle Assessment (LCA) as a tool to quantify the environmental impacts of processes for wastewater treatment. In a case study, the sludge treatment line of a large wastewater treatment plant (WWTP) is analysed in terms of cumulative energy demand and the emission of greenhouse gases (carbon footprint). Sludge treatment consists of anaerobic digestion, dewatering, drying, and disposal of stabilized sludge in mono- or co-incineration in power plants or cement kilns. All relevant forms of energy demand (electricity, heat, chemicals, fossil fuels, transport) and greenhouse gas emissions (fossil CO(2), CH(4), N(2)O) are accounted in the assessment, including the treatment of return liquor from dewatering in the WWTP. Results show that the existing process is positive in energy balance (-162 MJ/PE(COD) * a) and carbon footprint (-11.6 kg CO(2)-eq/PE(COD) * a) by supplying secondary products such as electricity from biogas production or mono-incineration and substituting fossil fuels in co-incineration. However, disposal routes for stabilized sludge differ considerably in their energy and greenhouse gas profiles. In total, LCA proves to be a suitable tool to support future investment decisions with information of environmental relevance on the impact of wastewater treatment, but also urban water systems in general.