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Sample records for activated sludge solids

  1. 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.

  2. Effects of total solids content on waste activated sludge thermophilic anaerobic digestion and its sludge dewaterability.

    PubMed

    Wang, Tianfeng; Chen, Jie; Shen, Honglang; An, Dong

    2016-10-01

    The role of total solids content on sludge thermophilic anaerobic digestion was investigated in batch reactors. A range of total solids content from 2% to 10% was evaluated with two replicates. The lowest inhibitory concentration for free ammonia and total ammonia of sludge thermophilic anaerobic digestion was 110.9-171.4mg/L and 1313.1-1806.7mg/L, respectively. The volumetric biogas production rate increased with increasing of total solids content, but the corresponding biogas yield per gram volatile solid decreased. The result of normalized capillary suction time indicated that the dewaterability of digested sludge at high total solids content was poor, while solid content of sediment obtained by centrifuging sludge at 2000g for 10min increased with increasing of total solids content of sludge. The results suggest that thickened sludge mixed with dewatered sludge at an appropriate ratio could get high organic loading rate, high biogas yield and adequate dewatering effort.

  3. Effect of microwave pre-treatment of thickened waste activated sludge on biogas production from co-digestion of organic fraction of municipal solid waste, thickened waste activated sludge and municipal sludge.

    PubMed

    Ara, E; Sartaj, M; Kennedy, K

    2014-12-01

    Anaerobic co-digestion of organic fraction of municipal solid waste, with thickened waste activated sludge and primary sludge has the potential to enhance biodegradation of solid waste, increase longevity of existing landfills and lead to more sustainable development by improving waste to energy production. This study reports on mesophilic batch and continuous studies using different concentrations and combinations (ratios) of organic fraction of municipal solid waste, thickened waste activated sludge (microwave pre-treated and untreated) and primary sludge to assess the potential for improved biodegradability and specific biogas production. Improvements in specific biogas production for batch assays, with concomitant improvements in total chemical oxygen demand and volatile solid removal, were obtained with organic fraction of municipal solid waste:thickened waste activated sludge:primary sludge mixtures at a ratio of 50:25:25 (with and without thickened waste activated sludge microwave pre-treatment). This combination was used for continuous digester studies. At 15 d hydraulic retention times, the co-digestion of organic fraction of municipal solid waste:organic fraction of municipal solid waste:primary sludge and organic fraction of municipal solid waste:thickened waste activated sludge microwave:primary sludge resulted in a 1.38- and 1.46-fold increase in biogas production and concomitant waste stabilisation when compared with thickened waste activated sludge:primary sludge (50:50) and thickened waste activated sludge microwave:primary sludge (50:50) digestion at the same hydraulic retention times and volumetric volatile solid loading rate, respectively. The digestion of organic fraction of municipal solid waste with primary sludge and thickened waste activated sludge provides beneficial effects that could be implemented at municipal wastewater treatment plants that are operating at loading rates of less than design capacity. PMID:25398411

  4. Effect of microwave pre-treatment of thickened waste activated sludge on biogas production from co-digestion of organic fraction of municipal solid waste, thickened waste activated sludge and municipal sludge.

    PubMed

    Ara, E; Sartaj, M; Kennedy, K

    2014-12-01

    Anaerobic co-digestion of organic fraction of municipal solid waste, with thickened waste activated sludge and primary sludge has the potential to enhance biodegradation of solid waste, increase longevity of existing landfills and lead to more sustainable development by improving waste to energy production. This study reports on mesophilic batch and continuous studies using different concentrations and combinations (ratios) of organic fraction of municipal solid waste, thickened waste activated sludge (microwave pre-treated and untreated) and primary sludge to assess the potential for improved biodegradability and specific biogas production. Improvements in specific biogas production for batch assays, with concomitant improvements in total chemical oxygen demand and volatile solid removal, were obtained with organic fraction of municipal solid waste:thickened waste activated sludge:primary sludge mixtures at a ratio of 50:25:25 (with and without thickened waste activated sludge microwave pre-treatment). This combination was used for continuous digester studies. At 15 d hydraulic retention times, the co-digestion of organic fraction of municipal solid waste:organic fraction of municipal solid waste:primary sludge and organic fraction of municipal solid waste:thickened waste activated sludge microwave:primary sludge resulted in a 1.38- and 1.46-fold increase in biogas production and concomitant waste stabilisation when compared with thickened waste activated sludge:primary sludge (50:50) and thickened waste activated sludge microwave:primary sludge (50:50) digestion at the same hydraulic retention times and volumetric volatile solid loading rate, respectively. The digestion of organic fraction of municipal solid waste with primary sludge and thickened waste activated sludge provides beneficial effects that could be implemented at municipal wastewater treatment plants that are operating at loading rates of less than design capacity.

  5. Solids Control in Sludge Pretreatment

    SciTech Connect

    Beahm, E.C., Weber, C.F., Hunt, R.D., Dillow, T.A.

    1997-12-31

    Sludge pretreatment will likely involve washing, followed by caustic or acidic leaching and washing of sludge residues after leaching. The principal goal of pretreatment is to obtain a low-volume high-activity waste stream and a high-volume low-activity waste stream. Also, some waste constituents such as chromium and phosphate can be included in glass formulations only at very low concentrations; therefore, it is desirable to remove them from high-level waste streams. Two aspects of sludge treatment and subsequent separations should be well delineated and predictable: (1) the distribution of chemical species between aqueous solutions and solids and (2) potential problems due to chemical interactions that could result in process difficulties or safety concerns.Before any treatment technology is adopted, it must be demonstrated that the process can be carried out as planned. Three pretreatment methods were considered in the Tri-Party (Washington State Ecology, U.S. Environmental Protection Agency, and U.S. Department of Energy) negotiations: (1) sludge washing with corrosion- inhibiting water, (2) Enhanced Sludge Washing, and (3)acidic dissolution with separations processes. Enhanced Sludge Washing is the baseline process. In Enhanced Sludge Washing, sludge is first washed with corrosion-inhibiting water; it is then leached with caustic (sodium hydroxide solution) and washed again with corrosion- inhibiting water. The initial concern is whether a pretreatment technique is effective in separating sludge components. This can be evaluated by bench-scale tests with sludge specimens from underground storage tanks. The results give data on the distribution of important species such as aluminum, phosphate, and radionuclides between wash and leach solutions and solid sludge residues.

  6. Feasibility of electroflotation to separate solids and liquid in an activated sludge process.

    PubMed

    Chung, C M; Cho, K W; Hong, S W; Kim, Y J; Chung, T H

    2009-12-14

    In this study, electroflotation (EF) has been applied as a secondary clarification in the activated sludge process to improve the efficiency of the solids-liquid separation, which is essential in maintaining effluent quality. The effects of sludge settleability were examined through a series of batch and semi-continuous experiments. The results of the batch experiments revealed that thickening efficiencies using EF were 2.6 to 9.2 times higher than those with gravity settling (GS). In addition, clarification efficiencies were not significantly influenced by sludge settling properties, as compared with GS as a control. In the semi-continuous EF experiments, the concentrations of solids in the float layer were maintained above 10 g L(-1) during flotation, regardless of variations in sludge settleability. Furthermore, the volumetric gas proportion in the float layer increased as the gas to solids (G/S) ratio rose. This allowed the float layer to be more stably suspended against gravity at the top of the reactor. Based on the results obtained from these batch and semi-continuous experiments, an anoxic/oxic (AO) reactor combined with EF clarifier remained in successful continuous operation for four months. In comparison with conventional AO processes using a GS clarifier, enhanced clarification and thickening efficiencies were achieved through the EF-AO system. In addition, higher mixed liquor suspended solids concentrations (averaging 5300 mg L(-1)) in the bioreactor (EF-AO) were maintained via the return of highly concentrated sludge (averaging 16,400 mg L(-1)) from the EF clarifier. These findings suggest that EF could be a promising and effective alternative for the solids-liquid separation of poorly settling sludge.

  7. 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.

  8. Net biomass production under complete solids retention in high organic load activated sludge process.

    PubMed

    Amanatidou, Elisavet; Samiotis, Georgios; Bellos, Dimitrios; Pekridis, George; Trikoilidou, Eleni

    2015-04-01

    The effect of complete solids retention on net biomass production, at a slaughterhouse's activated sludge wastewater treatment process, was studied for 425 days. The process reached equilibrium after 150 days. In equilibrium phase, and until the end of the study, relative constant MLVSS to MLSS ratio, low food to microorganisms ratio (F/M), low substrate utilization rate (SUR) and negligible observed sludge yield (Y obs) were measured. Y obs fluctuated between positive and negative values (± 0.03 gVSS gCOD(-1)), tending zero mean values, and leading to the conclusion that zero net sludge growth can be achieved. The high BOD ultimate/COD ratio and the zero sludge accumulation, leads to the conclusion that all fractions of organic matter, including cell debris, are biodegradable. The results were verified by comparing the measured Y obs values and those predicted using a conventional activated sludge model (ASM) and a modified ASM that incorporates the slow hydrolysis concept of the unbiodegradable compounds.

  9. Activated Sludge.

    ERIC Educational Resources Information Center

    Saunders, F. Michael

    1978-01-01

    Presents the 1978 literature review of wastewater treatment. This review covers: (1) activated sludge process; (2) process control; (3) oxygen uptake and transfer; (4) phosphorus removal; (5) nitrification; (6) industrial wastewater; and (7) aerobic digestion. A list of 136 references is also presented. (HM)

  10. Enhanced high-solids anaerobic digestion of waste activated sludge by the addition of scrap iron.

    PubMed

    Zhang, Yaobin; Feng, Yinghong; Yu, Qilin; Xu, Zibin; Quan, Xie

    2014-05-01

    Anaerobic digestion of waste activated sludge usually requires pretreatment procedure to improve the bioavailability of sludge, which involves considerable energy and high expenditures. This study proposes a cost-effective method for enhanced anaerobic digestion of sludge without a pretreatment by directly adding iron into the digester. The results showed that addition of Fe(0) powder could enhance 14.46% methane yield, and Fe scrap (clean scrap) could further enhance methane yield (improving rate 21.28%) because the scrap has better mass transfer efficiency with sludge and liquid than Fe(0) powder. The scrap of Fe with rust (rusty scrap) could induce microbial Fe(III) reduction, which resulted in achieving the highest methane yield (improving rate 29.51%), and the reduction rate of volatile suspended solids (VSS) was also highest (48.27%) among Fe powder, clean scrap and rusty scrap. PCR-DGGE proved that the addition of rusty scrap could enhance diversity of acetobacteria and enrich iron-reducing bacteria to enhance degradation of complex substrates. PMID:24657762

  11. Enhanced high-solids anaerobic digestion of waste activated sludge by the addition of scrap iron.

    PubMed

    Zhang, Yaobin; Feng, Yinghong; Yu, Qilin; Xu, Zibin; Quan, Xie

    2014-05-01

    Anaerobic digestion of waste activated sludge usually requires pretreatment procedure to improve the bioavailability of sludge, which involves considerable energy and high expenditures. This study proposes a cost-effective method for enhanced anaerobic digestion of sludge without a pretreatment by directly adding iron into the digester. The results showed that addition of Fe(0) powder could enhance 14.46% methane yield, and Fe scrap (clean scrap) could further enhance methane yield (improving rate 21.28%) because the scrap has better mass transfer efficiency with sludge and liquid than Fe(0) powder. The scrap of Fe with rust (rusty scrap) could induce microbial Fe(III) reduction, which resulted in achieving the highest methane yield (improving rate 29.51%), and the reduction rate of volatile suspended solids (VSS) was also highest (48.27%) among Fe powder, clean scrap and rusty scrap. PCR-DGGE proved that the addition of rusty scrap could enhance diversity of acetobacteria and enrich iron-reducing bacteria to enhance degradation of complex substrates.

  12. Influence of secondary settling tank performance on suspended solids mass balance in activated sludge systems.

    PubMed

    Patziger, M; Kainz, H; Hunze, M; Józsa, J

    2012-05-01

    Secondary settling is the final step of the activated sludge-based biological waste water treatment. Secondary settling tanks (SSTs) are therefore an essential unit of producing a clear effluent. A further important function of SSTs is the sufficient thickening to achieve highly concentrated return sludge and biomass within the biological reactor. In addition, the storage of activated sludge is also needed in case of peak flow events (Ekama et al., 1997). Due to the importance of a high SST performance the problem has long been investigated (Larsen, 1977; Krebs, 1991; Takács et al., 1991; Ekama et al., 1997; Freimann, 1999; Patziger et al., 2005; Bürger et al., 2011), however, a lot of questions are still to solve regarding e.g. the geometrical features (inflow, outflow) and operations (return sludge control, scraper mechanism, allowable maximum values of surface overflow rates). In our study we focused on SSTs under dynamic load considering both the overall unsteady behaviour and the features around the peaks, investigating the effect of various sludge return strategies as well as the inlet geometry on SST performance. The main research tool was a FLUENT-based novel mass transport model consisting of two modules, a 2D axisymmetric SST model and a mixed reactor model of the biological reactor (BR). The model was calibrated and verified against detailed measurements of flow and concentration patterns, sludge settling, accompanied with continuous on-line measurement of in- and outflow as well as returned flow rates of total suspended solids (TSS) and water. As to the inlet arrangement a reasonable modification of the geometry could result in the suppression of the large scale flow structures of the sludge-water interface thus providing a significant improvement in the SST performance. Furthermore, a critical value of the overflow rate (q(crit)) was found at which a pronounced large scale circulation pattern develops in the vertical plane, the density current in

  13. Influence of secondary settling tank performance on suspended solids mass balance in activated sludge systems.

    PubMed

    Patziger, M; Kainz, H; Hunze, M; Józsa, J

    2012-05-01

    Secondary settling is the final step of the activated sludge-based biological waste water treatment. Secondary settling tanks (SSTs) are therefore an essential unit of producing a clear effluent. A further important function of SSTs is the sufficient thickening to achieve highly concentrated return sludge and biomass within the biological reactor. In addition, the storage of activated sludge is also needed in case of peak flow events (Ekama et al., 1997). Due to the importance of a high SST performance the problem has long been investigated (Larsen, 1977; Krebs, 1991; Takács et al., 1991; Ekama et al., 1997; Freimann, 1999; Patziger et al., 2005; Bürger et al., 2011), however, a lot of questions are still to solve regarding e.g. the geometrical features (inflow, outflow) and operations (return sludge control, scraper mechanism, allowable maximum values of surface overflow rates). In our study we focused on SSTs under dynamic load considering both the overall unsteady behaviour and the features around the peaks, investigating the effect of various sludge return strategies as well as the inlet geometry on SST performance. The main research tool was a FLUENT-based novel mass transport model consisting of two modules, a 2D axisymmetric SST model and a mixed reactor model of the biological reactor (BR). The model was calibrated and verified against detailed measurements of flow and concentration patterns, sludge settling, accompanied with continuous on-line measurement of in- and outflow as well as returned flow rates of total suspended solids (TSS) and water. As to the inlet arrangement a reasonable modification of the geometry could result in the suppression of the large scale flow structures of the sludge-water interface thus providing a significant improvement in the SST performance. Furthermore, a critical value of the overflow rate (q(crit)) was found at which a pronounced large scale circulation pattern develops in the vertical plane, the density current in

  14. A comparison of BNR activated sludge systems with membrane and settling tank solid-liquid separation.

    PubMed

    Ramphao, M C; Wentzel, M C; Ekama, G A; Alexander, W V

    2006-01-01

    Installing membranes for solid-liquid separation into biological nutrient removal (BNR) activated sludge (AS) systems makes a profound difference not only to the design of the membrane bio-reactor (MBR) BNR system itself, but also to the design approach for the whole wastewater treatment plant (WWTP). In multi-zone BNR systems with membranes in the aerobic reactor and fixed volumes for the anaerobic, anoxic and aerobic zones (i.e. fixed volume fractions), the mass fractions can be controlled (within a range) with the inter-reactor recycle ratios. This zone mass fraction flexibility is a significant advantage of MBR BNR systems over BNR systems with secondary settling tanks (SSTs), because it allows changing the mass fractions to optimise biological N and P removal in conformity with influent wastewater characteristics and the effluent N and P concentrations required. For PWWF/ADWF ratios (fq) in the upper range (fq approximately 2.0), aerobic mass fractions in the lower range (f(maer) < 0.60) and high (usually raw) wastewater strengths, the indicated mode of operation of MBR BNR systems is as extended aeration WWTPs (no primary settling and long sludge age). However, the volume reduction compared with equivalent BNR systems with SSTs will not be large (40-60%), but the cost of the membranes can be offset against sludge thickening and stabilisation costs. Moving from a flow unbalanced raw wastewater system to a flow balanced (fq = 1) low (usually settled) wastewater strength system can double the ADWF capacity of the biological reactor, but the design approach of the WWTP changes away from extended aeration to include primary sludge stabilisation. The cost of primary sludge treatment then has to be offset against the savings of the increased WWTP capacity.

  15. A comparison of BNR activated sludge systems with membrane and settling tank solid-liquid separation.

    PubMed

    Ramphao, M C; Wentzel, M C; Ekama, G A; Alexander, W V

    2006-01-01

    Installing membranes for solid-liquid separation into biological nutrient removal (BNR) activated sludge (AS) systems makes a profound difference not only to the design of the membrane bio-reactor (MBR) BNR system itself, but also to the design approach for the whole wastewater treatment plant (WWTP). In multi-zone BNR systems with membranes in the aerobic reactor and fixed volumes for the anaerobic, anoxic and aerobic zones (i.e. fixed volume fractions), the mass fractions can be controlled (within a range) with the inter-reactor recycle ratios. This zone mass fraction flexibility is a significant advantage of MBR BNR systems over BNR systems with secondary settling tanks (SSTs), because it allows changing the mass fractions to optimise biological N and P removal in conformity with influent wastewater characteristics and the effluent N and P concentrations required. For PWWF/ADWF ratios (fq) in the upper range (fq approximately 2.0), aerobic mass fractions in the lower range (f(maer) < 0.60) and high (usually raw) wastewater strengths, the indicated mode of operation of MBR BNR systems is as extended aeration WWTPs (no primary settling and long sludge age). However, the volume reduction compared with equivalent BNR systems with SSTs will not be large (40-60%), but the cost of the membranes can be offset against sludge thickening and stabilisation costs. Moving from a flow unbalanced raw wastewater system to a flow balanced (fq = 1) low (usually settled) wastewater strength system can double the ADWF capacity of the biological reactor, but the design approach of the WWTP changes away from extended aeration to include primary sludge stabilisation. The cost of primary sludge treatment then has to be offset against the savings of the increased WWTP capacity. PMID:16889266

  16. Impact of membrane solid-liquid separation on design of biological nutrient removal activated sludge systems.

    PubMed

    Ramphao, M; Wentzel, M C; Merritt, R; Ekama, G A; Young, T; Buckley, C A

    2005-03-20

    Installing membranes for solid-liquid separation into biological nutrient removal (BNR) activated sludge (AS) systems makes a profound difference not only in the design of the BNR system itself, but also in the design approach for the whole wastewater treatment plant (WWTP). In multizone BNR systems with membranes in the aerobic reactor and fixed volumes for the anaerobic, anoxic, and aerobic zones (i.e., fixed volume fractions), the mass fractions can be controlled (within a range) with the interreactor recycle ratios. This zone mass fraction flexibility is a significant advantage in membrane BNR systems over conventional BNR systems with SSTs, because it allows for changing of the mass fractions to optimize biological N and P removal in conformity with influent wastewater characteristics and the effluent N and P concentrations required. For PWWF/ADWF ratios in the upper range (f(q) approximately 2.0), aerobic mass fractions in the lower range (f(maer) < 0.60), and high (usually raw) wastewater strengths, the indicated mode of operation of MBR BNR systems is as extended aeration WWTPs. Although the volume reduction compared with equivalent conventional BNR systems with secondary settling tanks is not as large (40% to 60%), the cost of the membranes can be offset against sludge thickening and stabilization costs. Moving from a flow-unbalanced raw wastewater system to a flow-balanced (f(q) = 1), low (usually settled) wastewater strength system can double the ADWF capacity of the biological reactor, but the design approach of the WWTP changes from extended aeration to include primary sludge stabilization. The cost of primary sludge treatment then has to be paid from the savings from the increased WWTP capacity.

  17. Impact of membrane solid-liquid separation on design of biological nutrient removal activated sludge systems.

    PubMed

    Ramphao, M; Wentzel, M C; Merritt, R; Ekama, G A; Young, T; Buckley, C A

    2005-03-20

    Installing membranes for solid-liquid separation into biological nutrient removal (BNR) activated sludge (AS) systems makes a profound difference not only in the design of the BNR system itself, but also in the design approach for the whole wastewater treatment plant (WWTP). In multizone BNR systems with membranes in the aerobic reactor and fixed volumes for the anaerobic, anoxic, and aerobic zones (i.e., fixed volume fractions), the mass fractions can be controlled (within a range) with the interreactor recycle ratios. This zone mass fraction flexibility is a significant advantage in membrane BNR systems over conventional BNR systems with SSTs, because it allows for changing of the mass fractions to optimize biological N and P removal in conformity with influent wastewater characteristics and the effluent N and P concentrations required. For PWWF/ADWF ratios in the upper range (f(q) approximately 2.0), aerobic mass fractions in the lower range (f(maer) < 0.60), and high (usually raw) wastewater strengths, the indicated mode of operation of MBR BNR systems is as extended aeration WWTPs. Although the volume reduction compared with equivalent conventional BNR systems with secondary settling tanks is not as large (40% to 60%), the cost of the membranes can be offset against sludge thickening and stabilization costs. Moving from a flow-unbalanced raw wastewater system to a flow-balanced (f(q) = 1), low (usually settled) wastewater strength system can double the ADWF capacity of the biological reactor, but the design approach of the WWTP changes from extended aeration to include primary sludge stabilization. The cost of primary sludge treatment then has to be paid from the savings from the increased WWTP capacity. PMID:15696540

  18. The application of constant recycle solids concentration in activated sludge process.

    PubMed

    Bonotan-Dura, F M; Yang, P Y

    1976-02-01

    The applicability of the model derived by Ramanathan and Gaudy (Biotechnol. Bioeng., 11, 207, (1969)) for completely mixed activated sludge treatment holding the recycle solids concentration as a system constant was investigated using an actual industrial organic wastewater. Short-term experiments were conducted at various dilution rates (1/8, 1/6, 1/4, 1/2, 1/1.5 hr-1) for two recycle solids concentration values (5000 and 7000 mg/liter). The influent substrate concentration was maintained at 1000 mg/liter COD and the hydraulic recycle ratio- alpha, was kept at 0.3. It was found that for bottling plant (Pepsi Cola) wastewaters, a steady state with respect to reactor biological solids and effluent COD, at different dilution rates, could be attained, lending experimental evidence to the assumption that a steady state could be reached in developing the model and also affecting the applicability of the model in industrial organic wastewater. The reactor biological solids and effluent COD calculated from the model closely agreed with the observed values at dilution rates lower than 0.5 hr-1. Operation at dilution rates higher than 0.5 hr-1 will washout the biological solids from the reactor and the recycle substrate concentration will be apparent if the concentration of XR were not increased.

  19. The application of constant recycle solids concentration in activated sludge process.

    PubMed

    Bonotan-Dura, F M; Yang, P Y

    1976-02-01

    The applicability of the model derived by Ramanathan and Gaudy (Biotechnol. Bioeng., 11, 207, (1969)) for completely mixed activated sludge treatment holding the recycle solids concentration as a system constant was investigated using an actual industrial organic wastewater. Short-term experiments were conducted at various dilution rates (1/8, 1/6, 1/4, 1/2, 1/1.5 hr-1) for two recycle solids concentration values (5000 and 7000 mg/liter). The influent substrate concentration was maintained at 1000 mg/liter COD and the hydraulic recycle ratio- alpha, was kept at 0.3. It was found that for bottling plant (Pepsi Cola) wastewaters, a steady state with respect to reactor biological solids and effluent COD, at different dilution rates, could be attained, lending experimental evidence to the assumption that a steady state could be reached in developing the model and also affecting the applicability of the model in industrial organic wastewater. The reactor biological solids and effluent COD calculated from the model closely agreed with the observed values at dilution rates lower than 0.5 hr-1. Operation at dilution rates higher than 0.5 hr-1 will washout the biological solids from the reactor and the recycle substrate concentration will be apparent if the concentration of XR were not increased. PMID:1252608

  20. Rheology Measurements for Online Monitoring of Solids in Activated Sludge Reactors of Municipal Wastewater Treatment Plant

    PubMed Central

    Papo, Adriano; Goi, Daniele

    2014-01-01

    Rheological behaviour of recycled sludge from a secondary clarifier of a municipal wastewater treatment plant was studied by using the rate controlled coaxial cylinder viscometer Rotovisko-Haake 20, system M5-osc., measuring device NV. The tests (hysteresis cycles) were performed under continuous flow conditions and following an ad hoc measurement protocol. Sludge shear stress versus shear rate curves were fitted very satisfactorily by rheological models. An experimental equation correlating the solid concentration of sludge to relative viscosity and fitting satisfactorily flow curves at different Total Suspended Solids (TTS%) was obtained. Application of the empirical correlation should allow the monitoring of the proper functioning of a wastewater treatment plant measuring viscosity of sludge. PMID:24550715

  1. [Pilot study of thermal treatment/thermophilic anaerobic digestion process treating waste activated sludge of high solid content].

    PubMed

    Wu, Jing; Wang, Guang-qi; Cao, Zhi-ping; Li, Zhong-hua; Hu, Yu-ying; Wang, Kai-jun; Zu, Jian-e

    2014-09-01

    A pilot-scale experiment about the process of "thermal pretreatment at 70°C/thermophilic anaerobic digestion" of waste activated sludge of high solid content (8% -9% ) was conducted. The process employed thermal treatment of 3 days to accelerate the hydrolysis and thermophilic digestion to enhance anaerobic reaction. Thus it was good at organic removal and stabilization. When the solid retention time (SRT) was longer than 20 days, the VSS removal rate was greater than 42. 22% and it was linearly correlated to the SRT of the aerobic digestion with the R2 of 0. 915 3. It was suggested that SRT of anaerobic digestion was 25 days in practice. VSS removal rate and biogas production rate of the pilot experiment were similar to those of the run-well traditional full-scale sludge anaerobic digestion plants (solid content 3% -5% ) and the plant of high solid content using German technique.

  2. Microbiological characterization and specific methanogenic activity of anaerobe sludges used in urban solid waste treatment

    SciTech Connect

    Sandoval Lozano, Claudia Johanna Vergara Mendoza, Marisol; Carreno de Arango, Mariela; Castillo Monroy, Edgar Fernando

    2009-02-15

    This study presents the microbiological characterization of the anaerobic sludge used in a two-stage anaerobic reactor for the treatment of organic fraction of urban solid waste (OFUSW). This treatment is one alternative for reducing solid waste in landfills at the same time producing a biogas (CH{sub 4} and CO{sub 2}) and an effluent that can be used as biofertilizer. The system was inoculated with sludge from a wastewater treatment plant (WWTP) (Rio Frio Plant in Bucaramanga-Colombia) and a methanogenic anaerobic digester for the treatment of pig manure (Mesa de los Santos in Santander). Bacterial populations were evaluated by counting groups related to oxygen sensitivity, while metabolic groups were determined by most probable number (MPN) technique. Specific methanogenic activity (SMA) for acetate, formate, methanol and ethanol substrates was also determined. In the acidogenic reactor (R1), volatile fatty acids (VFA) reached values of 25,000 mg L{sup -1} and a concentration of CO{sub 2} of 90%. In this reactor, the fermentative population was predominant (10{sup 5}-10{sup 6} MPN mL{sup -1}). The acetogenic population was (10{sup 5} MPN mL{sup -1}) and the sulphate-reducing population was (10{sup 4}-10{sup 5} MPN mL{sup -1}). In the methanogenic reactor (R2), levels of CH{sub 4} (70%) were higher than CO{sub 2} (25%), whereas the VFA values were lower than 4000 mg L{sup -1}. Substrate competition between sulphate-reducing (10{sup 4}-10{sup 5} MPN mL{sup -1}) and methanogenic bacteria (10{sup 5} MPN mL{sup -1}) was not detected. From the SMA results obtained, acetoclastic (2.39 g COD-CH{sub 4} g{sup -1} VSS{sup -1} day{sup -1}) and hydrogenophilic (0.94 g COD-CH{sub 4} g{sup -1} VSS{sup -1} day{sup -1}) transformations as possible metabolic pathways used by methanogenic bacteria is suggested from the SMA results obtained. Methanotrix sp., Methanosarcina sp., Methanoccocus sp. and Methanobacterium sp. were identified.

  3. Microbiological characterization and specific methanogenic activity of anaerobe sludges used in urban solid waste treatment.

    PubMed

    Lozano, Claudia Johanna Sandoval; Mendoza, Marisol Vergara; de Arango, Mariela Carreño; Monroy, Edgar Fernando Castillo

    2009-02-01

    This study presents the microbiological characterization of the anaerobic sludge used in a two-stage anaerobic reactor for the treatment of organic fraction of urban solid waste (OFUSW). This treatment is one alternative for reducing solid waste in landfills at the same time producing a biogas (CH(4) and CO(2)) and an effluent that can be used as biofertilizer. The system was inoculated with sludge from a wastewater treatment plant (WWTP) (Río Frío Plant in Bucaramanga-Colombia) and a methanogenic anaerobic digester for the treatment of pig manure (Mesa de los Santos in Santander). Bacterial populations were evaluated by counting groups related to oxygen sensitivity, while metabolic groups were determined by most probable number (MPN) technique. Specific methanogenic activity (SMA) for acetate, formate, methanol and ethanol substrates was also determined. In the acidogenic reactor (R1), volatile fatty acids (VFA) reached values of 25,000 mg L(-1) and a concentration of CO(2) of 90%. In this reactor, the fermentative population was predominant (10(5)-10(6)MPN mL(-1)). The acetogenic population was (10(5)MPN mL(-1)) and the sulphate-reducing population was (10(4)-10(5)MPN mL(-1)). In the methanogenic reactor (R2), levels of CH(4) (70%) were higher than CO(2) (25%), whereas the VFA values were lower than 4000 mg L(-1). Substrate competition between sulphate-reducing (10(4)-10(5)MPN mL(-1)) and methanogenic bacteria (10(5)MPN mL(-1)) was not detected. From the SMA results obtained, acetoclastic (2.39 g COD-CH(4)g(-1)VSS(-1)day(-1)) and hydrogenophilic (0.94 g COD-CH(4)g(-1)VSS(-1)day(-1)) transformations as possible metabolic pathways used by methanogenic bacteria is suggested from the SMA results obtained. Methanotrix sp., Methanosarcina sp., Methanoccocus sp. and Methanobacterium sp. were identified. PMID:18707861

  4. Fate of malathion and a phosphonic acid in activated sludge with varying solids retention times.

    PubMed

    Janeczko, Allen K; Walters, Edward B; Schuldt, Steven J; Magnuson, Matthew L; Willison, Stuart A; Brown, Lisa M; Ruiz, Oscar N; Felker, Daniel L; Racz, LeeAnn

    2014-06-15

    This study examined the ability of activated sludge (AS) to sorb and biodegrade ethylmethylphosphonic acid (EMPA) and malathion, a degradation product and surrogate, respectively, for an organophosphate chemical warfare agent. Sorption equilibrium isotherm experiments indicate that sorption of EMPA and malathion to AS is negligible. EMPA at a concentration of 1 mg L(-1) degraded by approximately 30% with apparent first-order kinetics, possibly via co-metabolism from nitrification. Heterotrophic bacteria and abiotic mechanisms, however, are largely responsible for malathion degradation also with apparent first-order kinetics. EMPA did not inhibit chemical oxygen demand (COD) oxidation or nitrification activity, although malathion did appear to induce a stress response resulting in inhibition of COD oxidation. The study also included a 30-day experiment in which malathion, at a concentration of 5 mg L(-1), was repeatedly fed to AS in bench-scale sequencing batch reactors (SBRs) operating at different solids retention times (SRTs). Peak malathion concentrations occurred at day 4.5, with the longer SRTs yielding greater peak malathion concentrations. The AS reduced the malathion concentrations to nearly zero by day 10 for all SRTs, even when the malathion concentration in the influent increased to 20.8 mg L(-1). The data suggest a biodegradation pathway for malathion involving an oxygenase. Phylogenetic analyses revealed that all samples had an abundance of Zoogloea, though there was greater bacterial diversity in the SBR with the SRT of 50 days. The SBR with an SRT of 9.5 days had an apparent reduction in the diversity of the bacterial community. PMID:24709533

  5. Design and performance of BNR activated sludge systems with flat sheet membranes for solid-liquid separation.

    PubMed

    du Toit, G J G; Ramphao, M C; Parco, V; Wentzel, M C; Ekama, G A

    2007-01-01

    The use of immersed membranes for solid-liquid separation in biological nutrient removal activated sludge (BNRAS) systems was investigated at lab scale. Two laboratory-scale BNR activated sludge systems were run in parallel, one a MBR system and the other a conventional system with secondary settling tanks. Both systems were in 3 reactor anaerobic, anoxic, aerobic UCT configurations. The systems were set up to have, as far as possible, identical design parameters such as reactor mass fractions, recycles and sludge age. Differences were the influent flow and total reactor volumes, and the higher reactor concentrations in the MBR system. The performances of the two systems were extensively monitored and compared to identify and quantify the influence of the membranes on system response. The MBR UCT system exhibited COD, FSA, TKN, TP and TSS removals that were consistently equivalent or superior to the conventional system. Better P removal in the MBR was attributed to lower observed P uptake in the anoxic zone. High nitrate loads to the anoxic reactor appeared to be the determining factor in stimulating P uptake. The MBR UCT system had a greater sludge production than the conventional system. This was partly attributable to the retention of all solids in the MBR reactor. For steady state design this increase is accommodated by increasing the influent unbiodegradable particulate COD fraction. Additionally an attempt was made to determine the Alpha values in the oxygen transfer rate. This paper briefly summarises and compares the results from both systems, and the conclusions that can be drawn from these results.

  6. Sorption of emerging trace organic compounds onto wastewater sludge solids.

    PubMed

    Stevens-Garmon, John; Drewes, Jörg E; Khan, Stuart J; McDonald, James A; Dickenson, Eric R V

    2011-05-01

    This work examined the sorption potential to wastewater primary- and activated-sludge solids for 34 emerging trace organic chemicals at environmentally relevant concentrations. These compounds represent a diverse range of physical and chemical properties, such as hydrophobicity and charge state, and a diverse range of classes, including steroidal hormones, pharmaceutically-active compounds, personal care products, and household chemicals. Solid-water partitioning coefficients (K(d)) were measured where 19 chemicals did not have previously reported values. Sludge solids were inactivated by a nonchemical lyophilization and dry-heat technique, which provided similar sorption behavior for recalcitrant compounds as compared to fresh activated-sludge. Sorption behavior was similar between primary- and activated-sludge solids from the same plant and between activated-sludge solids from two nitrified processes from different wastewater treatment systems. Positively-charged pharmaceutically-active compounds, amitriptyline, clozapine, verapamil, risperidone, and hydroxyzine, had the highest sorption potential, log K(d)=2.8-3.8 as compared to the neutral and negatively-charged chemicals. Sorption potentials correlated with a compound's hydrophobicity, however the higher sorption potentials observed for positively-charged compounds for a given log D(ow) indicate additional sorption mechanisms, such as electrostatic interactions, are important for these compounds. Previously published soil-based one-parameter models for predicting sorption from hydrophobicity (log K(ow)>2) can be used to predict sorption for emerging nonionic compounds to wastewater sludge solids.

  7. Mutual interactions of Pleurotus ostreatus with bacteria of activated sludge in solid-bed bioreactors.

    PubMed

    Svobodová, Kateřina; Petráčková, Denisa; Kozická, Barbora; Halada, Petr; Novotný, Čeněk

    2016-06-01

    White rot fungi are well known for their ability to degrade xenobiotics in pure cultures but few studies focus on their performance under bacterial stress in real wastewaters. This study investigated mutual interactions in co-cultures of Pleurotus ostreatus and activated sludge microbes in batch reactors and different culture media. Under the bacterial stress an increase in the dye decolorization efficiency (95 vs. 77.1 %) and a 2-fold elevated laccase activity (156.7 vs. 78.4 Ul(-1)) were observed in fungal-bacterial cultures compared to pure P. ostreatus despite a limited growth of bacteria in mixed cultures. According to 16S-rDNA analyses, P. ostreatus was able to alter the structure of bacterial communities. In malt extract-glucose medium the fungus inhibited growth of planktonic bacteria and prevented shifts in bacterial utilization of potential C-sources. A model bacterium, Rhodococcus erythropolis responded to fungal metabolites by down regulation of uridylate kinase and acetyl-CoA synthetase. PMID:27116960

  8. 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.

  9. 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.

  10. Effect of low ORP in anoxic sludge zone on excess sludge production in oxic-settling-anoxic activated sludge process.

    PubMed

    Saby, Sébastien; Djafer, Malik; Chen, Guang-Hao

    2003-01-01

    This paper studied the effect of oxidation-reduction potential (ORP) in the anoxic sludge zone on the excess sludge production in the oxic-settling-anoxic process (OSA process), a modified activated sludge process. Two pilot-scale activated sludge systems were employed in this study: (1) an OSA process that was modified from a conventional activated sludge process by inserting a sludge holding tank or namely the "anoxic" tank in the sludge return line; and (2) a conventional process used as the reference system. Each was composed of a membrane bioreactor to serve the aeration tank and solid/liquid separator. Both systems were operated with synthetic wastewater for 9 months. During the operation, the OSA system was operated with different ORP levels (+100 to -250 mV) in its anoxic tank. It has been confirmed that the OSA system produced much less excess sludge than the reference system. A lower ORP level than +100 mV in the anoxic tank is in favor of the excess sludge reduction. When the ORP level decreased from +100 to -250 mV the sludge reduction efficiency was increased from 23% to 58%. It has also been found that the OSA system performed better than the reference system with respect to the chemical oxygen demand removal efficiency and sludge settleability. The OSA process may present a potential low-cost solution to the excess sludge problem in an activated sludge process because addition of a sludge holding tank is only needed.

  11. Filterability of membrane bioreactor (MBR) sludge: impacts of polyelectrolytes and mixing with conventional activated sludge.

    PubMed

    Yigit, Nevzat O; Civelekoglu, Gokhan; Cinar, Ozer; Kitis, Mehmet

    2010-01-01

    The main objective of this work was to investigate the filterability of MBR sludge and its mixture with conventional activated sludge (CAS). In addition, the impacts of type and dose of various polyelectrolytes, filter type and sludge properties on the filterability of both MBR and Mixed sludges were determined. Specific cake resistance (SCR) measured by the Buchner funnel filtration test apparatus and the solids content of the resulting sludge cake were used to assess the dewaterability of tested sludges. The type of filter paper used in Buchner tests affected the results of filterability for MBR, CAS and Mixed sludges. SCR values and optimum polyelectrolyte doses increased with increasing MLSS concentrations in the MBR, which suggested that increase in MLSS concentrations accompanied by increases in EPS and SMP concentrations and a shift toward smaller particles caused poorer dewaterability of the MBR sludge. The significant differences observed among the filterability of CAS and MBR sludges suggested that MLSS alone is not a good predictor of sludge dewaterability. Combining CAS and MBR sludges at different proportions generally improved their dewaterability. Combining MBR sludges having typically high MLSS and EPS concentrations with CAS having much lower MLSS concentrations may be an option for full-scale treatment plants experiencing sludge dewaterability problems. Better filterability and higher cake dry solids were achieved with cationic polyelectrolytes compared to anionic and non-ionic ones for all sludge types tested.

  12. Screening wastewater for toxicity to activated sludge

    SciTech Connect

    Schneider, C.G.

    1987-01-01

    Several toxicity tests were compared to define their utility for prediction of toxicity to activated sludge. The tests included: (1) oxygen uptake rates in batch tests with activated sludge, (2) adenosine triphosphate (ATP) measurements in the same batch tests, (3) Warburg respirometer studies with activated sludge, and (4) a luminescent bacteria test (Microtox/sup TM/). An evaluation of the toxicity tests was made with several toxicants; nickel (II), mercury (II), 2,4-dichlorophenol (DCP) and 4,6-dinitro-o-cresol (DNOC). Because of differences in toxic mechanism, some of the toxicants produced greater toxic effects in some tests than in other tests. The ATP levels decreased significant when uncouplers of oxidative phosphorylation were studied (DCP and DNOC). Several procedures for measuring ATP were investigated and were found to be unsatisfactory when applied to activated sludge. A new method for extraction of ATP, which incorporated a sonic bath and trichloroacetic acid, was developed. The improved ATP method was used in the toxicity tests and for the additional studies. Current practice in environmental engineering relies on volatile suspended solids (VSS) as a measure of active biomass in activated sludge. After an improved ATP procedure was developed, ATP was investigated for estimation of active biomass. The fate of DCP in the toxicity tests was studied and an adsorptive mechanism was proposed that was based on membrane solubility. This mechanism explained the fate of DCP in the toxicity tests and is useful for understanding the fate of DCP in activated sludge.

  13. Improving the efficiency of case-based reasoning to deal with activated sludge solids separation problems.

    PubMed

    Martínez, M; Mérida-Campos, C; Sánchez-Marré, M; Comas, J; Rodríguez-Roda, I

    2006-06-01

    The potential of Case-Based Reasoning to use the knowledge gained from past experiences to solve problematic situations has made this Artificial Intelligence technique a useful decision support tool in different environmental domains such as wastewater treatment. Case-Based Reasoning tools automatically identify similarities between present and previous situations (cases) and reuse the experiences gained from the previous situations to solve current problems. Case retrieval can be considered to be the most important step in the process of Case-Based Reasoning. In the present study we propose incorporating a relevance network in order to increase the accuracy and the efficiency of case retrieval. The result is a context-sensitive feature-weighting methodology capable of defining the model of relationships between the different attributes or features that define the context in which Case-Based Reasoning is applied. These features affect the retrieval procedure directly. The feature's degree of relevance in the network is easily translated into a set of simple rules and applied during case retrieval, specifically during the similarity calculation. The results obtained in the present study show significant improvements in the accuracy of case retrieval. With the approach presented here experts considered more than 90% of the retrieved cases to be completely relevant according to the knowledge these cases provided for dealing with solids separation problems.

  14. Kinetic model of excess activated sludge thermohydrolysis.

    PubMed

    Imbierowicz, Mirosław; Chacuk, Andrzej

    2012-11-01

    Thermal hydrolysis of excess activated sludge suspensions was carried at temperatures ranging from 423 K to 523 K and under pressure 0.2-4.0 MPa. Changes of total organic carbon (TOC) concentration in a solid and liquid phase were measured during these studies. At the temperature 423 K, after 2 h of the process, TOC concentration in the reaction mixture decreased by 15-18% of the initial value. At 473 K total organic carbon removal from activated sludge suspension increased to 30%. It was also found that the solubilisation of particulate organic matter strongly depended on the process temperature. At 423 K the transfer of TOC from solid particles into liquid phase after 1 h of the process reached 25% of the initial value, however, at the temperature of 523 K the conversion degree of 'solid' TOC attained 50% just after 15 min of the process. In the article a lumped kinetic model of the process of activated sludge thermohydrolysis has been proposed. It was assumed that during heating of the activated sludge suspension to a temperature in the range of 423-523 K two parallel reactions occurred. One, connected with thermal destruction of activated sludge particles, caused solubilisation of organic carbon and an increase of dissolved organic carbon concentration in the liquid phase (hydrolysate). The parallel reaction led to a new kind of unsolvable solid phase, which was further decomposed into gaseous products (CO(2)). The collected experimental data were used to identify unknown parameters of the model, i.e. activation energies and pre-exponential factors of elementary reactions. The mathematical model of activated sludge thermohydrolysis appropriately describes the kinetics of reactions occurring in the studied system. PMID:22951329

  15. The activated sludge process: Fundamentals of operation

    SciTech Connect

    Junkins, R.; Deeny, K.J.; Eckhoff, T.H.

    1983-01-01

    The procedures given here - based on extensive and intensive experience. Background information on process mechanics is followed by detailed consideration of control and troubleshooting practices. Contents: PREFACE AND INTRODUCTION; PROCESS MECHANICS; Basic Mechanism of Activated Sludge Systems; Formation of Activated Sludge; Growth of Microorganisms; Classifications of Microorganisms: Type, Environment, Age; Solids Separation and Return; FACTORS AFFECTING OPERATION; Raw Wastewater Strength; Dissolved Oxygen; pH; Temperature; Nutrients; Toxicity; Mixing; Detention Time; Hydraulics; PROCESS MODIFICATIONS; Conventional; Complete Mix; Contact-Stabilization; Extended Aeration; Others; PROCESS MONITORING; Visual; Analytical Indicators; OPERATIONAL CONTROL; Sludge Volume Index; Sludge Age; Mean Cell Residence Time; Food/Microorganism Ratio; Organic Loading Rate; Solids Loading Rate; Clarifier Overflow Rate; Weir Overflow Rate; Sludge Recycle Rate, Sludge Wastage Rate; Chemical Feed Rate; TROUBLESHOOTING; Low BOD Removal; Low D.O. in Aeration Baisn; Poor Settling; PLANT START-UP; Introduction; Pre Start-up Checkup; Wastewater Analysis; Seed Screening; Process Checklist; Mechanical Checklist; Familiarization and Training; Start-up; Seeding; Process Monitoring; Transition; Typical Start-up Problems; Foaming; Settling Problems; Low BOD Removal; INDEX.

  16. Successful recycling for sludge and solid waste

    SciTech Connect

    Kovacik, T.L.

    1987-01-01

    We have mixed digested primary sewage sludge with undigested, thickened waste activated sludge, dewatered in polymer conditioned belt presses, and add lime and cement kiln dust in post press operations. For at least seven days the combined mixture is aerated. The product is far more community acceptable than traditional sludge cake, and is clearly environmentally safe and meets the most stringent new regulatory controls. Even when the kiln dust treated sludge was stressed to a pH of 4, which is far more acidic than would be expected in agricultural soils, the sludge/kiln dust mixture easily met EPA criteria. The process results in a reduction in the weight and in the volume of material. In our Sylvania Pilot Project, 555 tons of sludge were treated with 178 tons of kiln dust, resulting in 504 tons of finished product - a 10% reduction in sludge weight and a far greater reduction in sludge volume. The product can be stored for long periods of time without deterioration. Thus, we see a process that requires about seven days for total treatment. We see a process with limited capital requirements. We see a process with operating costs at or below traditional PSRP processes and far less than alternative PFRP options. We see a community acceptable, storable, nearly odorless, granular, pasteurized product that provides built in protection against pathogen regrowth, odors, and the migration of toxic compounds. We see a product that has multiple market options. The N-Viro Soil product optimizes the nutrient values of sludge, provides potassium, sulphur, and even trace minerals from kiln dust and provides sufficient calcium carbonate to provide both liming and long-term soil calcium requirements. This combination is attractive to agricultural interests, is ideal for reclamation projects or landfill cover materials, and is an excellent landscape fertilizer and soil conditioner.

  17. Removal of antibiotics in wastewater: Effect of hydraulic and solid retention times on the fate of tetracycline in the activated sludge process.

    PubMed

    Kim, Sungpyo; Eichhorn, Peter; Jensen, James N; Weber, A Scott; Aga, Diana S

    2005-08-01

    A study was conducted to examine the influence of hydraulic retention time (HRT) and solid retention time (SRT) on the removal of tetracycline in the activated sludge processes. Two lab-scale sequencing batch reactors (SBRs) were operated to simulate the activated sludge process. One SBR was spiked with 250 microg/L tetracycline, while the other SBR was evaluated at tetracycline concentrations found in the influent of the wastewater treatment plant (WWTP) where the activated sludge was obtained. The concentrations of tetracyclines in the influent of the WWTP ranged from 0.1 to 0.6 microg/L. Three different operating conditions were applied during the study (phase 1-HRT: 24 h and SRT: 10 days; phase 2-HRT: 7.4 h and SRT: 10 days; and phase 3-HRT: 7.4 h and SRT: 3 days). The removal efficiency of tetracycline in phase 3 (78.4 +/- 7.1%) was significantly lower than that observed in phase 1 (86.4 +/- 8.7%) and phase 2 (85.1 +/- 5.4%) at the 95% confidence level. The reduction of SRT in phase 3 while maintaining a constant HRT decreased tetracycline removal efficiency. Sorption kinetics reached equilibrium within 24 h. Batch equilibrium experiments yielded an adsorption coefficient (Kads) of 8400 +/- 500 mL/g and a desorption coefficient (Kdes) of 22 600 +/- 2200 mL/g. No evidence of biodegradation for tetracycline was observed during the biodegradability test, and sorption was found to be the principal removal mechanism of tetracycline in activated sludge.

  18. Rheology evolution of sludge through high-solid anaerobic digestion.

    PubMed

    Dai, Xiaohu; Gai, Xin; Dong, Bin

    2014-12-01

    The main purpose of this study was to investigate the rheology evolution of sludge through high-solid anaerobic digestion (AD) and its dependency on sludge retention time (SRT) and temperature of AD reactor. The operation performance of high-solid AD reactors were also studied. The results showed that sludge became much more flowable after high-solid AD. It was found that the sludge from reactors with long SRT exhibited low levels of shear stress, viscosity, yield stress, consistency index, and high value of flow behaviour index. While the flowability of sludge from thermophilic AD reactors were better than that of sludge from mesophilic AD reactors though the solid content of the formers were higher than that of the latters, which could be attributed to the fact that the formers had more amount of free and interstitial moisture. It might be feasible to use sludge rheology as an AD process controlling parameter.

  19. Comparative performance of mesophilic and thermophilic anaerobic digestion for high-solid sewage sludge.

    PubMed

    Hidaka, Taira; Wang, Feng; Togari, Taketo; Uchida, Tsutomu; Suzuki, Yutaka

    2013-12-01

    In local cities, many small sewage and waste treatment facilities are operated independently. To encourage processing by anaerobic digestion at a centralized sewage treatment plant (STP), high-solid sewage sludge is helpful because it reduces the energy and cost required for transporting the sludge from other STPs. Mesophilic and thermophilic anaerobic digestion of sewage sludge at total solids concentrations (TS) of 7.5% and 10% were evaluated using laboratory-scale continuous reactors. Under the mesophilic condition, sewage sludge of 10% TS was successfully treated. Under the thermophilic condition, sewage sludge of 7.5% TS was not successfully treated when the total ammonia concentration was over 2000 mg N/L. Batch experiments showed that it takes a few weeks for the methane fermentation activity to recover after being inhibited. The effectiveness of adding easily biodegradable organic matter was confirmed. These results show that high-solid sewage sludge is suitable for small facilities by controlling the operating conditions.

  20. New sludge pretreatment method to improve methane production in waste activated sludge digestion.

    PubMed

    Zhang, Dong; Chen, Yinguang; Zhao, Yuxiao; Zhu, Xiaoyu

    2010-06-15

    During two-phase sludge anaerobic digestion, sludge is usually hydrolyzed and acidified in the first phase, then methane is produced in the second stage. To get more methane from sludge, most studies in literature focused on the increase of sludge hydrolysis. In this paper a different sludge pretreatment method, i.e., pretreating sludge at pH 10 for 8 d is reported, by which both waste activated sludge hydrolysis and acidification were increased, and the methane production was significantly improved. First, the effect of different sludge pretreatment methods on methane yield was compared. The pH 10 pretreated sludge showed the highest accumulative methane yield (398 mL per g of volatile suspended solids), which was 4.4-, 3.5-, 3.1-, and 2.3-fold of the blank (unpretreated), ultrasonic, thermal, and thermal-alkaline pretreated sludge, respectively. Nevertheless, its total time involved in the first (hydrolysis and acidification) and second (methanogenesis) stages was 17 (8 + 9) d, which was almost the same as other pretreatments. Then, the mechanisms for pH 10 pretreatment significantly improving methane yield were investigated. It was found that pretreating sludge at pH 10 caused the greatest sludge hydrolysis, acidification, soluble C:N and C:P ratios, and Fe(3+) concentration with a suitable short-chain fatty acids composition in the first stage, which resulted in the highest microorganism activity (ATP) and methane production in the second phase. Further investigation on the second phase microorganisms with fluorescence in situ hybridization (FISH) and scanning electron microscopy (SEM) indicated that there were much greater active methanogenesis Archaea when methane was produced with the pH 10 pretreated sludge, and the predominant morphology of the microcolonies suggest a shift to Methanosarcina sp. like.

  1. A grit separation module for inorganic matter removal from activated sludge: investigation on characteristics of split sludge from the module.

    PubMed

    Chen, You-Peng; Guo, Jin-Song; Wang, Jing; Yan, Peng; Ji, Fang-Ying; Fang, Fang; Dong, Yang

    2016-12-01

    A grit separation module was developed to prevent the accumulation of inorganic solids in activated sludge systems, and it achieved effective separation of organic matter and inorganic solids. To provide technical and theoretical support for further comprehensive utilization of split sludge (underflow and overflow sludge from the separation module), the characteristics of split sludge were investigated. The settling and dewatering properties of the underflow sludge were excellent, and it had high inorganic matter content, whereas the overflow sludge had higher organic matter content. The most abundant inorganic constituent was SiO2 (59.34%), and SiO2, Al2O3, and Fe2O3 together accounted for 79.53% of the inorganic matter in the underflow sludge. The mass ratio of Fe2O3, CaO, and MgO to SiO2 and Al2O3 was 0.245 in the inorganic component of the underflow sludge. The underflow sludge had the beneficial characteristics of simple treatment and disposal, and it was suitable for use as a base raw material for ceramsite production. The overflow sludge with higher organic matter content was constantly returned from the separation module to the wastewater treatment system, gradually improving the volatile suspended solid/total suspended solid ratio of the activated sludge in the wastewater treatment system.

  2. 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.

  3. 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. PMID:27453288

  4. Pretreatment of high solid microbial sludges

    DOEpatents

    Rivard, C.J.; Nagle, N.J.

    1998-07-28

    A process and apparatus are disclosed for pretreating microbial sludges in order to enhance secondary anaerobic digestion. The pretreatment process involves disrupting the cellular integrity of municipal sewage sludge through a combination of thermal, explosive decompression and shear forces. The sludge is pressurized and pumped to a pretreatment reactor where it is mixed with steam to heat and soften the sludge. The pressure of the sludge is suddenly reduced and explosive decompression forces are imparted which partially disrupt the cellular integrity of the sludge. Shear forces are then applied to the sludge to further disrupt the cellular integrity of the sludge. Disrupting cellular integrity releases both soluble and insoluble organic constituents and thereby renders municipal sewage sludge more amenable to secondary anaerobic digestion. 1 fig.

  5. Pretreatment of high solid microbial sludges

    DOEpatents

    Rivard, Christopher J.; Nagle, Nicholas J.

    1998-01-01

    A process and apparatus for pretreating microbial sludges in order to enhance secondary anaerobic digestion. The pretreatment process involves disrupting the cellular integrity of municipal sewage sludge through a combination of thermal, explosive decompression and shear forces. The sludge is pressurized and pumped to a pretreatment reactor where it is mixed with steam to heat and soften the sludge. The pressure of the sludge is suddenly reduced and explosive decompression forces are imparted which partially disrupt the cellular integrity of the sludge. Shear forces are then applied to the sludge to further disrupt the cellular integrity of the sludge. Disrupting cellular integrity releases both soluble and insoluble organic constituents and thereby renders municipal sewage sludge more amenable to secondary anaerobic digestion.

  6. Effects of Time, Heat, and Oxygen on K Basin Sludge Agglomeration, Strength, and Solids Volume

    SciTech Connect

    Delegard, Calvin H.; Sinkov, Sergey I.; Schmidt, Andrew J.; Daniel, Richard C.; Burns, Carolyn A.

    2011-01-04

    Sludge disposition will be managed in two phases under the K Basin Sludge Treatment Project. The first phase is to retrieve the sludge that currently resides in engineered containers in the K West (KW) Basin pool at ~10 to 18°C. The second phase is to retrieve the sludge from interim storage in the sludge transport and storage containers (STSCs) and treat and package it in preparation for eventual shipment to the Waste Isolation Pilot Plant. The work described in this report was conducted to gain insight into how sludge may change during long-term containerized storage in the STSCs. To accelerate potential physical and chemical changes, the tests were performed at temperatures and oxygen partial pressures significantly greater than those expected in the T Plant canyon cells where the STSCs will be stored. Tests were conducted to determine the effects of 50°C oxygenated water exposure on settled quiescent uraninite (UO2) slurry and a full simulant of KW containerized sludge to determine the effects of oxygen and heat on the composition and mechanical properties of sludge. Shear-strength measurements by vane rheometry also were conducted for UO2 slurry, mixtures of UO2 and metaschoepite (UO3•2H2O), and for simulated KW containerized sludge. The results from these tests and related previous tests are compared to determine whether the settled solids in the K Basin sludge materials change in volume because of oxidation of UO2 by dissolved atmospheric oxygen to form metaschoepite. The test results also are compared to determine if heating or other factors alter sludge volumes and to determine the effects of sludge composition and settling times on sludge shear strength. It has been estimated that the sludge volume will increase with time because of a uranium metal → uraninite → metaschoepite oxidation sequence. This increase could increase the number of containers required for storage and increase overall costs of sludge management activities. However, the volume

  7. Application of forward osmosis (FO) under ultrasonication on sludge thickening of waste activated sludge.

    PubMed

    Nguyen, Nguyen Cong; Nguyen, Hau Thi; Chen, Shiao-Shing; Nguyen, Nhat Thien; Li, Chi-Wang

    2015-01-01

    Forward osmosis (FO) is an emerging process for dewatering solid-liquid stream which has the potential to be innovative and sustainable. However, the applications have still been hindered by low water flux and membrane fouling when activated sludge is used as the feed solution due to bound water from microbial cells. Hence, a novel strategy was designed to increase sludge thickening and reduce membrane fouling in the FO process under ultrasonic condition. The results from the ultrasound/FO hybrid system showed that the sludge concentration reached up to 20,400 and 28,400 mg/L from initial sludge concentrations of 3000 and 8000 mg/L with frequency of 40 kHz after 22 hours, while the system without ultrasound had to spend 26 hours to achieve the same sludge concentration. This identifies that the presence of ultrasound strongly affected sludge structure as well as sludge thickening of the FO process. Furthermore, the ultrasound/FO hybrid system could achieve NH4+-N removal efficiency of 96%, PO4(3-)-P of 98% and dissolved organic carbon (DOC) of 99%. The overall performance demonstrates that the proposed ultrasound/FO system using seawater as a draw solution is promising for sludge thickening application. PMID:26465299

  8. Application of forward osmosis (FO) under ultrasonication on sludge thickening of waste activated sludge.

    PubMed

    Nguyen, Nguyen Cong; Nguyen, Hau Thi; Chen, Shiao-Shing; Nguyen, Nhat Thien; Li, Chi-Wang

    2015-01-01

    Forward osmosis (FO) is an emerging process for dewatering solid-liquid stream which has the potential to be innovative and sustainable. However, the applications have still been hindered by low water flux and membrane fouling when activated sludge is used as the feed solution due to bound water from microbial cells. Hence, a novel strategy was designed to increase sludge thickening and reduce membrane fouling in the FO process under ultrasonic condition. The results from the ultrasound/FO hybrid system showed that the sludge concentration reached up to 20,400 and 28,400 mg/L from initial sludge concentrations of 3000 and 8000 mg/L with frequency of 40 kHz after 22 hours, while the system without ultrasound had to spend 26 hours to achieve the same sludge concentration. This identifies that the presence of ultrasound strongly affected sludge structure as well as sludge thickening of the FO process. Furthermore, the ultrasound/FO hybrid system could achieve NH4+-N removal efficiency of 96%, PO4(3-)-P of 98% and dissolved organic carbon (DOC) of 99%. The overall performance demonstrates that the proposed ultrasound/FO system using seawater as a draw solution is promising for sludge thickening application.

  9. Effect of solid contents on the controlled shear stress rheological properties of different types of sludge.

    PubMed

    Li, Ting; Wang, Yili; Dong, Yujing

    2012-01-01

    Controlled shear stress (CSS) test was used to study the effect of solid contents on the corresponding rheological parameters for sludge. Three types of sludge with or without conditioning, including activated sludge (AS), anaerobic digested sludge (ADS), and water treatment residuals (WTRs), were collected for the CSS test. Results showed that the yield stress and the cohesion energy of the sludge networks were improved with increased total suspending solid (TSS) contents in most cases. For the conditioned AS/ADS and the raw WTRs, exponential law was observed in the relationships between cohesion energy of material networks or yield stress and the TSS contents, whereas for the conditioned WTRs, only exponential law dependence was found between the parameters of shear modulus or critical strain and the TSS contents.

  10. Enzyme activities in activated sludge flocs.

    PubMed

    Yu, Guang-Hui; He, Pin-Jing; Shao, Li-Ming; Lee, Duu-Jong

    2007-12-01

    This study quantified the activities of enzymes in extracellular polymeric substances (EPS) and in pellets. Seven commonly adopted extraction schemes were utilized to extract from aerobic flocs the contained EPS, which were further categorized into loosely bound (LB) and tightly bound (TB) fractions. Ultrasonication effectively extracted the EPS from sludge flocs. Enzyme assay tests showed that the protease activity was localized mainly on the pellets, alpha-amylase and alpha-glucosidase activities were largely bound with LB-EPS, and few protease, alpha-amylase, or alpha-glucosidase activities were associated with the TB-EPS fraction. There exists no correlation between the biochemical compositions of EPS and the distribution of enzyme activities in the sludge matrix. The 44-65% of alpha-amylase and 59-100% of alpha-glucosidase activities noted with the LB-EPS indicate heterogeneous hydrolysis patterns in the sludge flocs with proteins and carbohydrates.

  11. A simple empirical model for activated sludge thickening in secondary clarifiers.

    PubMed

    Giokas, D L; Kim, Youngchul; Paraskevas, P A; Paleologos, E K; Lekkas, T D

    2002-07-01

    A simple empirical model for the thickening function of the activated sludge secondary clarifiers is presented. The proposed approach relies on the integration of previous models and it is based on the phenomenon of dilution of the incoming activated sludge in the feeding well of the settling tanks. The method provides a satisfactory description of sludge stratification within the clarifier. The only requirements are limited to parameters which are readily incorporated into the routine analysis performed in an activated sludge plant, thereby eliminating the need for additional experimental or computational effort. The method was tested in a full-scale activated sludge plant and it was found that it describes fairly well the return sludge concentration, the diluted sludge blanket concentration, the sludge blanket solids concentration and the sludge blanket height of full-scale secondary clarifiers.

  12. Role of Nocardia in Activated Sludge.

    PubMed

    Bafghi, Mehdi Fatahi; Yousefi, Nader

    2016-05-01

    Activated sludge process is a biological process that is widely used in the domestic and industrial wastewater treatment in over the world. The foam formation is often reported in wastewater treatment plants which are related to this process. Some operational problems can be created by foaming, such as effluent quality deteriorates, the creation of malodorous, increased time requirements in order to plant maintenance, and in extreme cases, hazardous working conditions resulting from foam spilling out of the aeration basin and as well as increased in operational costs. There are different ways to overcome this problem, such as reduce air flows into the aeration basin, reduction in the grease and oil content of the wastewater, surface and return activated sludge (RAS) chlorination, anoxic and anaerobic selectors, solid retention time (SRT) control and antifoams and organic polymer addition. On the other hand, rapid and accurate identification of the foam causes is in the first step to control bulking and foaming. Foam problem is often created by filamentous bacteria, such as Nocardia and Gordonia species. This bacterium has a role important in activated sludge. PMID:27418874

  13. Role of Nocardia in Activated Sludge

    PubMed Central

    Bafghi, Mehdi Fatahi; Yousefi, Nader

    2016-01-01

    Activated sludge process is a biological process that is widely used in the domestic and industrial wastewater treatment in over the world. The foam formation is often reported in wastewater treatment plants which are related to this process. Some operational problems can be created by foaming, such as effluent quality deteriorates, the creation of malodorous, increased time requirements in order to plant maintenance, and in extreme cases, hazardous working conditions resulting from foam spilling out of the aeration basin and as well as increased in operational costs. There are different ways to overcome this problem, such as reduce air flows into the aeration basin, reduction in the grease and oil content of the wastewater, surface and return activated sludge (RAS) chlorination, anoxic and anaerobic selectors, solid retention time (SRT) control and antifoams and organic polymer addition. On the other hand, rapid and accurate identification of the foam causes is in the first step to control bulking and foaming. Foam problem is often created by filamentous bacteria, such as Nocardia and Gordonia species. This bacterium has a role important in activated sludge. PMID:27418874

  14. Development of sludge filterability test to assess the solids removal potential of a sludge bed.

    PubMed

    Mahmoud, Nidal; Zandvoort, Marcel; van Lier, Jules; Zeeman, Grietje

    2006-12-01

    A qualitative sludge characterisation technique called "sludge filterability technique" has been developed. This technique enables the determination of the sludge potential for the physical removal of solids, weighing the effect of different process parameters on solids removal and identifying the mechanisms of solids removal in an upflow anaerobic sludge bed system. In this paper guidelines for conducting the test are given and a "standardised" set-up is presented. The experimental set-up and protocol are simple and the results can be obtained in a period as short as a few hours. A sludge sample is added to an upflow reactor incubated at 4 degrees C, to limit gas production, washed with an anaerobically pre-treated and suspended solids free wastewater to remove solids washed out from the sludge, and then fed with a model substrate, prepared from fish meal with a standard procedure. Several experimental runs were conducted to validate and optimise the technique. The results showed that the technique is reliable, workable and reproducible.

  15. Enhanced biodegradation of iopromide and trimethoprim in nitrifying activated sludge.

    PubMed

    Batt, Angela L; Kim, Sungpyo; Aga, Diana S

    2006-12-01

    Iopromide (an X-ray contrast agent) and trimethoprim (an antibacterial drug) are frequently detected pharmaceuticals in effluents of wastewater treatment plants (WWTPs) and in surface waters due to their persistence and high usage. Laboratory-scale experiments showed that a significantly higher removal rate in nitrifying activated sludge as compared to conventional activated sludge was observed for both iopromide and trimethoprim. When the activity of the nitrifying bacteria was inhibited, the percent removal of iopromide decreased from 97 to 86% while trimethoprim removal decreased from 70 to 25%. The metabolite of iopromide identified when nitrification was not inhibited was a dehydroxylated iopromide at the two side chains. However, when the nitrifying bacteria were inhibited the metabolite identified was a carboxylate, formed during the oxidation of the primary alcohol on the side chain of iopromide. These results suggest that the nitrifying bacteria are important in the observed biodegradation of iopromide in the activated sludge with higher solid retention time (SRT). Results from the laboratory-scale study were corroborated by the observed removal efficiencies in a full-scale municipal WWTP, which showed that iopromide (ranging from 0.10 to 0.27 microg/L) and trimethoprim (ranging from 0.0.08 to 0.53 microg/L) were removed more effectively in the nitrifying activate sludge which has a higher SRT (49 days) than in the conventional activated sludge (SRT of 6 days). In nitrifying activated sludge, the percent removal of iopromide in the WWTP reached 61%, while in conventional activated sludge, average removal was negligible. For trimethoprim, removal was limited to about 1% in the conventional activated sludge, while in the nitrifying activated sludge, the removal was increased to 50%.

  16. The digestibility of waste activated sludges.

    PubMed

    Park, Chul; Abu-Orf, Mohammad M; Novak, John T

    2006-01-01

    Laboratory digestion studies using waste activated sludges (WAS) were conducted to compare the digestion performance between anaerobic and aerobic processes. Nine samples of WAS from seven wastewater treatment plants were collected and batch-digested under both anaerobic and aerobic conditions for 30 days at 25 degrees C. The cation content of wastewater (both floc and solution phases) and solution biopolymer (protein and polysaccharide) was measured before and after digestion and compared with volatile solids destruction data. The study revealed that each digestion process was associated with a distinct biopolymer fraction, which accounted for differences in volatile solids reduction under anaerobic and aerobic conditions. The anaerobic digestion data showed strong correlations between soluble protein generation, ammonium production, percent volatile solids reduction, and floc iron (Fe). These data suggest that the amount of volatile solids destroyed by anaerobic digestion depends on the Fe content of floc. In aerobic digestion, polysaccharide accumulated in solution along with calcium and magnesium. For aerobic digestion, correlations between divalent cation release and the production of inorganic nitrogen were found. This implies that divalent cation-bound biopolymer, thought to be lectin-like protein, was the primary organic fraction degraded under aerobic conditions. The results of the study show that the cation content in wastewater is an important indicator of the material that will digest under anaerobic or aerobic conditions and that some of the volatile solids will digest only under either anaerobic or aerobic conditions. PMID:16553167

  17. Use of 16S rRNA Gene Terminal Restriction Fragment Analysis To Assess the Impact of Solids Retention Time on the Bacterial Diversity of Activated Sludge

    PubMed Central

    Saikaly, Pascal E.; Stroot, Peter G.; Oerther, Daniel B.

    2005-01-01

    Terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes was used to investigate the reproducibility and stability in the bacterial community structure of laboratory-scale sequencing batch bioreactors (SBR) and to assess the impact of solids retention time (SRT) on bacterial diversity. Two experiments were performed. In each experiment two sets of replicate SBRs were operated for a periods of three times the SRT. One set was operated at an SRT of 2 days and another set was operated at an SRT of 8 days. Samples for T-RFLP analysis were collected from the two sets of replicate reactors. HhaI, MspI, and RsaI T-RFLP profiles were analyzed using cluster analysis and diversity statistics. Cluster analysis with Ward's method using Jaccard distance and Hellinger distance showed that the bacterial community structure in both sets of reactors from both experimental runs was dynamic and that replicate reactors were clustered together and evolved similarly from startup. Richness (S), evenness (E), the Shannon-Weaver index (H), and the reciprocal of Simpson's index (1/D) were calculated, and the values were compared between the two sets of reactors. Evenness values were higher for reactors operated at an SRT of 2 days. Statistically significant differences in diversity (H and D) between the two sets of reactors were tested using a randomization procedure, and the results showed that reactors from both experimental runs that were operated at an SRT of 2 days had higher diversity (H and D) at the 5% level. T-RFLP analysis with diversity indices proved to be a powerful tool to analyze changes in the bacterial community diversity in response to changes in the operational parameters of activated-sludge systems. PMID:16204492

  18. Textile wastewater treatment: aerobic granular sludge vs activated sludge systems.

    PubMed

    Lotito, Adriana Maria; De Sanctis, Marco; Di Iaconi, Claudio; Bergna, Giovanni

    2014-05-01

    Textile effluents are characterised by high content of recalcitrant compounds and are often discharged (together with municipal wastewater to increase their treatability) into centralized wastewater treatment plants with a complex treatment scheme. This paper reports the results achieved adopting a granular sludge system (sequencing batch biofilter granular reactor - SBBGR) to treat mixed municipal-textile wastewater. Thanks to high average removals in SBBGR (82.1% chemical oxygen demand, 94.7% total suspended solids, 87.5% total Kjeldahl nitrogen, 77.1% surfactants), the Italian limits for discharge into a water receiver can be complied with the biological stage alone. The comparison with the performance of the centralized plant treating the same wastewater has showed that SBBGR system is able to produce an effluent of comparable quality with a simpler treatment scheme, a much lower hydraulic residence time (11 h against 30 h) and a lower sludge production.

  19. INTEC SBW Solid Sludge Surrogate Recipe and Validation

    SciTech Connect

    Maio, Vince; Janikowski, Stuart; Johnson, Jim; Maio, Vince; Pao, Jenn-Hai

    2004-06-01

    A nonhazardous INTEC tank farm sludge surrogate that incorporated metathesis reactions to generate solids from solutions of known elements present in the radioactive INTEC tank farm sodium-bearing waste sludges was formulated. Elemental analyses, physical property analyses, and filtration testing were performed on waste surrogate and tank farm waste samples, and the results were compared. For testing physical systems associated with moving the tank farm solids, the surrogate described in this report is the best currently available choice. No other available surrogate exhibits the noted similarities in behavior to the sludges. The chemical morphology, particle size distribution, and settling and flow characteristics of the surrogate were similar to those exhibited by the waste sludges. Nonetheless, there is a difference in chemical makeup of the surrogate and the tank farm waste. If a chemical treatment process were to be evaluated for final treatment and disposition of the waste sludges, the surrogate synthesis process would likely require modification to yield a surrogate with a closer matching chemical composition.

  20. Alkaline treatment of high-solids sludge and its application to anaerobic digestion.

    PubMed

    Li, Chenchen; Li, Huan; Zhang, Yuyao

    2015-01-01

    High-solids anaerobic digestion is a promising new process for sludge reduction and bioenergy recovery, requiring smaller digestion tanks and less energy for heating, but a longer digestion time, than traditional low-solids anaerobic digestion. To accelerate this process, alkaline sludge disintegration was tested as a pretreatment method for anaerobic digestion of high-solids sludge. The results showed that alkaline treatment effectively disintegrated both low-solids sludge and high-solids sludge, and treatment duration of 30 min was the most efficient. The relation between sludge disintegration degree and NaOH dose can be described by a transmutative power function model. At NaOH dose lower than 0.2 mol/L, sludge disintegration degree remained virtually unchanged when sludge total solids (TS) content increased from 2.0 to 11.0%, and decreased only slightly when sludge TS increased to 14.2%. Although high-solids sludge required a slightly higher molarity of NaOH to reach the same disintegration level of low-solids sludge, the required mass of NaOH actually decreased due to sludge thickening. From the view of NaOH consumption, sludge TS of 8-12% and a NaOH dose of 0.05 mol/L were optimum conditions for alkaline pretreatment, which resulted in a slight increase in accumulative biogas yield, but a decrease by 24-29% in digestion time during the subsequent anaerobic digestion.

  1. Virucidal activity of an activated sludge supernatant.

    PubMed

    Rehn, Y; Schwartzbrod, L

    1993-09-01

    The virucidal activity of the activated sludge aqueous phase was studied from the time of initial inoculation with a poliovirus type 1 suspension and for durations of three and nine days. The mixtures were incubated in presence of a nutritive medium at 26 degrees C and samples were drawn at regular intervals of time for viral titration. The activated sludge supernatant (ASS) caused an important decrease of the titer of the poliovirus type 1 suspension especially after nine days of incubation. There was an average reduction of the viral titer of 79% after three days and 97% after nine days. When incubating the ASS with a nutritive medium before inoculating it, the viral decrease was much greater than when incubating without nutritive medium. When sterilizing the ASS before incubation and then inoculating it, no significant virucidal activity was observed (0% to 6%). Furthermore, when the ASS was subjected to a sterilization by filtration after incubation and was then inoculated, there existed a lower but not negligible viral inactivation (53% to 64%). The virucidal activity potentiality of the ASS is therefore due to microorganisms acting both directly as a support for viral particles adsorption and indirectly via the synthesis of substances with virucidal activity. When freezing and thawing the incubated ASS, and then sterilizing it by filtration before inoculation, the viral decrease reached 87% to 94%. This proves that the virucidal substances are only partly excreted by the microorganisms.

  2. 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…

  3. Activated Sludge and other Aerobic Suspended Culture Processes.

    PubMed

    Li, Chunying; Wei, Li; Chang, Chein-Chi; Zhang, Yuhua; Wei, Dong

    2016-10-01

    This is a literature review for the year 2015 and contains information specifically associated with suspended growth processes including activated sludge, upflow anaerobic sludge blanket, and sequencing batch reactors. The review encompasses modeling and kinetics, nutrient removal, system design and operation. Compared to past reviews, many topics show increase in activity in 2015. These include, fate and effect of xenobiotics, industrial wastes treatment with sludge, and pretreatment for the activated sludge. These topics are referred to the degradation of constituents in activated sludge. Other sections include population dynamics, process microbiology give an insight into the activated sludge. The subsection in industrial wastes: converting sewage sludge into biogases was also mentioned.

  4. Activated Sludge and other Aerobic Suspended Culture Processes.

    PubMed

    Li, Chunying; Wei, Li; Chang, Chein-Chi; Zhang, Yuhua; Wei, Dong

    2016-10-01

    This is a literature review for the year 2015 and contains information specifically associated with suspended growth processes including activated sludge, upflow anaerobic sludge blanket, and sequencing batch reactors. The review encompasses modeling and kinetics, nutrient removal, system design and operation. Compared to past reviews, many topics show increase in activity in 2015. These include, fate and effect of xenobiotics, industrial wastes treatment with sludge, and pretreatment for the activated sludge. These topics are referred to the degradation of constituents in activated sludge. Other sections include population dynamics, process microbiology give an insight into the activated sludge. The subsection in industrial wastes: converting sewage sludge into biogases was also mentioned. PMID:27620082

  5. 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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26350761

  7. Thermal hydrolysis of waste activated sludge at Hengelo Wastewater Treatment Plant, the Netherlands.

    PubMed

    Oosterhuis, Mathijs; Ringoot, Davy; Hendriks, Alexander; Roeleveld, Paul

    2014-01-01

    The thermal hydrolysis process (THP) is a sludge treatment technique which affects anaerobic biodegradability, viscosity and dewaterability of waste activated sludge (WAS). In 2011 a THP-pilot plant was operated, connected to laboratory-scale digesters, at the water board Regge en Dinkel and in cooperation with Cambi A.S. and MWH Global. Thermal hydrolysis of WAS resulted in a 62% greater volatile solids (VS) reduction compared to non-hydrolysed sludge. Furthermore, the pilot digesters could be operated at a 2.3 times higher solids loading rate compared to conventional sludge digesters. By application of thermal sludge hydrolysis, the overall efficiency of the sludge treatment process can be improved. PMID:25026572

  8. Reduction of selenite to elemental selenium nanoparticles by activated sludge.

    PubMed

    Jain, Rohan; Matassa, Silvio; Singh, Satyendra; van Hullebusch, Eric D; Esposito, Giovanni; Lens, Piet N L

    2016-01-01

    Total selenium removal by the activated sludge process, where selenite is reduced to colloidal elemental selenium nanoparticles (BioSeNPs) that remain entrapped in the activated sludge flocs, was studied. Total selenium removal efficiencies with glucose as electron donor (2.0 g chemical oxygen demand (COD) L(-1)) at neutral pH and 30 °C gave 2.9 and 6.8 times higher removal efficiencies as compared to the electron donors lactate and acetate, respectively. Total selenium removal efficiencies of 79 (±3) and 86 (±1) % were achieved in shake flasks and fed batch reactors, respectively, at dissolved oxygen (DO) concentrations above 4.0 mg L(-1) and 30 °C when fed with 172 mg L(-1) (1 mM) Na2SeO3 and 2.0 g L(-1) COD of glucose. Continuously operated reactors operating at neutral pH, 30 °C and a DO >3 mg L(-1) removed 33.98 and 36.65 mg of total selenium per gram of total suspended solids (TSS) at TSS concentrations of 1.3 and 3.0 g L(-1), respectively. However, selenite toxicity to the activated sludge led to failure of a continuously operating activated sludge reactor at the applied loading rates. This suggests that a higher hydraulic retention time (HRT) or different reactor configurations need to be applied for selenium-removing activated sludge processes. Graphical Abstract Scheme representing the possible mechanisms of selenite reduction at high and low DO levels in the activated sludge process. PMID:26351196

  9. Reduction of selenite to elemental selenium nanoparticles by activated sludge.

    PubMed

    Jain, Rohan; Matassa, Silvio; Singh, Satyendra; van Hullebusch, Eric D; Esposito, Giovanni; Lens, Piet N L

    2016-01-01

    Total selenium removal by the activated sludge process, where selenite is reduced to colloidal elemental selenium nanoparticles (BioSeNPs) that remain entrapped in the activated sludge flocs, was studied. Total selenium removal efficiencies with glucose as electron donor (2.0 g chemical oxygen demand (COD) L(-1)) at neutral pH and 30 °C gave 2.9 and 6.8 times higher removal efficiencies as compared to the electron donors lactate and acetate, respectively. Total selenium removal efficiencies of 79 (±3) and 86 (±1) % were achieved in shake flasks and fed batch reactors, respectively, at dissolved oxygen (DO) concentrations above 4.0 mg L(-1) and 30 °C when fed with 172 mg L(-1) (1 mM) Na2SeO3 and 2.0 g L(-1) COD of glucose. Continuously operated reactors operating at neutral pH, 30 °C and a DO >3 mg L(-1) removed 33.98 and 36.65 mg of total selenium per gram of total suspended solids (TSS) at TSS concentrations of 1.3 and 3.0 g L(-1), respectively. However, selenite toxicity to the activated sludge led to failure of a continuously operating activated sludge reactor at the applied loading rates. This suggests that a higher hydraulic retention time (HRT) or different reactor configurations need to be applied for selenium-removing activated sludge processes. Graphical Abstract Scheme representing the possible mechanisms of selenite reduction at high and low DO levels in the activated sludge process.

  10. Is sonication effective to improve biogas production and solids reduction in excess sludge digestion?

    PubMed

    Braguglia, C M; Mininni, G; Gianico, A

    2008-01-01

    Results of three semi-continuous anaerobic tests were reported and discussed. Each test was carried out by two parallel anaerobic reactors fed with waste activated sludge, either as it was sampled from the sewage treatment plant of Rome North or previously disintegrated by ultra-sound treatment. Activated sludge was sonicated at the energy input of 5,000 or 2,500 kJ kg(-1) dry solids corresponding to a disintegration degree of approximately 8 or 4%, respectively. Sonication proved to be effective both in increasing VS destruction and cumulative biogas production. The best increase of VS destruction (from 30 to 35%) was achieved in test #3 carried out at high organic load (10 d residence time) and low energy input (2,500 kJ kg(-1) dry solids). The best increase in cumulative biogas production (from 472 to 640 NL after 67 d of tests i.e.) was obtained in test #1 at low organic load (20 d residence time) and high energy input (5,000 kJ kg(-1) dry solids). Specific biogas production varied in the tests carried out with untreated sludge (0.55 - 0.67 Nm3 kg(-1) VS destroyed) but was practically unchanged for all the tests with sonicated sludge (0.7 Nm3 kg(-1) VS destroyed). PMID:18359984

  11. Upflow Sludge Blanket Filtration (USBF): an Innovative Technology in Activated Sludge Process

    PubMed Central

    Mesdaghinia, AR; Mahvi, AH; Saeedi, R; Pishrafti, H

    2010-01-01

    Background: A new biological domestic wastewater treatment process, which has been presented these days in activated sludge modification, is Upflow Sludge Blanket Filtration (USBF). This process is aerobic and acts by using a sludge blanket in the separator of sedimentation tank. All biological flocs and suspended solids, which are presented in the aeration basin, pas through this blanket. The performance of a single stage USBF process for treatment of domestic wastewater was studied in laboratory scale. Methods: The pilot of USBF has been made from fiberglass and the main electromechanical equipments consisted of an air compressor, a mixing device and two pumps for sludge return and wastewater injection. The wastewater samples used for the experiments were prepared synthetically to have qualitative characteristics similar to a typical domestic wastewater (COD= 277 mg/l, BOD5= 250 mg/l and TSS= 1 mg/l). Results: On the average, the treatment system was capable to remove 82.2% of the BOD5 and 85.7% of COD in 6 h hydraulic retention time (HRT). At 2 h HRT BOD and COD removal efficiencies dramatically reduced to 50% and 46.5%, respectively. Conclusion: Even by increasing the concentrations of pollutants to as high as 50%, the removal rates of all pollutants were remained similar to the HRT of 6 h. PMID:23113000

  12. Extracellular polymers of ozonized waste activated sludge.

    PubMed

    Liu, J C; Lee, C H; Lai, J Y; Wang, K C; Hsu, Y C; Chang, B V

    2001-01-01

    Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% < 1,000 Da (low MW), 30% from 1,000 to 10,000 Da (medium MW), and 31% > 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.

  13. Microwave pyrolysis of oily sludge with activated carbon.

    PubMed

    Chen, Yi-Rong

    2016-12-01

    The aim of this study is to explore catalytic microwave pyrolysis of crude oil storage tank sludge for fuels using granular activated carbon (GAC) as a catalyst. The effect of GAC loading on the yield of pyrolysis products was also investigated. Heating rate of oily sludge and yield of microwave pyrolysis products such as oil and fuel gas was found to depend on the ratio of GAC to oily sludge. The optimal GAC loading was found to be 10%, while much smaller and larger feed sizes adversely influenced production. During oily sludge pyrolysis, a maximum oil yield of 77.5% was achieved. Pyrolytic oils with high concentrations of diesel oil and gasoline (about 70 wt% in the pyrolytic oil) were obtained. The leaching of heavy metals, such as Cr, As and Pb, was also suppressed in the solid residue after pyrolysis. This technique provides advantages such as harmless treatment of oily sludge and substantial reduction in the consumption of energy, time and cost.

  14. Fate of linear alkylbenzene sulfonate (LAS) in activated sludge plants.

    PubMed

    Temmink, H; Klapwijk, Bram

    2004-02-01

    Monitoring data were collected in a pilot-scale municipal activated sludge plant to assess the fate of the C12-homologue of linear alkyl benzene sulfonate (LAS-C12). The pilot-plant was operated at influent LAS-C12 concentrations between 2 and 12 mg l(-1) and at sludge retention times of 10 and 27 days. Effluent and waste sludge concentrations varied between 5 and 10 microg l(-1) and between 37 and 69 microg g(-1) VSS, respectively. In the sludge samples only 2-8% was present as dissolved LAS-C12, whereas the remaining 92-98% was found to be adsorbed to the sludge. In spite of this high degree of sorption, more than 99% of the LAS-C12 load was removed by biodegradation, showing that not only the soluble fraction but also the adsorbed fraction of LAS-C12 is readily available for biodegradation. Sorption and biodegradation of LAS-C12 were also investigated separately. Sorption was an extremely fast and reversible process and could be described by a linear isotherm with a partition coefficient of 3.2 l g(-1) volatile suspended solids. From the results of biodegradation kinetic tests it was concluded that primary biodegradation of LAS-C12 cannot be described by a (growth) Monod model, but a secondary utilisation model should be used instead. The apparent affinity of the sludge to biodegrade LAS-C12 increased when the sludge was loaded with higher influent concentrations of LAS-C12.

  15. Fate and effects of methylene chloride in activated sludge.

    PubMed Central

    Klecka, G M

    1982-01-01

    Activated sludge obtained from a municipal wastewater treatment plant was acclimated to methylene chloride at concentrations between 1 and 100 mg/liter by continuous exposure to the compound for 9 to 11 days. Acclimated cultures were shown to mineralize methylene chloride to carbon dioxide and chloride. Rates of methylene chloride degradation were 0.14, 2.3, and 7.4 mg of CH2Cl2 consumed per h per g of mixed-liquor suspended solids for cultures incubated in the presence of 1, 10, and 100 mg/liter, respectively. Concentrations of methylene chloride between 10 and 1,000 mg/liter had no significant effect on O2 consumption or glucose metabolism by activated sludge. A hypothetical model was developed to examine the significance of volatilization and biodegradation for the removal of methylene chloride from an activated sludge reactor. Application of the model indicated that the rate of biodegradation was approximately 12 times greater than the rate of volatilization. Thus, biodegradation may be the predominant process determining the fate of methylene chloride in activated sludge systems continuously exposed to the compound. PMID:7138008

  16. Electrochemical pretreatment of waste activated sludge: effect of process conditions on sludge disintegration degree and methane production.

    PubMed

    Ye, Caihong; Yuan, Haiping; Dai, Xiaohu; Lou, Ziyang; Zhu, Nanwen

    2016-11-01

    Waste activated sludge (WAS) requires a long digestion time because of a rate-limiting hydrolysis step - the first phase of anaerobic digestion (AD). Pretreatment can be used prior to AD to facilitate the hydrolysis step and improve the efficiency of WAS digestion. This study evaluated a novel application of electrochemical (EC) technology employed as the pretreatment method prior to AD of WAS, focusing on the effect of process conditions on sludge disintegration and subsequent AD process. A superior process condition of EC pretreatment was obtained by reaction time of 30 min, electrolysis voltage of 20 V, and electrode distance of 5 cm, under which the disintegration degree of WAS ranged between 9.02% and 9.72%. In the subsequent batch AD tests, 206 mL/g volatile solid (VS) methane production in EC pretreated sludge was obtained, which was 20.47% higher than that of unpretreated sludge. The AD time was 19 days shorter for EC pretreated sludge compared to the unpretreated sludge. Additionally, the EC + AD reactor achieved 41.84% of VS removal at the end of AD. The analysis of energy consumption showed that EC pretreatment could be effective in enhancing sludge AD with reduced energy consumption when compared to other pretreatment methods.

  17. Activated sludge optimization using ATP in pulp and paper industry.

    PubMed

    Bäckman, Göran; Gytel, Ulla

    2015-01-01

    The activated sludge process is an old technology, but still the most commonly used one for treatment of wastewater. Despite the wide spread usage the technology still suffers from instability (Tandoi et al. 2006) and high operating cost. Activated sludge processes often carry a large solids inventory. Managing the total inventory without interference is the key component of the optimization process described in this paper. Use of nutrients is common in pulp and paper effluent treatment. Feeding enough nutrients to support the biomass growth is a delicate balance. Overfeeding or underfeeding of nutrients can result in higher costs. Detrimental substances and toxic components in effluents entering a biological treatment system can cause severe, long lasting disturbances (Hynninen & Ingman 1998; Bergeron & Pelletier 2004). A LumiKem test kit is used to measure biological activity with adenosine triphosphate (ATP) in a pulp and paper mill. ATP data are integrated with other standardized mill parameters. Measurements of active volatile suspended solids based on ATP can be used to quantify the living biomass in the activated sludge process and to ensure that sufficient biomass is present in order to degrade the wastewater constituents entering the process. Information about active biomass will assist in optimizing sludge inventories and feeding of nutrients allowing the living biomass to re-populate to create optimal efficiency. ATP measurements can also be used to alert operators if any components toxic to bacteria are present in wastewater. The bio stress index represents the stress level experienced by the microbiological population. This parameter is very useful in monitoring toxicity in and around bioreactors. Results from the wastewater process optimization and ATP measurements showed that treatment cost could be reduced by approximately 20-30% with fewer disturbances and sustained biological activity compared to the reference period. This was mainly achieved by

  18. Design of nutrient removal activated sludge systems.

    PubMed

    Manga, J; Ferrer, J; Seco, A; Garcia-Usach, F

    2003-01-01

    A mechanistic mathematical model for nutrient and organic matter removal was used to describe the behavior of a nitrification denitrification enhanced biological phosphorus removal (NDEBPR) system. This model was implemented in a user-friendly software DESASS (design and simulation of activated sludge systems). A 484-L pilot plant was operated to verify the model results. The pilot plant was operated for three years over three different sludge ages. The validity of the model was confirmed with data from the pilot plant. Also, the utility of DESASS as a valuable tool for designing NDEBPR systems was confirmed.

  19. Design of nutrient removal activated sludge systems.

    PubMed

    Manga, J; Ferrer, J; Seco, A; Garcia-Usach, F

    2003-01-01

    A mechanistic mathematical model for nutrient and organic matter removal was used to describe the behavior of a nitrification denitrification enhanced biological phosphorus removal (NDEBPR) system. This model was implemented in a user-friendly software DESASS (design and simulation of activated sludge systems). A 484-L pilot plant was operated to verify the model results. The pilot plant was operated for three years over three different sludge ages. The validity of the model was confirmed with data from the pilot plant. Also, the utility of DESASS as a valuable tool for designing NDEBPR systems was confirmed. PMID:12906279

  20. 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.

  1. Activity, life time and effect of hydrolytic enzymes for enhanced biogas production from sludge anaerobic digestion.

    PubMed

    Odnell, Anna; Recktenwald, Michael; Stensén, Katarina; Jonsson, Bengt-Harald; Karlsson, Martin

    2016-10-15

    As an alternative to energy intensive physical methods, enzymatic treatment of sludge produced at wastewater treatment plants for increased hydrolysis and biogas production was investigated. Several hydrolytic enzymes were assessed with a focus on how enzyme activity and life time was influenced by sludge environments. It could be concluded that the activity life time of added enzymes was limited (<24 h) in both waste activated sludge and anaerobic digester sludge environments and that this was, for the majority of enzymes, due to endogenous protease activity. In biogas in situ experiments, subtilisin at a 1% mixture on basis of volatile solids, was the only enzyme providing a significantly increased biomethane production of 37%. However, even at this high concentration, subtilisin could not hydrolyze all available substrate within the life time of the enzyme. Thus, for large scale implementation, enzymes better suited to the sludge environments are needed. PMID:27498254

  2. Activity, life time and effect of hydrolytic enzymes for enhanced biogas production from sludge anaerobic digestion.

    PubMed

    Odnell, Anna; Recktenwald, Michael; Stensén, Katarina; Jonsson, Bengt-Harald; Karlsson, Martin

    2016-10-15

    As an alternative to energy intensive physical methods, enzymatic treatment of sludge produced at wastewater treatment plants for increased hydrolysis and biogas production was investigated. Several hydrolytic enzymes were assessed with a focus on how enzyme activity and life time was influenced by sludge environments. It could be concluded that the activity life time of added enzymes was limited (<24 h) in both waste activated sludge and anaerobic digester sludge environments and that this was, for the majority of enzymes, due to endogenous protease activity. In biogas in situ experiments, subtilisin at a 1% mixture on basis of volatile solids, was the only enzyme providing a significantly increased biomethane production of 37%. However, even at this high concentration, subtilisin could not hydrolyze all available substrate within the life time of the enzyme. Thus, for large scale implementation, enzymes better suited to the sludge environments are needed.

  3. Assessing the impact of chemicals on activated sludge microorganisms

    SciTech Connect

    Yancey, D.

    1996-10-01

    Aerobic biological processes utilize microorganisms, primarily bacteria, but including protozoa, to degrade colloidal or fine particulate matter and dissolved organics, resulting in carbon dioxide, water, and new cell biomass. Such processes produce settleable solids that can be removed in sedimentation tanks. The most commonly used biological treatment process is the activated sludge process. The organisms in this process are key players of effective wastewater treatment. Upon close inspection of the wastewater, a variety of protozoa can be observed having different sizes, shapes, life cycles, and roles in the processes. A procedure has been developed to monitor the toxicity of wastewaters to specific classes of organisms. This procedure will help evaluate and prevent upsets of activated sludge treatment systems.

  4. Proteomics reliability for micropollutants degradation insight into activated sludge systems.

    PubMed

    Buttiglieri, Gianluigi; Collado, Neus; Casas, Nuria; Comas, Joaquim; Rodriguez-Roda, Ignasi

    2015-01-01

    Little information is available on pharmaceutical trace compounds degradation pathways in wastewater. The potential of the proteomics approach has been evaluated to extract information on activated sludge microbial metabolism in degrading a trace concentration of a pharmaceutical compound (ibuprofen). Ibuprofen is one of the most consumed pharmaceuticals, measured in wastewater at very high concentrations and, despite its high removal rates, found in different environmental compartments. Aerated and completely mixed activated sludge batch tests were spiked with ibuprofen at 10 and 1,000 μg L(-1). Ibuprofen concentrations were determined in the liquid phase: 100% removal was observed and the kinetics were estimated. The solid phase was sampled for proteomics purposes. The first objective was to apply proteomics to evaluate protein profile variations in a complex matrix such as activated sludge. The second objective was to determine, at different ibuprofen concentrations, which proteins followed pre-defined trends. No newly expressed proteins were found. Nonetheless, the obtained results suggest that proteomics itself is a promising methodology to be applied in this field. Statistical and comparative studies analyses provided, in fact, useful information on biological reproducibility and permitted us to detect 62 proteins following coherent and plausible expected trends in terms of presence and intensity change. PMID:26360747

  5. Proteomics reliability for micropollutants degradation insight into activated sludge systems.

    PubMed

    Buttiglieri, Gianluigi; Collado, Neus; Casas, Nuria; Comas, Joaquim; Rodriguez-Roda, Ignasi

    2015-01-01

    Little information is available on pharmaceutical trace compounds degradation pathways in wastewater. The potential of the proteomics approach has been evaluated to extract information on activated sludge microbial metabolism in degrading a trace concentration of a pharmaceutical compound (ibuprofen). Ibuprofen is one of the most consumed pharmaceuticals, measured in wastewater at very high concentrations and, despite its high removal rates, found in different environmental compartments. Aerated and completely mixed activated sludge batch tests were spiked with ibuprofen at 10 and 1,000 μg L(-1). Ibuprofen concentrations were determined in the liquid phase: 100% removal was observed and the kinetics were estimated. The solid phase was sampled for proteomics purposes. The first objective was to apply proteomics to evaluate protein profile variations in a complex matrix such as activated sludge. The second objective was to determine, at different ibuprofen concentrations, which proteins followed pre-defined trends. No newly expressed proteins were found. Nonetheless, the obtained results suggest that proteomics itself is a promising methodology to be applied in this field. Statistical and comparative studies analyses provided, in fact, useful information on biological reproducibility and permitted us to detect 62 proteins following coherent and plausible expected trends in terms of presence and intensity change.

  6. 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.

  7. Specific chemical interactions between metal ions and biological solids exemplified by sludge particulates.

    PubMed

    Huang, C P; Wang, Jianmin

    2014-05-01

    The adsorption of metals onto biological surfaces was studied exemplified by municipal sludge particulates of the primary, the secondary, and the tertiary sludge types from four regional wastewater treatment plants. Major factors affecting the extent of metal adsorption including pH, DOM, total biomass, and total metal loading were studied. The acidity-basicity characteristics of the DOM, the metal ions (Lewis acids), and the surface of the sludge particulates make pH the most important parameter in metal adsorption. Change in pH can modify the speciation of the metal ions, the DOM, and the surface acidity of the sludge particulates and subsequently determines the degree of metal distribution between the aqueous phase and the sludge solids. Information on the acidity-basicity characteristics of the DOM and the sludge particulates are used to calculate the stability constant of metal ion-sludge complexes.

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

    PubMed

    Barañao, P A; Hall, E R

    2004-01-01

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

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

    PubMed

    Barañao, P A; Hall, E R

    2004-01-01

    Activated Sludge Model No 3 (ASM3) was chosen to model an activated sludge system treating effluents from a mechanical pulp and paper mill. The high COD concentration and the high content of readily biodegradable substrates of the wastewater make this model appropriate for this system. ASM3 was calibrated based on batch respirometric tests using fresh wastewater and sludge from the treatment plant, and on analytical measurements of COD, TSS and VSS. The model, developed for municipal wastewater, was found suitable for fitting a variety of respirometric batch tests, performed at different temperatures and food to microorganism ratios (F/M). Therefore, a set of calibrated parameters, as well as the wastewater COD fractions, was estimated for this industrial wastewater. The majority of the calibrated parameters were in the range of those found in the literature. PMID:15461393

  10. Experimental Studies on Co-composting of Municipal Solid Waste with Paper Mill Sludge.

    PubMed

    Manjula, G; Meenambal, T

    2014-07-01

    In this study, a series of experimental studies were conducted with regard to bioconversion of organic fraction of municipal solid waste along with paper mill sludge at different C/N ratios. About 10 kg of shredded waste containing paper mill sludge, saw dust and municipal solid waste was placed in reactors in different proportions and 100 mL of effective microorganisms was added to it. The variation in physical and chemical parameters was monitored throughout the process. The results indicate that co-composting of paper mill sludge with municipal solid waste produces compost that is more stable and homogenous and can be effectively used as soil conditioner. PMID:26563088

  11. Improvement of activated sludge bacteria growth by low intensity ultrasound

    NASA Astrophysics Data System (ADS)

    Yan, Y. X.; Ding, J. Y.; Gao, J. L.

    2016-08-01

    Influence of low intensity ultrasound (US) on growth rate of bacteria separated from aerobic activated sludge was studied. In order to reveal the optimal ultrasonic conditions,specific oxygen uptake rate (SOUR) of activated sludge was first detected and results showed that the maximum SOUR was obtained (increased by 40%) at US intensity of 3 Wcm-2 and irradiation time of 10min. Under the optimal conditions, 2 species of bacteria isolated from activated sludge were sonicated and then cultivated for 36h, and increment of 6% and 10% of growth rate were detected for the 2 species of bacteria, respectively, indicating US irradiation of suitable parameters effectively improved activated sludge bacteria growth.

  12. Micro-profiles of activated sludge floc determined using microelectrodes.

    PubMed

    Li, Baikun; Bishop, Paul L

    2004-03-01

    The microbial activity within activated sludge floc is a key factor in the performance of the activated sludge process. In this study, the microenvironment of activated sludge flocs from two wastewater treatment plants (Mill Creek Wastewater Treatment Plant and Muddy Creek Wastewater Treatment Plant, with aeration tank influent CODs of 60-120 and 15-35 mg/L, respectively) were studied by using microelectrodes. Due to microbial oxygen utilization, the aerobic region in the activated sludge floc was limited to the surface layer (0.1-0.2mm) of the sludge aggregate at the Mill Creek plant. The presence of an anoxic zone inside the sludge floc under aerobic conditions was confirmed in this study. When the dissolved oxygen (DO) in the bulk liquid was higher than 4.0mg/L, the anoxic zone inside the activated sludge floc disappeared, which is helpful for biodegradation. At the Muddy Creek plant, with its lower wastewater pollutant concentrations, the redox potential and DO inside the sludge aggregates were higher than those at the Mill Creek plant. The contaminant concentration in the bulk wastewater correlates with the oxygen utilization rate, which directly influences the oxygen penetration inside the activated sludge floc, and results in redox potential changes within the floc. The measured microprofiles revealed the continuous decrease of nitrate concentration inside the activated sludge floc, even though significant nitrification was observed in the bulk wastewater. The oxygen consumption and nitrification rate analyses reveal that the increase of ammonia flux under aerobic conditions correlates with nitrification. Due to the metabolic mechanisms of the microorganisms in activated sludge floc, which varies from one treatment plant to another, the oxygen flux inside the sludge floc changes accordingly.

  13. Fenton peroxidation improves the drying performance of waste activated sludge.

    PubMed

    Dewil, Raf; Baeyens, Jan; Neyens, Elisabeth

    2005-01-31

    Advanced sludge treatment processes (AST) reduce the amount of sludge produced and improve the dewaterability, thus probably also affecting the heat transfer properties and the drying characteristics of the sludge. This paper studies the influence of the Fenton peroxidation on the thermal conductivity of the sludge. Results demonstrate that the Fenton's peroxidation positively influences the sludge cake consistency and hence enhances the mechanical dewaterability and the drying characteristics of the dewatered sludge. For the two sludges used in this study, i.e. obtained from the wastewater treatment plants (WWTP) of Tienen and Sint-Niklaas--the dry solids content of the mechanically dewatered sludge increased from 22.5% to 40.3% and from 18.7% to 35.2%, respectively. The effective thermal conductivity k(e) of the untreated and the peroxidized sludges is measured and used to determine the heat transfer coefficient h(s). An average improvement for k(e) of 16.7% (Tienen) and 5.8% (Sint-Niklaas) was observed. Consequently the value of h(s) increased with 15.6% (Tienen) and 5.0% (Sint-Niklaas). This increased heat transfer coefficient in combination with the increased dewaterability has direct implications on the design of sludge dryers. A plate-to-plate calculation of a multiple hearth dryer illustrates that the number of plates required to dry the peroxidized sludge to 90% DS is less than half the number of plates needed to dry untreated sludge. This results in reduced dryer dimensions or a higher capacity for an existing dryer of given dimensions.

  14. Addition of polyaluminiumchloride (PACl) to waste activated sludge to mitigate the negative effects of its sticky phase in dewatering-drying operations.

    PubMed

    Peeters, Bart; Dewil, Raf; Vernimmen, Luc; Van den Bogaert, Benno; Smets, Ilse Y

    2013-07-01

    This paper presents a new application of polyaluminiumchloride (PACl) as a conditioner for waste activated sludge prior its dewatering and drying. It is demonstrated at lab scale with a shear test-based protocol that a dose ranging from 50 to 150 g PACl/kg MLSS (mixed liquor suspended solids) mitigates the stickiness of partially dried sludge with a dry solids content between 25 and 60 %DS (dry solids). E.g., at a solids dryness of 46% DS the shear stress required to have the pre-consolidated sludge slip over a steel surface is reduced with 35%. The salient feature of PACl is further supported by torque data from a full scale decanter centrifuge used to dewater waste sludge. The maximal torque developed by the screw conveyor inside the decanter centrifuge is substantially reduced with 20% in the case the sludge feed is conditioned with PACl. The beneficial effect of waste sludge conditioning with PACl is proposed to be the result of the bound water associated with the aluminium polymers in PACl solutions which act as a type of lubrication for the intrinsically sticky sludge solids during the course of drying. It can be anticipated that PACl addition to waste sludge will become a technically feasible and very effective method to avoid worldwide fouling problems in direct sludge dryers, and to reduce torque issues in indirect sludge dryers as well as in sludge decanter centrifuges.

  15. Microbial diversity differences within aerobic granular sludge and activated sludge flocs.

    PubMed

    Winkler, M-K H; Kleerebezem, R; de Bruin, L M M; Verheijen, P J T; Abbas, B; Habermacher, J; van Loosdrecht, M C M

    2013-08-01

    In this study, we investigated during 400 days the microbial community variations as observed from 16S DNA gene DGGE banding patterns from an aerobic granular sludge pilot plant as well as the from a full-scale activated sludge treatment plant in Epe, the Netherlands. Both plants obtained the same wastewater and had the same relative hydraulic variations and run stable over time. For the total bacterial population, a similarity analysis was conducted showing that the community composition of both sludge types was very dissimilar. Despite this difference, general bacterial population of both systems had on average comparable species richness, entropy, and evenness, suggesting that different bacteria were sharing the same functionality. Moreover, multi-dimensional scaling analysis revealed that the microbial populations of the flocculent sludge system moved closely around the initial population, whereas the bacterial population in the aerobic granular sludge moved away from its initial population representing a permanent change. In addition, the ammonium-oxidizing community of both sludge systems was studied in detail showing more unevenness than the general bacterial community. Nitrosomonas was the dominant AOB in flocculent sludge, whereas in granular sludge, Nitrosomonas and Nitrosospira were present in equal amounts. A correlation analysis of process data and microbial data from DGGE gels showed that the microbial diversity shift in ammonium-oxidizing bacteria clearly correlated with fluctuations in temperature. PMID:23064482

  16. Incorporation of inorganic material in anoxic/aerobic-activated sludge system mixed liquor.

    PubMed

    Wentzel, M C; Ubisi, M F; Lakay, M T; Ekama, G A

    2002-12-01

    In the bioreactor of the nitrification denitrification (ND)-activated sludge system, the mixed liquor is made up of organic and inorganic materials. In the current design procedures and simulation models, the influent wastewater characteristics and biological processes that influence the bioreactor mixed liquor organic solids (as volatile suspended solids, VSS, or COD) are explicitly included. However, the mixed liquor total suspended solids (TSS, i.e. organic + inorganic solids) are calculated simply from empirical ratios of VSS/TSS. The TSS concentration is fundamental in the design of secondary settling tanks and waste activated sludge disposal. Clearly, the empirical approach to obtaining an estimate for TSS is not satisfactory within the framework of a fundamentally based model. Accordingly, the incorporation of the inorganic material present in the influent wastewater into ND-activated sludge system mixed liquor was investigated. From an experimental investigation into the distribution of inorganics in the influent, mixed liquor and effluent of a laboratory-scale ND-activated sludge system, it was concluded inter alia that (i) of the total inorganic solids in the influent, only a small fraction (2.8-7.5%) is incorporated into the mixed liquor, (ii) most of the inorganics in the influent (mean 88%) and effluent (mean 98.5%) are in the dissolved form, the balance being particulate, and (iii) the influent and effluent inorganic dissolved solids concentrations are closely equal (mean effluent to influent ratio 100%). Further, a number of models were developed to quantify the mixed liquor inorganic, and, hence, total solids. From an evaluation of these models against the experimental data, it would appear that the best approach to model the incorporation of inorganics into the activated sludge mixed liquor is to follow the concepts and principles used to develop the existing models for organic materials. With this approach, reasonably close correlation between

  17. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-05-01

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

  18. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge

    PubMed Central

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-01-01

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them. PMID:27166174

  19. Effects of Metal Nanoparticles on Methane Production from Waste-Activated Sludge and Microorganism Community Shift in Anaerobic Granular Sludge.

    PubMed

    Wang, Tao; Zhang, Dong; Dai, Lingling; Chen, Yinguang; Dai, Xiaohu

    2016-05-11

    Extensive use of nanoparticles (NPs) in consumer and industrial products has led to concerns about their potential environmental impacts; however, the influences of different NPs (e.g., nZVI (nano zero-valent iron), Ag NPs, Fe2O3 NPs and MgO NPs) on the anaerobic digestion of sludge have not yet been studied in depth. Additionally, a new guideline or the use of different NPs in the anaerobic digestion of sludge should be established to improve the anaerobic digestion of sludge and avoid inhibitory effects. This study investigated the effects of four representative NPs (i.e., nZVI, Ag NPs, Fe2O3 NPs and MgO NPs) on methane production during the anaerobic digestion of waste activated sludge (WAS). The presence of 10 mg/g total suspended solids (TSS) nZVI and 100 mg/g TSS Fe2O3 NPs increased methane production to 120% and 117% of the control, respectively, whereas 500 mg/g TSS Ag NPs and 500 mg/g TSS MgO NPs generated lower levels of methane production (73.52% and 1.08% that of the control, respectively). These results showed that low concentrations of nZVI and Fe2O3 NPs promoted the amount of microbes (Bacteria and Archaea) and activities of key enzymes but that higher concentrations of Ag NPs and MgO NPs inhibited them.

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

    SciTech Connect

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

    1982-08-01

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

  1. Sludge.

    ERIC Educational Resources Information Center

    Tenenbaum, David

    1992-01-01

    Cites a recycling success story involving sludge production from wastewater and transformation into an effective plant fertilizer. Discusses related concerns such as dealing with pollutants like heavy metals and PCBs often found in sludge. Provides an example of an application of sludge produced in Chicago to an area reclamation site. (MCO)

  2. Production of carboxylates from high rate activated sludge through fermentation.

    PubMed

    Cagnetta, C; Coma, M; Vlaeminck, S E; Rabaey, K

    2016-10-01

    The aim of this work was to study the key parameters affecting fermentation of high rate activated A-sludge to carboxylates, including pH, temperature, inoculum, sludge composition and iron content. The maximum volatile fatty acids production was 141mgCg(-1) VSSfed, at pH 7. Subsequently the potential for carboxylate and methane production for A-sludge from four different plants at pH 7 and 35°C were compared. Initial BOD of the sludge appeared to be key determining carboxylate yield from A-sludge. Whereas methanogenesis could be correlated linearly to the quantity of ferric used for coagulation, fermentation did not show a dependency on iron presence. This difference may enable a strategy whereby A-stage sludge is separated to achieve fermentation, and iron dosing for phosphate removal is only implemented at the B-stage. PMID:27020399

  3. Compression and swelling of activated sludge cakes during dewatering.

    PubMed

    Sveegaard, Steffen Gralert; Keiding, Kristian; Christensen, Morten Lykkegaard

    2012-10-15

    A drainage/filtration apparatus was developed for automatically determining sedimentation velocity and dewatering rate. Pressure-step testing was used to study filter cake compressibility, resistance, and swelling. Activated sludge was analysed, and the data indicate that the sludge is highly compressible even at low pressures (10 kPa). Furthermore, compressed sludge cakes swell if the pressure is released. Hence, the average specific cake resistance decreases if the pressure is released, though the resistance is higher after the compression cycle than before. Sludge must be dewatered under low pressure, because higher pressure only compresses the cake and does not improve the dewatering rate.

  4. Rheological characterization of digested sludge by solid sphere impact.

    PubMed

    Jiang, Jiankai; Wu, Jing; Poncin, Souhila; Li, Huai Z

    2016-10-01

    An impact method was applied to investigate the rheological characteristics of digested sludge and reveal its transient dynamics. A high-speed camera allowed visualizing the dynamic impact process and observing interaction between impacting sphere and targeted sludge. A damping oscillation was observed after the impact. The crater diameter followed an exponential function, while the crater depth varied as a logarithmic function of both sphere diameter and free fall height. Furthermore, the viscosity and elasticity of digested sludge were evaluated by establishing a simplified impact drag force model. The impact elastic modulus was consistent with the Young's modulus measured by a penetrometer. The impact viscosity was reasonable as the estimated impact shear stress was greater than the yield stress of digested sludge resulting in the formation of crater. The impact method offers an alternative way to reveal the viscoelasticity of digested sludge through a dynamic process.

  5. Rheological characterization of digested sludge by solid sphere impact.

    PubMed

    Jiang, Jiankai; Wu, Jing; Poncin, Souhila; Li, Huai Z

    2016-10-01

    An impact method was applied to investigate the rheological characteristics of digested sludge and reveal its transient dynamics. A high-speed camera allowed visualizing the dynamic impact process and observing interaction between impacting sphere and targeted sludge. A damping oscillation was observed after the impact. The crater diameter followed an exponential function, while the crater depth varied as a logarithmic function of both sphere diameter and free fall height. Furthermore, the viscosity and elasticity of digested sludge were evaluated by establishing a simplified impact drag force model. The impact elastic modulus was consistent with the Young's modulus measured by a penetrometer. The impact viscosity was reasonable as the estimated impact shear stress was greater than the yield stress of digested sludge resulting in the formation of crater. The impact method offers an alternative way to reveal the viscoelasticity of digested sludge through a dynamic process. PMID:27372010

  6. Disturbance and temporal partitioning of the activated sludge metacommunity.

    PubMed

    Vuono, David C; Benecke, Jan; Henkel, Jochen; Navidi, William C; Cath, Tzahi Y; Munakata-Marr, Junko; Spear, John R; Drewes, Jörg E

    2015-02-01

    The resilience of microbial communities to press disturbances and whether ecosystem function is governed by microbial composition or by the environment have not been empirically tested. To address these issues, a whole-ecosystem manipulation was performed in a full-scale activated sludge wastewater treatment plant. The parameter solids retention time (SRT) was used to manipulate microbial composition, which started at 30 days, then decreased to 12 and 3 days, before operation was restored to starting conditions (30-day SRT). Activated sludge samples were collected throughout the 313-day time series in parallel with bioreactor performance ('ecosystem function'). Bacterial small subunit (SSU) rRNA genes were surveyed from sludge samples resulting in a sequence library of >417,000 SSU rRNA genes. A shift in community composition was observed for 12- and 3-day SRTs. The composition was altered such that r-strategists were enriched in the system during the 3-day SRT, whereas K-strategists were only present at SRTs⩾12 days. This shift corresponded to loss of ecosystem functions (nitrification, denitrification and biological phosphorus removal) for SRTs⩽12 days. Upon return to a 30-day SRT, complete recovery of the bioreactor performance was observed after 54 days despite an incomplete recovery of bacterial diversity. In addition, a different, yet phylogenetically related, community with fewer of its original rare members displaced the pre-disturbance community. Our results support the hypothesis that microbial ecosystems harbor functionally redundant phylotypes with regard to general ecosystem functions (carbon oxidation, nitrification, denitrification and phosphorus accumulation). However, the impacts of decreased rare phylotype membership on ecosystem stability and micropollutant removal remain unknown. PMID:25126758

  7. Disturbance and temporal partitioning of the activated sludge metacommunity

    PubMed Central

    Vuono, David C; Benecke, Jan; Henkel, Jochen; Navidi, William C; Cath, Tzahi Y; Munakata-Marr, Junko; Spear, John R; Drewes, Jörg E

    2015-01-01

    The resilience of microbial communities to press disturbances and whether ecosystem function is governed by microbial composition or by the environment have not been empirically tested. To address these issues, a whole-ecosystem manipulation was performed in a full-scale activated sludge wastewater treatment plant. The parameter solids retention time (SRT) was used to manipulate microbial composition, which started at 30 days, then decreased to 12 and 3 days, before operation was restored to starting conditions (30-day SRT). Activated sludge samples were collected throughout the 313-day time series in parallel with bioreactor performance (‘ecosystem function'). Bacterial small subunit (SSU) rRNA genes were surveyed from sludge samples resulting in a sequence library of >417 000 SSU rRNA genes. A shift in community composition was observed for 12- and 3-day SRTs. The composition was altered such that r-strategists were enriched in the system during the 3-day SRT, whereas K-strategists were only present at SRTs⩾12 days. This shift corresponded to loss of ecosystem functions (nitrification, denitrification and biological phosphorus removal) for SRTs⩽12 days. Upon return to a 30-day SRT, complete recovery of the bioreactor performance was observed after 54 days despite an incomplete recovery of bacterial diversity. In addition, a different, yet phylogenetically related, community with fewer of its original rare members displaced the pre-disturbance community. Our results support the hypothesis that microbial ecosystems harbor functionally redundant phylotypes with regard to general ecosystem functions (carbon oxidation, nitrification, denitrification and phosphorus accumulation). However, the impacts of decreased rare phylotype membership on ecosystem stability and micropollutant removal remain unknown. PMID:25126758

  8. High-solid Anaerobic Co-digestion of Sewage Sludge and Cattle Manure: The Effects of Volatile Solid Ratio and pH

    PubMed Central

    Dai, Xiaohu; Chen, Yang; Zhang, Dong; Yi, Jing

    2016-01-01

    High-solid anaerobic digestion is an attractive solution to the problem of sewage sludge disposal. One method that can be used to enhance the production of volatile fatty acids (VFAs) and the generation of methane from anaerobic digestion involves combining an alkaline pretreatment step with the synergistic effects of sewage sludge and cattle manure co-digestion, which improves the activity of key enzymes and microorganisms in the anaerobic co-digestion system to promote the digestion of organic waste. In this study, we describe an efficient strategy that involves adjusting the volatile solid (VS) ratio (sewage sludge/cattle manure: 3/7) and initial pH (9.0) to improve VFA production and methane generation from the co-digestion of sludge and manure. The experimental results indicate that the maximum VFA production was 98.33 g/kg-TS (total solid) at the optimal conditions. Furthermore, methane generation in a long-term semi-continuously operated reactor (at a VS ratio of 3/7 and pH of 9.0) was greater than 120.0 L/kg-TS. PMID:27725704

  9. High-solid Anaerobic Co-digestion of Sewage Sludge and Cattle Manure: The Effects of Volatile Solid Ratio and pH

    NASA Astrophysics Data System (ADS)

    Dai, Xiaohu; Chen, Yang; Zhang, Dong; Yi, Jing

    2016-10-01

    High-solid anaerobic digestion is an attractive solution to the problem of sewage sludge disposal. One method that can be used to enhance the production of volatile fatty acids (VFAs) and the generation of methane from anaerobic digestion involves combining an alkaline pretreatment step with the synergistic effects of sewage sludge and cattle manure co-digestion, which improves the activity of key enzymes and microorganisms in the anaerobic co-digestion system to promote the digestion of organic waste. In this study, we describe an efficient strategy that involves adjusting the volatile solid (VS) ratio (sewage sludge/cattle manure: 3/7) and initial pH (9.0) to improve VFA production and methane generation from the co-digestion of sludge and manure. The experimental results indicate that the maximum VFA production was 98.33 g/kg-TS (total solid) at the optimal conditions. Furthermore, methane generation in a long-term semi-continuously operated reactor (at a VS ratio of 3/7 and pH of 9.0) was greater than 120.0 L/kg-TS.

  10. Determination of fluoroquinolone antibacterial agents in sewage sludge and sludge-treated soil using accelerated solvent extraction followed by solid-phase extraction.

    PubMed

    Golet, Eva M; Strehler, Adrian; Alder, Alfredo C; Giger, Walter

    2002-11-01

    A method for the quantitative determination of humanuse fluoroquinolone antibacterial agents (FQs) ciprofloxacin and norfloxacin in sewage sludge and sludge-treated soil samples was developed. The accelerated solvent extraction was optimized with regard to solvents and operational parameters, such as temperature, pressure, and extraction time. A 50 mM aqueous phosphoric acid/ acetonitrile mixture (1:1) was found to be optimum in combination with an extraction temperature of 100 degrees C at 100 bar, during 60 and 90 min for sewage sludge and sludge-treated soil samples, respectively. A cleanup step using solid-phase extraction substantially improved the selectivity of the method. Overall recovery rates for FQs ranged from 82 to 94% for sewage sludge and from 75 to 92% for sludge-treated soil, with relative standard deviations between 8 and 11%. Limits of quantification were 0.45 and 0.18 mg/kg of dry matter for sewage sludge and sludge-treated soils, respectively. The presented method was successfully applied to untreated and anaerobically digested sewage sludges and sludge-treated soils. Ciprofloxacin and norfloxacin were determined in sewage sludges from several wastewater treatment plants with concentrations ranging from 1.40 to 2.42 mg/kg of dry matter. Therefore, contrary to what may be expected for human-use pharmaceuticals, FQs may reach the terrestrial environment as indicated by the occurrence of FQs in topsoil samples from experimental fields, to which sewage sludge had been applied. PMID:12433073

  11. Ultrasonic waste activated sludge disintegration for recovering multiple nutrients for biofuel production.

    PubMed

    Xie, Guo-Jun; Liu, Bing-Feng; Wang, Qilin; Ding, Jie; Ren, Nan-Qi

    2016-04-15

    Waste activated sludge is a valuable resource containing multiple nutrients, but is currently treated and disposed of as an important source of pollution. In this work, waste activated sludge after ultrasound pretreatment was reused as multiple nutrients for biofuel production. The nutrients trapped in sludge floc were transferred into liquid medium by ultrasonic disintegration during first 30 min, while further increase of pretreatment time only resulted in slight increase of nutrients release. Hydrogen production by Ethanoligenens harbinense B49 from glucose significantly increased with the concentration of ultrasonic sludge, and reached maximum yield of 1.97 mol H2/mol glucose at sludge concentration of 7.75 g volatile suspended solids/l. Without addition of any other chemicals, waste molasses rich in carbohydrate was efficiently turned into hydrogen with yield of 189.34 ml H2/g total sugar by E. harbinense B49 using ultrasonic sludge as nutrients. The results also showed that hydrogen production using pretreated sludge as multiple nutrients was higher than those using standard nutrients. Acetic acid produced by E. harbinense B49 together with the residual nutrients in the liquid medium were further converted into hydrogen (271.36 ml H2/g total sugar) by Rhodopseudomonas faecalis RLD-53 through photo fermentation, while ethanol was the sole end product with yield of 220.26 mg/g total sugar. Thus, pretreated sludge was an efficient nutrients source for biofuel production, which could replace the standard nutrients. This research provided a novel strategy to achieve environmental friendly sludge disposal and simultaneous efficient biofuel recovery from organic waste. PMID:26896823

  12. Can aquatic worms enhance methane production from waste activated sludge?

    PubMed

    Serrano, Antonio; Hendrickx, Tim L G; Elissen, Hellen H J; Laarhoven, Bob; Buisman, Cees J N; Temmink, Hardy

    2016-07-01

    Although literature suggests that aquatic worms can help to enhance the methane production from excess activated sludge, clear evidence for this is missing. Therefore, anaerobic digestion tests were performed at 20 and at 30°C with sludge from a high-loaded membrane bioreactor, the aquatic worm Lumbriculus variegatus, feces from these worms and with mixtures of these substrates. A significant synergistic effect of the worms or their feces on methane production from the high-loaded sludge or on its digestion rate was not observed. However, a positive effect on low-loaded activated sludge, which generally has a lower anaerobic biodegradability, cannot be excluded. The results furthermore showed that the high-loaded sludge provides an excellent feed for L. variegatus, which is promising for concepts where worm biomass is considered a resource for technical grade products such as coatings and glues.

  13. 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.

  14. 40 CFR 721.10636 - Slimes and sludges, automotive coating, wastewater treatment, solid waste.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., wastewater treatment, solid waste. 721.10636 Section 721.10636 Protection of Environment ENVIRONMENTAL..., wastewater treatment, solid waste. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as slimes and sludges, automotive coating, wastewater...

  15. 40 CFR 721.10636 - Slimes and sludges, automotive coating, wastewater treatment, solid waste.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., wastewater treatment, solid waste. 721.10636 Section 721.10636 Protection of Environment ENVIRONMENTAL..., wastewater treatment, solid waste. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as slimes and sludges, automotive coating, wastewater...

  16. Protists as bioindicators in activated sludge: Identification, ecology and future needs.

    PubMed

    Foissner, Wilhelm

    2016-08-01

    When the activated sludge process was developed, operators and scientists soon recognized protists as valuable indicators. However, only when Curds et al. (1968) showed with a few photographs the need of ciliates for a clear plant effluent, sewage protistology began to bloom but was limited by the need of species identification. Still, this is a major problem although several good guides are available. Thus, molecular kits should be developed for identification. Protists are indicators in two stages of wastewater treatment, viz., in the activated sludge and in the environmental water receiving the plant effluent. Continuous control of the protist and bacterial communities can prevent biological sludge foaming and bulking and may greatly save money for sludge oxygenation because several protist species are excellent indicators for the amount of oxygen present. The investigation of the effluent-receiving rivers gives a solid indication about the long term function of sewage works. The literature on protist bioindication in activated sludge is widely distributed. Thus, I compiled the data in a simple Table, showing which communities and species indicate good, mediocre, or poor plant performance. Further, many details on indication are provided, such as sludge loading and nitrifying conditions. Such specific features should be improved by appropriate statistics and more reliable identification of species. Then, protistologists have a fair chance to become important in wastewater works. Activated sludge is a unique habitat for particular species, often poorly or even undescribed. As an example, I present two new species. The first is a minute (∼30μm) Metacystis that makes an up to 300μm-sized mucous envelope mimicking a sludge floc. The second is a Phialina that is unique in having the contractile vacuole slightly posterior to mid-body. Finally, I provide a list of species which have the type locality in sewage plants.

  17. 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. PMID:25277968

  18. Performance of calcium peroxide for removal of endocrine-disrupting compounds in waste activated sludge and promotion of sludge solubilization.

    PubMed

    Zhang, Ai; Wang, Jie; Li, Yongmei

    2015-03-15

    Removal of six phenolic endocrine disrupting compounds (EDCs) (estrone, 17β-estradiol, 17α-ethinylestradiol, estriol, bisphenol A, and 4-nonylphenols) from waste activated sludge (WAS) was investigated using calcium peroxide (CaO2) oxidation. Effects of initial pH and CaO2 dosage were investigated. The impacts of CaO2 treatment on sludge solubilization and anaerobic digestion were also evaluated. Specifically, the role of reactive oxygen species (ROS) in EDC degradation during CaO2 oxidation was tested. Effects of 6 metal ions contained in the sludge matrix on EDC degradation were also evaluated. The results showed that CaO2 treatment can be a promising technology for EDC removal and facilitating sludge reuse. The EDC removal efficiencies increased with the increase in CaO2 dosage. At CaO2 doses of more than 0.34 g per gram of total solid (g g(-1) TS), more than 50% of EDCs were removed in a wide pH range of 2-12. Higher removal efficiencies were achieved at initial pH values of 12 and 2. The products of EDCs during CaO2 oxidation had less estrogenic activity than the originals. Under the conditions of neutral pH and CaO2 dosage = 0.34 g g(-1) TS, the sludge solubilization can be improved by increasing the soluble total organic carbon (STOC) and volatile suspended solids (VSS) reduction by 25% and 27% in 7 d, respectively; the volatile fatty acid (VFA) production was enhanced by 96% in the 15 d following anaerobic digestion. The ROS released by CaO2 are the main factors contributing to EDC removal, among which, hydroxyl radicals (OH) play the most important role. Metal ions contained in the sludge matrix also affected EDC removal. For most cases, Fe, Cu, and Zn had positive effects; Mn and Ag had negative effects; and Mg had an insignificant effect on EDC removal. PMID:25613412

  19. Polyphosphate Kinase from Activated Sludge Performing Enhanced Biological Phosphorus Removal†

    PubMed Central

    McMahon, Katherine D.; Dojka, Michael A.; Pace, Norman R.; Jenkins, David; Keasling, Jay D.

    2002-01-01

    A novel polyphosphate kinase (PPK) was retrieved from an uncultivated organism in activated sludge carrying out enhanced biological phosphorus removal (EBPR). Acetate-fed laboratory-scale sequencing batch reactors were used to maintain sludge with a high phosphorus content (approximately 11% of the biomass). PCR-based clone libraries of small subunit rRNA genes and fluorescent in situ hybridization (FISH) were used to verify that the sludge was enriched in Rhodocyclus-like β-Proteobacteria known to be associated with sludges carrying out EBPR. These organisms comprised approximately 80% of total bacteria in the sludge, as assessed by FISH. Degenerate PCR primers were designed to retrieve fragments of putative ppk genes from a pure culture of Rhodocyclus tenuis and from organisms in the sludge. Four novel ppk homologs were found in the sludge, and two of these (types I and II) shared a high degree of amino acid similarity with R. tenuis PPK (86 and 87% similarity, respectively). Dot blot analysis of total RNA extracted from sludge demonstrated that the Type I ppk mRNA was present, indicating that this gene is expressed during EBPR. Inverse PCR was used to obtain the full Type I sequence from sludge DNA, and a full-length PPK was cloned, overexpressed, and purified to near homogeneity. The purified PPK has a specific activity comparable to that of other PPKs, has a requirement for Mg2+, and does not appear to operate in reverse. PPK activity was found mainly in the particulate fraction of lysed sludge microorganisms. PMID:12324346

  20. Gravity drainage of activated sludge: new experimental method and considerations of settling velocity, specific cake resistance and cake compressibility.

    PubMed

    Dominiak, Dominik; Christensen, Morten; Keiding, Kristian; Nielsen, Per Halkjær

    2011-02-01

    A laboratory scale setup was used for characterization of gravitational drainage of waste activated sludge. The aim of the study was to assess how time of drainage and cake dry matter depended on volumetric load, SS content and sludge floc properties. It was demonstrated that activated sludge forms compressible cakes, even at the low pressures found in gravitational drainage. The values of specific cake resistance were two to three orders of magnitude lower than those obtained in pressure filtration. Despite the compressible nature of sludge, key macroscopic parameters such as time of drainage and cake solid content showed simple functional dependency of the volumetric load and SS of a given sludge. This suggests that the proposed method may be applied for design purposes without the use of extensive numerical modeling. The possibilities for application of this new technique are, among others, the estimation of sludge drainability prior to mechanical dewatering on a belt filter, or the application of surplus sludge on reed beds, as well as adjustments of sludge loading, concentration or sludge pre-treatment in order to optimize the drainage process.

  1. Accurate assessment of the biodegradation of cationic surfactants in activated sludge reactors (OECD TG 303A).

    PubMed

    Geerts, Roy; van Ginkel, Cornelis G; Plugge, Caroline M

    2015-08-01

    The continuous-fed activated sludge test (OECD TG 303A) was used to predict the removal of cationic surfactants from wastewater in activated sludge plants. However, a method to differentiate between adsorption and biodegradation is not provided in these guidelines. Assessment of removal by biodegradation was possible with analysis of the surfactant present in mixed liquid suspended solids in combination with a simple equation. This equation was derived from the mass balance of the activated sludge unit in steady state. The removal by biodegradation of decylamine, tetradecylamine, octadecylamine, dioctadecylmethylamine and dioctadecyldimethylammonium chloride that have different capacities to adsorb was >99.9%, >99.9%, 98.2%, 94.2%, and 69.0%, respectively. The total removal of all five cationic surfactants from the influent was ≥98.8%. The removal of octadecylamine spiked at different influent concentrations indicated first order kinetics. PMID:25913361

  2. Two stage activated sludge plants--influence of different operational modes on sludge bulking and nitrification.

    PubMed

    Wandl, G; Müller-Rechberger, H; Matsché, N; Svardal, K; Winkler, S

    2002-01-01

    Conventional two stage activated sludge plants often lack sufficient nutrient removal performance due to substrate limitation for denitrification in the second stage. For the extension of the Vienna Main WWTP a two stage concept has been developed and tested by means of a pilot plant (scale 1:10.000). The new concept enables the operation of two different modes: In BYPASS-mode a portion of the primary clarifier effluent is fed directly to the second stage; the HYBRID-mode includes the exchange of mixed liquor between the two stages; over the course of the pilot plant investigations it turned out that nutrient removal is strongly increased in comparison to conventional two stage mode, but the two modes of operation lead to different results with regard to the sludge quality and the nitrification performance. BYPASS mode yields a higher SVI in both stages and a lower nitrification performance in comparison to HYBRID mode. This is caused by the negative influence of the primary effluent on the biocoenosis of the second stage. Additionally, the reduced sludge loading of the first stage in this mode results in a higher sludge age which favours the growth of filaments (Microthrix and Nocardia). In HYBRID-mode the higher load of the first stage results in a lower sludge age, fatty components are metabolized and incorporated in the sludge, thus, the growth of filaments is significantly reduced. Additionally, nitrification inhibiting substances are degraded in the first stage, which results in a higher nitrification performance in the second stage.

  3. 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.

  4. Retrofitting activated sludge systems to intermittent aeration for nitrogen removal.

    PubMed

    Hanhan, O; Artan, N; Orhon, D

    2002-01-01

    The paper provides the basis and the conceptual approach of applying process kinetics and modelling to the design of alternating activated sludge systems for retrofitting existing activated sludge plants to intermittent aeration for nitrogen removal. It shows the significant role of the two specific parameters, namely, the aerated fraction and the cycle time ratio on process performance through model simulations and proposes a way to incorporate them into a design procedure using process stoichiometry and mass balance. It illustrates the effect of these parameters, together with the sludge age, in establishing the balance between the denitrification potential and the available nitrogen created in the anoxic/aerobic sequences of system operation.

  5. Retrofitting activated sludge systems to intermittent aeration for nitrogen removal.

    PubMed

    Hanhan, O; Artan, N; Orhon, D

    2002-01-01

    The paper provides the basis and the conceptual approach of applying process kinetics and modelling to the design of alternating activated sludge systems for retrofitting existing activated sludge plants to intermittent aeration for nitrogen removal. It shows the significant role of the two specific parameters, namely, the aerated fraction and the cycle time ratio on process performance through model simulations and proposes a way to incorporate them into a design procedure using process stoichiometry and mass balance. It illustrates the effect of these parameters, together with the sludge age, in establishing the balance between the denitrification potential and the available nitrogen created in the anoxic/aerobic sequences of system operation. PMID:12420968

  6. 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. PMID:26901714

  7. MiDAS: the field guide to the microbes of activated sludge.

    PubMed

    McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2015-01-01

    The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes--knowledge that will be an invaluable resource for the optimal design and operation of these systems. PMID:26120139

  8. Aerobic composting of waste activated sludge: Kinetic analysis for microbiological reaction and oxygen consumption

    SciTech Connect

    Yamada, Y.; Kawase, Y. . E-mail: bckawase@mail.eng.toyo.ac.jp

    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 composting 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%.

  9. MiDAS: the field guide to the microbes of activated sludge

    PubMed Central

    McIlroy, Simon Jon; Saunders, Aaron Marc; Albertsen, Mads; Nierychlo, Marta; McIlroy, Bianca; Hansen, Aviaja Anna; Karst, Søren Michael; Nielsen, Jeppe Lund; Nielsen, Per Halkjær

    2015-01-01

    The Microbial Database for Activated Sludge (MiDAS) field guide is a freely available online resource linking the identity of abundant and process critical microorganisms in activated sludge wastewater treatment systems to available data related to their functional importance. Phenotypic properties of some of these genera are described, but most are known only from sequence data. The MiDAS taxonomy is a manual curation of the SILVA taxonomy that proposes a name for all genus-level taxa observed to be abundant by large-scale 16 S rRNA gene amplicon sequencing of full-scale activated sludge communities. The taxonomy can be used to classify unknown sequences, and the online MiDAS field guide links the identity to the available information about their morphology, diversity, physiology and distribution. The use of a common taxonomy across the field will provide a solid foundation for the study of microbial ecology of the activated sludge process and related treatment processes. The online MiDAS field guide is a collaborative workspace intended to facilitate a better understanding of the ecology of activated sludge and related treatment processes—knowledge that will be an invaluable resource for the optimal design and operation of these systems. Database URL: http://www.midasfieldguide.org PMID:26120139

  10. Dynamics and control of substrate inhibition in activated sludge

    SciTech Connect

    Allsop, P.J.; Moo-Young, M.; Sullivan, G.R. )

    1990-01-01

    The activated sludge wastewater treatment process predominantly used in the chemical and steel industries was reviewed to determine the dynamics and control of activated sludge systems treating inhibitory wastes. While this process has the capability to degrade a variety of toxic or inhibitory wastes, the underlying mechanisms are not clear. A variety of issues exist requiring further study: (1) the role of various microorganisms in waste removal and system stability, (2) the mechanisms of inhibitory action at both the level of the primary consumer and at the level of the whole process, (3) the suitability of phenol as a model inhibitory substrate, (4) the appropriateness of using pure culture, CSTR results obtained at relatively high specific growth rates to predict the response of activated sludge systems, (5) the rationalization of microbiological predictions for oligotrophic systems with observations in activated sludge systems, and (6) the development of appropriate monitoring tools for detecting process instabilities. 265 refs., 8 figs., 2 tabs.

  11. Evaluation of Control Parameters for the Activated Sludge Process

    ERIC Educational Resources Information Center

    Stall, T. Ray; Sherrard, Josephy H.

    1978-01-01

    An evaluation of the use of the parameters currently being used to design and operate the activated sludge process is presented. The advantages and disadvantages for the use of each parameter are discussed. (MR)

  12. ENHANCED BIODEGRADATION OF IOPROMIDE AND TRIMETHOPRIM IN NITRIFYING ACTIVATED SLUDGE

    EPA Science Inventory

    Iopromide and trimethoprim are frequently detected pharmaceuticals in effluents of wastewater treatment plants and in surface waters due to their persistence and high usage. Laboratory scale experiments showed that a significantly higher removal rate in nutrifying activated sludg...

  13. 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.

  14. Process performance of high-solids batch anaerobic digestion of sewage sludge.

    PubMed

    Liao, Xiaocong; Li, Huan; Cheng, Yingchao; Chen, Nan; Li, Chenchen; Yang, Yuning

    2014-01-01

    The characteristics of high-solids anaerobic digestion (AD) of sewage sludge were investigated by comparison with conventional low-solids processes. A series of batch experiments were conducted under mesophilic condition and the initial solid contents were controlled at four levels of 1.79%, 4.47%, 10.28% and 15.67%. During these experiments, biogas production, organic degradation and intermediate products were monitored. The results verified that high-solids batch AD of sewage sludge was feasible. Compared with the low-solids AD with solid contents of 1.79% or 4.47%, the high-solids processes decreased the specific biogas yield per gram of sludge volatile solids slightly, achieved the same organic degradation rate of about 40% within extended degradation time, but increased the volumetric biogas production rate and the treatment capability of digesters significantly. The blocked mass and energy transfer, the low substrate to inoculum rate and the excessive cumulative free ammonia were the main factors impacting the performance of high-solids batch AD.

  15. Comparison of different thickening methods for active biomass recycle for anaerobic digestion of wastewater sludge.

    PubMed

    Vanyushina, A Ya; Agarev, A M; Moyzhes, S I; Nikolaev, Yu A; Kevbrina, M V; Kozlov, M N

    2012-01-01

    The effect of returning solids to the digester, after one of three thickening processes, on volatile solids reduction (VSR) and gas production was investigated. Three different thickening methods were compared: centrifugation, flotation and gravitational sedimentation. The amount and activity of retained biomass in thickened recycled sludge affected the efficiency of digestion. Semi-continuous laboratory digesters were used to study the influence of thickening processes on thermophilic sludge digestion efficiency. Centrifugation was the most effective method used and caused an increase of VSR from 43% (control) up to 70% and gas generation from 0.40 to 0.44 L g(-1) VS. Flotation and gravitational sedimentation ways of thickening appeared to be less effective if compared with centrifugation. These methods increased VSR only by up to 65 and 51%, respectively and showed no significant increase of gas production. The dewatering capacity of digested sludge, as measured by its specific resistance to filtration, was essentially better for the sludge digested in the reactors with centrifugated and settled recycle. The VS concentration of recycle (g L(-1)), as reflecting the amount of retained biomass, appeared to be one of the most important factors influencing the efficiency of sludge digestion in the recycling technology.

  16. Improvement of activated sludge dewaterability by humus soil induced bioflocculation.

    PubMed

    Choi, Young-Gyun; Kim, Seong-Hong; Kim, Hee-Jun; Kim, Gyu Dong; Chung, Tai-Hak

    2004-01-01

    Effects of humus soil particles on the dewaterability of activated sludge were investigated. Cations leaching increased proportionally with the dosage of humus soil, and the leaching was not significant after 2 h. Divalent cations, Ca2+ and Mg2+, leaching from the humus soil played an important role in improving dewaterability of the biological sludge. On the contrary, dewaterability was not affected or slightly deteriorated by the monovalent cations, K+ and Na+ leached from the humus soil. Improvement in dewaterability of the sludge by addition of humus soil was higher than that of equivalent cations mixture. It seemed that the decrease of supracolloidal bio-particles (1 to 100 microm in diameter) resulted in diminishing of the blinding effect on cake and filter medium. SRF (specific resistance to filtration) of the humus soil added sludge varied in parallel with the M/D (monovalent to divalent cation) ratio, and the M/D ratio could be utilized as a useful tool for evaluation of the sludge dewatering characteristics. Long-term effects of humus soil on the improvement of activated sludge dewaterability were clearly identified by continuous operation results of a bench-scale MLE (Modified Ludzack Ettinger) system combined with a humus soil contactor. On the other hand, dewaterability of the control sludge was only slightly improved by a decrease in M/D ratio of the wastewater influent.

  17. Exploring the potential of applying proteomics for tracking bisphenol A and nonylphenol degradation in activated sludge.

    PubMed

    Collado, Neus; Buttiglieri, Gianluigi; Kolvenbach, Boris A; Comas, Joaquim; Corvini, Philippe F-X; Rodríguez-Roda, Ignasi

    2013-02-01

    A significant percentage of bisphenol A and nonylphenol removal in municipal wastewater treatment plants relies on biodegradation. Nonetheless, incomplete information is available concerning their degradation pathways performed by microbial communities in activated sludge systems. Hydroquinone dioxygenase (HQDO) is a specific degradation marker enzyme, involved in bisphenol A and nonylphenol biodegradation, and it can be produced by axenic cultures of the bacterium Sphingomonas sp. strain TTNP3. Proteomics, a technique based on the analysis of microbial community proteins, was applied to this strain. The bacterium proteome map was obtained and a HQDO subunit was successfully identified. Additionally, the reliability of the applied proteomics protocol was evaluated in activated sludge samples. Proteins belonging to Sphingomonas were searched at decreasing biomass ratios, i.e. serially diluting the bacterium in activated sludge. The protein patterns were compared and Sphingomonas proteins were discriminated against the ones from sludge itself on 2D-gels. The detection limit of the applied protocol was defined as 10(-3) g TTNP3 g(-1) total suspended solids (TSSs). The results proved that proteomics can be a promising methodology to assess the presence of specific enzymes in activated sludge samples, however improvements of its sensitivity are still needed.

  18. Effect of polyhydroxyalkanoates on dark fermentative hydrogen production from waste activated sludge.

    PubMed

    Wang, Dongbo; Zeng, Guangming; Chen, Yinguang; Li, Xiaoming

    2015-04-15

    Polyhydroxyalkanoates (PHA), an intracellular energy and carbon storage polymer, can be accumulated in activated sludge in substantial quantities under wastewater dynamic treatment (i.e., substrate feast-famine) conditions. However, its influence on hydrogen production has never been investigated before. This study therefore evaluated the influences of PHA level and composition in waste activated sludge (WAS) on hydrogen production. The results showed that with the increase of sludge PHA content from 25 to 178 mg per gram volatile suspended solids (VSS) hydrogen production from WAS alkaline anaerobic fermentation increased from 26.5 to 58.7 mL/g VSS. The composition of PHA was also found to affect hydrogen production. When the dominant composition shifted from polyhydroxybutyrate (PHB) to polyhydroxyvalerate (PHV), the amount of generated hydrogen decreased from 51.2 to 41.1 mL/g VSS even under the same PHA level (around 130 mg/g VSS). The mechanism studies exhibited that the increased PHA content accelerated both the cell solubilization and the hydrolysis process of solubilized substrates. Compared with the PHB-dominant sludge, the increased PHV fraction not only slowed the hydrolysis process but also caused more propionic acid production, with less theoretical hydrogen generation in this fermentation type. It was also found that the increased PHA content enhanced the soluble protein conversion of non-PHA biomass. Further investigations with enzyme analyses showed that both the key hydrolytic enzyme activities and hydrogen-forming enzyme activities were in the sequence of the PHB-dominant sludge > the PHV-dominant sludge > the low PHA sludge, which was in accord with the observed order of hydrogen yield.

  19. SLUDGE BATCH 7B QUALIFICATION ACTIVITIES WITH SRS TANK FARM SLUDGE

    SciTech Connect

    Pareizs, J.; Click, D.; Lambert, D.; Reboul, S.

    2011-11-16

    Waste Solidification Engineering (WSE) has requested that characterization and a radioactive demonstration of the next batch of sludge slurry - Sludge Batch 7b (SB7b) - be completed in the Shielded Cells Facility of the Savannah River National Laboratory (SRNL) via a Technical Task Request (TTR). This characterization and demonstration, or sludge batch qualification process, is required prior to transfer of the sludge from Tank 51 to the Defense Waste Processing Facility (DWPF) feed tank (Tank 40). The current WSE practice is to prepare sludge batches in Tank 51 by transferring sludge from other tanks. Discharges of nuclear materials from H Canyon are often added to Tank 51 during sludge batch preparation. The sludge is washed and transferred to Tank 40, the current DWPF feed tank. Prior to transfer of Tank 51 to Tank 40, SRNL typically simulates the Tank Farm and DWPF processes with a Tank 51 sample (referred to as the qualification sample). With the tight schedule constraints for SB7b and the potential need for caustic addition to allow for an acceptable glass processing window, the qualification for SB7b was approached differently than past batches. For SB7b, SRNL prepared a Tank 51 and a Tank 40 sample for qualification. SRNL did not receive the qualification sample from Tank 51 nor did it simulate all of the Tank Farm washing and decanting operations. Instead, SRNL prepared a Tank 51 SB7b sample from samples of Tank 7 and Tank 51, along with a wash solution to adjust the supernatant composition to the final SB7b Tank 51 Tank Farm projections. SRNL then prepared a sample to represent SB7b in Tank 40 by combining portions of the SRNL-prepared Tank 51 SB7b sample and a Tank 40 Sludge Batch 7a (SB7a) sample. The blended sample was 71% Tank 40 (SB7a) and 29% Tank 7/Tank 51 on an insoluble solids basis. This sample is referred to as the SB7b Qualification Sample. The blend represented the highest projected Tank 40 heel (as of May 25, 2011), and thus, the highest

  20. [Biodiversity and Function Analyses of BIOLAK Activated Sludge Metagenome].

    PubMed

    Tian, Mei; Liu, Han-hu; Shen, Xin; Zhao, Fang-qing; Chen, Shuai; Yao, Yong-jia

    2015-05-01

    The BIOLAK is a multi-stage activated sludge process, which has been successfully promoted worldwide. However, the biological community and function of the BIOLAK activated sludge ( the core component in the process) have not been reported so far. In this study, taking Lianyungang Dapu Industrial Zone WWTP as an example, a large-scale metagenomic data (428 588 high-quality DNA sequences) of the BIOLAK activated sludge were obtained by means of a new generation of high-throughput sequencing technology. Amazing biodiversity was revealed in the BIOLAK activated sludge, which included 47 phyla, 872 genera and 1351 species. There were 33 phyla identified in the Bacteria domain (289 933 sequences). Proteohacteria was the most abundant phylum (62.54%), followed by Bacteroidetes (11.29%), Nitrospirae ( 5. 65%) and Planctomycetes (4.79%), suggesting that these groups played a key role in the BIOLAK wastewater treatment system. Among the 748 bacterial genera, Nitrospira (5.60%) was the most prevalent genus, which was a key group in the nitrogen cycle. Followed by Gemmatimonas (2.45%), which was an important genus in the biological phosphorus removal process. In Archaea domain (1019 sequences), three phyla and 39 genera were detected. In Eukaryota domain (1055 sequences), 60 genera and 10 phyla were identified, among which Ciliophora was the largest phylum (257 sequences). Meanwhile, 448 viral sequences were detected in the BIOLAK sludge metagenome, which were dominated by bacteriophages. The proportions of nitrogen, aromatic compounds and phosphorus metabolism in the BIOLAK sludge were 2.50%, 2.28% and 1.56%, respectively, which were higher than those in the sludge of United States and Australia. Among four processes of nitrogen metabolism, denitrification-related genes were most abundant (80.81%), followed by ammonification (12.78%), nitrification,(4.38%) and nitrogen fixation (2.04%). In conclusion, the BIOLAK activated sludge had amazing biodiversity, meanwhile

  1. Heavy metal immobilization during the codisposal of municipal solid waste bottom ash and wastewater sludges

    SciTech Connect

    Eighmy, T.T.; Guay, M.A.; McHugh, S.; Kinner, N.E.; Ballestero, T.P. )

    1988-01-01

    One of the problems attendant to the incineration of municipal solid waste (MSW) is the siting and design of secure landfills to receive combustion residues from the incineration process. The authors have completed a study for a solid waste cooperative that was interested in codisposing MSW bottom ash and wastewater sludges. This codisposal scheme was initiated to address severe ash disposal problems within the Lamprey Regional Solid Waste Cooperative, and a severe sludge disposal problem in the City of Somersworth, NH, a member of the Cooperative and host city to the proposed codisposal site. The design of the landfill indicated that mixtures of bottom ash and combined sludges would range between 10:1 and 5:1 (by volume). An assessment of the leachate characteristics over time was required to address issues of pretreatment requirements, groundwater monitoring, and the potential sequestration and mobilization of heavy metals from the ash by organic ligands present in the sludge. This paper focuses on the biogeochemical conditions in the ash/sludge matrix that are conductive to the immobilization of heavy metals within the matrix via sulfide or polysulfide precipitation.

  2. Fermentation of municipal primary sludge: effect of SRT and solids concentration on volatile fatty acid production.

    PubMed

    Bouzas, A; Gabaldón, C; Marzal, P; Penya-Roja, J M; Seco, A

    2002-08-01

    Laboratory bench-scale experiments were conducted to investigate the performance of primary sludge fermentation for volatile fatty acids production. Primary sludges from two major wastewater treatment plants located in Valencia (Pinedo and Carraixet) were used. Experiments were performed at solids retention times between 4 and 10 days, and total volatile solids concentrations between 0.6% and 2.8%. Operation at two temperatures (20 degrees C and 30 degrees C) was also checked. Results indicated the importance of feed sludge characteristics on volatile fatty acids yields, being approximately double for the Carraixet wastewater treatment plant sludge than for the Pinedo plant. In both cases, higher volatile fatty acids yields were observed at higher total volatile solids concentrations. Solids retention times above 6 days scarcely improve volatile fatty acids yields, while experiments conducted at 4 days of solids retention times show an important decrease in volatile fatty acids yields. On raising temperature an increase in volatile fatty acids yields was observed, mainly due to an improvement in the hydrolysis of particulate organic matter.

  3. Enhanced anaerobic digestion of waste activated sludge of low organic content in a novel digester.

    PubMed

    Wu, J; Jiang, Y; Cao, Z P; Li, Z H; Hu, Y Y; Li, H Z; Zuo, J E; Wang, K J

    2015-01-01

    A novel digester, termed an internal circulation anaerobic digester (ICAD), was developed to intensify sludge digestion. It consists of reaction zone, settling zone, thickening zone, riser and downcomer. Internal circulation in the digester is intensified by backflow biogas. The mesophilic ICAD treating thermal pretreated waste activated sludge with volatile suspended solids (VSS)/suspended solids (SS) of 0.45-0.49 was conducted in this study to reduce and stabilize the low organic content sludge. The results showed that the VSS removal rate and biogas rate reached 46.0% and 0.72 m(3)/kg VSS(fed) at hydraulic retention time (HRT) of 15 days. VSS/SS and soluble chemical oxygen demand (SCOD) of the effluent sludge ranged from 0.39 to 0.41 and 274 mg/L to 473 mg/L, respectively, under various HRTs from 10 to 27 days. The degradation ability of ICAD derived from the improved mass transfer by internal circulation and long solid retention time at short HRT is compared with continuous stirred tank reactor.

  4. Cometabolic degradation of organic wastewater micropollutants by activated sludge and sludge-inherent microorganisms.

    PubMed

    Fischer, Klaus; Majewsky, Marius

    2014-08-01

    Municipal wastewaters contain a multitude of organic trace pollutants. Often, their biodegradability by activated sludge microorganisms is decisive for their elimination during wastewater treatment. Since the amounts of micropollutants seem too low to serve as growth substrate, cometabolism is supposed to be the dominating biodegradation process. Nevertheless, as many biodegradation studies were performed without the intention to discriminate between metabolic and cometabolic processes, the specific contribution of the latter to substance transformations is often not clarified. This minireview summarizes current knowledge about the cometabolic degradation of organic trace pollutants by activated sludge and sludge-inherent microorganisms. Due to their relevance for communal wastewater contamination, the focus is laid on pharmaceuticals, personal care products, antibiotics, estrogens, and nonylphenols. Wherever possible, reference is made to the molecular process level, i.e., cometabolic pathways, involved enzymes, and formed transformation products. Particular cometabolic capabilities of different activated sludge consortia and various microbial species are highlighted. Process conditions favoring cometabolic activities are emphasized. Finally, knowledge gaps are identified, and research perspectives are outlined. PMID:24866947

  5. Pilot-scale test of an advanced, integrated wastewater treatment process with sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal (SIPER).

    PubMed

    Yan, Peng; Ji, Fangying; Wang, Jing; Fan, Jianping; Guan, Wei; Chen, Qingkong

    2013-08-01

    Sludge reduction technologies are increasingly important in wastewater treatment, but have some defects. In order to remedy them, a novel, integrated process including sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal was developed. The pilot-scale system was operated steadily at a treatment scale of 10 m(3)/d for 90 days. The results showed excellent nutrient removal, with average removal efficiencies for NH4(+)-N, TN, TP, and COD reaching 98.2 ± 1.34%, 75.5 ± 3.46%, 95.3 ± 1.65%, and 92.7 ± 2.49%, respectively. The ratio of mixed liquor volatile suspended solids (MLVSS) to mixed liquor suspended solids (MLSS) in the system gradually increased, from 0.33 to 0.52. The process effectively prevented the accumulation of inert or inorganic solids in activated sludge. Phosphorus was recovered as a crystalline product with aluminum ion from wastewater. The observed sludge yield Yobs of the system was 0.103 gVSS/g COD, demonstrating that the system's sludge reduction potential is excellent.

  6. Effect of experimental conditions on gas quality and solids produced by sewage sludge cogasification. 1. Sewage sludge mixed with coal

    SciTech Connect

    Filomena Pinto; Helena Lopes; Rui Neto Andre; Mario Dias; I. Gulyurtlu; I. Cabrita

    2007-09-15

    Cogasification of sewage sludge mixed with coal showed that the amount of sewage sludge supplied to the gasifier, depending on its availability, could vary without affecting the gasifier performance; however, it had an influence on the syngas composition. The use of sewage sludge during coal gasification gave rise to an increasing gas yield and energy conversion, mainly because the gas produced had a greater hydrocarbon content. H{sub 2}S, HCl, and especially NH{sub 3} were also found to increase, due to higher contents of nitrogen in the sewage sludge compared with coal. The rise of both the temperature and the air flow rate resulted in the production of more gas and a lowering of hydrocarbon, char, and tar contents. A decrease in NH{sub 3} content was also observed, as the increase of these parameters promoted the destruction of this compound. The rise in the equivalent ratio also led to lower contents of H{sub 2}S and HCl, probably due to the partial oxidation of these compounds; however, the total amount of these elements released to the gas phase was not considerably affected. On the other hand, H{sub 2}S formation was favored by the rise in temperature up to 850{sup o}C, while the HCl concentration was not significantly affected. Heavy metals supplied with the fuel were mostly retained in solid residues, with Pb and Hg being the most volatile at 850{sup o}C. However, the leachability of these metals was found to be below the analytical detection levels, and only small quantities of SO{sub 4}{sup 2-} and Cl{sup -} were released. 28 refs., 15 figs., 1 tab.

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

    PubMed

    Lu, Qin; Yi, Jing; Yang, Dianhai

    2016-01-01

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

  8. 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.

  9. Modification of activated sludge properties caused by application of continuous and intermittent current.

    PubMed

    Ibeid, S; Elektorowicz, M; Oleszkiewicz, J A

    2013-02-01

    This study investigated the impact of direct current (DC) field on the activated sludge properties for potential improvement of the biological as well as membrane treatment processes. Three mixed-liquor suspended solids (MLSS) concentrations (5,000, 10,000 and 15,000 mg/l) were subjected to current densities (CD) ranging from 5 to 50 A/m² at five electrical exposure modes (time-ON/time-OFF). The results showed that CD between 15 and 35 A/m² increased the filterability of the sludge more than 200 times when compared with the untreated reference sludge. The average removals of protein, polysaccharides and organic colloids from the sludge supernatant at this range of CD were 43%, 73% and 91%, respectively, while the average reduction of the specific resistance to filtration (SRF) was 4.8 times higher. The changes of sludge properties depended on the current density, electrical exposure mode and the MLSS concentration. At CD of 25 A/m² and MLSS below 10,000 mg/l, shorter time-OFF was needed in each electrical cycle, while more time-OFF was needed at higher MLSS concentrations. It was concluded that proper application of the DC field could improve biomass in terms of its dewaterability and the removal of SMP, which are highly correlated to membrane fouling in the submerged membrane electro-bioreactor (SMEBR).

  10. Anaerobic bioleaching of metals from waste activated sludge.

    PubMed

    Meulepas, Roel J W; Gonzalez-Gil, Graciela; Teshager, Fitfety Melese; Witharana, Ayoma; Saikaly, Pascal E; Lens, Piet N L

    2015-05-01

    Heavy metal contamination of anaerobically digested waste activated sludge hampers its reuse as fertilizer or soil conditioner. Conventional methods to leach metals require aeration or the addition of leaching agents. This paper investigates whether metals can be leached from waste activated sludge during the first, acidifying stage of two-stage anaerobic digestion without the supply of leaching agents. These leaching experiments were done with waste activated sludge from the Hoek van Holland municipal wastewater treatment plant (The Netherlands), which contained 342 μg g(-1) of copper, 487 μg g(-1) of lead, 793 μg g(-1) of zinc, 27 μg g(-1) of nickel and 2.3 μg g(-1) of cadmium. During the anaerobic acidification of 3 gdry weight L(-1) waste activated sludge, 80-85% of the copper, 66-69% of the lead, 87% of the zinc, 94-99% of the nickel and 73-83% of the cadmium were leached. The first stage of two-stage anaerobic digestion can thus be optimized as an anaerobic bioleaching process and produce a treated sludge (i.e., digestate) that meets the land-use standards in The Netherlands for copper, zinc, nickel and cadmium, but not for lead.

  11. Investigation of Rheological Impacts on Sludge Batch 3 as Insoluble Solids and Wash Endpoints are Adjusted

    SciTech Connect

    Fellinger, T. L.

    2005-07-12

    The Defense Waste Processing Facility (DWPF) is currently processing and immobilizing radioactive sludge slurry into a durable borosilicate glass. The DWPF has already processed three sludge batches (Sludge Batch 1A, Sludge Batch 1B, and Sludge Batch 2) and is currently processing the fourth sludge batch (Sludge Batch 3). A sludge batch is defined as a single tank of sludge slurry or a combination of sludge slurries from different tanks that has been or will be qualified before being transferred to DWPF. As a part of the Sludge Batch 3 (SB3) qualification task, rheology measurements of the sludge slurry were requested at different insoluble solids loadings. These measurements were requested in order to gain insight into potential processing problems that may occur as the insoluble solids are adjusted up or down (by concentration or dilution) during the process. As a part of this study, a portion of the ''as received'' SB3 sample was washed with inhibited water (0.015 M NaOH and 0.015 M NaNO2) to target 0.5M Na versus a measured 1M Na in the supernate. The purpose of the ''washing'' step was to allow a comparison of the SB3 rheological data to the rheological data collected for Sludge Batch 2 (SB2) and to determine if there was a dependence of the yield stress and consistency as a function of washing. The ''as received'' SB3 rheology data was also compared to SB3 simulants prepared by the Simulant Development Program in order to provide guidance for selecting a simulant that is more representative of the rheological properties of the radioactive sludge slurry. A summary of the observations, conclusions are: (1) The yield stress and plastic viscosity increased as the weight percent insoluble solids were increased for the ''as received'' and ''washed'' SB3 samples, at a fixed pH. (2) For the same insoluble solids loading, the yield stress for the SB2 sample is approximately a factor of three higher than the ''as received'' SB3 sample. There also appears to be small

  12. 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.

  13. [Activated Sludge Bacteria Transforming Cyanopyridines and Amides of Pyridinecarboxylic Acids].

    PubMed

    Demakov, V A; Vasil'ev, D M; Maksimova, Yu G; Pavlova, Yu A; Ovechkina, G V; Maksimov, A Yu

    2015-01-01

    Species diversity of bacteria from the activated sludge of Perm biological waste treatment facilities capable of transformation of cyanopyridines and amides of pyridinecarboxylic acids was investigated. Enrichment cultures in mineral media with 3-cyanopyridine as the sole carbon and nitrogen source were used to obtain 32 clones of gram-negative heterotrophic bacteria exhibiting moderate growth on solid and liquid media with 3- and 4-cyanopyridine. Sequencing of the 16S rRNA gene fragments revealed that the clones with homology of at least 99% belonged to the genera Acinetobacte, Alcaligenes, Delftia, Ochrobactrum, Pseudomonas, Stenotrophomonas, and Xanthobacter. PCR analysis showed that 13 out of 32 isolates contained the sequences (-1070 bp) homologous to the nitrilase genes reported previously in Alcaligenes faecalis JM3 (GenBank, D13419.1). Nine clones were capable of nitrile and amide transformation in minimal salt medium. Acinetobacter sp. 11 h and Alcaligenes sp. osv transformed 3-cyanopyridine to nicotinamide, while most of the clones possessed amidase activity (0.5 to 46.3 mmol/(g h) for acetamide and 0.1 to 5.6 mmol/(g h) for nicotinamide). Nicotinamide utilization by strain A. faecalis 2 was shown to result in excretion of a secondary metabolite, which was identified as dodecyl acrylate at 91% probability. PMID:26263697

  14. High-solids anaerobic digestion of municipal sludge pretreated by thermal hydrolysis.

    PubMed

    Jolis, Domènec

    2008-07-01

    High-solids anaerobic digestion can consistently achieve 55 to 60% volatile solids destruction after thermal hydrolysis pretreatment, which reduces its viscosity and increases the fraction of soluble organic matter. For feed sludge with total solids concentrations between 6.8 and 8.2%, the process is stable at hydraulic retention times of 9 to 12 days, significantly increasing the treatment capacity of existing digesters or, in treatment plants without spare capacity, helping to postpone, reduce, or even avoid costly infrastructure investments. Process stability is related to the high concentration of soluble organic matter in the digesters. High-solids temperature-phased digestion appears to be superior to high-solids mesophilic digestion, with respect to process flexibility and stability, biosolids stabilization, and biogas generation, although ammonia inhibition may have occurred. Implementation of high-solids digestion could significantly reduce operation and maintenance costs of solids-handling operations. PMID:18710149

  15. Radionuclide Leaching from Residual Solids Remaining after Acid Dissolution of Composite K East Canister Sludge

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.; Soderquist, C.Z.; Fadeff, S.K.

    1999-04-02

    Laboratory tests were performed to examine mixed nitric/hydrofluoric acid leach treatments for decontaminating dissolver residual solids (KECDVSR24H-2) produced during a 20- to 24-hr dissolution of a composite K East (KE) Basin canister sludge in 95 C 6 M nitric acid (HNO{sub 3}). The scope of this testing has been described in Section 4.5 of ''Testing Strategy to Support the Development of K Basin Sludge Treatment Process'' (Flament 1998). Radionuclides sorbed or associated with the residual solids generated in the K Basin sludge treatment process can restrict disposal of this solid to the Environmental Restoration Disposal Facility (ERDF). The starting dissolver residual solid for this testing, KECDVSR24H-2, contains radionuclides at concentrations which exceed the ERDF Waste Acceptance Criteria for TRU by about a factor of 70, for {sup 239}Pu by a factor of 200, and for {sup 241}Am by a factor of 50. The solids also exceed the ERDF criterion for {sup 137}Cs by a factor of 2 and uranium by a factor of 5. Therefore, the radionuclides of greatest interest in this leaching study are first {sup 239}Pu and {sup 241}Am (both components of TRU) and then uranium and {sup 137}Cs.

  16. Nonoxidative removal of organics in the activated sludge process

    PubMed Central

    Modin, Oskar; Persson, Frank; Wilén, Britt-Marie; Hermansson, Malte

    2016-01-01

    ABSTRACT The activated sludge process is commonly used to treat wastewater by aerobic oxidation of organic pollutants into carbon dioxide and water. However, several nonoxidative mechanisms can also contribute to removal of organics. Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics. Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products. Recently, several environmental, economic, and technological drivers have stimulated research on nonoxidative removal of organics for wastewater treatment. In this paper, we review these nonoxidative removal mechanisms as well as the existing and emerging process configurations that make use of them for wastewater treatment. Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants. PMID:27453679

  17. 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.

  18. Effect of Worm Predation on Changes in Waste Activated Sludge Properties.

    PubMed

    Zhu, Xuefeng; Yuan, Wenyi; Wang, Zhiwei; Zhou, Mingyuan; Guan, Jie

    2016-05-01

    This study explored the effects of worm predation on changes in waste activated sludge properties. Results showed that the rate by which worm predation reduced mixed liquor volatile suspended solids (MLVSS) was approximately 23.7% ± 3.1%. Particle size distribution and extracellular polymeric substance (EPS) analyses indicated that the reduction of fine particles and EPS content in sludge predated by worms mainly increased dewaterability and reduced the ratio of MLVSS/mixed liquor suspended solids. Moreover, both mean particle size and protein/carbohydrate ratio increased. The results of three-dimensional excitation-emission matrix and gel filtration chromatogram analyses demonstrated the varied properties of soluble microbial products and EPS were attributed to the worms' selective predation of low molecular-weight organic matter, which facilitated the hydrolysis of macromolecular organic matter. PMID:27131302

  19. Biodegradability of wastewater and activated sludge organics in anaerobic digestion.

    PubMed

    Ikumi, D S; Harding, T H; Ekama, G A

    2014-06-01

    The investigation provides experimental evidence that the unbiodegradable particulate organics fractions of primary sludge and waste activated sludge calculated from activated sludge models remain essentially unbiodegradable in anaerobic digestion. This was tested by feeding the waste activated sludge (WAS) from three different laboratory activated sludge (AS) systems to three separate anaerobic digesters (AD). Two of the AS systems were Modified Ludzack - Ettinger (MLE) nitrification-denitrification (ND) systems and the third was a membrane University of Cape Town (UCT) ND and enhanced biological P removal system. One of the MLE systems and the UCT system were fed the same real settled wastewater. The other MLE system was fed raw wastewater which was made by adding a measured constant flux (gCOD/d) of macerated primary sludge (PS) to the real settled wastewater. This PS was also fed to a fourth AD and a blend of PS and WAS from settled wastewater MLE system was fed to a fifth AD. The five ADs were each operated at five different sludge ages (10-60d). From the measured performance results of the AS systems, the unbiodegradable particulate organic (UPO) COD fractions of the raw and settled wastewaters, the PS and the WAS from the three AS systems were calculated with AS models. These AS model based UPO fractions of the PS and WAS were compared with the UPO fractions calculated from the performance results of the ADs fed these sludges. For the PS, the UPO fraction calculated from the AS and AD models matched closely, i.e. 0.30 and 0.31. Provided the UPO of heterotrophic (OHO, fE_OHO) and phosphorus accumulating (PAO, fE_PAO) biomass were accepted to be those associated with the death regeneration model of organism "decay", the UPO of the WAS calculated from the AS and AD models also matched well - if the steady state AS model fE_OHO = 0.20 and fE_PAO = 0.25 values were used, then the UPO fraction of the WAS calculated from the AS models deviated significantly

  20. Paper sludge (PS) to bioethanol: Evaluation of virgin and recycle mill sludge for low enzyme, high-solids fermentation.

    PubMed

    Boshoff, Sonja; Gottumukkala, Lalitha Devi; van Rensburg, Eugéne; Görgens, Johann

    2016-03-01

    Paper sludge (PS) from the paper and pulp industry consists primarily of cellulose and ash and has significant potential for ethanol production. Thirty-seven PS samples from 11 South African paper and pulp mills exhibited large variation in chemical composition and resulting ethanol production. Simultaneous saccharification and fermentation (SSF) of PS in fed-batch culture was investigated at high solid loadings and low enzyme dosages. Water holding capacity and viscosity of the PS influenced ethanol production at elevated solid loadings of PS. High viscosity of PS from virgin pulp mills restricted the solid loading to 18% (w/w) at an enzyme dosage of 20 FPU/gram dry PS (gdPS), whereas an optimal solid loading of 27% (w/w) was achieved with corrugated recycle mill PS at 11 FPU/gdPS. Ethanol concentration and yield of virgin pulp and corrugated recycle PS were 34.2g/L at 66.9% and 45.5 g/L at 78.2%, respectively.

  1. Performance of coarse pore filtration activated sludge system.

    PubMed

    Alavi Moghaddam, M R; Satoh, H; Mino, T

    2002-01-01

    A coarse pore filter can be applied inside the aeration tank to facilitate the separation of sludge from liquid instead of sedimentation. This filter has pores, which are irregular in shape, and the pore size is bigger than those of MF. The objectives of the study were to maintain as much as MLSS in the activated sludge process with coarse pore filter and to investigate the performance under high MLSS condition. Small-scale reactor results so far show good quality of effluent specially after starting the sludge bulking in the system in terms of SS, TOC, DOC and turbidity. The average carbon removal for 62 days operation of this system was about 94% (based on effluent DOC) and 87% (based on effluent TOC). The average sludge yield in this system is about 0.44 kg MLSS/kg TOC which is about 0.24 kg MLSS/kg BOD. This amount is less than those of conventional activated sludge and trickling filter.

  2. Activated sludge acclimatisation kinetics to non-ionic surfactants.

    PubMed

    Carvalho, G; Novais, J M; Pinheiro, H M

    2003-01-01

    The biodegradation of surfactants is a frequent and complex problem in domestic and industrial wastewater treatment processes. In addition to the resulting metabolites being sometimes refractory, the complete biodegradation of many of the most employed non-ionic surfactants requires long hydraulic retention times and the presence of specialised bacterial consortia. Preliminary acclimatisation tests highlighted the importance of the sludge acclimatisation state to a specific surfactant substrate for biotreatment efficiency. This paper reports on studies aimed at quantifying activated sludge acclimatisation and memory retention levels when subjected to changes in the type of surfactant included in the feed. Several transitions were tested, namely from an alkylphenol ethoxylate to a linear alkyl ethoxylate and the reverse, and between alkyl ethoxylates with different hydrophobic and hydrophilic molecular chain lengths. The kinetic results showed that sludge activation and memory loss were more dynamic for primary biodegradation It was found that the sludge was harder to adapt to alkylphenol ethoxylate than to alkyl ethoxylate. The former also apparently introduced an inhibitory effect, resulting in very slow degradation kinetics when imposed to alkyl ethoxylate acclimatised sludge. When replacing an alkyl ethoxylate with another surfactant of the same family, a longer ethoxylate chain reduced the degradation rates. This effect was further enhanced by simultaneously increasing the hydrophobic chain length of the substrate. The acclimatisation kinetic after the replacement of an alkyl ethoxylate by a longer counterpart was slower than the reverse case, and memory was also more easily lost. PMID:12641258

  3. Disturbance opens recruitment sites for bacterial colonization in activated sludge.

    PubMed

    Vuono, David C; Munakata-Marr, Junko; Spear, John R; Drewes, Jörg E

    2016-01-01

    Little is known about the role of immigration in shaping bacterial communities or the factors that may dictate success or failure of colonization by bacteria from regional species pools. To address these knowledge gaps, the influence of bacterial colonization into an ecosystem (activated sludge bioreactor) was measured through a disturbance gradient (successive decreases in the parameter solids retention time) relative to stable operational conditions. Through a DNA sequencing approach, we show that the most abundant bacteria within the immigrant community have a greater probability of colonizing the receiving ecosystem, but mostly as low abundance community members. Only during the disturbance do some of these bacterial populations significantly increase in abundance beyond background levels and in few cases become dominant community members post-disturbance. Two mechanisms facilitate the enhanced enrichment of immigrant populations during disturbance: (i) the availability of resources left unconsumed by established species and (ii) the increased availability of niche space for colonizers to establish and displace resident populations. Thus, as a disturbance decreases local diversity, recruitment sites become available to promote colonization. This work advances our understanding of microbial resource management and diversity maintenance in complex ecosystems. PMID:25727891

  4. Radionuclide Leaching from Residual Solids Remaining after Acid Dissolution of K East Area Sludge Composite

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.; Carlson, C.D.; Soderquist, C.Z.; Fadeff, S.K.

    1999-04-02

    Laboratory tests were performed to examine the efficacy of various leach treatments for decontaminating dissolver residual solids (KEACRESID1) produced during a 24-hour dissolution of K East Basin floor and Weasel Pit sludge composite in boiling 6 M HNO{sub 3}. The scope of this testing has been described in Section 4.5 of ''Testing Strategy to Support the Development of K Basin Sludge Treatment Process'' (Flament 1998). Radionuclides sorbed or associated with the residual solids generated in the K Basin sludge treatment process can restrict disposal of this solid to the Environmental Restoration Disposal Facility (ERDF). The starting dissolver residual solid for this testing, KEACRESID1, is a visibly heterogeneous material. This material contains radionuclides at concentrations above the ERDF Waste Acceptance Criteria for transuranics (TRU) by about a factor of 3, for {sup 239}Pu by a factor of 10, and for {sup 241}Am by a factor of 1.6. It meets the ERDF criterion for {sup 137}Cs by a factor of 4 and for uranium by a factor of 10. Therefore, the radionuclides of greatest interest in this leaching study are first {sup 239}Pu, and then {sup 241}Am, {sup 137}Cs, and uranium.

  5. Reduction by sonication of excess sludge production in a conventional activated sludge system: continuous flow and lab-scale reactor.

    PubMed

    Vaxelaire, S; Gonze, E; Merlin, G; Gonthier, Y

    2008-12-01

    Conventional activated sludge wastewater treatment plants currently produce a large quantity of excess sludge. To reduce this sludge production and to improve sludge characteristics in view of their subsequent elimination, an ultrasonic cell disintegration process was studied. In a lab-scale continuous flow pilot plant, part of the return sludge was sonicated by low-frequency and high-powered ultrasound and then recycled to the aeration tank. Two parallel lines were used: one as a control and the other as an assay with ultrasonic treatment. The reactors were continuously fed with synthetic domestic wastewater with a COD (chemical oxygen demand) of approximately 0.5 g l(-) corresponding to a daily load of 0.35-0.50 kg COD kg(-1) TS d(-1). Removal efficiencies (carbon, particles), excess sludge production and sludge characteristics (particle size distribution, mineralization, respiration rate, biological component) were measured every day during the 56-day experiment. This study showed that whilst organic removal efficiency did not deteriorate, excess sludge production was decreased by about 25-30% by an ultrasonic treatment. Several hypotheses are advanced: (i) the treatment made a part of the organic matter soluble as a consequence of the floc disintegration, and optimised the conversion of the carbonaceous pollutants into carbon dioxide and (ii) the treatment modified the physical characteristics of sludge by a mechanical effect: floc size was reduced, increasing the exchange surface and sludge activity. The originality of this study is that experiments were conducted in a continuous-flow activated sludge reactor rather than in a batch reactor. PMID:19149352

  6. Evaluating the solid retention time of bacteria in flocculent and granular sludge.

    PubMed

    Winkler, Mari K H; Kleerebezem, Robbert; Khunjar, Wendell O; de Bruin, Bart; van Loosdrecht, Mark C M

    2012-10-15

    The specific solid retention time for different bacteria within flocculent and granular sludge was determined. Samples were collected from reactor and effluent sludge and the number of a specific bacterial group was evaluated in respect to the total bacterial community with quantitative polymerase chain reaction (qPCR). The ratio of the relative presence of a specific bacterial group in the reactor sludge and wasted sludge was established to observe if preferential wash-out occurred. From the data also the solid retention time for different microbial groups can be estimated. Using this tool, we were able to show that the SRT of populations found on the exterior of granules is slightly lower than the SRT for population in the interior. Archaea were not found in the flocculent system but were present in small amounts within the granular system. It was further observed that protozoa were grazing on the bacterial community within the system indicating that they have the potential to shorten the specific SRT of bacteria.

  7. 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

  8. Sorption and release of organics by primary, anaerobic, and aerobic activated sludge mixed with raw municipal wastewater.

    PubMed

    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.

  9. The influence of temperature and SRT on high-solid digestion of municipal sewage sludge.

    PubMed

    Jahn, L; Baumgartner, T; Svardal, K; Krampe, J

    2016-01-01

    The influence of temperature and solids retention time (SRT) on high-solid digestion of municipal sewage sludge was investigated in laboratory-scale reactors. Digestion with high-solid concentration reduces the required digestion volume and is advantageous for urban areas. The experimental conditions comprised total suspended solids (TSS) in digested sludge between 4.0 and 4.6%, temperatures in a range of 33 to 41 °C and the SRT between 10 and 25 d. High-solid digestion operates with increased NH4-N concentrations released from organic compounds. The anaerobic process can be limited by high NH4-N concentration and toxic NH3. In this study a stable digestion was observed up to 2,000 mg L(-1) NH4-N and 75 mg L(-1) NH3. Volatile suspended solids (VSS) and chemical oxygen demand removal was 53% and 57% respectively. However, digestion with 10 d SRT led to a declined VSS removal of 49%. The removal at 41 and 37 °C showed minor differences, while reduced NH4-N release and reduced methane production were observed at 33 °C. For economic reasons, high-solid digestion at 41 °C is not recommended, but will not impair VSS removal. The outcomes of this study confirm that digestion with up to 7.8% TSS in the feed is feasible for the tested temperatures and SRT down to 15 d.

  10. The influence of temperature and SRT on high-solid digestion of municipal sewage sludge.

    PubMed

    Jahn, L; Baumgartner, T; Svardal, K; Krampe, J

    2016-01-01

    The influence of temperature and solids retention time (SRT) on high-solid digestion of municipal sewage sludge was investigated in laboratory-scale reactors. Digestion with high-solid concentration reduces the required digestion volume and is advantageous for urban areas. The experimental conditions comprised total suspended solids (TSS) in digested sludge between 4.0 and 4.6%, temperatures in a range of 33 to 41 °C and the SRT between 10 and 25 d. High-solid digestion operates with increased NH4-N concentrations released from organic compounds. The anaerobic process can be limited by high NH4-N concentration and toxic NH3. In this study a stable digestion was observed up to 2,000 mg L(-1) NH4-N and 75 mg L(-1) NH3. Volatile suspended solids (VSS) and chemical oxygen demand removal was 53% and 57% respectively. However, digestion with 10 d SRT led to a declined VSS removal of 49%. The removal at 41 and 37 °C showed minor differences, while reduced NH4-N release and reduced methane production were observed at 33 °C. For economic reasons, high-solid digestion at 41 °C is not recommended, but will not impair VSS removal. The outcomes of this study confirm that digestion with up to 7.8% TSS in the feed is feasible for the tested temperatures and SRT down to 15 d. PMID:27533858

  11. Analysis and modelling of predation on biofilm activated sludge process: Influence on microbial distribution, sludge production and nutrient dosage.

    PubMed

    Revilla, Marta; Galán, Berta; Viguri, Javier R

    2016-11-01

    The influence of predation on the biofilm activated sludge (BAS) process is studied using a unified model that incorporates hydrolysis and predation phenomena into the two stages of the BAS system: moving bed biofilm reactor pre-treatment (bacterial-predator stage) and activated sludge (predator stage). The unified model adequately describes the experimental results obtained in a cellulose and viscose full-scale wastewater plant and has been used to evaluate the role and contribution of predator microorganisms towards removal of COD, nutrient requirements, sludge production and microbial distribution. The results indicate that predation is the main factor responsible for the reduction of both nutrient requirements and sludge production. Furthermore, increasing the sludge retention time (SRT) does not influence the total biomass content in the AS reactor of a BAS process in two different industrial wastewater treatments. PMID:27614580

  12. Analysis and modelling of predation on biofilm activated sludge process: Influence on microbial distribution, sludge production and nutrient dosage.

    PubMed

    Revilla, Marta; Galán, Berta; Viguri, Javier R

    2016-11-01

    The influence of predation on the biofilm activated sludge (BAS) process is studied using a unified model that incorporates hydrolysis and predation phenomena into the two stages of the BAS system: moving bed biofilm reactor pre-treatment (bacterial-predator stage) and activated sludge (predator stage). The unified model adequately describes the experimental results obtained in a cellulose and viscose full-scale wastewater plant and has been used to evaluate the role and contribution of predator microorganisms towards removal of COD, nutrient requirements, sludge production and microbial distribution. The results indicate that predation is the main factor responsible for the reduction of both nutrient requirements and sludge production. Furthermore, increasing the sludge retention time (SRT) does not influence the total biomass content in the AS reactor of a BAS process in two different industrial wastewater treatments.

  13. The impact of peroxydisulphate and peroxymonosulphate on disintegration and settleability of activated sludge.

    PubMed

    Wacławek, Stanisław; Grübel, Klaudiusz; Černík, Miroslav

    2016-01-01

    Chemical treatment processes have mostly been considered as an efficient way for biosolid minimization. The improvement of sludge dewatering was more a welcome side-effect of these sequential processes. In this study, heat-activated sodium peroxydisulphate (PDS) and potassium peroxymonosulphate (MPS) were applied in order to disintegrate waste activated sludge (WAS). PDS and MPS treatment of WAS results in the polymer transfer of organic matter from the solid phase to the liquid phase. Our research work was done for chemical disintegration of WAS by PDS and MPS in doses of 0.2%, 0.4%, 0.6%, 0.8% and 1% (169.5, 339.0, 508.5, 678.0 and 847.5 mg [Formula: see text]) activated at temperatures of 60°C and 90°C for 30 min. The application of these methods causes the soluble chemical oxygen demand value to increase in the supernatant. In addition, there was a positive influence on the sludge volume index which decreased for the highest doses of PDS of over 63% and 77% and MPS of over 78% and 82% through heat activation at temperatures of 60°C and 90°C, respectively. Furthermore, MPS was more successful in the floc particle destruction, therefore it caused a higher sludge settlement acceleration (sedimentation/compaction speed) than PDS. The experimental results demonstrated that the application of heat-activated PDS and MPS may become a novel effective way of processing sewage sludge. PMID:26503018

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  16. Microscopic Analysis of Plankton, Periphyton, and Activated Sludge. Training Manual.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC. Office of Water Programs.

    This manual is intended for professional personnel in the fields of water pollution control, limnology, water supply and waste treatment. Primary emphasis is given to practice in the identification and enumeration of microscopic organisms which may be encountered in water and activated sludge. Methods for the chemical and instrumental evaluation…

  17. Activated Sludge. Instructor's Guide. Biological Treatment Process Control.

    ERIC Educational Resources Information Center

    Boe, Owen K.

    This instructor's guide contains the materials needed to teach a seven-lesson unit on activated sludge. These materials include an overview of the unit, lesson plans, lecture outlines (keyed to slides designed for use with the lessons), student worksheets for each of the seven lessons (with answers), and two copies of a final quiz (with and…

  18. BIOLOGICALLY ENHANCED OXYGEN TRANSFER IN THE ACTIVATED SLUDGE PROCESS (JOURNAL)

    EPA Science Inventory

    Biologically enhanced oxgyen transfer has been a hypothesis to explain observed oxygen transfer rates in activated sludge systems that were well above that predicted from aerator clean-water testing. The enhanced oxygen transfer rates were based on tests using BOD bottle oxygen ...

  19. Intermediate Activated Sludge. Training Module 2.116.3.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with operation of activated sludge wastewater treatment plants. Included are objectives, instructor guides, student handouts and transparency masters. This is the second level of a three module series and considers aeration devices,…

  20. Operational Control Procedures for the Activated Sludge Process: Appendix.

    ERIC Educational Resources Information Center

    West, Alfred W.

    This document is the appendix for a series of documents developed by the National Training and Operational Technology Center describing operational control procedures for the activated sludge process used in wastewater treatment. Categories discussed include: control test data, trend charts, moving averages, semi-logarithmic plots, probability…

  1. Advanced Activated Sludge. Training Module 2.117.4.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with operation of activated sludge wastewater treatment plants. Included are objectives, instructor guides, student handouts and transparency masters. This is the third level of a three module series and considers design and operation…

  2. Basic Activated Sludge. Training Module 2.115.2.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with operation of activated sludge wastewater treatment plants. Included are objectives, instructor guides, student handouts, and transparency masters. This is the first of a three module series and considers definition of terms, design…

  3. Municipal incineration studies: Sludge, refuse, and solid wastes. (Latest citations from the NTIS database). Published Search

    SciTech Connect

    Not Available

    1993-05-01

    The bibliography contains citations concerning the use of incineration processes for the destruction of municipal wastes, including sewage sludge, refuse, and solid wastes. Topics include systems design and management, combustion and emissions studies, pollution and toxicity studies, heat recovery operations, pollution control devices, and economic aspects. Analytical methods for pollution identification, marine vessel incinerators, catalytic incineration, and risk assessment studies are also considered. (Contains 250 citations and includes a subject term index and title list.)

  4. New mechanistically based model for predicting reduction of biosolids waste by ozonation of return activated sludge.

    PubMed

    Isazadeh, Siavash; Feng, Min; Urbina Rivas, Luis Enrique; Frigon, Dominic

    2014-04-15

    Two pilot-scale activated sludge reactors were operated for 98 days to provide the necessary data to develop and validate a new mathematical model predicting the reduction of biosolids production by ozonation of the return activated sludge (RAS). Three ozone doses were tested during the study. In addition to the pilot-scale study, laboratory-scale experiments were conducted with mixed liquor suspended solids and with pure cultures to parameterize the biomass inactivation process during exposure to ozone. The experiments revealed that biomass inactivation occurred even at the lowest doses, but that it was not associated with extensive COD solubilization. For validation, the model was used to simulate the temporal dynamics of the pilot-scale operational data. Increasing the description accuracy of the inactivation process improved the precision of the model in predicting the operational data.

  5. New mechanistically based model for predicting reduction of biosolids waste by ozonation of return activated sludge.

    PubMed

    Isazadeh, Siavash; Feng, Min; Urbina Rivas, Luis Enrique; Frigon, Dominic

    2014-04-15

    Two pilot-scale activated sludge reactors were operated for 98 days to provide the necessary data to develop and validate a new mathematical model predicting the reduction of biosolids production by ozonation of the return activated sludge (RAS). Three ozone doses were tested during the study. In addition to the pilot-scale study, laboratory-scale experiments were conducted with mixed liquor suspended solids and with pure cultures to parameterize the biomass inactivation process during exposure to ozone. The experiments revealed that biomass inactivation occurred even at the lowest doses, but that it was not associated with extensive COD solubilization. For validation, the model was used to simulate the temporal dynamics of the pilot-scale operational data. Increasing the description accuracy of the inactivation process improved the precision of the model in predicting the operational data. PMID:24572272

  6. Treatment of mixed municipal and winery wastewaters in a conventional activated sludge process: a case study.

    PubMed

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

    2005-01-01

    The possibility of co-treating municipal and winery wastewaters in a conventional activated sludge process was studied at full scale. The wastewater treatment plant considered in this paper operated an extended-oxidation process during vintage (four month per year) and a pre-denitrification/ oxidation process during the rest of the year. The experimentation showed that good performances, in terms of COD and nitrogen removal, could be obtained in both cases: 90% and 60%, for COD and nitrogen removal, respectively. Thanks to the high solid retention times applied to the system (up to 48 days) the waste activated sludge production was low (0.20 kgMLVSS/kgCODremoved) and respiration was the main process for carbon removal. Nitrification was always satisfactory while the behaviour of the denitrification process during vintage was not totally understood and further studies are going on. PMID:15771103

  7. Methane production and microbial community structure for alkaline pretreated waste activated sludge.

    PubMed

    Sun, Rui; Xing, Defeng; Jia, Jianna; Zhou, Aijuan; Zhang, Lu; Ren, Nanqi

    2014-10-01

    Alkaline pretreatment was studied to analyze the influence on waste activated sludge (WAS) reduction, methane production and microbial community structure during anaerobic digestion. Methane production from alkaline pretreated sludge (A-WAS) (pH = 12) increased from 251.2 mL/Ld to 362.2 mL/Ld with the methane content of 68.7% compared to raw sludge (R-WAS). Sludge reduction had been improved, and volatile suspended solids (VSS) removal rate and protein reduction had increased by ∼ 10% and ∼ 35%, respectively. The bacterial and methanogenic communities were analyzed using 454 pyrosequencing and clone libraries of 16S rRNA gene. Remarkable shifts were observed in microbial community structures after alkaline pretreatment, especially for Archaea. The dominant methanogenic population changed from Methanosaeta for R-WAS to Methanosarcina for A-WAS. In addition to the enhancement of solubilization and hydrolysis of anaerobic digestion of WAS, alkaline pretreatment showed significant impacts on the enrichment and syntrophic interactions between microbial communities.

  8. Polyphosphate-degrading enzymes in Acinetobacter spp. and activated sludge.

    PubMed Central

    van Groenestijn, J W; Bentvelsen, M M; Deinema, M H; Zehnder, A J

    1989-01-01

    Polyphosphate-degrading enzymes were studied in Acinetobacter spp. and activated sludge. Polyphosphate: AMP phosphotransferase activity in Acinetobacter strain 210A decreased with increasing growth rates. The activity of this enzyme in cell extracts of Acinetobacter strain 210A was maximal at a pH of 8.5 and a temperature of 40 degrees C and was stimulated by (NH4)2SO4. The Km for AMP was 0.6 mM, and the Vmax was 60 nmol/min per mg of protein. Cell extracts of this strain also contained polyphosphatase, which was able to degrade native polyphosphate and synthetic magnesium polyphosphate and was strongly stimulated by 300 to 400 mM NH4Cl. A positive correlation was found between polyphosphate:AMP phosphotransferase activity, adenylate kinase activity, and phosphorus accumulation in six Acinetobacter strains. Significant activities of polyphosphate kinase were detected only in strain P, which contained no polyphosphate:AMP phosphotransferase. In samples of activated sludge from different plants, the activity of adenylate kinase correlated well with the ability of the sludge to remove phosphate biologically from wastewater. PMID:2539774

  9. Removal of Cu(II) ions by biosorption onto powdered waste sludge (PWS) prior to biological treatment in an activated sludge unit: a statistical design approach.

    PubMed

    Pamukoglu, M Yunus; Kargi, Fikret

    2009-04-01

    Biological treatment of synthetic wastewater containing Cu(II) ions was realized in an activated sludge unit with pre-adsorption of Cu(II) onto powdered waste sludge (PWS). Box-Behnken experimental design method was used to investigate Cu(II), chemical oxygen demand (COD) and toxicity removal performance of the activated sludge unit under different operating conditions. The independent variables were the solids retention time (SRT, 5-30 d), hydraulic residence time (HRT, 5-25 h), feed Cu(II) concentration (0-50 mg L(-1)) and PWS loading rate (0-4 g h(-1)) while percent Cu(II), COD, toxicity (TOX) removals and the sludge volume index (SVI) were the objective functions. The data were correlated with a quadratic response function (R2=0.99). Cu(II), COD and toxicity removals increased with increasing PWS loading rate and SRT while decreasing with the increasing feed Cu(II) concentration and HRT. Optimum conditions resulting in maximum Cu(II), COD, toxicity removals and SVI values were found to be SRT of 30 d, HRT 15 h, PWS loading rate 3 g h(-1) and feed Cu(II) concentration of less than 30 mg L(-1).

  10. Influence of magnetic field on activity of given anaerobic sludge.

    PubMed

    Xu, Y B; Duan, X J; Yan, J N; Du, Y Y; Sun, S Y

    2009-11-01

    Two modes of magnetic fields were applied in the Cr(6+) removal sludge reactors containing two predominated strains--Bacillus sp. and Brevibacillus sp., respectively. The magnetic field mode I* of 0-4.5 or 0-14 mT between pieces was obtained by setting the magnetic pieces with the surface magnetic density of 0-6 or 0-20 mT into the reactor, and the magnetic field mode II* of 6, 20, or 40 mT on the return line was obtained by controlling the working distance of the permanent magnet outside the sludge return line. The effects of different magnetic fields on the activity of the given anaerobic sludge were studied by comparing with the control (absent of magnetic field). The results showed that the magnetic field of 0-4 mT improved the activity of given sludge most effectively, U(max) CH(4) (the peak methane-producing rate) and the methane producing volume per gCOD(Cr) reached 64.3 mlCH(4)/gVSS.d and 124 mlCH(4)/gCOD(Cr), which increased by 20.6 and 70.7%, respectively, compared with the control. And the magnetic field of 20 mT took second place. It could be concluded that the input of some magnetic field could improve the activity of anaerobic sludge by increasing the transformation efficiency of COD(Cr) matters to methane, and the total organic wastage did not increase.

  11. Improve bio-activity of anaerobic sludge by low energy ultrasound.

    PubMed

    Zhu, Yichun; Li, Xin; Du, Maoan; Liu, Zuwen; Luo, Hui; Zhang, Tao

    2015-01-01

    This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound. PMID:26676010

  12. Improve bio-activity of anaerobic sludge by low energy ultrasound.

    PubMed

    Zhu, Yichun; Li, Xin; Du, Maoan; Liu, Zuwen; Luo, Hui; Zhang, Tao

    2015-01-01

    This research focused on ultrasound-enhanced bio-activity of anaerobic sludge. Low energy ultrasound irradiation can increase the bio-activity of anaerobic sludge. Ultrasonic parameter, characteristics of anaerobic sludge and experimental conditions are important parameters which affect the enhancement effect on anaerobic sludge. In order to assess the effects of characteristics of anaerobic sludge and experimental conditions on ultrasonic irradiation of anaerobic sludge, experiments with different characteristics of anaerobic sludge were carried out and analyzed with the content of coenzyme F420 and dehydrogenase activity (DHA). The results showed that anaerobic sludge bio-activity was impacted by the initial temperature, initial chemical oxygen demand (COD), sludge concentration, and stirring during the ultrasonic process. Optimal performance was achieved when sound frequency, power density, and ultrasonic irradiation period was 20 kHz, 0.1 W/mL, and 10 min, respectively, under which the wastewater COD removal efficiency was increased by 12.9 percentage points. The results indicated that low temperature could affect the anaerobic sludge irradiation effect, while intermittent stirring could enhance the bio-activity of anaerobic sludge irradiation effect and low substrate concentration improved anaerobic sludge activity by ultrasound.

  13. Decontamination of heavy metal laden sewage sludge with simultaneous solids reduction using thermophilic sulfur and ferrous oxidizing species.

    PubMed

    Mehrotra, A; Kundu, K; Sreekrishnan, T R

    2016-02-01

    A possibility of using simultaneous sewage sludge digestion and metal leaching (SSDML) process at the thermophilic temperature to remove heavy metals and suspended solids from sewage sludge is explored in this study. Though thermophilic sludge digestion efficiently produces a stable sludge, its inability to remove heavy metals requires it to be used in tandem with another process like bioleaching for metal reduction. Previously, different temperature optima were known for the heterotrophs (thermophilic) responsible for the sludge digestion and the autotrophs involved in bioleaching (mesophilic), because of which the metal concentration was brought down separately in a different reactor. In our study, SSDML process was carried out at 50 °C (thermophilic) by using ferrous sulfate (batch-1) and sulfur (batch-2) as the energy source in two reactors. The concentration of volatile suspended solids reduced by >40% in both batches, while that of heavy metals zinc, copper, chromium, cadmium and nickel decreased by >50% in both batch-1 and batch-2. Lead got leached out only in batch-1. Using 16S rRNA gene-based PCR-denaturing gradient gel electrophoresis analysis, Alicyclobacillus tolerans was found to be the microorganism responsible for lowering the pH in both the reactors at thermophilic temperature. The indicator organism count was also below the maximum permissible limit making sludge suitable for agricultural use. Our results indicate that SSDML at thermophilic temperature can be effectively used for reduction of heavy metals and suspended solids from sewage sludge.

  14. Decontamination of heavy metal laden sewage sludge with simultaneous solids reduction using thermophilic sulfur and ferrous oxidizing species.

    PubMed

    Mehrotra, A; Kundu, K; Sreekrishnan, T R

    2016-02-01

    A possibility of using simultaneous sewage sludge digestion and metal leaching (SSDML) process at the thermophilic temperature to remove heavy metals and suspended solids from sewage sludge is explored in this study. Though thermophilic sludge digestion efficiently produces a stable sludge, its inability to remove heavy metals requires it to be used in tandem with another process like bioleaching for metal reduction. Previously, different temperature optima were known for the heterotrophs (thermophilic) responsible for the sludge digestion and the autotrophs involved in bioleaching (mesophilic), because of which the metal concentration was brought down separately in a different reactor. In our study, SSDML process was carried out at 50 °C (thermophilic) by using ferrous sulfate (batch-1) and sulfur (batch-2) as the energy source in two reactors. The concentration of volatile suspended solids reduced by >40% in both batches, while that of heavy metals zinc, copper, chromium, cadmium and nickel decreased by >50% in both batch-1 and batch-2. Lead got leached out only in batch-1. Using 16S rRNA gene-based PCR-denaturing gradient gel electrophoresis analysis, Alicyclobacillus tolerans was found to be the microorganism responsible for lowering the pH in both the reactors at thermophilic temperature. The indicator organism count was also below the maximum permissible limit making sludge suitable for agricultural use. Our results indicate that SSDML at thermophilic temperature can be effectively used for reduction of heavy metals and suspended solids from sewage sludge. PMID:26686075

  15. Suitability of Sludge Biotic Index (SBI), Sludge Index (SI) and filamentous bacteria analysis for assessing activated sludge process performance: the case of piggery slaughterhouse wastewater.

    PubMed

    Pedrazzani, Roberta; Menoni, Laura; Nembrini, Stefano; Manili, Livia; Bertanza, Giorgio

    2016-07-01

    Piggery slaughterhouse wastewater poses serious issues in terms of disposal feasibility and environmental impact, due to its huge organic load and variability. It is commonly treated by means of activated sludge processes, whose performance, in case of municipal wastewater, can be monitored by means of specific analyses, such as Sludge Biotic Index (SBI), Sludge Index (SI) and floc and filamentous bacteria observation. Therefore, this paper was aimed at assessing the applicability of these techniques to piggery slaughterhouse sewage. A plant located in Northern Italy was monitored for 1 year. Physical, chemical and operation parameters were measured; the activated sludge community (ciliates, flagellates, amoebae and small metazoa) was analysed for calculating SBI and SI. Floc and filamentous bacteria were examined and described accordingly with internationally adopted criteria. The results showed the full applicability of the studied techniques for optimizing the operation of a piggery slaughterhouse wastewater treatment plant. PMID:27072565

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

    PubMed Central

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

    2015-01-01

    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. PMID:26160685

  17. Evaluation-of soil enzyme activities as soil quality indicators in sludge-amended soils.

    PubMed

    Dindar, Efsun; Şağban, Fatma Olcay Topaç; Başkaya, Hüseyin Savaş

    2015-07-01

    Soil enzymatic activities are commonly used as biomarkers of soil quality. Several organic and inorganic compounds found in municipal wastewater sludges can possibly be used as fertilizers. Monitoring and evaluating the quality of sludge amended soils with enzyme activities accepted as a beneficial practice with respect to sustainable soil management. In the present study, variation of some enzyme activities (Alkaline phosphatase, dehydrogenase, urease and beta-glucosidase activities) in soils amended with municipal wastewater sludge at different application rates (50, 100 and 200 t ha(-1) dry sludge) was evaluated. Air dried sludge samples were applied to soil pots and sludge-soil mixtures were incubated during a period of three months at 28 degrees C. The results of the study showed that municipal wastewater sludge amendment apparently increased urease, dehydrogenase, alkaline phosphatase and P-glucosidase activities in soil by 48-70%, 14-47%, 33-66% and 9-14%, respectively. The maximum activity was generally observed in sludge amended soil with dose of 200 t ha(-1). Urease activity appeared to be a better indicator of soil enhancement with wastewater sludge, as its activity was more strongly increased by sludge amendment. Accordingly, urease activity is suggested to be soil quality indicator best suited for measuring existing conditions and potential changes in sludge-amended soil.

  18. The partitioning of alkylphenolic surfactants and polybrominated diphenyl ether flame retardants in activated sludge batch tests.

    PubMed

    Langford, Katherine H; Scrimshaw, Mark D; Birkett, Jason W; Lester, John N

    2005-12-01

    Polybrominated diphenyl ethers and nonylphenol polyethoxylates have been reported to be estrogenic and may enter the aquatic environment through the discharge of treated sewage effluent. Therefore, their fate during wastewater treatment processes is an important factor in determining their environmental impact. Batch tests with activated sludge from a Husmann apparatus were used to determine the effects of physico-chemical properties and sludge characteristics on the partitioning of polybrominated diphenyl ether flame retardants and nonylphenol polyethoxylate surfactants during biological wastewater treatment. Hydrophobic compounds, those with high logK(ow) values, were sorbed more rapidly and to a greater extent to the solid phase than more soluble compounds. For these hydrophobic compounds sorption may become an increasingly important removal mechanism as sludge age and therefore solids content increase. The initial rate of partitioning was greatest for the most hydrophobic compounds but all rates diminished with time as a result of progressive saturation of sorbent binding sites, a reduction of sorbate availability and as a consequence of the system reaching equilibrium. The sorption of polybrominated diphenyl ethers fit Freundlich adsorption isotherms demonstrating generally increasing adsorption capacity and efficiency with increasing hydrophobic nature. A correlation between increasing logK(ow) and increasing organic matter content was also observed for both polybrominated diphenyl ethers and nonylphenol polyethoxylates indicating the organic content of mixed liquor will also be influential in removing compounds during wastewater treatment. PMID:15950259

  19. Improving Settling Characteristics of Pure Oxygen Activated Sludge by Stripping of Carbon Dioxide.

    PubMed

    Kundral, Somshekhar; Mudragada, Ratnaji; Coro, Ernesto; Moncholi, Manny; Mora, Nelson; Laha, Shonali; Tansel, Berrin

    2015-06-01

    Increased microbial activity at high ambient temperatures can be problematic for secondary clarifiers and gravity concentrators due to carbon dioxide (CO2) production. Production of CO2 in gravity concentrators leads to septic conditions and poor solids separation. The CO2 production can also be corrosive for the concrete surfaces. Effectiveness of CO2 stripping to improve solids settling was investigated using the sludge volume index (SVI) as the indicator parameter. Carbon dioxide was stripped by aeration from the sludge samples. Results from the study show that aeration also increased the pH values in the mixed liquor while removing CO2 and improving sludge settling. After 10 minutes of aeration at a rate of 0.37 m3 air/m3 water/min, 90% CO2 stripping was achieved. Based on the 30 min settling tests, the SVI increased by 26±1% after CO2 stripping while the pH increased by 0.8±0.1 pH units. PMID:26459818

  20. Thermo-alkaline pretreatment of waste activated sludge at low-temperatures: effects on sludge disintegration, methane production, and methanogen community structure.

    PubMed

    Kim, Jaai; Yu, Youngseob; Lee, Changsoo

    2013-09-01

    Low-temperature thermo-alkaline pretreatment of waste activated sludge (WAS) was studied, within the region of 0-0.2 M NaOH and 60-90°C, for the effects of NaOH concentration and temperature on sludge degradability in anaerobic digestion (AD). Significant disintegration of sludge solids (up to 75.6%) and an increase in methane production (up to 70.6%) were observed in the pretreatment trials. Two quadratic models were successfully generated by response surface analysis (R(2)>0.9, p<0.05) to approximate how the degree of sludge disintegration (SD) and methane production (MP) respond to changes in the pretreatment conditions. The maximum responses of SD (77.8%) and MP (73.9% increase over the control) were shown at [0.16 M NaOH, 90°C] and [0.10 M NaOH, 73.7°C], respectively. NaOH addition showed a significant influence on the evolution of methanogen community structure during AD, whereas temperature did not. Aceticlastic Methanosaeta and Methanosarcina speceies were likely the major methanogens.

  1. Chlorine-Susceptible and Chlorine-Resistant Type 021N Bacteria Occurring in Bulking Activated Sludges

    PubMed Central

    Séka, M. A.; Kalogo, Y.; Hammes, F.; Kielemoes, J.; Verstraete, W.

    2001-01-01

    Two filamentous bacteria causing bulking in two activated sludges were examined. Investigations using morphological features, staining techniques, and fluorescent in situ hybridization identified both filaments as type 021N. However, an examination of the effect of chlorine on the sludges revealed a chlorine-susceptible type 021N in one sludge and a chlorine-resistant type 021N in the other. PMID:11679359

  2. 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...

  3. Degradation of the unbiodegradable particulate fraction (XU) from different activated sludges during batch digestion tests at ambient temperature.

    PubMed

    Habermacher, Jonathan; Benetti, Antonio Domingues; Derlon, Nicolas; Morgenroth, Eberhard

    2016-07-01

    One strategy for the management of excess sludge in small wastewater treatment plants (WWTPs) consists in minimizing the excess sludge production by operating the WWTP at very long solids retention times (SRTs > 30 days). A number of recent studies have suggested that sludge minimization at very long SRT results from the degradation of the unbiodegradable particulate fraction (XU) (influent unbiodegradable compounds and endogenous decay products). But the biodegradability of the unbiodegradable particulate fraction has only been evaluated during batch digestion test performed at ambient temperature with sludge fed with synthetic wastewaters. It is not clear to what extent observations made for sludge fed with synthetic influents can be transposed to sludge fed with real influent. The current study thus focused on evaluating the biodegradability of the unbiodegradable particulate fraction for sludge fed with real wastewater. Batch digestion tests (400 days, ambient temperature) were conducted with three different sludges fed with either synthetic or real influents and exposed to aerobic or intermittent aeration conditions. Our results indicate that volatile suspended solids (VSS) decreased even after complete decay of the active biomass (i.e., after 30 days of aerobic batch digestion) indicating that the unbiodegradable particulate fraction is biodegradable. However, very low degradation rates of the unbiodegradable particulate fraction were monitored after day 30 of digestion (0.7-1.7·10(-3) d(-1)). These values were in the lower range of previously published values for synthetic wastewaters (1-7.5·10(-3) d(-1)). The low values determined in our study indicate that the rate could decrease over time or that sludge composition influences the degradability of the unbiodegradable particulate fraction. But our results also demonstrate that extracellular polymeric substances (EPS) have a minor impact on the biodegradability of the unbiodegradable particulate

  4. Minimization of excess sludge production by in-situ activated sludge treatment processes--a comprehensive review.

    PubMed

    Guo, Wan-Qian; Yang, Shan-Shan; Xiang, Wen-Sheng; Wang, Xiang-Jing; Ren, Nan-Qi

    2013-12-01

    The widespread application of conventional activated sludge treatment process has been employed to deal with a variety of municipal and industrial sewage. While the generation of waste activated sludge (WAS) was considerably huge, the management and disposal expenses were substantially costly. A promising process aimed for WAS reduction during the operation process is urgently needed. Thus, increasing attentions emphasizing on the improved or novel sludge reduction processes should be intensively recommended in the future. This review presents the current and emerging technologies for excess sludge minimization within the process of sewage treatment. The ultimate purpose of this paper is to guide or inspire researchers who are seeking feasible and promising technologies (or processes) to tackle the severe WAS problem.

  5. Anaerobic treatment of activated sludge from Swedish pulp and paper mills--biogas production potential and limitations.

    PubMed

    Karlsson, Anna; Truong, Xu-Bin; Gustavsson, Jenny; Svensson, Bo H; Nilsson, Fredrik; Ejlertsson, Jörgen

    2011-10-01

    The methane potential of activated sludge from six Swedish pulp and paper mills was evaluated. The methane production potential of sludge samples ranged from 100-200 NmL CH4 g(-1) volatile solids (VS) and for four of the six sludge samples the potential exceeded 170 NmL CH4 g(-1) VS. The effects of sludge age and dewatering on the methane production potential were evaluated. The effects of enzymatic and ultrasonic pre-treatment on the digestibility of sludge were also investigated, but energy or enzyme inputs in viable ranges did not exert a detectable, positive effect. Long-term, semi-continuous trials with sludge from two of the mills were also conducted in attempts to develop stable biogas production at loading rates up to 4 g VS L(-1). Cobalt addition (0.5 mg L(-1)) was here found to positively affect the turnover of acetate. High viscosity was a problem in all the experimental reactors and this limited the organic loading rate.

  6. Influence of wastewater treatment plants' operational conditions on activated sludge microbiological and morphological characteristics.

    PubMed

    Amanatidou, Elisavet; Samiotis, Georgios; Trikoilidou, Eleni; Tzelios, Dimitrios; Michailidis, Avraam

    2016-01-01

    The effect of wastewater composition and operating conditions in activated sludge (AS) microbiological and morphological characteristics was studied in three AS wastewater treatment plants (WWTPs): (a) a high organic load slaughterhouse AS WWTP, operating at complete solids retention, monitored from its start-up and for 425 days; (b) a seasonally operational, low nitrogen load fruit canning industry AS WWTP, operating at complete solids retention, monitored from its start-up and until the end of the season (87 days); (c) a municipal AS WWTP, treating wastewater from a semi-combined sewer system, monitored during the transitions from dry to rainy and again to dry periods of operation. The sludge microbiological and morphological characteristics were correlated to nutrients' availability, solids retention time, hydraulic retention time, dissolved oxygen, mixed liquor suspended solids (MLVSS), organic load (F/M) and substrate utilization rate. The AS WWTPs' operation was distinguished in periods based on biomass growth phase, characterized by different biological and morphological characteristics and on operational conditions. An anoxic/aerobic selector minimizes the readily biodegradable compounds in influent, inhibiting filamentous growth. Plant performance controlling is presented in a logic flowchart in which operational parameters are linked to microbial manipulation, resulting in a useful tool for researchers and engineers. PMID:26145184

  7. Influence of wastewater treatment plants' operational conditions on activated sludge microbiological and morphological characteristics.

    PubMed

    Amanatidou, Elisavet; Samiotis, Georgios; Trikoilidou, Eleni; Tzelios, Dimitrios; Michailidis, Avraam

    2016-01-01

    The effect of wastewater composition and operating conditions in activated sludge (AS) microbiological and morphological characteristics was studied in three AS wastewater treatment plants (WWTPs): (a) a high organic load slaughterhouse AS WWTP, operating at complete solids retention, monitored from its start-up and for 425 days; (b) a seasonally operational, low nitrogen load fruit canning industry AS WWTP, operating at complete solids retention, monitored from its start-up and until the end of the season (87 days); (c) a municipal AS WWTP, treating wastewater from a semi-combined sewer system, monitored during the transitions from dry to rainy and again to dry periods of operation. The sludge microbiological and morphological characteristics were correlated to nutrients' availability, solids retention time, hydraulic retention time, dissolved oxygen, mixed liquor suspended solids (MLVSS), organic load (F/M) and substrate utilization rate. The AS WWTPs' operation was distinguished in periods based on biomass growth phase, characterized by different biological and morphological characteristics and on operational conditions. An anoxic/aerobic selector minimizes the readily biodegradable compounds in influent, inhibiting filamentous growth. Plant performance controlling is presented in a logic flowchart in which operational parameters are linked to microbial manipulation, resulting in a useful tool for researchers and engineers.

  8. Effect of copper in the protistan community of activated sludge.

    PubMed

    Nicolau, Ana; Martins, Maria João; Mota, Manuel; Lima, Nelson

    2005-02-01

    Protists have proved to be an interesting tool for assessing the occurrence of pollution in wastewater treatment systems along with its role in the control of pollution itself through grazing of dispersed bacteria and maintenance of a healthy trophic web in those artificial ecosystems. Two sets of assays were carried on in a bench scale pilot plant in order to study the response of the activated sludge community of protists to the exposure of copper: the first set was carried on with synthetic sewage and the second one with real sewage. The results emphasize the ability of activated sludge biological communities to survive and to react to toxicants and highlight the role of protistan communities as indicators of toxicants entrance in treatment systems.

  9. Fate and effect of naphthenic acids on oil refinery activated sludge wastewater treatment systems.

    PubMed

    Misiti, Teresa; Tezel, Ulas; Pavlostathis, Spyros G

    2013-01-01

    Naphthenic acids (NAs) are a complex group of alkyl-substituted acyclic, monocyclic and polycyclic carboxylic acids present in oil sands process waters, crude oil, refinery wastewater and petroleum products. Crude oil, desalter brine, influent, activated sludge mixed liquor and effluent refinery samples were received from six United States refineries. The total acid number (TAN) of the six crudes tested ranged from 0.12 to 1.5 mg KOH/g crude oil and correlated to the total NA concentration in the crudes. The total NA concentration in the desalter brine, influent, activated sludge mixed liquor and effluent samples ranged from 4.2 to 40.4, 4.5 to 16.6, 9.6 to 140.3 and 2.8 to 11.6 mg NA/L, respectively. The NAs in all wastewater streams accounted for less than 16% of the total COD, indicating that many other organic compounds are present and that NAs are a minor component in refinery wastewaters. Susceptibility tests showed that none of the activated sludge heterotrophic microcosms was completely inhibited by NAs up to 400 mg/L. Growth inhibition ranging from 10 to 59% was observed in all microcosms at and above 100 mg NA/L. NAs chronically-sorbed to activated sludge mixed liquor biomass and powdered activated carbon (PAC) were recalcitrant and persistent. More than 80% of the total NAs remained in the solid phase at the end of the 10-day desorption period (five successive desorption steps). Throughout a 90-day incubation period, the total NA concentration decreased by 33 and 51% in PAC-free and PAC-containing mixed liquor microcosms, respectively. The lower molecular weight fraction of NAs was preferentially degraded in both mixed liquors. The persistence of the residual, higher molecular weight NAs is likely a combination of molecular recalcitrance and decreased bioavailability when chronically-sorbed to the biomass and/or PAC. PMID:23141768

  10. Fate and effect of naphthenic acids on oil refinery activated sludge wastewater treatment systems.

    PubMed

    Misiti, Teresa; Tezel, Ulas; Pavlostathis, Spyros G

    2013-01-01

    Naphthenic acids (NAs) are a complex group of alkyl-substituted acyclic, monocyclic and polycyclic carboxylic acids present in oil sands process waters, crude oil, refinery wastewater and petroleum products. Crude oil, desalter brine, influent, activated sludge mixed liquor and effluent refinery samples were received from six United States refineries. The total acid number (TAN) of the six crudes tested ranged from 0.12 to 1.5 mg KOH/g crude oil and correlated to the total NA concentration in the crudes. The total NA concentration in the desalter brine, influent, activated sludge mixed liquor and effluent samples ranged from 4.2 to 40.4, 4.5 to 16.6, 9.6 to 140.3 and 2.8 to 11.6 mg NA/L, respectively. The NAs in all wastewater streams accounted for less than 16% of the total COD, indicating that many other organic compounds are present and that NAs are a minor component in refinery wastewaters. Susceptibility tests showed that none of the activated sludge heterotrophic microcosms was completely inhibited by NAs up to 400 mg/L. Growth inhibition ranging from 10 to 59% was observed in all microcosms at and above 100 mg NA/L. NAs chronically-sorbed to activated sludge mixed liquor biomass and powdered activated carbon (PAC) were recalcitrant and persistent. More than 80% of the total NAs remained in the solid phase at the end of the 10-day desorption period (five successive desorption steps). Throughout a 90-day incubation period, the total NA concentration decreased by 33 and 51% in PAC-free and PAC-containing mixed liquor microcosms, respectively. The lower molecular weight fraction of NAs was preferentially degraded in both mixed liquors. The persistence of the residual, higher molecular weight NAs is likely a combination of molecular recalcitrance and decreased bioavailability when chronically-sorbed to the biomass and/or PAC.

  11. Investigating the fundamental basis for selectors to improve activated sludge settling.

    PubMed

    Gray, Donald M D; De Lange, Vincent P; Chien, Mark H; Esquer, Mark A; Shao, Y J

    2010-06-01

    Aerobic, anoxic, and anaerobic selectors have become popular for controlling filamentous bulking in activated sludge systems; however, selectors are not always successful. Regression analyses of data collected from 48 full-scale wastewater treatment plants, with operating selectors, provided a method for ranking the importance of selector operating and design parameters (with respect to their influence on activated sludge settleability) and suggests optimum numerical ranges for these parameters for best selector performance. Selectors do not appear to control filamentous bulking in long mean cell residence time (MCRT) plants. Further, the elimination of all selector zones may help to control bulking in these plants. However, other design/operating parameters were shown to influence activated sludge settleability in long-MCRT plants. Aerobic selectors in short-MCRT plants can control filamentous bulking, if they are small enough to produce a biochemical oxygen demand (BOD) concentration gradient. Anoxic and anaerobic selectors can control filamentous bulking in short-MCRT plants, if the selector volume is large enough and/or the selector mixed-liquor suspended solids concentration is high enough. These unaerated selector systems do not appear to benefit from a BOD concentration gradient as the aerobic selectors in short-MCRT plants do. Although anaerobic/anoxic selector compartmentalization in these plants appears to improve settleability, this presumably is because of reduced selector short-circuiting. PMID:20572462

  12. A new, pellet-forming fungal strain: its isolation, molecular identification, and performance for simultaneous sludge-solids reduction, flocculation, and dewatering.

    PubMed

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

    2008-09-01

    Filamentous and nonfilamentous microorganisms can cause bulking and foaming in wastewater sludge settling and dewatering. In this research, sludge degradation and bioflocculation was studied using pellet-forming filamentous fungi isolated from municipal wastewater sludge. To understand the role of filamentous fungi in sludge settling and dewatering, the isolated fungi was inoculated with both spores and pellets (beads) into sterilized and nonsterilized sludge having different suspended-solids concentrations. Biofloc formation, sludge settling, sludge degradation, change in pH of fungal-grown medium, zeta potential, and microscopic analysis of bioflocs were performed. The suspended-solids concentration was found to decrease over 5 d of incubation because of use and biodegradation by fungal biomass. The isolated fungal strain was well adapted to forming biofloc and to interacting with natural microbial flora and exhibited low capillary-suction time for sludge dewatering. PMID:18939607

  13. Enhancement in hydrogen production by thermophilic anaerobic co-digestion of organic fraction of municipal solid waste and sewage sludge--optimization of treatment conditions.

    PubMed

    Tyagi, Vinay Kumar; Angériz Campoy, Rubén; Álvarez-Gallego, C J; Romero García, L I

    2014-07-01

    Batch dry-thermophilic anaerobic co-digestion (55°C) of organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) for hydrogen production was studied under several sludge combinations (primary sludge, PS; waste activated sludge, WAS; and mixed sludge, MS), TS concentrations (10-25%) and mixing ratios of OFMSW and SS (1:1, 2.5:1, 5:1, 10:1). The co-digestion of OFMSW and SS showed a 70% improvement in hydrogen production rate over the OFMSW fermentation only. The co-digestion of OFMSW with MS showed 47% and 115% higher hydrogen production potential as compared with OFMSW+PS and OFMSW+WAS, respectively. The maximum hydrogen yield of 51 mL H2/g VS consumed was observed at TS concentration of 20% and OFMSW to MS mixing ratio of 5:1, respectively. The acetic and butyric acids were the main acids in VFAs evolution; however, the higher butyric acid evolution indicated that the H2 fermentation was butyrate type fermentation.

  14. Preparation of activated carbon from wet sludge by electrochemical-NaClO activation.

    PubMed

    Miao, Chen; Ye, Caihong; Zhu, Tianxing; Lou, Ziyang; Yuan, Haiping; Zhu, Nanwen

    2014-01-01

    Activated carbon (AC) from sludge is one potential solution for sewage sludge disposal, while the drying sludge is cost and time consuming for preparation. AC preparation from the wet sludge with electrochemical-NaClO activation was studied in this work. Three pretreatment processes, i.e. chemical activation, electrolysis and electrochemical-reagent reaction, were introduced to improve the sludge-derived AC properties, and the optimum dosage of reagent was tested from the 0.1:1 to 1:1 (mass rate, reagent:dried sludge). It was shown that the electrochemical-NaClO preparation is the best method under the test conditions, in which AC has the maximum Brunauer, Emmett and Teller area of 436 m²/g at a mass ratio of 0.7. Extracellular polymeric substances in sludge can be disintegrated by electrochemical-NaClO pretreatment, with a disintegration degree of more than 45%. The percentage of carbon decreased from 34.16 to 8.81 after treated by electrochemical-NaClO activation. Fourier transform infrared spectra showed that a strong C-Cl stretching was formed in electrochemical-NaClO prepared AC. The maximum adsorption capacity of AC reaches 109 mg/g on MB adsorption experiment at pH 10 and can be repeated for three times with high removal efficiency after regeneration.

  15. Micropollutant degradation via extracted native enzymes from activated sludge.

    PubMed

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

    2016-05-15

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

  16. Micropollutant degradation via extracted native enzymes from activated sludge.

    PubMed

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

    2016-05-15

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

  17. Investigating the fate of activated sludge extracellular proteins in sludge digestion using sodium dodecyl sulfate polyacrylamide gel electrophoresis.

    PubMed

    Park, Chul; Helm, Richard F; Novak, John T

    2008-12-01

    The fate of activated sludge extracellular proteins in sludge digestion was investigated using three different cation-associated extraction methods and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Extraction methods used were the cation exchange resin (CER) method for extracting calcium (Ca2+) and magnesium (Mg2+), sulfide extraction for removing iron, and base treatment (pH 10.5) for dissolving aluminum. Extracellular polymeric substances extracted were then subjected to SDS-PAGE, and the resultant protein profiles were examined before and after sludge digestion. The SDS-PAGE results showed that three methods led to different SDS-PAGE profiles for both undigested and digested sludges. The results further revealed that CER-extracted proteins remained mainly undegraded in anaerobic digestion, but were degraded in aerobic digestion. While the fate of sulfide- and base-extracted proteins was not clear for aerobic digestion, their changes in anaerobic digestion were elucidated. Most sulfide-extracted proteins were removed by anaerobic digestion, while the increase in protein band intensity and diversity was observed for base-extracted proteins. These results suggest that activated sludge flocs contain different fractions of proteins that are distinguishable by their association with certain cations and that each fraction undergoes different fates in anaerobic and aerobic digestion. The proteins that were resistant to degradation and generated during anaerobic digestion were identified by liquid chromatography tandem mass spectrometry. Protein identification results and their putative roles in activated sludge and anaerobic digestion are discussed in this study. PMID:19146099

  18. Simple method for the measurement of the hydrogenotrophic methanogenic activity of anaerobic sludges

    USGS Publications Warehouse

    Coates, J.D.; Coughlan, M.F.; Colleran, E.

    1996-01-01

    The specific hydrogenotrophic activity of anaerobic sludges is usually assayed by gas chromatographic analysis for methane in the headspace of sealed test vials. Gas is sampled with a pressure lock syringe which allows quantification independent of the pressure prevailing in the vials. An alternative method was developed using pressure transducer monitoring of the decrease in headspace gas pressure as the H2/CO2 substrate is converted to CH4. Application of a simple formula related the decrease at each sample point to millilitres of CH4 produced and gave values for the specific hydrogenotrophic activity of granular anaerobic sludge which were in good agreement with the values obtained by the more labor-intensive gas chromatographic method. The simplicity of the method facilitates multiple replicate analyses and allows more accurate determination of initial rates than is achievable by the gas chromatographic method which is prone to analytical error at the very low concentrations of CH4 present in the headspace during the early stages of the assay. Mass transfer of H2 from headspace to liquid was found to be rate-limiting and to result in significant under-estimation of the specific hydrogenotrophic activity of the granular sludge. A test protocol, which used a vial volatile suspended solids concentration between 1.7 and 8 g l-1; a 1:5 ratio between liquid and headspace; incubation of the vials horizontally with vigorous shaking (180 rev./min) and an initial H2/CO2 (80/20) gas pressure of 100-150 kPa was found to give reproducible and maximal values for the specific hydrogenotrophic activity of the test sludge.

  19. Evaluation of the persistence of micropollutants through pure-oxygen activated sludge nitrification and denitrification

    USGS Publications Warehouse

    Levine, A.D.; Meyer, M.T.; Kish, G.

    2006-01-01

    The persistence of pharmaceuticals, hormones, and household and industrial chemicals through a pure-oxygen activated sludge, nitrification, denitrification wastewater treatment facility was evaluated. Of the 125 micropollutants that were tested in this study, 55 compounds were detected in the untreated wastewater, and 27 compounds were detected in the disinfected effluent. The persistent compounds included surfactants, fire-retardant chemicals, pesticides, fragrance compounds, hormones, and one pharmaceutical. Physical-chemical properties of micropollutants that affected partitioning onto wastewater solids included vapor pressure and octanol-water partition coefficients.

  20. Effects of additives on the co-pyrolysis of municipal solid waste and paper sludge by using thermogravimetric analysis.

    PubMed

    Fang, Shiwen; Yu, Zhaosheng; Lin, Yan; Lin, Yousheng; Fan, Yunlong; Liao, Yanfen; Ma, Xiaoqian

    2016-06-01

    By using thermogravimetric analysis (TGA), the effects of different additives (MgO, Al2O3 and ZnO) on the pyrolysis characteristics and activation energy of municipal solid waste (MSW), paper sludge (PS) and their blends in N2 atmosphere had been investigated in this study. The experiments resulted that these additives were effective in reducing the initial temperature and activation energy. However, not all the additives were beneficial to reduce the residue mass and enhance the index D. For the different ratios of MSW and PS, the same additive even had the different influences. The catalytic effects of additives were not obvious and the pyrolysis became difficult with the increase of the proportion of PS. Based on all the contrast of the pyrolysis characteristics, MgO was the best additive and 70M30P was the best ratio, respectively. PMID:26985626

  1. Enzymatic extraction of activated sludge extracellular polymers and implications on bioflocculation.

    PubMed

    Sesay, Mohamed Lamin; Ozcengiz, Gülay; Dilek Sanin, F

    2006-04-01

    This study examines enzyme hydrolysis, a mild, effective, but a rarely used method of extracellular polymer extraction, in removing polymers from mixed culture activated sludge flocs. Two carbohydrate specific enzymes (alpha-amylase and cellulase) and a protein specific enzyme (proteinase) are used during the study. First, the kinetic aspect is investigated, then enzyme dose optimization is carried out on laboratory grown activated sludge samples cultured at solids retention times (SRT) of 4 and 20 days. A more commonly used cation exchange resin (CER) extraction technique is also employed for comparison purposes. Results indicate that the extraction of extracellular polymers by enzymes is a rather quick process reaching equilibrium within only a few hours. As the doses of enzymes are increased, the extracted polymer quantities increase up to a certain dose, beyond which not much extraction is observed. The method does not cause any significant cell lysis as measured by the viable cell counts. Carbohydrate-hydrolyzing enzymes extract small amount of proteins along with the carbohydrates and protein-hydrolyzing enzyme extracts some carbohydrates together with the proteins, indicating that proteins and carbohydrates exist bound to each other in the extracellular polymer network of sludge. Enzyme extraction generally gives a lower estimate of polymers compared to the CER method, but correctly detects the trends in the polymer quantity.

  2. The influence of multivalent cations on the flocculation of activated sludge with different sludge retention times.

    PubMed

    Li, Haisong; Wen, Yue; Cao, Asheng; Huang, Jingshui; Zhou, Qi

    2014-05-15

    The mechanism governing the flocculation of activated sludge (AS) with different sludge retention times (SRTs) was studied in this paper. AS samples were cultivated in 8 lab-scale reactors with SRTs of 5 d, 7.5 d, 10 d, 12.5 d, 15 d, 20 d, 30 d, and 40 d. The bulk solution, loosely bound extracellular polymeric substances (LB-EPS), tightly bound EPS (TB-EPS), and pellet were extracted for all 8 AS samples. There was a clear trend that the effluent turbidity decreased as the SRT increased, and we deduced that this is because AS samples with longer SRTs have lower interaction energy barriers and lower LB-EPS content. Furthermore, the concentrations of multivalent cations (especially trivalent cations) in the pellets were found to be closely correlated to the AS flocculability, total interaction energy (Wtot), and LB-EPS content. The multivalent (especially trivalent) cations possess greater binding ability, and this ability to bind tightly to AS in large quantities is responsible for the superior flocculability of AS samples with longer SRTs. Hence, the concentrations of multivalent cations in the pellets are an important indicator of AS flocculability. We deduced that variations in the quantities of multivalent cations that tightly bind with the AS rather than remaining in the influent are the core reason behind observed fluctuations in the AS flocculability with different SRTs.

  3. Simultaneous removal of organic matter and nitrogen from milking parlor wastewater by a magnetic activated sludge (MAS) process.

    PubMed

    Ying, Chun; Umetsu, Kazutaka; Ihara, Ikko; Sakai, Yasuzo; Yamashiro, Takaki

    2010-06-01

    The magnetic activated sludge (MAS) process is a modification of the conventional activated sludge process to improve the solid-liquid separation characteristics. It was developed to reduce the production of excess sludge and the time required for the conventional activated sludge process. In this study, actual milking parlor wastewater was treated with a MAS process and no sludge was removed. The effectiveness of continuous aeration and intermittent aeration in removing organic matter and nitrogen were compared. Both processes were highly efficient at removing chemical oxygen demand (COD) (averaged 91% removal) and ammonium nitrogen (NH(4)-N) (averaged 99% removal). In marked contrast to the continuous aeration process, the 30-min aeration/90-min non-aeration cycle of the intermittent aeration process rapidly reduced the nitrate nitrogen (NO(3)-N) concentration to near-zero. This result indicates that NO(3)-N was almost completely denitrified via nitrite nitrogen (NO(2)-N) to nitrogen gas. Removal of organic material and nitrogen can be considered to have occurred simultaneously in the single tank of the MAS process.

  4. Hazard Evaluation for Storage of Spent Nuclear Fuel (SNF) Sludge at the Solid Waste Treatment Facility

    SciTech Connect

    SCHULTZ, M.V.

    2000-08-22

    As part of the Spent Nuclear Fuel (SNF) storage basin clean-up project, sludge that has accumulated in the K Basins due to corrosion of damaged irradiated N Reactor will be loaded into containers and placed in interim storage. The Hanford Site Treatment Complex (T Plant) has been identified as the location where the sludge will be stored until final disposition of the material occurs. Long term storage of sludge from the K Basin fuel storage facilities requires identification and analysis of potential accidents involving sludge storage in T Plant. This report is prepared as the initial step in the safety assurance process described in DOE Order 5480.23, Nuclear Safety Analysis Reports and HNF-PRO-704, Hazards and Accident Analysis Process. This report documents the evaluation of potential hazards and off-normal events associated with sludge storage activities. This information will be used in subsequent safety analyses, design, and operations procedure development to ensure safe storage. The hazards evaluation for the storage of SNF sludge in T-Plant used the Hazards and Operability Analysis (HazOp) method. The hazard evaluation identified 42 potential hazardous conditions. No hazardous conditions involving hazardous/toxic chemical concerns were identified. Of the 42 items identified in the HazOp study, eight were determined to have potential for onsite worker consequences. No items with potential offsite consequences were identified in the HazOp study. Hazardous conditions with potential onsite worker or offsite consequences are candidates for quantitative consequence analysis. The hazardous conditions with potential onsite worker consequences were grouped into two event categories, Container failure due to overpressure - internal to T Plant, and Spill of multiple containers. The two event categories will be developed into accident scenarios that will be quantitatively analyzed to determine release consequences. A third category, Container failure due to

  5. 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.

  6. Synergistic cooperation between wastewater-born algae and activated sludge for wastewater treatment: influence of algae and sludge inoculation ratios.

    PubMed

    Su, Yanyan; Mennerich, Artur; Urban, Brigitte

    2012-02-01

    An algal-bacterial culture, composed of wastewater-born algae and activated sludge, was cultivated to treat domestic wastewater and accumulate biomass simultaneously. The influence of algae and sludge inoculation ratios on the treatment efficiency and the settleability of the accumulated biomass were investigated. There was no significant effect of the inoculation ratios on the chemical oxygen demand removal. Comparatively, the nutrients removal and related mechanism were varied with different inoculation ratios. The highest nitrogen and phosphorus removal efficiencies were observed with 5:1 (algae/sludge) culture (91.0±7.0% and 93.5±2.5%, respectively) within 10 days, which was 5-40% higher and 2-4 days faster than those with other inoculation ratios. The biomass settleability was improved with the assistance of sludge, and the 1:5 (algae/sludge) culture showed the best settleability. Furthermore, 16S rDNA gene analysis showed that the bacterial communities were varying with different algae and sludge inoculation ratios and some specific bacteria were enriched during operation.

  7. Evaluating sludge minimization caused by predation and viral infection based on the extended activated sludge model No. 2d.

    PubMed

    Hao, Xiaodi; Wang, Qilin; Cao, Yali; van Loosdrecht, Mark C M

    2011-10-15

    The Activated Sludge Model No. 2d (ASM2d) was extended to incorporate the processes of both predation and viral infection. The extended model was used to evaluate the contributions of predation and viral infection to sludge minimization in a sequencing batch reactor (SBR) system enriching polyphosphate-accumulating organisms (PAOs). Three individual decay processes formulated according to the general model rules were used in the extended model. The model was firstly calibrated and validated by different experimental results. It was used to evaluate the potential extent of predation and viral infection on sludge minimization. Simulations indicate that predation contributes roughly two times more to sludge minimization than viral infection in the SBR system enriching PAOs. The sensitivity analyses of the selected key parameters reveal that there are thresholds on both predation and viral infection rates, if they are too large a minimal sludge retention time is obtained and the effluent quality is deteriorating. Due to the thresholds, the contributions of predation and viral infection to sludge minimization are limited to a maximal extent of about 21% and 9%, respectively. However, it should be noted that the parameters concerning predation and viral infection were not calibrated separately by independent experiment in our study due to the lack of an effective method, especially for the parameters regarding viral infection. Therefore, it is essential to better evaluate these parameters in the future.

  8. Solid-liquid separation of faecal sludge using drying beds in Ghana: implications for nutrient recycling in urban agriculture.

    PubMed

    Cofie, O O; Agbottah, S; Strauss, M; Esseku, H; Montangero, A; Awuah, E; Kone, D

    2006-01-01

    This study investigated the possibility of recycling nutrients in human excreta and municipal solid waste for use in agriculture. It reports on the use of drying beds in separating solid and liquid fractions of faecal sludge (FS) so that the solids can be co-composted and the organic matter and part of the nutrients captured for urban agriculture. Sludge influent onto drying beds, percolate effluent, and dewatered sludge (biosolids) were monitored over eight loading cycles in 2002. The unplanted drying beds were made of 15 cm of sand (0.2-0.6mm diameter) and 25 cm gravel (10 and 19 mm diameter). The loading rate of sludge ranged from 196 to 321 kg total solids (TS) /m(2)y. Biosolids with TS 20% were obtained after an average drying time of 2 weeks. The drying beds retained 80% of solids and 100% of helminth eggs. The biosolids had average organic matter content of 61%; hence, allowing for co-composting with biodegradable organic solid waste for hygienisation. The process is being investigated further to attain higher efficiency and reliability.

  9. [Synergistic effects of nano-sized magnetic particles and uncoupler to the characteristics of activated sludge].

    PubMed

    Gao, Li-ying; Tang, Bing; Liang, Ling-yan; Huang, Shao-song; Fu, Feng-lian; Luo, Jian-zhong

    2012-08-01

    For improving the performance and sludge settling property of an activated sludge reduction process with uncoupler, in this investigation, uncoupler and nano-sized magnetic particles were added simultaneously to a sequencing batch reactor for exploring their synergistic effects to the characteristics of activated sludge. The results showed that the volume reduction of sludge reached 41% with single 2,4,5-Trichlorophenol (TCP) Comparing with the control experiment, the biodegradability and settling properties of the activated sludge decreased. Under the actions of TCP combined with nano-sized magnetic particles, the volume reduction of sludge reached 34%, the removal efficiencies of COD, nitrogen, and phosphorus as well as the sludge settling property were not significantly influenced. After 31 d's operation, the dehydrogenase activity was improved by 10%-18% and exhibited an accumulative effect over time. It was observed with an optical microscope that the species and amounts of protozoon and metazoan increased and a compact structure of sludge floc was formed. The results also indicated that using nano-sized magnetic particles and uncoupler could restrict the yield of excess sludge and improve the performance of an activated sludge system. PMID:23213903

  10. Engineering evaluation of solids/liquids separation processes applicable to sludge treatment project

    SciTech Connect

    Duncan, J.B.

    1998-08-25

    This engineering study looks at the solids/liquids separation unit operations after the acid dissolution of the K Basin sludge treatment. Unit operations considered were centrifugation, filtration (cartridge, cross flow, and high shear filtration) and gravity settling. The recommended unit operations for the solids/liquids separations are based upon the efficiency, complexity, and off-the-shelf availability and adaptability. The unit operations recommended were a Robatel DPC 900 centrifuge followed by a nuclearized 31WM cartridge filter. The Robatel DPC 900 has been successfully employed in the nuclear industry on a world wide scale. The 31WM cartridge filter has been employed for filtration campaigns in both the government and civilian nuclear arenas.

  11. Entrapped elemental selenium nanoparticles affect physicochemical properties of selenium fed activated sludge.

    PubMed

    Jain, Rohan; Seder-Colomina, Marina; Jordan, Norbert; Dessi, Paolo; Cosmidis, Julie; van Hullebusch, Eric D; Weiss, Stephan; Farges, François; Lens, Piet N L

    2015-09-15

    Selenite containing wastewaters can be treated in activated sludge systems, where the total selenium is removed from the wastewater by the formation of elemental selenium nanoparticles, which are trapped in the biomass. No studies have been carried out so far on the characterization of selenium fed activated sludge flocs, which is important for the development of this novel selenium removal process. This study showed that more than 94% of the trapped selenium in activated sludge flocs is in the form of elemental selenium, both as amorphous/monoclinic selenium nanospheres and trigonal selenium nanorods. The entrapment of the elemental selenium nanoparticles in the selenium fed activated sludge flocs leads to faster settling rates, higher hydrophilicity and poorer dewaterability compared to the control activated sludge (i.e., not fed with selenite). The selenium fed activated sludge showed a less negative surface charge density as compared to the control activated sludge. The presence of trapped elemental selenium nanoparticles further affected the spatial distribution of Al and Mg in the activated sludge flocs. This study demonstrated that the formation and subsequent trapping of elemental selenium nanoparticles in the activated sludge flocs affects their physicochemical properties.

  12. Chemically coupled microwave and ultrasonic pre-hydrolysis of pulp and paper mill waste-activated sludge: effect on sludge solubilisation and anaerobic digestion.

    PubMed

    Tyagi, Vinay Kumar; Lo, Shang-Lien; Rajpal, Ankur

    2014-05-01

    The effects of alkali-enhanced microwave (MW; 50-175 °C) and ultrasonic (US) (0.75 W/mL, 15-60 min) pretreatments, on solubilisation and subsequent anaerobic digestion efficiency of pulp and paper mill waste-activated sludge, were investigated. Improvements in total chemical oxygen demand and volatile suspended solids (VSS) solubilisation were limited to 33 and 39 % in MW pretreatment only (175 °C). It reached 78 and 66 % in combined MW-alkali pretreatment (pH 12 + 175 °C), respectively. Similarly, chemical oxygen demand and VSS solubilisation were 58 and 37 % in US pretreatment alone (60 min) and it improved by 66 and 49 % after US-alkali pretreatment (pH 12 + 60 min), respectively. The biogas yield for US 60 min-alkali (pH 12)-pretreated sludge was significantly improved by 47 and 20 % over the control and US 60 reactors, respectively. The biogas generation for MW (150 °C)-alkali (pH 12)-pretreated sludge was only 6.3 % higher than control; however, it was 8.3 % lower than the MW (150 °C) reactor, which was due to the inhibition of anaerobic activity under harsh thermal-alkali treatment condition. PMID:24488518

  13. Treatment of coke-oven wastewater with the powdered activated carbon-contact stabilization activated sludge process. Final report

    SciTech Connect

    Suidan, M.T.; Deady, M.A.; Gee, C.S.

    1983-11-01

    The objective of the study was to determine optimum parameters for the operation of an innovative process train used in the treatment of coke-over wastewater. The treatment process train consisted of a contact-stabilization activated sludge system with powdered activated carbon (PAC) addition, followed by activated sludge nitrification, followed by denitrification in an anoxic filter. The control and operating parameters evaluated during the study were: (a) the average mixed-liquor PAC concentration maintained in the contact-stabilization system, (b) the solids retention time practiced in the contact-stabilization system, and (c) the hydraulic detention time maintained in the contact aeration tank. Three identical treatement process trains were constructed and employed in this study. The coke-oven wastewater used for this investigation was fed to the treatment units at 30% strength. The first part of the study was devoted to determining the interactions between the mixed liquor PAC concentration and the solids retention time in the contact-stabilization tanks. Results showed that optimum overall system performance is attainable when the highest sludge age (30 day) and highest mixed liquor PAC concentration were practiced. During the second phase of the study, all three systems were operated at a 30 day solids retention time while different detention times of 1, 2/3 and 1/3 day were evaluated in the contact tank. PAC addition rates were maintained at the former levels and, consequently, reduced contact times entailed higher mixed liquor carbon concentrations. Once again, the system receiving the highest PAC addition rate of PAC exhibited the best overall performance. This system exhibited no deterioration in process performance as a result of decreased contact detention time. 72 references, 41 figures, 24 tables.

  14. 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

  15. Diversity and dynamics of Archaea in an activated sludge wastewater treatment plant

    PubMed Central

    2012-01-01

    Background The activated sludge process is one of the most widely used methods for treatment of wastewater and the microbial community composition in the sludge is important for the process operation. While the bacterial communities have been characterized in various activated sludge systems little is known about archaeal communities in activated sludge. The diversity and dynamics of the Archaea community in a full-scale activated sludge wastewater treatment plant were investigated by fluorescence in situ hybridization, terminal restriction fragment length polymorphism analysis and cloning and sequencing of 16S rRNA genes. Results The Archaea community was dominated by Methanosaeta-like species. During a 15 month period major changes in the community composition were only observed twice despite seasonal variations in environmental and operating conditions. Water temperature appeared to be the process parameter that affected the community composition the most. Several terminal restriction fragments also showed strong correlations with sludge properties and effluent water properties. The Archaea were estimated to make up 1.6% of total cell numbers in the activated sludge and were present both as single cells and colonies of varying sizes. Conclusions The results presented here show that Archaea can constitute a constant and integral part of the activated sludge and that it can therefore be useful to include Archaea in future studies of microbial communities in activated sludge. PMID:22784022

  16. Sewage sludge pretreatment by microwave irradiation combined with activated carbon fibre at alkaline pH for anaerobic digestion.

    PubMed

    Sun, Dedong; Guo, Sixiao; Ma, Nina; Wang, Guowen; Ma, Chun; Hao, Jun; Xue, Mang; Zhang, Xinxin

    2016-01-01

    This research focuses on the effects of microwave-assisted activated carbon fibre (ACF) (MW-ACF) treatment on sewage sludge at alkaline pH. The disintegration and biodegradability of sewage sludge were studied. It was found that the MW-ACF process at alkaline pH provided a rapid and efficient process to disrupt the microbial cells in the sludge. The results suggested that when irradiated at 800 W MW for 110 s with a dose of 1.0 g ACF/g solid concentration (SS) at pH 10.5, the MW-ACF pretreatment achieved 55% SS disintegration, 23% greater than the value of MW alone (32%). The concentration of total nitrogen, total phosphorus, supernatant soluble chemical oxygen demand, protein, and polysaccharide increased by 60%, 144%, 145%, 74%, and 77%, respectively. An increase in biogas production by 63.7% was achieved after 20 days of anaerobic digestion (AD), compared to the control. The results indicated that the MW-ACF pretreatment process at alkaline pH provides novel sludge management options in disintegration of sewage sludge for further AD.

  17. Sewage sludge pretreatment by microwave irradiation combined with activated carbon fibre at alkaline pH for anaerobic digestion.

    PubMed

    Sun, Dedong; Guo, Sixiao; Ma, Nina; Wang, Guowen; Ma, Chun; Hao, Jun; Xue, Mang; Zhang, Xinxin

    2016-01-01

    This research focuses on the effects of microwave-assisted activated carbon fibre (ACF) (MW-ACF) treatment on sewage sludge at alkaline pH. The disintegration and biodegradability of sewage sludge were studied. It was found that the MW-ACF process at alkaline pH provided a rapid and efficient process to disrupt the microbial cells in the sludge. The results suggested that when irradiated at 800 W MW for 110 s with a dose of 1.0 g ACF/g solid concentration (SS) at pH 10.5, the MW-ACF pretreatment achieved 55% SS disintegration, 23% greater than the value of MW alone (32%). The concentration of total nitrogen, total phosphorus, supernatant soluble chemical oxygen demand, protein, and polysaccharide increased by 60%, 144%, 145%, 74%, and 77%, respectively. An increase in biogas production by 63.7% was achieved after 20 days of anaerobic digestion (AD), compared to the control. The results indicated that the MW-ACF pretreatment process at alkaline pH provides novel sludge management options in disintegration of sewage sludge for further AD. PMID:27332832

  18. Enhancement of waste activated sludge anaerobic digestion by a novel chemical free acid/alkaline pretreatment using electrolysis.

    PubMed

    Charles, W; Ng, B; Cord-Ruwisch, R; Cheng, L; Ho, G; Kayaalp, A

    2013-01-01

    Anaerobic digestion of waste activated sludge (WAS) is relatively poor due to hydrolysis limitations. Acid and alkaline pretreatments are effective in enhancing hydrolysis leading to higher methane yields. However, chemical costs often prohibit full-scale application. In this study, 12 V two-chamber electrolysis using an anion exchange membrane alters sludge pH without chemical dosing. pH dropped from 6.9 to 2.5 in the anode chamber and increased to 10.1 in the cathode chamber within 15 h. The volatile suspended solids solubilisation of WAS was 31.1% in the anode chamber and 34.0% in the cathode chamber. As a result, dissolved chemical oxygen demand increased from 164 to 1,787 mg/L and 1,256 mg/L in the anode and cathode chambers, respectively. Remixing of sludge from the two chambers brought the pH back to 6.5, hence no chemical neutralisation was required prior to anaerobic digestion. Methane yield during anaerobic digestion at 20 d retention time was 31% higher than that of untreated sludge. An energy balance assessment indicated that the non-optimised process could approximately recover the energy (electricity) expended in the electrolysis process. With suitable optimisation of treatment time and voltages, significant energy savings would be expected in addition to the benefit of decreased sludge volume.

  19. Bifurcation and chaotic in a model for activated sludge reactors

    NASA Astrophysics Data System (ADS)

    El-Marouf, S. A. A.; Bahaa, G. M.

    2015-04-01

    A dynamical model of an activated sludge process system is considered and analyzed. Numerical techniques are used to show when the system exhibits chaos. Three choices of bifurcation parameters produce different pictures of solution behavior in the form of limit cycles, two-torus and chaotic behavior. For some range of the reactor residence time the model exhibits chaotic behavior as well. Practical criteria are also derived for the effects of feed conditions and purge fraction on the dynamic characteristics of the bioreactor model.

  20. Physicochemical changes effected in activated sludge by the earthworm Eisenia foetida. [Concentration of heavy metals during sludge catabolism

    SciTech Connect

    Hartenstein, R.; Hartenstein, F.

    1981-09-01

    Measurements were made of some physicochemical changes effected in activated sludge by the earthworm Eisenia foetida following conversion of the sludge into wormcasts. Mineralization was accelerated 1.3-fold and 2% of the minerals were assimilated. The rate at which heavy metals were concentrated during sludge catabolism was also accelerated. Castings stabilized within 2 weeks, as indexed by respirometry. Nucleic acids, which can be used as an index of microbial biomass, were present at a greater concentration in the wormcasts than in the sludge, while the phenolic content, which may potentially serve as an index of humification, was less concentrated. Other changes included a reduction in pH and an increase in oxidation-reduction potential and cation exchange capacity. The major general effect of E. foetida on the physicochemical properties of activated sludge is to convert a material which has a relatively small surface/volume ratio into numerous particles with an overall large S/V ratio, thus accelerating decomposition, mineralization, drying, and preclusion of malodor.

  1. Relationship between methanogenic cofactor content and maximum specific methanogenic activity of anaerobic granular sludges

    SciTech Connect

    Gorris, L.G.; de Kok, T.M.; Kroon, B.M.; van der Drift, C.; Vogels, G.D.

    1988-05-01

    In this study we investigated whether a relationship exists between the methanogenic activity and the content of specific methanogenic cofactors of granular sludges cultured on different combinations of volatile fatty acids in upflow anaerobic sludge blanket or fluidized-bed reactors. Significant correlations were measured in both cases between the contents of coenzyme F/sub 420/-2 or methanopterin and the maximum specific methanogenic activities on propionate, butyrate, and hydrogen, but not acetate. For both sludges the content of sarcinapterin appeared to be correlated with methanogenic activities on propionate, butyrate, and acetate, but not hydrogen. Similar correlations were measured with regard to the total content of coenzyme F/sub 420/-4 and F/sub 420/-5 sludges from fluidized-bed reactors. The results indicate that the contents of specific methanogenic cofactors measured in anaerobic granular sludges can be used to estimate the hydrogenotrophic or acetotrophic methanogenic potential of these sludges.

  2. Gamma irradiation induced disintegration of waste activated sludge for biological hydrogen production

    NASA Astrophysics Data System (ADS)

    Yin, Yanan; Wang, Jianlong

    2016-04-01

    In this paper, gamma irradiation was applied for the disintegration and dissolution of waste activated sludge produced during the biological wastewater treatment, and the solubilized sludge was used as substrate for bio-hydrogen production. The experimental results showed that the solubilization of waste activated sludge was 53.7% at 20 kGy and pH=12, and the SCOD, polysaccharides, protein, TN and TP contents in the irradiated sludge solutions was 3789.6 mg/L, 268.3 mg/L, 1881.5 mg/L, 132.3 mg/L and 80.4 mg/L, respectively. The irradiated sludge was used for fermentative hydrogen production, and the hydrogen yield was 10.5±0.7 mL/g SCODconsumed. It can be concluded that the irradiated waste activated sludge could be used as a low-cost substrate for fermentative hydrogen production.

  3. CHEMICAL DIFFERENCES BETWEEN SLUDGE SOLIDS AT THE F AND H AREA TANK FARMS

    SciTech Connect

    Reboul, S.

    2012-08-29

    and HTF samples indicated that the primary crystalline compounds of iron in sludge solids are Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, and FeO(OH), and the primary crystalline compounds of aluminum are Al(OH){sub 3} and AlO(OH). Also identified were carbonate compounds of calcium, magnesium, and sodium; a nitrated sodium aluminosilicate; and various uranium compounds. Consistent with expectations, oxalate compounds were identified in solids associated with oxalic acid cleaning operations. The most likely oxidation states and chemical forms of technetium are assessed in the context of solubility, since technetium-99 is a key risk driver from an environmental fate and transport perspective. The primary oxidation state of technetium in SRS sludge solids is expected to be Tc(IV). In salt waste, the primary oxidation state is expected to be Tc(VII). The primary form of technetium in sludge is expected to be a hydrated technetium dioxide, TcO{sub 2} {center_dot} xH{sub 2}O, which is relatively insoluble and likely co-precipitated with iron. In salt waste solutions, the primary form of technetium is expected to be the very soluble pertechnetate anion, TcO{sub 4}{sup -}. The relative differences between the F and H Tank Farm waste provide a basis for anticipating differences that will occur as constituents of FTF and HTF waste residue enter the environment over the long-term future. If a constituent is significantly more dominant in one of the Tank Farms, its long-term environmental contribution will likely be commensurately higher, assuming the environmental transport conditions of the two Tank Farms share some commonality. It is in this vein that the information cited in this document is provided - for use during the generation, assessment, and validation of Performance Assessment modeling results.

  4. Cost estimation and economical evaluation of three configurations of activated sludge process for a wastewater treatment plant (WWTP) using simulation

    NASA Astrophysics Data System (ADS)

    Jafarinejad, Shahryar

    2016-07-01

    The activated sludge (AS) process is a type of suspended growth biological wastewater treatment that is used for treating both municipal sewage and a variety of industrial wastewaters. Economical modeling and cost estimation of activated sludge processes are crucial for designing, construction, and forecasting future economical requirements of wastewater treatment plants (WWTPs). In this study, three configurations containing conventional activated sludge (CAS), extended aeration activated sludge (EAAS), and sequencing batch reactor (SBR) processes for a wastewater treatment plant in Tehran city were proposed and the total project construction, operation labor, maintenance, material, chemical, energy and amortization costs of these WWTPs were calculated and compared. Besides, effect of mixed liquor suspended solid (MLSS) amounts on costs of WWTPs was investigated. Results demonstrated that increase of MLSS decreases the total project construction, material and amortization costs of WWTPs containing EAAS and CAS. In addition, increase of this value increases the total operation, maintenance and energy costs, but does not affect chemical cost of WWTPs containing EAAS and CAS.

  5. Co-digestion of organic solid waste and sludge from sewage treatment.

    PubMed

    Edelmann, W; Engeli, H; Gradenecker, M

    2000-01-01

    Solid organic wastes were codigested together with sludge of a sewage treatment plant (STP). In the practical part of the study, a plant to pretreat the organic solid wastes provided by local super markets was constructed at the STP of Frutigen, Switzerland. Up to more than 1 cubic metre of wastes was added to the fermenter of the STP every day. Data collected during 14 months of practical works, showed that for raw fruit and vegetable wastes a two step pretreatment is necessary: First the wastes were chopped and afterwards reduced to a size of 1-2 millimetres, in order to get a homogeneous suspension together with the primary sludge. The vegetable wastes showed excellent digestibility: They seemed to accelerate the digestion process as well as to increase the degree of the anaerobic degradation of the sludge. The energy demand for both, pretreatment and digestion, was 85 kWh/ton of fresh wastes. 20% of the energy was used for the hygienization, a step which does not seem to be necessary for this kind of waste in most of the cases, however. After using the gas for energy conversion, a net yield of 65 kWh/ton of electricity and 166 kWh/ton of heat was measured. Treating cooked kitchen wastes, the net energy production will be higher, because in this case a one step pretreatment will be sufficient. The pretreatment and treatment costs for codigestion on STP's were calculated to be in the range of 55 US$/ton treating half a ton per day and 39 US$/ton treating one ton, respectively. A theoretical feasibility study showed that in Switzerland there is a short term potential on STP's for the codigestion of about 120,000 tons of biogenic wastes per year without big investments. Economic studies about codigestion on agricultural biogas plants showed that the codigestion is a must at the current energy prices, which are far too low for agricultural AD without an additional income by treating solid wastes for third parties.

  6. The Active Solid Earth

    NASA Astrophysics Data System (ADS)

    Ebinger, Cynthia

    2016-04-01

    Dynamic processes in Earth's crust, mantle and core shape Earth's surface and magnetic field over time scales of seconds to millennia, and even longer time scales as recorded in the ca. 4 Ga rock record. Our focus is the earthquake-volcano deformation cycles that occur over human time scales, and their comparison with time-averaged deformation studies, with emphasis on mantle plume provinces where magma and volatile release and vertical tectonics are readily detectable. Active deformation processes at continental and oceanic rift and back arc zones provide critical constraints on mantle dynamics, the role of fluids (volatiles, magma, water), and plate rheology. For example, recent studies of the East African rift zone, which formed above one of Earth's largest mantle upwellings reveal that magma production and volatile release rates are comparable to those of magmatic arcs, the archetypal zones of continental crustal creation. Finite-length faults achieve some plate deformation, but magma intrusion in the form of dikes accommodates extension in continental, back-arc, and oceanic rifts, and intrusion as sills causes permanent uplift that modulates the local time-space scales of earthquakes and volcanoes. Volatile release from magma intrusion may reduce fault friction and permeability, facilitating aseismic slip and creating magma pathways. We explore the implications of active deformation studies to models of the time-averaged structure of plume and extensional provinces in continental and oceanic plate settings.

  7. Pyrolysis of activated sludge: energy analysis and its technical feasibility.

    PubMed

    Agarwal, Manu; Tardio, James; Venkata Mohan, S

    2015-02-01

    A comprehensive study on the potential of pyrolysis of activated sludge to generate substances that can be used to produce energy was evaluated for its technical and environmental viability. The products of the process viz., pyrolysis gas, pyrolysis oil and char can readily be used by the major energy consumers viz., electricity and transportation. Based on the results obtained it is estimated that a 1 ton capacity process for pyrolysis of activated sludge can serve the electrical needs of a maximum of 239, 95 and 47 Indian houses per day, considering lower middle class, middle class and upper middle class, respectively. In addition the process would also produce the daily methane (CNG) requirement of 128 public transport buses. The process was determined to be technically feasible at low and medium temperatures for both, pyrolysis gas and electrical energy. The gas generated could be utilized as fuel directly while the oil generated would require pretreatment before its potential application. The process is potentially sustainable when commercialized and can self-sustain in continuous mode of operation in biorefinery context.

  8. Pyrolysis of activated sludge: energy analysis and its technical feasibility.

    PubMed

    Agarwal, Manu; Tardio, James; Venkata Mohan, S

    2015-02-01

    A comprehensive study on the potential of pyrolysis of activated sludge to generate substances that can be used to produce energy was evaluated for its technical and environmental viability. The products of the process viz., pyrolysis gas, pyrolysis oil and char can readily be used by the major energy consumers viz., electricity and transportation. Based on the results obtained it is estimated that a 1 ton capacity process for pyrolysis of activated sludge can serve the electrical needs of a maximum of 239, 95 and 47 Indian houses per day, considering lower middle class, middle class and upper middle class, respectively. In addition the process would also produce the daily methane (CNG) requirement of 128 public transport buses. The process was determined to be technically feasible at low and medium temperatures for both, pyrolysis gas and electrical energy. The gas generated could be utilized as fuel directly while the oil generated would require pretreatment before its potential application. The process is potentially sustainable when commercialized and can self-sustain in continuous mode of operation in biorefinery context. PMID:25451771

  9. Bacterial Diversity of Active Sludge in Wastewater Treatment Plant

    NASA Astrophysics Data System (ADS)

    Jiang, Xin; Ma, Mingchao; Li, Jun; Lu, Anhuai; Zhong, Zuoshen

    A bacterial 16S rDNA gene clone library was constructed to analyze the bacterial diversity of active sludge in Gaobeidian Wastewater Treatment Plant, Beijing. The results indicated that the bacterial diversity of active sludge was very high, and the clones could be divided into 5 different groups. The dominant bacterial community was proteobacteria, which accounted for 76.7%. The dominant succession of bacterial community were as follows: the β-proteobacteria (39.8%), the uncultured bacteria (22.33%), the γ-proteobacteria (20.15%), the α-proteobacteria (6.79%), and the σ-proteobacteria (4.85%). Nitrosomonas-like and Nitrospira-like bacteria, such as Nitrosomonas sp. (1.94%) and uncultured Nitrospirae bacterium (11.65%) were also detected, which have played important roles in ammonia and nitrite oxidisers in the system. However, they were only a little amount because of their slow growth and less competitive advantage than heterotrophic bacteria. Denitrifying bacteria like Thauera sp. was at a high percentage, which implies a strong denitrification ability; Roseomonas sp. was also detected in the clone library, which could be related to the degradation of organophosphorus pesticide.

  10. Leachability of heavy metals from lightweight aggregates made with sewage sludge and municipal solid waste incineration fly ash.

    PubMed

    Wei, Na

    2015-05-07

    Lightweight aggregate (LWA) production with sewage sludge and municipal solid waste incineration (MSWI) fly ash is an effective approach for waste disposal. This study investigated the stability of heavy metals in LWA made from sewage sludge and MSWI fly ash. Leaching tests were conducted to find out the effects of MSWI fly ash/sewage sludge (MSWI FA/SS) ratio, sintering temperature and sintering time. It was found that with the increase of MSWI FA/SS ratio, leaching rates of all heavy metals firstly decreased and then increased, indicating the optimal ratio of MSWI fly ash/sewage sludge was 2:8. With the increase of sintering temperature and sintering time, the heavy metal solidifying efficiencies were strongly enhanced by crystallization and chemical incorporations within the aluminosilicate or silicate frameworks during the sintering process. However, taking cost-savings and lower energy consumption into account, 1100 °C and 8 min were selected as the optimal parameters for LWA sample- containing sludge production. Furthermore, heavy metal leaching concentrations under these optimal LWA production parameters were found to be in the range of China's regulatory requirements. It is concluded that heavy metals can be properly stabilized in LWA samples containing sludge and cannot be easily released into the environment again to cause secondary pollution.

  11. Leachability of heavy metals from lightweight aggregates made with sewage sludge and municipal solid waste incineration fly ash.

    PubMed

    Wei, Na

    2015-05-01

    Lightweight aggregate (LWA) production with sewage sludge and municipal solid waste incineration (MSWI) fly ash is an effective approach for waste disposal. This study investigated the stability of heavy metals in LWA made from sewage sludge and MSWI fly ash. Leaching tests were conducted to find out the effects of MSWI fly ash/sewage sludge (MSWI FA/SS) ratio, sintering temperature and sintering time. It was found that with the increase of MSWI FA/SS ratio, leaching rates of all heavy metals firstly decreased and then increased, indicating the optimal ratio of MSWI fly ash/sewage sludge was 2:8. With the increase of sintering temperature and sintering time, the heavy metal solidifying efficiencies were strongly enhanced by crystallization and chemical incorporations within the aluminosilicate or silicate frameworks during the sintering process. However, taking cost-savings and lower energy consumption into account, 1100 °C and 8 min were selected as the optimal parameters for LWA sample- containing sludge production. Furthermore, heavy metal leaching concentrations under these optimal LWA production parameters were found to be in the range of China's regulatory requirements. It is concluded that heavy metals can be properly stabilized in LWA samples containing sludge and cannot be easily released into the environment again to cause secondary pollution. PMID:25961800

  12. Leachability of Heavy Metals from Lightweight Aggregates Made with Sewage Sludge and Municipal Solid Waste Incineration Fly Ash

    PubMed Central

    Wei, Na

    2015-01-01

    Lightweight aggregate (LWA) production with sewage sludge and municipal solid waste incineration (MSWI) fly ash is an effective approach for waste disposal. This study investigated the stability of heavy metals in LWA made from sewage sludge and MSWI fly ash. Leaching tests were conducted to find out the effects of MSWI fly ash/sewage sludge (MSWI FA/SS) ratio, sintering temperature and sintering time. It was found that with the increase of MSWI FA/SS ratio, leaching rates of all heavy metals firstly decreased and then increased, indicating the optimal ratio of MSWI fly ash/sewage sludge was 2:8. With the increase of sintering temperature and sintering time, the heavy metal solidifying efficiencies were strongly enhanced by crystallization and chemical incorporations within the aluminosilicate or silicate frameworks during the sintering process. However, taking cost-savings and lower energy consumption into account, 1100 °C and 8 min were selected as the optimal parameters for LWA sample- containing sludge production. Furthermore, heavy metal leaching concentrations under these optimal LWA production parameters were found to be in the range of China’s regulatory requirements. It is concluded that heavy metals can be properly stabilized in LWA samples containing sludge and cannot be easily released into the environment again to cause secondary pollution. PMID:25961800

  13. [Bioleaching of fly ash from municipal solid waste incinerator using sewage sludge and pig manure as culture media].

    PubMed

    Zhou, Shun-gui; Chang, Ming; Hu, Pei; Ni, Jin-ren

    2005-11-01

    A mixed culture of Acidihiobacillus ferrooaidans and Acidihiobacillus thiooxidans was used to leach heavy metals from municipal solid waste incineration fly ash (MSWI fly ash). This study explored the possibility of using sewage sludge or pig manure as nutrients for supporting the growth of the leaching bacteria and allowing metal solubilization like a synthetic mineral medium. In contrast to pig manure, there is a high ability for acidification of the fly ash and solubilization of toxic metals using sewage sludge at the same content. After 15 d of bioleaching, the following removal efficiencies were obtained for the treatment with the addition of 1% sewage sludge: Cd 88.1%; Zn 78.7%; Cu 69.6%, whereas their removal efficiencies for the treatment with the addition of 1% pig manure were 82.4%, 73.5% and 60.0%, respectively. Results demonstrate that the inhibition by sewage sludge DOM is much more significant than by pig manure DOM at the same concentration level. The dissolved organic carbon in excess of 400 and 150 mg/L was inhibitory to the bacterial growth using sludge DOM and manure DOM, respectively. Compared with sewage sludge, pig manure contained a higher fraction of DOM with molecular size <1000, which led to its higher toxicity. PMID:16447455

  14. Waste activated sludge treatment based on temperature staged and biologically phased anaerobic digestion system.

    PubMed

    Yu, Jingwen; Zheng, Mingxia; Tao, Tao; Zuo, Jiane; Wang, Kaijun

    2013-10-01

    The concept of temperature staged and biological phased (TSBP) was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect of temperature (35 to 70 degrees C) as well as the hydraulic retention time (HRT) (2, 4 and 6 days) on the acidogenic phase. The results showed that the solubilization degree of waste-activated sludge increased from 14.7% to 30.1% with temperature increasing from 35 to 70 degrees C, while the acidification degree was highest at 45 degrees C (17.6%), and this was quite different from the temperature impact on hydrolysis. Compared with HRT of 2 and 6 days, 4 days was chosen as the appropriate HRT because of its relatively high solubilization degree (24.6%) and acidification degree (20.1%) at 45 degrees C. The TSBP system combined the acidogenic reactor (45 degrees C, 4 days) with the methanogenic reactor (35 degrees C, 16 days) and the results showed 84.8% and 11.4% higher methane yield and volatile solid reduction, respectively, compared with that of the single-stage anaerobic digestion system with HRT of 20 days at 35 degrees C. Moreover, different microbial morphologies were observed in the acidogenic- and methanogenic-phase reactors, which resulted from the temperature control and HRT adjustment. All the above results indicated that 45 degrees C was the optimum temperature to inhibit the activity of methanogenic bacteria in the acidogenic phase, and temperature staging and phase separation was thus accomplished. The advantages of the TSBP process were also confirmed by a full-scale waste-activated sludge anaerobic digestion project which was an energy self-sufficient system.

  15. Color removal from cotton textile industry wastewater in an activated sludge system with various additives.

    PubMed

    Pala, Ayşegül; Tokat, Enis

    2002-06-01

    The low biodegradability of many dyes and textile chemicals indicates that biological treatment is not always successful in the treatment of cotton textile wastewater, in terms of color removal. In this study, a specific organic flocculant (Marwichem DEC), powdered activated carbon (PAC), bentonite, activated clay and commercial synthetic inorganic clay (Macrosorb) were directly added into the activated sludge laboratory pilot plant model. Before dosage, the optimum sludge retention time and hydraulic retention time were determined as 30 days and 1.6 days, respectively. The Monod kinetic constants were determined as Y = 0.76 kg MLSS/kg COD, Kd = 0.026 l/day, K(S) = 113.3 mg/L, k = 0.42 l/day and mu(max) = 0.32 kg MLSS/kg COD day. Under these conditions the average COD removal was 94% and color removal was 36%. The addition of these materials did not change COD removal significantly. The most effective materials were found to be DEC and PAC for color removal. While the color removal efficiency for 120 mg/L DEC addition was 78%, it was 65% for 100 mg/L, 77% for 200 mg/L and 86% for 400 mg/L PAC addition. The advantage of DEC compared to PAC was the lower sludge production. Statistical analyses using multiple linear regression indicate that there is no relationship between the effluent color with the influent color and total suspended solids (TSS) for DEC and PAC addition. On the other hand, when only bentonite, activated clay and Macrosorb were added, the effluent color was primarily dependent on the influent color and the TSS concentration had little effect. When the data is examined by using Kruskal-Wallis H and Mann-Whitney U tests and it was found that there was a significant difference between the color data groups.

  16. Effect of low temperature on highly unsaturated fatty acid biosynthesis in activated sludge.

    PubMed

    He, Su; Ding, Li-Li; Xu, Ke; Geng, Jin-Ju; Ren, Hong-Qiang

    2016-07-01

    Low temperature is a limiting factor for the microbial activity of activated sludge for sewage treatment plant in winter. Highly unsaturated fatty acid (UFA) biosynthesis, phospholipid fatty acid (PLFA) constituents and microbial structure in activated sludge at low temperature were investigated. Over 12 gigabases of metagenomic sequence data were generated with the Illumina HiSeq 2000 platform. The result showed 43.11% of phospholipid fatty acid (PLFA) in the activated sludge participated in UFA biosynthesis, and γ-Linolenic could be converted to Arachidonic acid at low temperature. The highly UFA biosynthesis in activated sludge was n-6 highly UFA biosynthesis, rather than n-3 highly UFA biosynthesis. The microbial community structures of activated sludge were analyzed by PLFA and high-throughput sequencing (HiSeq) simultaneously. Acidovorax, Pseudomonas, Flavobacterium and Polaromonas occupied higher percentage at 5°C, and genetic changes of highly UFA biosynthesis derived from microbial community structures change.

  17. Composition analysis of fractions of extracellular polymeric substances from an activated sludge culture and identification of dominant forces affecting microbial aggregation

    PubMed Central

    Guo, Xuan; Wang, Xu; Liu, Junxin

    2016-01-01

    Extracellular polymeric substances (EPS) appear to play a critical role in the formation of bioaggregates, such as sludge flocs, in activated sludge processes. Here, we systematically investigated the composition and chemical structure of various EPS fractions excreted from an activated sludge culture using multi-analysis techniques to examine the ability of the sludge to aggregate. Chemical analysis was used with a three-dimensional excitation emission matrix and Fourier transform infrared spectroscopy, applying inter-particle forces theory. The combined findings revealed that hydrophobic groups, especially protein-related N–H, were present in a greater proportion in tightly bound EPS (TB-EPS). This result, which explained the specificity of TB-EPS in the chemical structure, was consistent with data indicating that TB-EPS contained a large amount of protein-like substances (86.7 mg/g of mixed liquor volatile suspended solids, 39.7% of the total EPS). Subsequently, a novel experimental procedure was developed to pinpoint key inter-particle forces in sludge aggregation. The result revealed that hydrogen bonds are the predominant triggers that promote sludge aggregation. This comprehensive analysis indicated that hydrophobic proteins in TB-EPS are responsible for the critical role played by hydrogen bonds in sludge formation. Our findings highlight the need to elucidate the mechanisms of TB-EPS-mediated flocculation in future efforts. PMID:27311788

  18. Composition analysis of fractions of extracellular polymeric substances from an activated sludge culture and identification of dominant forces affecting microbial aggregation

    NASA Astrophysics Data System (ADS)

    Guo, Xuan; Wang, Xu; Liu, Junxin

    2016-06-01

    Extracellular polymeric substances (EPS) appear to play a critical role in the formation of bioaggregates, such as sludge flocs, in activated sludge processes. Here, we systematically investigated the composition and chemical structure of various EPS fractions excreted from an activated sludge culture using multi-analysis techniques to examine the ability of the sludge to aggregate. Chemical analysis was used with a three-dimensional excitation emission matrix and Fourier transform infrared spectroscopy, applying inter-particle forces theory. The combined findings revealed that hydrophobic groups, especially protein-related N–H, were present in a greater proportion in tightly bound EPS (TB-EPS). This result, which explained the specificity of TB-EPS in the chemical structure, was consistent with data indicating that TB-EPS contained a large amount of protein-like substances (86.7 mg/g of mixed liquor volatile suspended solids, 39.7% of the total EPS). Subsequently, a novel experimental procedure was developed to pinpoint key inter-particle forces in sludge aggregation. The result revealed that hydrogen bonds are the predominant triggers that promote sludge aggregation. This comprehensive analysis indicated that hydrophobic proteins in TB-EPS are responsible for the critical role played by hydrogen bonds in sludge formation. Our findings highlight the need to elucidate the mechanisms of TB-EPS-mediated flocculation in future efforts.

  19. Solar assisted sludge and energy recycling disposal system utilizing the old Princeton sewage treatment and solid waste incineration facilities

    SciTech Connect

    Slaby, S.M.

    1980-12-01

    Princeton, New Jersey, a town of 30,000 people is in a unique position to utilize solid waste and sewage sludge as supplementary energy sources. The Stony Brook Sewage Authority recently constructed a new twenty million dollar sewage treatment plant next to the old sewage treatment plant which served the community of Princeton for forty years. On the site of the old plant is an abandoned incinerator plant which presently is being used as a transfer station. The new sewage treatment plant is disposing of its sludge by burning it in multiple hearth furnaces using sixty gallons of precious oil to do this. The proposed Princeton Energy Recycling Center is designed to be retrofitted with solar sludge dryers to dry the sewage sludge which would be transported by conveyer to the old incinerator plant where it would be mixed with garbage and be burned in rehabilitated furnaces which would be retrofitted for steam generators, a steam engine driven electric generator and air pollution control equipment. It is estimated that the proposed energy recycling center would fulfill all electrical needs of the new sewage treatment plant in addition to solving the solid waste and sludge disposal problems of the Princeton community. The paper presents a detailed discussion on the proposed Princeton Energy Recycling Center.

  20. Influence of influent wastewater communities on temporal variation of activated sludge communities.

    PubMed

    Lee, Sang-Hoon; Kang, Hyun-Jin; Park, Hee-Deung

    2015-04-15

    Continuously feeding influent wastewater containing diverse bacterial species to a wastewater treatment activated sludge bioreactor may influence the activated sludge bacterial community temporal dynamics. To explore this possibility, this study tracked influent wastewater and activated sludge bacterial communities by pyrosequencing 16S rRNA genes from four full-scale wastewater treatment plants over a 9-month period. The activated sludge communities showed significantly higher richness and evenness than the influent wastewater communities. Furthermore, the two communities were different in composition and temporal dynamics. These results demonstrate that the impact of the influent wastewater communities on the activated sludge communities was weak. Nevertheless, 4.3-9.3% of the operational taxonomic units (OTUs) detected in the activated sludge were shared with the influent wastewater, implying contribution from influent wastewater communities to some extent. However, the relative OTU abundance of the influent wastewater was not maintained in the activated sludge communities (i.e., weak neutral assembly). In addition, the variability of the communities of the shared OTUs was moderately correlated with abiotic factors imposed to the bioreactors. Taken together, temporal dynamics of activated sludge communities appear to be predominantly explained by species sorting processes in response to influent wastewater communities. PMID:25655320

  1. Alternative fuel production by catalytic hydroliquefaction of solid municipal wastes, primary sludges and microalgae.

    PubMed

    Lemoine, F; Maupin, I; Lemée, L; Lavoie, J-M; Lemberton, J-L; Pouilloux, Y; Pinard, L

    2013-08-01

    An alternative fuel production was investigated through catalytic hydroliquefaction of three different carbonaceous sources: solid municipal wastes (MW), primary sludges (PS), and microalgae (MA). The reaction was carried out under hydrogen pressure, at different temperatures (330, 380 and 450°C), with a Raney nickel catalyst and two different hydrogen donor solvents: a "fossil solvent" (tetralin) and a "green solvent" (2-methyl-hydro-furan). The feeds analyses (TDA-TGA, ICP-AES, lipids quantification) showed that MW and PS had similar characteristics and physico-chemical properties, but different from those of MA. The hydroliquefaction of these feeds allowed to obtain high oil yields, with a significant energetic value, similar to that of a bio-petroleum. 2-methyl-hydro-furan was more efficient than tetralin for the treatment of the strongly bio-degraded biomasses MW and PS, while better results were obtained with tetralin in the case of MA.

  2. Anaerobic digestion of waste activated sludge pretreated by a combined ultrasound and chemical process.

    PubMed

    Seng, Bunrith; Khanal, Samir Kumar; Visvanathan, Chettiyappan

    2010-03-01

    Waste activated sludge (WAS) requires a long digestion time because of a rate-limiting hydrolysis step - the first phase of anaerobic digestion. Pretreatment of WAS facilitates the hydrolysis step and improves the digestibility. This study examined the effects of ultrasonic, chemical, and combined chemical-ultrasonic pretreatments on WAS disintegration and its subsequent digestion at different solids retention times (SRTs). The efficient conditions for each pretreatment were evaluated based on per cent soluble chemical oxygen demand (%SCOD). The results showed that the combined chemical-ultrasonic pretreatment resulted in better WAS disintegration, based on %SCOD release, compared with individual chemical and ultrasonic pretreatments. At the optimum operating conditions of the combined chemical-ultrasonic pretreatment (NaOH dose of 10 mg g(-1) TS (total solids) and specific energy input of 3.8 kJ g(-1)TS), the %SCOD release was 18.1% +/- 0.5%, whereas 13.5% +/- 0.9%, 13.0% +/- 0.5% and 1.1% +/- 0.1% corresponded to individual chemical (50 mg g(-1) TS) and ultrasonic (3.8 kJ g(-1) TS) pretreatments and control (without pretreatment), respectively. The anaerobic digestion studies in continuous stirred tank reactors showed an increase in methane production of 23.4% +/- 1.3% and 31.1 +/- 1.2% for digesters fed with WAS pretreated with ultrasonic and combined chemical-ultrasonic, respectively, with respect to controls at the effective SRT of 15 days. The highest total solids removal was achieved in the digester fed with ultrasonic pretreated WAS (16.6% +/- 0.3%), whereas the highest volatile solids removal was achieved from the digester fed with combined chemical-ultrasonic pretreated WAS (24.8 +/- 0.4%). The findings from this study are a useful contribution to new pretreatment techniques in the field of sludge treatment technology through anaerobic digestion.

  3. Effect of petrochemical sludge concentrations of changes in mutagenic activity during soil bioremediation process.

    PubMed

    Morelli, I S; Vecchioli, G I; Del Panno, M T; Painceira, M T

    2001-10-01

    The present study was performed to assess the effect of the petrochemical sludge application rate on the mutagenic activity (Ames test) of soil and the persistence of mutagenic activity during laboratory soil bioremediation process. Sludge-soil systems were prepared at four different sludge application rates (1.25, 2.5, 5, and 10% w/w). Unamended soil was used as a control. Immediately following sludge application, in the absence or presence of S9, a linear correlation between sludge application rates and mutagenicity was found but differed significantly (p < 0.05) from the control system only at higher application rates (5 and 10% w/w). The direct mutagenicity of all systems decreases during the bioremediation process, and after a year of treatment only the 10% system induced a mutagenic response that was significantly different from the control system. On the other hand, an initial increase of the indirect mutagenicity was observed at all application rates. The time required for observing this increase was inversely proportional to the initial sludge concentration. After a year of treatment, the indirect mutagenicity of all sludge-amended soils was not significantly different but was significantly different from the unamended soils. The persistence of the direct mutagenic activity of the sludge-amended soils was related to the sludge concentration, whereas the indirect mutagenic persistence was related to the relationship between easily degradable hydrocarbons and polynuclear aromatic hydrocarbons concentration and independent from the initial application rate. PMID:11596747

  4. Effect of petrochemical sludge concentrations of changes in mutagenic activity during soil bioremediation process.

    PubMed

    Morelli, I S; Vecchioli, G I; Del Panno, M T; Painceira, M T

    2001-10-01

    The present study was performed to assess the effect of the petrochemical sludge application rate on the mutagenic activity (Ames test) of soil and the persistence of mutagenic activity during laboratory soil bioremediation process. Sludge-soil systems were prepared at four different sludge application rates (1.25, 2.5, 5, and 10% w/w). Unamended soil was used as a control. Immediately following sludge application, in the absence or presence of S9, a linear correlation between sludge application rates and mutagenicity was found but differed significantly (p < 0.05) from the control system only at higher application rates (5 and 10% w/w). The direct mutagenicity of all systems decreases during the bioremediation process, and after a year of treatment only the 10% system induced a mutagenic response that was significantly different from the control system. On the other hand, an initial increase of the indirect mutagenicity was observed at all application rates. The time required for observing this increase was inversely proportional to the initial sludge concentration. After a year of treatment, the indirect mutagenicity of all sludge-amended soils was not significantly different but was significantly different from the unamended soils. The persistence of the direct mutagenic activity of the sludge-amended soils was related to the sludge concentration, whereas the indirect mutagenic persistence was related to the relationship between easily degradable hydrocarbons and polynuclear aromatic hydrocarbons concentration and independent from the initial application rate.

  5. A practical method for quantification of phosphorus- and glycogen-accumulating organism populations in activated sludge systems.

    PubMed

    López-Vázquez, Carlos M; Hooijmans, Christine M; Brdjanovic, Damir; Gijzen, Huub J; van Loosdrecht, Mark C M

    2007-12-01

    Enhanced biological phosphorus removal (EBPR) from wastewater relies on the enrichment of activated sludge with phosphorus-accumulating organisms (PAOs). The presence and proliferation of glycogen-accumulating organisms (GAOs), which compete for substrate with PAOs, may be detrimental for EBPR systems, leading to deterioration and, in extreme cases, failure of the process. Therefore, from both process evaluation and modeling perspectives, the estimation of PAO and GAO populations in activated sludge systems is a relevant issue. A simple method for the quantification of PAO and GAO population fractions in activated sludge systems is presented in this paper. To develop such a method, the activity observed in anaerobic batch tests executed with different PAO/GAO ratios, by mixing highly enriched PAO and GAO cultures, was studied. Strong correlations between PAO/GAO population ratios and biomass activity were observed (R2 > 0.97). This served as a basis for the proposal of a simple and practical method to quantify the PAO and GAO populations in activated sludge systems, based on commonly measured and reliable analytical parameters (i.e., mixed liquor suspended solids, acetate, and orthophosphate) without requiring molecular techniques. This method relies on the estimation of the total active biomass population under anaerobic conditions (PAO plus GAO populations), by measuring the maximum acetate uptake rate in the presence of excess acetate. Later, the PAO and GAO populations present in the activated sludge system can be estimated, by taking into account the PAO/GAO ratio calculated on the basis of the anaerobic phosphorus release-to-acetate consumed ratio. The proposed method was evaluated using activated sludge from municipal wastewater treatment plants. The results from the quantification performed following the proposed method were compared with direct population estimations carried out with fluorescence in situ hybridization analysis (determining Candidatus

  6. SEISMIC DESIGN REQUIREMENTS SELECTION METHODOLOGY FOR THE SLUDGE TREATMENT & M-91 SOLID WASTE PROCESSING FACILITIES PROJECTS

    SciTech Connect

    RYAN GW

    2008-04-25

    In complying with direction from the U.S. Department of Energy (DOE), Richland Operations Office (RL) (07-KBC-0055, 'Direction Associated with Implementation of DOE-STD-1189 for the Sludge Treatment Project,' and 08-SED-0063, 'RL Action on the Safety Design Strategy (SDS) for Obtaining Additional Solid Waste Processing Capabilities (M-91 Project) and Use of Draft DOE-STD-I 189-YR'), it has been determined that the seismic design requirements currently in the Project Hanford Management Contract (PHMC) will be modified by DOE-STD-1189, Integration of Safety into the Design Process (March 2007 draft), for these two key PHMC projects. Seismic design requirements for other PHMC facilities and projects will remain unchanged. Considering the current early Critical Decision (CD) phases of both the Sludge Treatment Project (STP) and the Solid Waste Processing Facilities (M-91) Project and a strong intent to avoid potentially costly re-work of both engineering and nuclear safety analyses, this document describes how Fluor Hanford, Inc. (FH) will maintain compliance with the PHMC by considering both the current seismic standards referenced by DOE 0 420.1 B, Facility Safety, and draft DOE-STD-1189 (i.e., ASCE/SEI 43-05, Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities, and ANSI!ANS 2.26-2004, Categorization of Nuclear Facility Structures, Systems and Components for Seismic Design, as modified by draft DOE-STD-1189) to choose the criteria that will result in the most conservative seismic design categorization and engineering design. Following the process described in this document will result in a conservative seismic design categorization and design products. This approach is expected to resolve discrepancies between the existing and new requirements and reduce the risk that project designs and analyses will require revision when the draft DOE-STD-1189 is finalized.

  7. High-rate activated sludge system for carbon management--Evaluation of crucial process mechanisms and design parameters.

    PubMed

    Jimenez, Jose; Miller, Mark; Bott, Charles; Murthy, Sudhir; De Clippeleir, Haydee; Wett, Bernhard

    2015-12-15

    The high-rate activated sludge (HRAS) process is a technology suitable for the removal and redirection of organics from wastewater to energy generating processes in an efficient manner. A HRAS pilot plant was operated under controlled conditions resulting in concentrating the influent particulate, colloidal, and soluble COD to a waste solids stream with minimal energy input by maximizing sludge production, bacterial storage, and bioflocculation. The impact of important process parameters such as solids retention time (SRT), hydraulic residence time (HRT) and dissolved oxygen (DO) levels on the performance of a HRAS system was demonstrated in a pilot study. The results showed that maximum removal efficiencies of soluble COD were reached at a DO > 0.3 mg O2/L, SRT > 0.5 days and HRT > 15 min which indicates that minimizing the oxidation of the soluble COD in the high-rate activated sludge process is difficult. The study of DO, SRT and HRT exhibited high degree of impact on the colloidal and particulate COD removal. Thus, more attention should be focused on controlling the removal of these COD fractions. Colloidal COD removal plateaued at a DO > 0.7 mg O2/L, SRT > 1.5 days and HRT > 30 min, similar to particulate COD removal. Concurrent increase in extracellular polymers (EPS) production in the reactor and the association of particulate and colloidal material into sludge flocs (bioflocculation) indicated carbon capture by biomass. The SRT impacted the overall mass and energy balance of the high-rate process indicating that at low SRT conditions, lower COD mineralization or loss of COD content occurred. In addition, the lower SRT conditions resulted in higher sludge yields and higher COD content in the WAS.

  8. High-rate activated sludge system for carbon management--Evaluation of crucial process mechanisms and design parameters.

    PubMed

    Jimenez, Jose; Miller, Mark; Bott, Charles; Murthy, Sudhir; De Clippeleir, Haydee; Wett, Bernhard

    2015-12-15

    The high-rate activated sludge (HRAS) process is a technology suitable for the removal and redirection of organics from wastewater to energy generating processes in an efficient manner. A HRAS pilot plant was operated under controlled conditions resulting in concentrating the influent particulate, colloidal, and soluble COD to a waste solids stream with minimal energy input by maximizing sludge production, bacterial storage, and bioflocculation. The impact of important process parameters such as solids retention time (SRT), hydraulic residence time (HRT) and dissolved oxygen (DO) levels on the performance of a HRAS system was demonstrated in a pilot study. The results showed that maximum removal efficiencies of soluble COD were reached at a DO > 0.3 mg O2/L, SRT > 0.5 days and HRT > 15 min which indicates that minimizing the oxidation of the soluble COD in the high-rate activated sludge process is difficult. The study of DO, SRT and HRT exhibited high degree of impact on the colloidal and particulate COD removal. Thus, more attention should be focused on controlling the removal of these COD fractions. Colloidal COD removal plateaued at a DO > 0.7 mg O2/L, SRT > 1.5 days and HRT > 30 min, similar to particulate COD removal. Concurrent increase in extracellular polymers (EPS) production in the reactor and the association of particulate and colloidal material into sludge flocs (bioflocculation) indicated carbon capture by biomass. The SRT impacted the overall mass and energy balance of the high-rate process indicating that at low SRT conditions, lower COD mineralization or loss of COD content occurred. In addition, the lower SRT conditions resulted in higher sludge yields and higher COD content in the WAS. PMID:26260539

  9. Biliary sludge.

    PubMed

    Ko, C W; Sekijima, J H; Lee, S P

    1999-02-16

    Biliary sludge was first described with the advent of ultrasonography in the 1970s. It is defined as a mixture of particulate matter and bile that occurs when solutes in bile precipitate. Its composition varies, but cholesterol monohydrate crystals, calcium bilirubinate, and other calcium salts are the most common components. The clinical course of biliary sludge varies, and complete resolution, a waxing and waning course, and progression to gallstones are all possible outcomes. Biliary sludge may cause complications, including biliary colic, acute pancreatitis, and acute cholecystitis. Clinical conditions and events associated with the formation of biliary sludge include rapid weight loss, pregnancy, ceftriaxone therapy, octreotide therapy, and bone marrow or solid organ transplantation. Sludge may be diagnosed on ultrasonography or bile microscopy, and the optimal diagnostic method depends on the clinical setting. This paper proposes a protocol for the microscopic diagnosis of sludge. There are no proven methods for the prevention of sludge formation, even in high-risk patients, and patients should not be routinely monitored for the development of sludge. Asymptomatic patients with sludge can be managed expectantly. If patients with sludge develop symptoms or complications, cholecystectomy should be considered as the definitive therapy. Further studies of the pathogenesis, natural history, and clinical associations of biliary sludge will be essential to our understanding of gallstones and other biliary tract abnormalities.

  10. A Guide for Developing Standard Operating Job Procedures for the Activated Sludge - Aeration & Sedimentation Process Wastewater Treatment Facility. SOJP No. 5.

    ERIC Educational Resources Information Center

    Mason, George J.

    This guide for developing standard operating job procedures for wastewater treatment facilities is devoted to the activated sludge aeration and sedimentation process. This process is for conversion of nonsettleable and nonfloatable materials in wastewater to settleable, floculated biological groups and separation of the settleable solids from the…

  11. Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste.

    PubMed

    Liu, Chuanyang; Li, Huan; Zhang, Yuyao; Liu, Can

    2016-11-01

    Anaerobic co-digestion of sewage sludge and food waste was tested at two different total solid (TS) concentrations. In the low-solids group with TS 4.8%, the biogas production increased linearly as the ratio of food waste in substrate increased from 0 to 100%, but no synergetic effect was found between the two substrates. Moreover, the additive food waste resulted in the accumulation of volatile fatty acids and decelerated biogas production. Thus, the blend ratio of food waste should be lower than 50%. While in the high-solids group with TS 14%, the weak alkaline environment with pH 7.5-8.5 avoided excessive acidification but high concentration of free ammonia was a potential risk. However, good synergetic effect was found between the two substrates because the added food waste improved mass transfer in sludge cake. Thus, 50% was recommended as the optimum ratio of food waste in substrate because of the best synergetic effect.

  12. 40 CFR 721.10667 - Slimes and sludges, aluminum and iron casting, wastewater treatment, solid waste.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Slimes and sludges, aluminum and iron... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10667 Slimes and sludges, aluminum and... subject to reporting. (1) The chemical substance identified generically as slimes and sludges,...

  13. 40 CFR 721.10667 - Slimes and sludges, aluminum and iron casting, wastewater treatment, solid waste.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Slimes and sludges, aluminum and iron... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10667 Slimes and sludges, aluminum and... subject to reporting. (1) The chemical substance identified generically as slimes and sludges,...

  14. Enrichment and activity of methanotrophic microorganisms from municipal wastewater sludge.

    PubMed

    Siniscalchi, Luciene Alves Batista; Vale, Isabel Campante; Dell'Isola, Jéssica; Chernicharo, Carlos Augusto; Calabria Araujo, Juliana

    2015-01-01

    In this study, methanotrophic microorganisms were enriched from a municipal wastewater sludge taken from an Upflow Anaerobic Sludge Blanket reactor. The enrichment was performed in a sequencing batch reactor (SBR) with an autotrophic medium containing nitrite and nitrate. The microbial community composition of the inoculum and of the enrichment culture after 100 days of SBR operation was investigated and compared with the help of data obtained from 454 pyrosequencing analyses. The nitrite and nitrate removal efficiencies were 68% and 53%, respectively, probably due to heterotrophic denitrification. Archaeal cells of the anaerobic methanotrophic Archaic (ANME)-I and ANME-II groups were detected by polymerase chain reaction throughout the whole cultivation period. Pyrosequencing analysis showed that community composition was different among the two samples analysed. The dominant phyla found in the inoculum were Synergistestes, Firmicutes and Euryarchaeota, while Planctomycetes, Verrucomicrobia, Chloroflexi and Proteobacteria prevailed in the enriched biomass. The cultivation conditions decreased Methanobacterium abundance from 8% to 1%, and enriched for methanotrophic bacteria such as Methylocaldum, Methylocistis and Methylosinus. Sequences of Methylocaldum sp. accounted for 2.5% of the total reads. The presence and high predominance of Verrucomicrobia in the enriched biomass suggested that other unknown methanotrophic species related to that phylum might also have occurred in the reactor. Anaerobic methane oxidation activity was measured for both samples, and showed that the activity of the enrichment culture was nearly three times higher than the activity of the inoculum. Taken together, these results showed that the inoculum type and cultivation conditions were properly suited for methanotrophic enrichment.

  15. Evaluation of non-thermal effects by microwave irradiation in hydrolysis of waste-activated sludge.

    PubMed

    Byun, I G; Lee, J H; Lee, J M; Lim, J S; Park, T J

    2014-01-01

    The activation energy (Ea) for waste-activated sludge (WAS) hydrolysis was compared between microwave irradiation (MW) and conventional heating (CH) methods to evaluate the non-thermal effect of MW. The microwave-assisted hydrolysis of WAS was assumed to follow the first-order kinetics on the basis of volatile suspended solids (VSS) conversion to soluble chemical oxygen demand (SCOD) for different initial VSS concentrations. By comparing the VSS decrement and the SCOD increment between MW and CH at different absolute temperatures of 323, 348 and 373 K, the average ratio of VSS conversion to SCOD was determined to range from 1.42 to 1.64 g SCOD/g VSS. These results corresponded to the theoretical value of 1.69 g SCOD/g VSS based on the assumption that the molecular formula of sludge was C10H19O3N. Consequently, the Ea of the MW-assisted WAS hydrolysis was much lower than that of CH for the same temperature conditions. The non-thermal effect of MW in the hydrolysis of WAS could be identified with the lower Ea than that of CH. PMID:25116507

  16. Biotransformation of the antiviral drugs acyclovir and penciclovir in activated sludge treatment.

    PubMed

    Prasse, Carsten; Wagner, Manfred; Schulz, Ralf; Ternes, Thomas A

    2011-04-01

    The biotransformation of the two antiviral drugs, acyclovir (ACV) and penciclovir (PCV), was investigated in contact with activated sludge. Biodegradation kinetics were determined, and transformation products (TPs) were identified using Hybrid Linear Ion Trap- FT Mass Spectrometry (LTQ Orbitrap Velos) and 1D (1H NMR, 13C NMR) and 2D (1H,1H-COSY, 1H-(13)C-HSQC) NMR Spectroscopy. ACV and PCV rapidly dissipated in the activated sludge batch systems with half-lives of 5.3 and 3.4 h and first-order rate constants in relation to the amount of suspended solids (SS) of 4.9±0.1 L gss(-1) d(-1) and 7.6±0.3 L gss(-1) d(-1), respectively. For ACV only a single TP was found, whereas eight TPs were identified for PCV. Structural elucidation of TPs exhibited that transformation only took place at the side chain leaving the guanine moiety unaltered. The oxidation of the primary hydroxyl group in ACV resulted in the formation of carboxy-acyclovir (Carboxy-ACV). For PCV, transformation was more diverse with several enzymatic reactions taking place such as the oxidation of terminal hydroxyl groups and β-oxidation followed by acetate cleavage. Analysis of different environmental samples revealed the presence of Carboxy-ACV in surface and drinking water with concentrations up to 3200 ng L(-1) and 40 ng L(-1), respectively.

  17. Evaluation of non-thermal effects by microwave irradiation in hydrolysis of waste-activated sludge.

    PubMed

    Byun, I G; Lee, J H; Lee, J M; Lim, J S; Park, T J

    2014-01-01

    The activation energy (Ea) for waste-activated sludge (WAS) hydrolysis was compared between microwave irradiation (MW) and conventional heating (CH) methods to evaluate the non-thermal effect of MW. The microwave-assisted hydrolysis of WAS was assumed to follow the first-order kinetics on the basis of volatile suspended solids (VSS) conversion to soluble chemical oxygen demand (SCOD) for different initial VSS concentrations. By comparing the VSS decrement and the SCOD increment between MW and CH at different absolute temperatures of 323, 348 and 373 K, the average ratio of VSS conversion to SCOD was determined to range from 1.42 to 1.64 g SCOD/g VSS. These results corresponded to the theoretical value of 1.69 g SCOD/g VSS based on the assumption that the molecular formula of sludge was C10H19O3N. Consequently, the Ea of the MW-assisted WAS hydrolysis was much lower than that of CH for the same temperature conditions. The non-thermal effect of MW in the hydrolysis of WAS could be identified with the lower Ea than that of CH.

  18. 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 ...

  19. New insight into the biological treatment by activated sludge: the role of adsorption process.

    PubMed

    Zhang, Xiaochun; Li, Xinrun; Zhang, Qingrui; Peng, Qiuming; Zhang, Wen; Gao, Faming

    2014-02-01

    The objective of this study was to evaluate the effect of adsorption on the biological treatment process of wastewater. In the absence of substrate in the water, activated sludge developed well in the first hour, indicating that the growth of microorganism was not directly related to substrate concentration and the dissolved organic matter in the water assays were performed, no organic matter was detected out, revealing that there was no desorption in the activated sludge adsorption process. Activated sludge batch growth experiments in the presence of different adsorption capacities indicated that specific growth rate increased as specific adsorption capacity increased. The experiment on the relationship of adsorption capacity and substrate concentration or sludge concentration was also carried out. Specific adsorption capacity increased as sludge load increased, presenting linear correlation. The experiment results showed that adsorption should be taken into account in the study of the biological treatment process of wastewater.

  20. Pilot-scale waste activated sludge alkaline fermentation, fermentation liquid separation, and application of fermentation liquid to improve biological nutrient removal.

    PubMed

    Li, Xiang; Chen, Hong; Hu, Lanfang; Yu, Lei; Chen, Yinguang; Gu, Guowei

    2011-03-01

    The use of sludge fermentative short-chain fatty acids (SCFA) as an additional carbon source of biological nutrient removal (BNR) has drawn much attention recently as it can reuse sludge organics, reduce waste activated sludge production, and improve BNR performance. Our previous laboratory study had shown that the SCFA production was significantly enhanced by controlling sludge fermentation at pH 10 with NaOH. This paper focused on a pilot-scale study of alkaline fermentation of waste activated sludge, separation of the fermentation liquid from the alkaline fermentation system, and application of the fermentation liquid to improve municipal biological nitrogen and phosphorus removal. NaOH and Ca(OH)(2) were used respectively to adjust the alkaline fermentation pH, and their effects on sludge fermentation and fermentation liquid separation were compared. The results showed that the use of Ca(OH)(2) had almost the same effect on SCFA production improvement and sludge volatile suspended solids reduction as that of NaOH, but it exhibited better sludge dewatering, lower chemical costs, and higher fermentation liquid recovery efficiency. When the fermentation liquids, adjusted with Ca(OH)(2) and NaOH respectively, were added continuously to an anaerobic-anoxic-aerobic municipal wastewater BNR system, both the nitrogen and phosphorus removals, compared with the control, were improved to the same levels. This was attributed to the increase of not only influent COD but also denitrifying phosphorus removal capability. It seems that the use of Ca(OH)(2) to control sludge fermentation at pH 10 for efficiently producing a carbon source for BNR is feasible.

  1. A laboratory batch reactor test for assessing nonspeciated volatile organic compound biodegradation in activated sludge.

    PubMed

    Cano, M L; Saterbak, A; van Compernolle, R; Williams, M P; Huot, M E; Rhodes, I A; Allen, C C

    2003-01-01

    The relative rates of biodegradation and stripping and volatilization of nonspeciated volatile organic compounds (VOCs) in wastewater treated with aerobic activated-sludge processes can be quantified using a newly developed procedure. This method was adapted from the original aerated draft tube reactor test that was developed to measure biodegradation rate constants for specific volatile pollutants of interest. The original batch test has been modified to include solid-phase microextraction (SPME) fibers for sampling in the gas phase. The experimental procedure using SPME fibers does not require specific identification and quantitation of individual pollutants and can be used to evaluate wastewater with multiple VOCs. To illustrate use of this procedure, laboratory experiments were conducted using biomass and wastewater or effluent from three activated-sludge treatment systems. Each experiment consisted of two trials: a stripping-only trial without biomass and a stripping plus biodegradation trial using biomass from the activated-sludge unit of interest. Data from the two trials were used to quantify the rates of biodegradation by difference. The activated-sludge systems tested were a laboratory diffused-air reactor treating refinery wastewater, a full-scale surface aerated reactor treating a petrochemical wastewater, and a full-scale diffused-air reactor treating a variety of industrial effluents. The biodegradation rate constant data from each laboratory batch experiment were used in model calculations to quantify the fraction emitted (fe) and the fraction biodegraded (fbio) for each system. The fe values ranged from a maximum of 0.01 to a maximum of 0.32, whereas fbio values ranged from a minimum of 0.40 to a minimum 0.95. Two of these systems had been previously tested using a more complicated experimental approach, and the current results were in good agreement with previous results. These results indicate that biodegradation rate constant data from this

  2. A laboratory batch reactor test for assessing nonspeciated volatile organic compound biodegradation in activated sludge.

    PubMed

    Cano, M L; Saterbak, A; van Compernolle, R; Williams, M P; Huot, M E; Rhodes, I A; Allen, C C

    2003-01-01

    The relative rates of biodegradation and stripping and volatilization of nonspeciated volatile organic compounds (VOCs) in wastewater treated with aerobic activated-sludge processes can be quantified using a newly developed procedure. This method was adapted from the original aerated draft tube reactor test that was developed to measure biodegradation rate constants for specific volatile pollutants of interest. The original batch test has been modified to include solid-phase microextraction (SPME) fibers for sampling in the gas phase. The experimental procedure using SPME fibers does not require specific identification and quantitation of individual pollutants and can be used to evaluate wastewater with multiple VOCs. To illustrate use of this procedure, laboratory experiments were conducted using biomass and wastewater or effluent from three activated-sludge treatment systems. Each experiment consisted of two trials: a stripping-only trial without biomass and a stripping plus biodegradation trial using biomass from the activated-sludge unit of interest. Data from the two trials were used to quantify the rates of biodegradation by difference. The activated-sludge systems tested were a laboratory diffused-air reactor treating refinery wastewater, a full-scale surface aerated reactor treating a petrochemical wastewater, and a full-scale diffused-air reactor treating a variety of industrial effluents. The biodegradation rate constant data from each laboratory batch experiment were used in model calculations to quantify the fraction emitted (fe) and the fraction biodegraded (fbio) for each system. The fe values ranged from a maximum of 0.01 to a maximum of 0.32, whereas fbio values ranged from a minimum of 0.40 to a minimum 0.95. Two of these systems had been previously tested using a more complicated experimental approach, and the current results were in good agreement with previous results. These results indicate that biodegradation rate constant data from this

  3. Selenite bioremediation potential of indigenous microorganisms from industrial activated sludge.

    PubMed

    Garbisu, C; Alkorta, I; Carlson, D E; Leighton, T; Buchanan, B B

    1997-12-01

    Ten bacterial strains were isolated from the activated sludge waste treatment system (BIOX) at the Exxon refinery in Benicia, California. Half of these isolates could be grown in minimal medium. When tested for selenite detoxification capability, these five isolates (members of the genera Bacillus, Pseudomonas, Enterobacter and Aeromonas), were capable of detoxifying selenite with kinetics similar to those of a well characterized Bacillus subtilis strain (168 Trp+) studied previously. The selenite detoxification phenotype of the Exxon isolates was stable to repeated transfer on culture media which did not contain selenium. Microorganisms isolated from the Exxon BIOX reactor were capable of detoxifying selenite. Treatability studies using the whole BIOX microbial community were also carried out to evaluate substrates for their ability to support growth and selenite bioremediation. Under the appropriate conditions, indigenous microbial communities are capable of remediating selenite in situ.

  4. Denitrification kinetics in anoxic/aerobic activated sludge systems

    SciTech Connect

    Horne, G.M.

    1998-12-11

    Nitrogen removal needs at municipal wastewater treatment plants (WWTPs) have increased due to greater concerns about eutrophication and increased interest in reuse of treated municipal effluents. Biological processes are the most cost-effective method for nitrogen removal. Biological nitrogen removal is accomplished in two distinctly different processes by the conversion of nitrogen in the wastewater from organic nitrogen and ammonia to nitrate, followed by reduction of the nitrate to nitrogen gas. Nitrate production occurs in an aerobic activated sludge treatment zone during a process called nitrification. The nitrate is then converted through a series of intermediate steps to nitrogen gas in an anoxic zone (an anaerobic condition with nitrate present) during a process called denitrification, effectively removing the nitrogen from the wastewater. Many different WWTP designs have been developed to incorporate these two conditions for nitrogen removal.

  5. Tetracycline as a selector for resistant bacteria in activated sludge.

    PubMed

    Kim, Sungpyo; Jensen, James N; Aga, Diana S; Weber, A Scott

    2007-01-01

    Tetracycline, one of the most widely used antibiotics, is excreted into wastewater after consumption by humans and animals. The focus of this research was to evaluate the fate of tetracycline resistant bacteria in the activated sludge process as a function of tetracycline loading. The studies were conducted with aerobic biological sequencing batch reactors (SBRs). When comparing 250 microgl(-1) tetracycline fed SBRs with parallel SBRs having a background influent wastewater tetracycline concentration of approximately 1 microgl(-1), tetracycline fed reactors were found to have increased concentrations and production rates of tetracycline resistant bacteria, higher net growth rates of resistant bacteria, and higher percentages of tetracycline resistant bacteria, which were amplified by increase in organic loading and growth rates.

  6. A solid-phase extraction method for rapidly determining the adsorption coefficient of pharmaceuticals in sewage sludge

    PubMed Central

    Berthod, Laurence; Roberts, Gary; Whitley, David C.; Sharpe, Alan; Mills, Graham A.

    2014-01-01

    The partitioning of pharmaceuticals in the environment can be assessed by measuring their adsorption coefficients (Kd) between aqueous and solid phases. Measuring this coefficient in sewage sludge gives an indication of their partitioning behaviour in a wastewater treatment plant and hence contributes to an understanding of their subsequent fate. The regulatory approved method for measuring Kd in sewage sludge is the US Environmental Protection Agency's Office of Prevention, Pesticides and Toxic Substances (OPPTS) guideline 835.1110, which is labour intensive and time consuming. We describe an alternative method for measuring the Kd of pharmaceuticals in sewage sludge using a modified solid-phase extraction (SPE) technique. SPE cartridges were packed at different sludge/PTFE ratios (0.4, 6.0, 24.0 and 40.0% w/w sludge) and eluted with phosphate buffer at pH 7.4. The approach was tested initially using three pharmaceuticals (clofibric acid, diclofenac and oxytetracycline) that covered a range of Kd values. Subsequently, the sorption behaviour of ten further pharmaceuticals with varying physico-chemical properties was evaluated. Results from the SPE method were comparable to those of the OPPTS test, with a correlation coefficient of 0.93 between the two approaches. SPE cartridges packed with sludge and PTFE were stable for up to one year; use within one month reduced variability in measurements (to a maximum of 0.6 log units). The SPE method is low-cost, easy to use and enables the rapid measurement of Kd values for a large number of chemicals. It can be used as an alternative to the more laborious full OPPTS test in environmental fate studies and risk assessments. PMID:25299795

  7. Nitrogen removal from wastewater and external waste activated sludge reutilization/reduction by simultaneous sludge fermentation, denitrification and anammox (SFDA).

    PubMed

    Wang, Bo; Peng, Yongzhen; Guo, Yuanyuan; Zhao, Mengyue; Wang, Shuying

    2016-08-01

    This work demonstrates the feasibility of simultaneous nitrogen removal and external waste activated sludge (WAS) reutilization/reduction by using the synergy of sludge fermentation, denitrification and anammox processes in up-flow reactors (SFDA). Pre-treated domestic wastewater and synthetic wastewater (containing nitrite ∼20mg/L, ammonium ∼10mg/L in both) were fed to 1# and 2# SFDA, respectively. Long-term operation of 1# SFDA was investigated with achieving the peak ammonium removal rate of 0.021 and nitrite removal rate of 0.081kgN/(m(3)d) as nitrogen loading rate elevated from 0.075 to 0.106kgN/(m(3)d). Negative effect of dissolved oxygen on anammox or fermentation in the 2# SFDA was demonstrated negligible due to rapid depletion by microorganisms. Furthermore, a "net" sludge reduction of 38.8% was obtained due to sludge decay and organics consumption by denitrification. The SFDA process was expected to potentially be used for nitrogen removal and WAS reutilization/reduction in full-scale application. PMID:27140818

  8. 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%.

  9. Co-digestion of the hydromechanically separated organic fraction of municipal solid waste with sewage sludge.

    PubMed

    Borowski, Sebastian

    2015-01-01

    This study investigates the anaerobic digestion of the hydromechanically sorted organic fraction of municipal solid wastes (HS-OFMSW) co-digested with sewage sludge (SS). Eight laboratory-scale experiments were conducted under semi-continuous conditions at 15 and 20 days of solids retention time (SRT). The biogas yield from the waste reached 309 to 315 dm(3)/kgVS and 320 to 361 dm(3)/kgVS under mesophilic and thermophilic conditions, respectively. The addition of SS to HS-OFMSW (1:1 by weight) improved the C/N balance of the mixture, and the production of biogas through anaerobic mesophilic digestion increased to 494 dm(3)/kgVS, which corresponded to 316 dm(3)CH4/kgVS. However, when SS and HS-OFMSW were treated under thermophilic conditions, methanogenesis was inhibited by volatile fatty acids and free ammonia, which concentrations reached 5744 gCH3COOH/m(3) and 1009 gNH3/m(3), respectively. PMID:25262391

  10. Activated sludge process: Waste treatment. (Latest citations from the Biobusiness database). Published Search

    SciTech Connect

    1996-01-01

    The bibliography contains citations concerning the use of the activated sludge process in waste and wastewater treatment. Topics include biochemistry of the activated sludge process, effects of various pollutants on process activity, effects of environmental variables such as oxygen and water levels, and nutrient requirements of microorganisms employed in activated sludge processes. The citations also explore use of the process to treat specific wastes, such as halocarbons, metallic wastes, and petrochemical effluents; and wastes from pharmaceutical and dairy processes. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  11. Activated sludge process: Waste treatment. (Latest citations from the Biobusiness database). Published Search

    SciTech Connect

    Not Available

    1993-07-01

    The bibliography contains citations concerning the use of the activated sludge process in waste and wastewater treatment. Topics include biochemistry of the activated sludge process, effects of various pollutants on process activity, effects of environmental variables such as oxygen and water levels, and nutrient requirements of microorganisms employed in activated sludge processes. The citations also explore use of the process to treat specific wastes, such as halocarbons, metallic wastes, and petrochemical effluents; and wastes from pharmaceutical and dairy processes. (Contains 250 citations and includes a subject term index and title list.)

  12. Activated sludge process: Waste treatment. (Latest citations from the Biobusiness database). Published Search

    SciTech Connect

    Not Available

    1993-10-01

    The bibliography contains citations concerning the use of the activated sludge process in waste and wastewater treatment. Topics include biochemistry of the activated sludge process, effects of various pollutants on process activity, effects of environmental variables such as oxygen and water levels, and nutrient requirements of microorganisms employed in activated sludge processes. The citations also explore use of the process to treat specific wastes, such as halocarbons, metallic wastes, and petrochemical effluents; and wastes from pharmaceutical and dairy processes. (Contains 250 citations and includes a subject term index and title list.)

  13. Activated-sludge process: Waste treatment. (Latest citations from the biobusiness database). Published Search

    SciTech Connect

    Not Available

    1992-07-01

    The bibliography contains citations concerning the use of the activated sludge process in waste and wastewater treatment. Topics include biochemistry of the activated sludge process, effects of various pollutants on process activity, effects of environmental variables such as oxygen and water levels, and nutrient requirements of microorganisms employed in activated sludge processes. The citations also explore use of the process to treat specific wastes, such as halocarbons, metallic wastes, and petrochemical effluents; and wastes from pharmaceutical and dairy processes. (Contains 250 citations and includes a subject term index and title list.)

  14. Iron and phosphorus speciation in Fe-conditioned membrane bioreactor activated sludge.

    PubMed

    Wu, Hao; Ikeda-Ohno, Atsushi; Wang, Yuan; Waite, T David

    2015-06-01

    Iron dosing of membrane bioreactors (MBRs) is widely used as a means of meeting effluent phosphorus targets but there is limited understanding of the nature of iron and phosphorus-containing solids that are formed within the bioreactor (an important issue in view of the increasing interest in recovering phosphorus from wastewaters). Of particular challenge is the complexity of the MBR system and the variety of reactions that can occur on addition of iron salts to a membrane bioreactor. In this study, the performances of bench scale MBRs with dosing of either ferrous or ferric salts were monitored for a period of four months. The distributions of Fe and P-species in the Fe-conditioned sludges were determined using X-ray absorption spectroscopy (XAS) at the Fe K-edge and the P K-edge. Regardless of whether iron was dosed to the anoxic or aerobic chambers and regardless of whether ferrous (Fe(II)) or ferric (Fe(III)) iron was dosed, iron present in the minerals in the conditioned sludges was consistently in the +III oxidation state. Fitting of the Fe K-edge EXAFS spectra revealed that an Fe(III)-phosphate species was the main Fe species present in all cases with the remaining fraction dominated by lepidocrocite (γ-FeOOH) in the Fe(II)-dosed case and ferrihydrite (am-FeOOH) in the Fe(III)-dosed case. Approximately half the phosphorus in the activated sludge samples was present as a distinct Fe-PO4 mineral (such as strengite or an amorphous ferric hydroxyl phosphate analogue of strengite) and half as phosphorus adsorbed to an iron oxyhydroxide mineral phase indicating that both co-precipitation and adsorption of phosphorus by iron contribute to removal of phosphorus from the MBR supernatant.

  15. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    NASA Astrophysics Data System (ADS)

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d-1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

  16. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    PubMed Central

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d−1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery. PMID:26791952

  17. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate.

    PubMed

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d(-1)) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery. PMID:26791952

  18. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate

    NASA Astrophysics Data System (ADS)

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-01

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d‑1) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

  19. Polyhydroxyalkanoates in waste activated sludge enhances anaerobic methane production through improving biochemical methane potential instead of hydrolysis rate.

    PubMed

    Wang, Qilin; Sun, Jing; Zhang, Chang; Xie, Guo-Jun; Zhou, Xu; Qian, Jin; Yang, Guojing; Zeng, Guangming; Liu, Yiqi; Wang, Dongbo

    2016-01-21

    Anaerobic sludge digestion is the main technology for sludge reduction and stabilization prior to sludge disposal. Nevertheless, methane production from anaerobic digestion of waste activated sludge (WAS) is often restricted by the poor biochemical methane potential and slow hydrolysis rate of WAS. This work systematically investigated the effect of PHA levels of WAS on anaerobic methane production, using both experimental and mathematical modeling approaches. Biochemical methane potential tests showed that methane production increased with increased PHA levels in WAS. Model-based analysis suggested that the PHA-based method enhanced methane production by improving biochemical methane potential of WAS, with the highest enhancement being around 40% (from 192 to 274 L CH4/kg VS added; VS: volatile solid) when the PHA levels increased from 21 to 143 mg/g VS. In contrast, the hydrolysis rate (approximately 0.10 d(-1)) was not significantly affected by the PHA levels. Economic analysis suggested that the PHA-based method could save $1.2/PE/y (PE: population equivalent) in a typical wastewater treatment plant (WWTP). The PHA-based method can be easily integrated into the current WWTP to enhance methane production, thereby providing a strong support to the on-going paradigm shift in wastewater management from pollutant removal to resource recovery.

  20. [Comparative Metagenomics of BIOLAK and A2O Activated Sludge Based on Next-generation Sequencing Technology].

    PubMed

    Tian, Mei; Liu, Han-hu; Shen, Xin

    2016-02-15

    This is the first report of comparative metagenomic analyses of BIOLAK sludge and anaerobic/anoxic/oxic (A2O) sludge. In the BIOLAK and A2O sludge metagenomes, 47 and 51 phyla were identified respectively, more than the numbers of phyla identified in Australia EBPR (enhanced biological phosphorus removal), USA EBPR and Bibby sludge. All phyla found in the BIOLAK sludge were detected in the A2O sludge, but four phyla were exclusively found in the A20 sludge. The proportion of the phylum Ignavibacteriae in the A2O sludge was 2.0440%, which was 3.2 times as much as that in the BIOLAK sludge (0.6376%). Meanwhile, the proportion of the bacterial phylum Gemmatimonadetes in the BIOLAK sludge was 2.4673%, which was >17 times as much as that in the A2O sludge (0.1404%). The proportion of the bacterial phylum Chlamydiae in the BIOLAK metagenome (0.2192%) was >6 times higher than that in the A2O (0.0360%). Furthermore, 167 genera found in the A20 sludge were not detected in the BIOLAK sludge. And 50 genera found in the BIOLAK sludge were not detected in the A20 sludge. From the analyses of both the phylum and genus levels, there were huge differences between the two biological communities of A2O and BIOLAK sludge. However, the proportions of each group of functional genes associated with metabolism of nitrogen, phosphor, sulfur and aromatic compounds in BIOLAK were very similar to those in A2O sludge. Moreover, the rankings of all six KEGG (Kyoto Encyclopedia for Genes and Genomes) categories were identical in the two sludges. In addition, the analyses of functional classification and pathway related nitrogen metabolism showed that the abundant enzymes had identical ranking in the BIOLAK and A2O metagenomes. Therefore, comparative metagenomics of BIOLAK and A2O activated sludge indicated similar function assignments from the two different biological communities.

  1. [Changes of Microbial Community Structure in Activated Sludge Bulking at Low Temperature].

    PubMed

    Duan, Zheng-hua; Pan, Liu-ming; Chen, Xiao-ou; Wang, Xiu-duo; Zhao, Le-jun; Tian, Le-qi

    2016-03-15

    The mechanism of activated sludge bulking in Zhengzhou wastewater treatment plant was studied by measurement of water quality parameters and high-throughput sequencing technology. The change of SVI value was significantly negatively correlated with the seasonal temperature variation, and sludge bulking was easy to occur during December to the next April, but the water quality was not affected. The result verified by high-throughput sequencing technology analysis showed that the microbial community structure of bulking sludge was significantly different from that of the non-bulking one. The dominant filamentous bacteria in the bulking sludge in this plant were Saprospiraceae and Flavobacterium. Therefore, the activated sludge bulking in this wastewater treatment plant was caused by the propagation of filamentous bacteria at low temperature. PMID:27337902

  2. [Changes of Microbial Community Structure in Activated Sludge Bulking at Low Temperature].

    PubMed

    Duan, Zheng-hua; Pan, Liu-ming; Chen, Xiao-ou; Wang, Xiu-duo; Zhao, Le-jun; Tian, Le-qi

    2016-03-15

    The mechanism of activated sludge bulking in Zhengzhou wastewater treatment plant was studied by measurement of water quality parameters and high-throughput sequencing technology. The change of SVI value was significantly negatively correlated with the seasonal temperature variation, and sludge bulking was easy to occur during December to the next April, but the water quality was not affected. The result verified by high-throughput sequencing technology analysis showed that the microbial community structure of bulking sludge was significantly different from that of the non-bulking one. The dominant filamentous bacteria in the bulking sludge in this plant were Saprospiraceae and Flavobacterium. Therefore, the activated sludge bulking in this wastewater treatment plant was caused by the propagation of filamentous bacteria at low temperature.

  3. Residues of pharmaceutical products in recycled organic manure produced from sewage sludge and solid waste from livestock and relationship to their fermentation level.

    PubMed

    Motoyama, Miki; Nakagawa, Shuhei; Tanoue, Rumi; Sato, Yuri; Nomiyama, Kei; Shinohara, Ryota

    2011-07-01

    In recent years, sludge generated in sewage treatment plants (STPs) and solid waste from livestock being utilized is useful for circulation of nourishment in farmlands as recycled organic manure (ROM). In this study, we determined the residue levels and patterns of 12 pharmaceutical products generated by human activity in the ROMs produced from human waste sludge (HWS), sewage sludge (SS), cattle manure (CM), poultry manure (PM), swine manure (SM) and horse manure (HM). The kind and number of pharmaceutical products detected in ROMs were different. Fluoroquinolones (FQs) were detected at high levels in HWS and SS samples. In addition, the detection frequency and concentration levels of sulfonamides (SAs) in PM and SM were high. Moreover, high concentrations of chlortetracycline (CTC) were found in only SM. These differences reflect specific adherence adsorption of the pharmaceutical products to different livestock and humans. Moreover, it was found that the concentrations of pharmaceutical products and fermentation levels of ROMs had significant positive correlation (r=0.41, p=0.024). When the fermentation test of ROM was conducted in a rotary fermentor in a lab scale test, the residue levels of pharmaceutical products decreased effectively except carbamazepine (CBZ). The rates of decrease were in the case of tetracyclines (TCs): 85-92%, FQs: 81-100%, erythromycine: 67%, SAs: 79-95%, trimethoprim: 86% and CBZ: 37% by 30 d. Pharmaceutical products that can be decomposed by fermentation process at the lowest impact of residual antibiotic activities may therefore be considered as environmentally friendly medicines.

  4. Activated Sludge. Selected Instructional Activities and References. Instructional Resources Monograph Series.

    ERIC Educational Resources Information Center

    Shepard, Clinton L.; Walasek, James B.

    This monograph contains a variety of selected materials related to wastewater treatment and water quality education and instruction. Part I presents a brief discussion of the activated sludge process in wastewater treatment operations. Part II, Instructional Units, contains selected portions of existing programs which may be utilized in…

  5. Aerobic degradation of sulfanilic acid using activated sludge.

    PubMed

    Chen, Gang; Cheng, Ka Yu; Ginige, Maneesha P; Kaksonen, Anna H

    2012-01-01

    This paper evaluates the aerobic degradation of sulfanilic acid (SA) by an acclimatized activated sludge. The sludge was enriched for over three months with SA (>500 mg/L) as the sole carbon and energy source and dissolved oxygen (DO, >5mg/L) as the primary electron acceptor. Effects of aeration rate (0-1.74 L/min), DO concentration (0-7 mg/L) and initial SA concentration (104-1085 mg/L) on SA biodegradation were quantified. A modified Haldane substrate inhibition model was used to obtain kinetic parameters of SA biodegradation and oxygen uptake rate (OUR). Positive linear correlations were obtained between OUR and SA degradation rate (R(2)≥ 0.91). Over time, the culture consumed more oxygen per SA degraded, signifying a gradual improvement in SA mineralization (mass ratio of O(2): SA at day 30, 60 and 120 were 0.44, 0.51 and 0.78, respectively). The concomitant release of near stoichiometric quantity of sulphate (3.2 mmol SO(4)(2-) released from 3.3 mmol SA) and the high chemical oxygen demand (COD) removal efficacy (97.1%) indicated that the enriched microbial consortia could drive the overall SA oxidation close to a complete mineralization. In contrast to other pure-culture systems, the ammonium released from the SA oxidation was predominately converted into nitrate, revealing the presence of ammonium-oxidizing bacteria (AOB) in the mixed culture. No apparent inhibitory effect of SA on the nitrification was noted. This work also indicates that aerobic SA biodegradation could be monitored by real-time DO measurement.

  6. Design and performance of a porous pot bioreactor for assessing biodegradation in activated sludge treatment

    SciTech Connect

    Nielsen, A.M.; McCormick, T.P.; Russell, G.L.; Filler, P.A.; Britton, L.N.

    1994-12-31

    It is useful to be able to predict biodegradation rates and extents of consumer chemicals in activated sludge (AS), municipal waste treatment units. This study describes an apparatus based on the porous pot concept developed in the United Kingdom. The benchtop apparatus is a single vessel and is constructed of glass that houses a porous, polypropylene ``candle`` to facilitate the control of the sludge retention time (SRT). Hydraulic retention time (HRT) in the fixed-volume vessel is controlled by the feed rate using low-volume pumps. At a typical volatile suspended solids concentration of 2,000 2,500 mg/L, the apparatus achieved 90--92% COD removal and 96--98% BOD removal from municipal sewage when operated at 6 hrs. HRT and 10 days SRT. Biodegradation of test compounds can be followed using specific analytical chemistry techniques or radiolabel recovery from {sup 14}C-substrates. {sup 14}C-benzene ring labelled linear alkyl benzene sulfonate (LAS) and four other radiolabeled surfactant compounds were used to determine the utility of the apparatus to follow biodegradation rates and extents in simulated AS treatment. Mineralization rates, as determined by {sup 14}CO{sub 2} trapping and measurement, were consistent during continuous operation, and total radiolabel recoveries ranged from 95--102% indicating excellent ability to follow the catabolic fate of test chemicals.

  7. Determination of the required surface area of a final clarifier for an activated-sludge system.

    PubMed

    Yuen, Weng Ah

    2004-01-01

    A generic methodology for determining the required surface area of a final clarifier is presented. Clarification and thickening requirements are integrated to form a unified procedure for final clarifier design. The new method is based on results obtained by Yuen (2002) on the solids flux theory for a secondary clarifier; it does not require the specification of recycle rate, which is computed as an output of the method. The author shows that there is a minimum required surface area (A(m)) for a final clarifier under the thickening requirement when the designed recycle rate is set at the maximum allowable value (FR)m (at the critical state). The designed surface area and the return activated sludge pumping capacity can be determined by applying a safety factor to A(m) and (FR)m, respectively. The method is shown to conform to conventional design criteria under typical design conditions.

  8. Experimental investigation of the external nitrification biological nutrient removal activated sludge (ENBNRAS) system.

    PubMed

    Hu, Zhi-Rong; Sötemann, S; Moodley, R; Wentzel, M C; Ekama, G A

    2003-08-01

    A systematic lab-scale experimental investigation is reported for the external nitrification (EN) biological nutrient removal (BNR) activated sludge (ENBNRAS) system, which is a combined fixed and suspended medium system. The ENBNRAS system was proposed to intensify the treatment capacity of BNR-activated sludge (BNRAS) systems by addressing two difficulties often encountered in practice: (a) the long sludge age for nitrification requirement; and (b) sludge bulking. In the ENBNRAS system, nitrification is transferred from the aerobic reactor in the suspended medium activated sludge system to a fixed medium nitrification system. Thus, the sludge age of the suspended medium activated sludge system can be reduced from 20 to 25 days to 8 to 10 days, resulting in a decrease in reactor volume per ML wastewater treated of about 30%. Furthermore, the aerobic mass fraction can also be reduced from 50% to 60% to <30% and concommitantly the anoxic mass fraction can be increased from 25% to 35% to >55% (if the anaerobic mass fraction is 15%), and thus complete denitrification in the anoxic reactors becomes possible. Research indicates that both the short sludge age and complete denitrification could ameliorate anoxic aerobic (AA) or low food/microorganism (F/M) ratio filamentous bulking, and hence reduce the surface area of secondary settling tanks or increase the treatment capacity of existing systems. The lab-scale experimental investigations indicate that the ENBNRAS system can obtain: (i) very good chemical oxygen demand (COD) removal, even with an aerobic mass fraction as low as 20%; (ii) high nitrogen removal, even for a wastewater with a high total kjeldahl nitrogen (TKN)/COD ratio, up to 0.14; (iii) adequate settling sludge (diluted sludge volume index [DSVI] <100 mL/g); and (iv) a significant reduction in oxygen demand.

  9. On the occurrence of anoxic microniches, denitrification, and sulfate reduction in aerated activated sludge

    SciTech Connect

    Schramm, A.; Santegoeds, C.M.; Nielsen, H.K.; Ploug, H.; Wagner, M.; Pribyl, M.; Wanner, J.; Amann, R.; De Beer, D.

    1999-09-01

    A combination of different methods was applied to investigate the occurrence of anaerobic processes in aerated activated sludge. Microsensor measurements (O{sub 2}, NO{sub 2}{sup {minus}}, NO{sub 3}{sup {minus}}, and H{sub 2}S) were performed on single sludge flocs to detect anoxic niches, nitrate reduction, or sulfate reduction on a microscale. Incubations of activated sludge with {sup 15}NO{sub 3}{sup {minus}} and {sup 35}SO{sub 4}{sup 2{minus}} were used to determine denitrification and sulfate reduction rates on a batch scale. In four of six investigated sludges, no anoxic zones developed during aeration, and consequently denitrification rates were very low. However, in two sludges anoxia in flocs coincided with significant denitrification rates. Sulfate reduction could not be detected in any sludge in either the microsensor or the batch investigation, not even under short-term anoxic conditions. In contrast, the presence of sulfate-reducing bacteria was shown by fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes and by PCR-based detection of genes coding for the dissimilatory sulfite reductase. A possible explanation for the absence of advection, i.e., facilitated by flow through pores and channels. This possibility is suggested by the irregularity of some oxygen profiles and by confocal laser scanning microscopy of the three-dimensional floc structures, which showed that flocs from the two sludges in which anoxic zones were found were apparently denser than flocs from the other sludges.

  10. 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

  11. 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

  12. Hybrid alkali-hydrodynamic disintegration of waste-activated sludge before two-stage anaerobic digestion process.

    PubMed

    Grübel, Klaudiusz; Suschka, Jan

    2015-05-01

    The first step of anaerobic digestion, the hydrolysis, is regarded as the rate-limiting step in the degradation of complex organic compounds, such as waste-activated sludge (WAS). The aim of lab-scale experiments was to pre-hydrolyze the sludge by means of low intensive alkaline sludge conditioning before applying hydrodynamic disintegration, as the pre-treatment procedure. Application of both processes as a hybrid disintegration sludge technology resulted in a higher organic matter release (soluble chemical oxygen demand (SCOD)) to the liquid sludge phase compared with the effects of processes conducted separately. The total SCOD after alkalization at 9 pH (pH in the range of 8.96-9.10, SCOD = 600 mg O2/L) and after hydrodynamic (SCOD = 1450 mg O2/L) disintegration equaled to 2050 mg/L. However, due to the synergistic effect, the obtained SCOD value amounted to 2800 mg/L, which constitutes an additional chemical oxygen demand (COD) dissolution of about 35 %. Similarly, the synergistic effect after alkalization at 10 pH was also obtained. The applied hybrid pre-hydrolysis technology resulted in a disintegration degree of 28-35%. The experiments aimed at selection of the most appropriate procedures in terms of optimal sludge digestion results, including high organic matter degradation (removal) and high biogas production. The analyzed soft hybrid technology influenced the effectiveness of mesophilic/thermophilic anaerobic digestion in a positive way and ensured the sludge minimization. The adopted pre-treatment technology (alkalization + hydrodynamic cavitation) resulted in 22-27% higher biogas production and 13-28% higher biogas yield. After two stages of anaerobic digestion (mesophilic conditions (MAD) + thermophilic anaerobic digestion (TAD)), the highest total solids (TS) reduction amounted to 45.6% and was received for the following sample at 7 days MAD + 17 days TAD. About 7% higher TS reduction was noticed compared with the sample after 9

  13. 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.

  14. How Does Poly(hydroxyalkanoate) Affect Methane Production from the Anaerobic Digestion of Waste-Activated Sludge?

    PubMed

    Wang, Dongbo; Zhao, Jianwei; Zeng, Guangming; Chen, Yinguang; Bond, Philip L; Li, Xiaoming

    2015-10-20

    Recent studies demonstrate that, besides being used for production of biodegradable plastics, poly(hydroxyalkanoate) (PHA) that is accumulated in heterotrophic microorganisms during wastewater treatment has another novel application direction, i.e., being utilized for enhancing methane yield during the anaerobic digestion of waste-activated sludge (WAS). To date, however, the underlying mechanism of how PHA affects methane production remains largely unknown, and this limits optimization and application of the strategy. This study therefore aims to fill this knowledge gap. Experimental results showed that with the increase of sludge PHA levels from 21 to 184 mg/g of volatile suspended solids (VSS) the methane yield linearly increased from 168.0 to 246.1 mL/g of VSS (R(2) = 0.9834). Compared with protein and carbohydrate (the main components of a cell), PHA exhibited a higher biochemical methane potential on a unit VSS basis. It was also found that the increased PHA not only enhanced cell disruption of PHA cells but also benefited the soluble protein conversion of both PHA- and non-PHA cells. Moreover, the reactor fed with higher PHA sludge showed greater sludge hydrolysis and acidification than those fed with the lower PHA sludges. Further investigations using fluorescence in situ hybridization and enzyme analysis revealed that the increased PHA enhanced the abundance of methanogenic Archaea and increased the activities of protease, acetate kinase, and coenzyme F420, which were consistent with the observed methane yield. This work provides insights into PHA-involved WAS digestion systems and may have important implications for future operation of wastewater treatment plants. PMID:26381110

  15. How Does Poly(hydroxyalkanoate) Affect Methane Production from the Anaerobic Digestion of Waste-Activated Sludge?

    PubMed

    Wang, Dongbo; Zhao, Jianwei; Zeng, Guangming; Chen, Yinguang; Bond, Philip L; Li, Xiaoming

    2015-10-20

    Recent studies demonstrate that, besides being used for production of biodegradable plastics, poly(hydroxyalkanoate) (PHA) that is accumulated in heterotrophic microorganisms during wastewater treatment has another novel application direction, i.e., being utilized for enhancing methane yield during the anaerobic digestion of waste-activated sludge (WAS). To date, however, the underlying mechanism of how PHA affects methane production remains largely unknown, and this limits optimization and application of the strategy. This study therefore aims to fill this knowledge gap. Experimental results showed that with the increase of sludge PHA levels from 21 to 184 mg/g of volatile suspended solids (VSS) the methane yield linearly increased from 168.0 to 246.1 mL/g of VSS (R(2) = 0.9834). Compared with protein and carbohydrate (the main components of a cell), PHA exhibited a higher biochemical methane potential on a unit VSS basis. It was also found that the increased PHA not only enhanced cell disruption of PHA cells but also benefited the soluble protein conversion of both PHA- and non-PHA cells. Moreover, the reactor fed with higher PHA sludge showed greater sludge hydrolysis and acidification than those fed with the lower PHA sludges. Further investigations using fluorescence in situ hybridization and enzyme analysis revealed that the increased PHA enhanced the abundance of methanogenic Archaea and increased the activities of protease, acetate kinase, and coenzyme F420, which were consistent with the observed methane yield. This work provides insights into PHA-involved WAS digestion systems and may have important implications for future operation of wastewater treatment plants.

  16. Bioproduction of volatile fatty acid from the fermentation of waste activated sludge for in situ denitritation.

    PubMed

    Wang, Bo; Peng, Yongzhen; Guo, Yuanyuan; Wang, Shuying

    2016-04-01

    Waste activated sludge (WAS) fermentation integrated with denitritation (the reduction of nitrite to dinitrogen gas) at different pHs was investigated in batch-mode reactors over a 24-day period. The results showed that in comparison with controlled pHs, the volatile fatty acid (VFA) bioproduction for in situ denitritation was significantly improved at uncontrolled pH. VFA fermented from WAS was quickly consumed by denitritation at uncontrolled pH, which accelerated sludge degradation. On the other hand, sludge digestion was benefited from the alkalinity produced from denitritation, while methanogenesis was prohibited by alkalinity and nitrite. The integrated sludge fermentation and denitritation can be cost-effectively applied to wastewater treatment plants, so that organic substrates (e.g., VFAs) are produced for denitritation via simultaneous sludge fermentation, which enables WAS reutilization and enhances nitrogen removal efficiency without the need of external carbon sources.

  17. Municipal incineration studies: Sludge, refuse, and solid wastes. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1996-02-01

    The bibliography contains citations concerning the use of incineration processes for the destruction of municipal wastes, including sewage sludge, refuse, and solid wastes. Topics include systems design and management, combustion and emissions studies, pollution and toxicity studies, heat recovery operations, pollution control devices, and economic aspects. Analytical methods for pollution identification, marine vessel incinerators, catalytic incineration, and risk assessment studies are also considered.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  18. Municipal incineration studies: Sludge, refuse, and solid wastes. (Latest citations from the NTIS bibliographic database). NewSearch

    SciTech Connect

    Not Available

    1994-11-01

    The bibliography contains citations concerning the use of incineration processes for the destruction of municipal wastes, including sewage sludge, refuse, and solid wastes. Topics include systems design and management, combustion and emissions studies, pollution and toxicity studies, heat recovery operations, pollution control devices, and economic aspects. Analytical methods for pollution identification, marine vessel incinerators, catalytic incineration, and risk assessment studies are also considered. (Contains 250 citations and includes a subject term index and title list.)

  19. Influence of Copper Nanoparticles on the Physical-Chemical Properties of Activated Sludge

    PubMed Central

    Chen, Hong; Zheng, Xiong; Chen, Yinguang; Li, Mu; Liu, Kun; Li, Xiang

    2014-01-01

    The physical-chemical properties of activated sludge, such as flocculating ability, hydrophobicity, surface charge, settleability, dewaterability and bacteria extracellular polymer substances (EPS), play vital roles in the normal operation of wastewater treatment plants (WWTPs). The nanoparticles released from commercial products will enter WWTPs and can induce potential adverse effects on activated sludge. This paper focused on the effects of copper nanoparticles (CuNPs) on these specific physical-chemical properties of activated sludge. It was found that most of these properties were unaffected by the exposure to lower CuNPs concentration (5 ppm), but different observation were made at higher CuNPs concentrations (30 and 50 ppm). At the higher CuNPs concentrations, the sludge surface charge increased and the hydrophobicity decreased, which were attributed to more Cu2+ ions released from the CuNPs. The carbohydrate content of EPS was enhanced to defense the toxicity of CuNPs. The flocculating ability was found to be deteriorated due to the increased cell surface charge, the decreased hydrophobicity, and the damaged cell membrane. The worsened flocculating ability made the sludge flocs more dispersed, which further increased the toxicity of the CuNPs by increasing the availability of the CuNPs to the bacteria present in the sludge. Further investigation indicated that the phosphorus removal efficiency decreased at higher CuNPs concentrations, which was consistent with the deteriorated physical-chemical properties of activated sludge. It seems that the physical-chemical properties can be used as an indicator for determining CuNPs toxicity to the bacteria in activated sludge. This work is important because bacteria toxicity effects to the activated sludge caused by nanoparticles may lead to the deteriorated treatment efficiency of wastewater treatment, and it is therefore necessary to find an easy way to indicate this toxicity. PMID:24663333

  20. Influence of copper nanoparticles on the physical-chemical properties of activated sludge.

    PubMed

    Chen, Hong; Zheng, Xiong; Chen, Yinguang; Li, Mu; Liu, Kun; Li, Xiang

    2014-01-01

    The physical-chemical properties of activated sludge, such as flocculating ability, hydrophobicity, surface charge, settleability, dewaterability and bacteria extracellular polymer substances (EPS), play vital roles in the normal operation of wastewater treatment plants (WWTPs). The nanoparticles released from commercial products will enter WWTPs and can induce potential adverse effects on activated sludge. This paper focused on the effects of copper nanoparticles (CuNPs) on these specific physical-chemical properties of activated sludge. It was found that most of these properties were unaffected by the exposure to lower CuNPs concentration (5 ppm), but different observation were made at higher CuNPs concentrations (30 and 50 ppm). At the higher CuNPs concentrations, the sludge surface charge increased and the hydrophobicity decreased, which were attributed to more Cu2+ ions released from the CuNPs. The carbohydrate content of EPS was enhanced to defense the toxicity of CuNPs. The flocculating ability was found to be deteriorated due to the increased cell surface charge, the decreased hydrophobicity, and the damaged cell membrane. The worsened flocculating ability made the sludge flocs more dispersed, which further increased the toxicity of the CuNPs by increasing the availability of the CuNPs to the bacteria present in the sludge. Further investigation indicated that the phosphorus removal efficiency decreased at higher CuNPs concentrations, which was consistent with the deteriorated physical-chemical properties of activated sludge. It seems that the physical-chemical properties can be used as an indicator for determining CuNPs toxicity to the bacteria in activated sludge. This work is important because bacteria toxicity effects to the activated sludge caused by nanoparticles may lead to the deteriorated treatment efficiency of wastewater treatment, and it is therefore necessary to find an easy way to indicate this toxicity.

  1. Simultaneous fluorescent gram staining and activity assessment of activated sludge bacteria.

    PubMed

    Forster, Scott; Snape, Jason R; Lappin-Scott, Hilary M; Porter, Jonathan

    2002-10-01

    Wastewater treatment is one of the most important commercial biotechnological processes, and yet the component bacterial populations and their associated metabolic activities are poorly understood. The novel fluorescent dye hexidium iodide allows assessment of Gram status by differential absorption through bacterial cell walls. Differentiation between gram-positive and gram-negative wastewater bacteria was achieved after flow cytometric analysis. This study shows that the relative proportions of gram-positive and gram-negative bacterial cells identified by traditional microscopy and hexidium iodide staining were not significantly different. Dual staining of cells for Gram status and activity proved effective in analyzing mixtures of cultured bacteria and wastewater populations. Levels of highly active organisms at two wastewater treatment plants, both gram positive and gram negative, ranged from 1.5% in activated sludge flocs to 16% in the activated sludge fluid. Gram-positive organisms comprised <5% of the total bacterial numbers but accounted for 19 and 55% of the highly active organisms within flocs at the two plants. Assessment of Gram status and activity within activated sludge samples over a 4-day period showed significant differences over time. This method provides a rapid, quantitative measure of Gram status linked with in situ activity within wastewater systems.

  2. Determination of chiral pharmaceuticals and illicit drugs in wastewater and sludge using microwave assisted extraction, solid-phase extraction and chiral liquid chromatography coupled with tandem mass spectrometry.

    PubMed

    Evans, Sian E; Davies, Paul; Lubben, Anneke; Kasprzyk-Hordern, Barbara

    2015-07-01

    This is the first study presenting a multi-residue method allowing for comprehensive analysis of several chiral pharmacologically active compounds (cPACs) including beta-blockers, antidepressants and amphetamines in wastewater and digested sludge at the enantiomeric level. Analysis of both the liquid and solid matrices within wastewater treatment is crucial to being able to carry out mass balance within these systems. The method developed comprises filtration, microwave assisted extraction and solid phase extraction followed by chiral liquid chromatography coupled with tandem mass spectrometry to analyse the enantiomers of 18 compounds within all three matrices. The method was successfully validated for 10 compounds within all three matrices (amphetamine, methamphetamine, MDMA, MDA, venlafaxine, desmethylvenlafaxine, citalopram, metoprolol, propranolol and sotalol), 7 compounds validated for the liquid matrices only (mirtazapine, salbutamol, fluoxetine, desmethylcitalopram, atenolol, ephedrine and pseudoephedrine) and 1 compound (alprenolol) passing the criteria for solid samples only. The method was then applied to wastewater samples; cPACs were found at concentration ranges in liquid matrices of: 1.7 ng L(-1) (metoprolol) - 1321 ng L(-1) (tramadol) in influent, solid matrix digested sludge: 0.4 ng g(-1) (metoprolol) - 275 ng g(-1) (citalopram). Enantiomeric profiling revealed that studied compounds were present in analysed samples in non-racemic composition. Furthermore, enantiomeric composition of studied analytes differed in liquid and solid matrices. This demonstrates that not analysing the solid fraction of wastewater may lead to over-estimation of the removal rates of cPACs as well as possible misrepresentation of the enantiomeric fraction of the compounds as they leave the wastewater treatment plant. Consequently risks from cPACs entering the environment might be higher than

  3. Anaerobic waste-activated sludge digestion - A bioconversion mechanism and kinetic model

    SciTech Connect

    Shimizu, Tatsuo; Kudo, Kenzo; Nasu, Yoshikazu )

    1993-05-01

    The anaerobic bioconversion of raw and mechanically lysed waste-activated sludge was kinetically investigated. The hydrolysis of the biopolymers, such as protein, which leaked out from the biological sludge with ultrasonic lysis, was a first-order reaction in anaerobic digestion and the rate constant was much higher than the decay rate constant of the raw waste activated sludge. An anaerobic digestion model that is capable of evaluating the effect of the mechanical sludge lysis on digestive performance was developed. The present model includes four major biological processes - the release of intracellular matter with sludge lysis; hydrolysis of biopolymers to volatile acids; the degradation of various volatile acids to acetate; and the conversion of acetate and hydrogen to methane. Each process was assumed to follow first-order kinetics. The model approximately simulated the overall process performance of the anaerobic digestion of waste-activated sludge. The model suggested that when the lysed waste-activated sludge was fed, the overall digestive performance remarkably increased in the two-phase system consisting of an acid forming process and a methanogenic process, which ensured the symbiotic growth of acetogenic and methanogenic bacteria.

  4. Characterizing the fluorescent products of waste activated sludge in dissolved organic matter following ultrasound assisted ozone pretreatments.

    PubMed

    Yang, Shan-Shan; Guo, Wan-Qian; Meng, Zhao-Hui; Zhou, Xian-Jiao; Feng, Xiao-Chi; Zheng, He-Shan; Liu, Bo; Ren, Nan-Qi; Cui, Ya-Shan

    2013-03-01

    This study investigated the effects of ozone and ultrasound (US) pretreatments, both individually and combined, on waste activated sludge reduction. Batch tests were conducted first to optimize the individual ozone and US pretreatments. Maximum sludge reduction ratios of 10.89% and 23% were obtained at 0.15g O3/g total solids ozone dose and 1.5W/mL US energy density, respectively. The combined ozone and US pretreatments were studied using response surface methodology. A maximum sludge reduction ratio of 40.14% was achieved by the combined ozone/US pretreatment with an ozone dose of 0.154g O3/g total solids and an US energy density of 1.445W/mL. The analysis of the dissolved organic matter by three-dimensional excitation-emission matrix fluorescence spectroscopy showed that the combined pretreatment was superior to the individual ozone and US pretreatments, and also demonstrated the synergetic effect of these two combined pretreatments.

  5. [Using Excess Activated Sludge Treated 4-Chlorophenol Contained Waste Water to Cultivate Chlorella vulgaris].

    PubMed

    Wang, Lu; Chen, Xiu-rong; Yan, Long; He, Yi-xuan; Shi, Zhen-dong

    2015-04-01

    Using different rations of sludge extracts and supernate from 4-Chlorophenol (4-CP) simulated wastewater's excess sludge after centrifugation to cultivate the Chlorella vulgaris to achieve the goal of excess sludge utilization together with chlorella cultivating. The experiments were performed in 500 mL flasks with different rations of sludge extracts & BG-11 and supernate & BG-11 in a light growth chamber respectively. Number of algal cells, Chlorophyll, enzyme activity, oil and water total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), toxicity index were investigated. Result showed that the nutrition supplies and toxicity in the excess sludge were removed efficiently via Chlorella vulgaris, the removal rates of TN and TP were at least 40% and 90% respectively; After 10 days cultivation, the density growth of 50% sludge extracts was 20 times higher of the beginning while its chlorophyll content was lower than that of the blank group. Sludge extracts could promote the proliferation of algae, but were not conducive to the synthesis of chlorophyll. The quantity of SOD in per cell showed Chlorella vulgaris gave a positive response via stimulation from toxicant in sludge extracts and supernate. The best time for collecting chlorella vulgaris was the fifth day of cultivation, taking neutral oil accumulation as the evaluating indicator for its utilization combined with the removal of supplies and toxicity.

  6. Effective anaerobic biodegradation of municipal solid waste fresh leachate using a novel pilot-scale reactor: comparison under different seeding granular sludge.

    PubMed

    Luo, Jinghuan; Zhou, Jizhi; Qian, Guangren; Liu, Jianyong

    2014-08-01

    A novel integrated internal and external circulation (IIEC) reactor was developed for anaerobic biodegradation of municipal solid waste (MSW) fresh leachate with chemical oxygen demand (COD) between 40,000 and 60,000mg/l. The pilot-scale IIEC reactor was inoculated with two kinds of granular sludge from paper mill (SPM) and from citric acid factory (SCF), respectively. The bio-treating capacity in contaminant removal and biogas production performed much superior to others' results, principally attributed to appropriate configuration modification. Compared to SCF, much higher organic loading rate (40.5 vs 23.0kgCOD/m(3)d) and COD removal efficiency (>80% vs 60-75%) were achieved for the reactor with SPM. For methane production, 11.77 or ∼6m(3)STP/m(3)d of rate and 66-85% of content were observed with SPM or SCF, respectively. Due to better sludge concentrations and methanogenic activity, these findings indicate the anaerobic reactor could effectively bio-treat MSW leachate for methane generation, especially inoculated with granular sludge derived from leachate-like-wastewater.

  7. A new process for efficiently producing methane from waste activated sludge: alkaline pretreatment of sludge followed by treatment of fermentation liquid in an EGSB reactor.

    PubMed

    Zhang, Dong; Chen, Yinguang; Zhao, Yuxiao; Ye, Zhengxiang

    2011-01-15

    In the literature the production of methane from waste activated sludge (WAS) was usually conducted in a continuous stirred tank reactor (CSTR) after sludge was pretreated. It was reported in our previous publication that compared with other pretreatment methods the methane production in CSTR could be significantly enhanced when sludge was pretreated by NaOH at pH 10 for 8 days. In order to further improve methane production, this study reported a new process for efficiently producing methane from sludge, that is, sludge was fermented at pH 10 for 8 days, which was adjusted by Ca(OH)(2), and then the fermentation liquid was treated in an expanded granular sludge bed (EGSB) for methane generation. First, for comparing the methane production observed in this study with that reported in the literature, the conventional operational model was applied to produce methane from the pH 10 pretreated sludge, that is, directly using the pH 10 pretreated sludge to produce methane in a CSTR. It was observed that the maximal methane production was only 0.61 m(3)CH(4)/m(3)-reactor/day. Then, the use of fermentation liquid of pH 10 pretreated sludge to produce methane in the reactors of up-flow anaerobic sludge bed (UASB), anaerobic sequencing batch reactor (ASBR) and EGSB was compared. The maximal methane production in UASB, ASBR, and EGSB reached 1.41, 3.01, and 12.43 m(3)CH(4)/m(3)-reactor/day, respectively. Finally, the mechanisms for EGSB exhibiting remarkably higher methane production were investigated by enzyme, adenosine-triphosphate (ATP), scanning electron microscope (SEM) and fluorescence in situ hybridization (FISH) analyses. It was found that the granular sludge in EGSB had the highest conversion efficiency of acetic acid to methane, and the greatest activity of hydrolysis and acidification enzymes and general physiology with much more Methanosarcinaceae.

  8. [Development of Determination Method of Fluoroquinolone Antibiotics in Sludge Based on Solid Phase Extraction and HPLC-Fluorescence Detection Analysis].

    PubMed

    Dai, Xiao-hu; Xue, Yong-gang; Liu, Hua-jie; Dai, Ling-ling; Yan, Han; Li, Ning

    2016-04-15

    Fluoroquinolone antibiotics (FQs), as the common pharmaceuticals and personal care products (PPCPs), are widespread in the environment. FQs contained in wastewater would be ultimately enriched in sludge, posing a potential threat to the consequent sludge utilization. To optimize the analytical method applicable to the determination of FQs in sludge, the authors selected ofloxacin (OFL), norfioxacin (NOR), ciprofloxacin (CIP) and lomefloxacin (LOM) as the target FQs, and established a method which was based on cell lysis, FQs extraction with triethylamine/methanol/water solution, Solid Phase Extraction (SPE) and HPLC-Fluorescence Detection (FLD) determination. After the investigation, phosphoric acid-triethylamine was decided to be the buffer salt, and methanol was chosen as the organic mobile phase. The gradient fluorescence scanning strategy was proved to be necessary for the optimal detection as well. Furthermore, by the designed orthogonal experiments, the effects of the extraction materials, pH, and the eluents on the efficiency of SPE extraction were evaluated, by which the optimal extraction conditions were determined. As a result, FQs in liquid samples could be analyzed by utilizing HLB extraction cartridge, and the recovery rates of the four FQs were in the range of 82%-103%. As for solid samples, the recovery rates of the four FQs contained reached up to 71%-101%. Finally, the adsorptivity of the sludge from the different tanks ( anaerobic, anoxic and oxic tanks) was investigated, showing gradual decrease in the adsorption capacity, but all adsorbed over 90% of the EQs. This conclusion also confirmed that 50% removal of FQs in the domestic wastewater treatment plant was realized by sludge adsorption. PMID:27548982

  9. [Development of Determination Method of Fluoroquinolone Antibiotics in Sludge Based on Solid Phase Extraction and HPLC-Fluorescence Detection Analysis].

    PubMed

    Dai, Xiao-hu; Xue, Yong-gang; Liu, Hua-jie; Dai, Ling-ling; Yan, Han; Li, Ning

    2016-04-15

    Fluoroquinolone antibiotics (FQs), as the common pharmaceuticals and personal care products (PPCPs), are widespread in the environment. FQs contained in wastewater would be ultimately enriched in sludge, posing a potential threat to the consequent sludge utilization. To optimize the analytical method applicable to the determination of FQs in sludge, the authors selected ofloxacin (OFL), norfioxacin (NOR), ciprofloxacin (CIP) and lomefloxacin (LOM) as the target FQs, and established a method which was based on cell lysis, FQs extraction with triethylamine/methanol/water solution, Solid Phase Extraction (SPE) and HPLC-Fluorescence Detection (FLD) determination. After the investigation, phosphoric acid-triethylamine was decided to be the buffer salt, and methanol was chosen as the organic mobile phase. The gradient fluorescence scanning strategy was proved to be necessary for the optimal detection as well. Furthermore, by the designed orthogonal experiments, the effects of the extraction materials, pH, and the eluents on the efficiency of SPE extraction were evaluated, by which the optimal extraction conditions were determined. As a result, FQs in liquid samples could be analyzed by utilizing HLB extraction cartridge, and the recovery rates of the four FQs were in the range of 82%-103%. As for solid samples, the recovery rates of the four FQs contained reached up to 71%-101%. Finally, the adsorptivity of the sludge from the different tanks ( anaerobic, anoxic and oxic tanks) was investigated, showing gradual decrease in the adsorption capacity, but all adsorbed over 90% of the EQs. This conclusion also confirmed that 50% removal of FQs in the domestic wastewater treatment plant was realized by sludge adsorption.

  10. Determination of the solid-water distribution coefficient (Kd) for pharmaceuticals, estrogens and musk fragrances in digested sludge.

    PubMed

    Carballa, Marta; Fink, Guido; Omil, Francisco; Lema, Juan M; Ternes, Thomas

    2008-01-01

    This work determined the solid-water distribution coefficient (K(d)) and the organic carbon normalized distribution coefficient (K(oc)) of several pharmaceuticals (carbamazepine, ibuprofen, naproxen, diclofenac, iopromide, sulfamethoxazole and roxithromycin), three estrogens (estrone, 17beta-estradiol and 17alpha-ethinylestradiol) and two musk fragrances (HHCB and AHTN) in digested sludge. These sorption coefficients can be used to evaluate the fate of these substances during sludge treatment, thus avoiding the expensive and time-consuming analysis in the sludge phase. For determining the K(d) and K(oc) values of the target compounds in digested sludge, their concentrations were measured in the aqueous and solid phase of the effluent of an anaerobic digestion pilot plant run at several operational conditions. The results obtained were compared with the values modelled by using simple K(ow) approaches. The resulting log K(d) values ranged between 3.5 and 4.4 for the two musk fragrances (log K(oc) of 4.5-6.0), between 2.1 and 2.9 for estrogens (log K(oc) of 2.9-4.2) and between 0.8 and 1.9 for the remaining pharmaceuticals (log K(oc) of 1.8-3.5). These values are in the same range as those reported in the literature for primary and secondary sludge and no significant influence of the anaerobic digestion operational conditions was observed. For most compounds, the modelled K(oc) were close or within the lower range of the experimentally determined K(oc). Major deviations of the modelled K(oc) values were found for iopromide, sulfamethoxazole and roxithromycin, which were 1-3 orders of magnitude lower than the measured values.

  11. Low temperature thermo-chemical pretreatment of dairy waste activated sludge for anaerobic digestion process.

    PubMed

    Rani, R Uma; Kumar, S Adish; Kaliappan, S; Yeom, Ick-Tae; Banu, J Rajesh

    2012-01-01

    An investigation into the influence of low temperature thermo-chemical pretreatment on sludge reduction in a semi-continuous anaerobic reactor was performed. Firstly, effect of sludge pretreatment was evaluated by COD solubilization, suspended solids reduction and biogas production. At optimized condition (60 °C with pH 12), COD solubilization, suspended solids, reduction and biogas production was 23%, 22% and 51% higher than the control, respectively. Secondly, semi-continuous process performance was studied in a lab-scale semi-continuous anaerobic reactor (5 L), with 4 L working volume. With three operated SRTs, the SRT of 15 days was found to be most appropriate for economic operation of the reactor. Combining pretreatment with anaerobic digestion led to 80.5%, 117% and 90.4% of TS, SS and VS reduction respectively, with an improvement of 103% in biogas production. Thus, low temperature thermo-chemical can play an important role in reducing sludge production.

  12. Efficiency of biological activator formulated material (BAFM) for volatile organic compounds removal--preliminary batch culture tests with activated sludge.

    PubMed

    Corre, Charline; Couriol, Catherine; Amrane, Abdeltif; Dumont, Eric; Andrès, Yves; Le Cloirec, Pierre

    2012-01-01

    During biological degradation, such as biofiltration of air loaded with volatile organic compounds, the pollutant is passed through a bed packed with a solid medium acting as a biofilm support. To improve microorganism nutritional equilibrium and hence to enhance the purification capacities, a Biological Activator Formulated Material (BAFM) was developed, which is a mixture of solid nutrients dissolving slowly in a liquid phase. This solid was previously validated on mineral pollutants: ammonia and hydrogen sulphide. To evaluate the efficiency of such a material for biodegradation of some organic compounds, a simple experiment using an activated sludge batch reactor was carried out. The pollutants (sodium benzoate, phenol, p-nitrophenol and 2-4-dichlorophenol) were in the concentration range 100 to 1200 mg L(-1). The positive impact of the formulated material was shown. The improvement of the degradation rates was in the range 10-30%. This was the consequence of the low dissolution of the nutrients incorporated during material formulation, followed by their consumption by the biomass, as shown for urea used as a nitrogen source. Owing to its twofold interest (mechanical resistance and nutritional supplementation), the Biological Activator Formulated Material seems to be a promising material. Its addition to organic or inorganic supports should be investigated to confirm its relevance for implementation in biofilters. PMID:22988627

  13. 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. PMID:26072019

  14. 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.

  15. 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

  16. [Copper and cadmium toxicities to activated sludge investigated with ToxTell biosensor].

    PubMed

    Wang, Xue-Jiang; Wang, Xin; Liu, Mian; Wu, Zhen; Yang, Lian-Zhen; Xia, Si-Qing

    2012-06-01

    Effects of different concentrations of Cu2+, Cu2+ and Cd2+ combined pollution on the removal performance of COD in activated sludge system were investigated, and the ToxTell biosensor with activated sludge was constructed to determine the toxicity of Cu2+, Cu2+ and Cd2+ combined pollution. The results showed that there was no significant impact on the activated sludge process when Cu2+ concentration was lower than 10 mg x L(-1), and the addition of Cd2+ enhanced the inhibition of COD removal, and the maximum inhibition efficiency of COD reached at about 1.5 h. With the increase of aeration time, the COD removal efficiency increased slowly again. The toxicity measurement with ToxTell biosensor was close to the biological effects (inhibition efficiencies of COD), which showed that the ToxTell biosensor could be used well in the early warming determination of Cu2+ and Cd2+ in the activated sludge process.

  17. Characterization of total organic carbon in solid residues provides insight into sludge incineration processes

    SciTech Connect

    Rubli, S.; Medilanski, E.; Belevi, H.

    2000-05-01

    In this paper, an analytical method is presented to determine the concentrations of elemental carbon (EC) and organic carbon (OC) in incinerator residues. This method is applied to sewage sludge incinerators with different combustion technologies. The results show that the OC concentrations are below the detection limit of 0.01 g/kg of dry matter (DM) and that the EC concentrations are lower than 0.3 g/kg of DM in the solid residues of the investigated stationary fluidized-bed furnace and of the multiple-hearth furnace. The OC concentrations in the investigated rotary kiln are lower than 2.5 g/kg of DM, and the EC concentrations are between 20 and 35 g/kg of DM in the rotary kiln bottom ash. Information on processes occurring in the rotary kiln are obtained by determining the EC and OC concentrations in different particle size classes of the bottom ash as well as by sampling the bottom ash during the turn-off of the rotary kiln and determining the EC and OC concentrations in these samples. By combining the results with the process parameters, it is concluded that the OC/EC ratio is a viable indicator for the temperatures within the furnace bed, while the EC concentration indicates the oxygen supply into the furnace bed.

  18. [High-solids anaerobic co-digestion of sludge and kitchen garbage under mesophilic conditions].

    PubMed

    Duan, Ni-Na; Dong, Bin; Li, Jiang-Hua; Dai, Ling-Ling; Dai, Xiao-Hu

    2013-01-01

    At solid retention time (SRT) of 20 days, biogas production, volatile solid (VS) degradation and system stability in co-digestion systems of dewatered sludge (DS) and kitchen garbage (KG) were investigated in semi-continuous completely mixed reactors numbered R1-R5 (the DS/KG of their feeding substrate based on wet mass was 1:0, 4:1, 3:2, 2:3 and 0:1, respectively). The results showed that, with larger proportion of KG in feeding substrate, higher methane yield and biogas yield were obtained with lower methane content. For certain reactor at given SRT, KG addition could significantly improve the organic loading rate (OLR) and volume biogas production. System with more KG addition favored higher hydraulic constant k and VS reduction. The hydraulic constant k was 0.25 d(-1), 0.61 d(-1), 1.09 d(-1) and 1.56 d(-1), and the VS reduction was 37.4%, 50.6%, 60.7% and 68.2% for R1-R4, respectively, indicating higher hydrolysis rates with more KG addition, which led to increased VS reductions. With larger KG proportion in feeding substrate, pH, total alkalinity (TA), total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) showed decreasing trend. As KG addition increased by 60%, pH, TA, TAN and FAN decreased by 6%, 16%, 22% and 75%, respectively. FAN and Na+ respectively were potential inhibitory chemicals that threatened the stability of the mono-system of DS and KG. In comparison with the mono-system of DS or KG, the co-system showed higher stability by diluting toxic chemicals like ammonia or Na+ to much lower levels.

  19. [High-solids anaerobic co-digestion of sludge and kitchen garbage under mesophilic conditions].

    PubMed

    Duan, Ni-Na; Dong, Bin; Li, Jiang-Hua; Dai, Ling-Ling; Dai, Xiao-Hu

    2013-01-01

    At solid retention time (SRT) of 20 days, biogas production, volatile solid (VS) degradation and system stability in co-digestion systems of dewatered sludge (DS) and kitchen garbage (KG) were investigated in semi-continuous completely mixed reactors numbered R1-R5 (the DS/KG of their feeding substrate based on wet mass was 1:0, 4:1, 3:2, 2:3 and 0:1, respectively). The results showed that, with larger proportion of KG in feeding substrate, higher methane yield and biogas yield were obtained with lower methane content. For certain reactor at given SRT, KG addition could significantly improve the organic loading rate (OLR) and volume biogas production. System with more KG addition favored higher hydraulic constant k and VS reduction. The hydraulic constant k was 0.25 d(-1), 0.61 d(-1), 1.09 d(-1) and 1.56 d(-1), and the VS reduction was 37.4%, 50.6%, 60.7% and 68.2% for R1-R4, respectively, indicating higher hydrolysis rates with more KG addition, which led to increased VS reductions. With larger KG proportion in feeding substrate, pH, total alkalinity (TA), total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) showed decreasing trend. As KG addition increased by 60%, pH, TA, TAN and FAN decreased by 6%, 16%, 22% and 75%, respectively. FAN and Na+ respectively were potential inhibitory chemicals that threatened the stability of the mono-system of DS and KG. In comparison with the mono-system of DS or KG, the co-system showed higher stability by diluting toxic chemicals like ammonia or Na+ to much lower levels. PMID:23487958

  20. Interference sources in ATP bioluminescence assay of silica nanoparticle toxicity to activated sludge.

    PubMed

    Sibag, Mark; Kim, Seung Hwan; Kim, Choah; Kim, Hee Jun; Cho, Jinwoo

    2015-06-01

    ATP measurement provides an overview of the general state of microbial activity, and thus it has proven useful for the evaluation of nanoparticle toxicity in activated sludge. ATP bioluminescence assay, however, is susceptible to interference by the components of activated sludge other than biomass. This paper presents the interference identified specific to the use of this assay after activated sludge respiration inhibition test of silica nanoparticles (OECD 209). We observed a high degree of interference (90%) in the presence of 100 mg/L silica nanoparticles and a low level of ATP being measured (0.01 μM); and 30% interference by the synthetic medium regardless of silica nanoparticle concentration and ATP level in the samples. ATP measurement in activated sludge with different MLSS concentrations revealed interference of high biomass content. In conclusion, silica nanoparticles, synthetic medium and activated sludge samples themselves interfere with ATP bioluminescence; this will need to be considered in the evaluation of silica nanoparticle toxicity to activated sludge when this type of assay is used. PMID:25892589

  1. Interference sources in ATP bioluminescence assay of silica nanoparticle toxicity to activated sludge.

    PubMed

    Sibag, Mark; Kim, Seung Hwan; Kim, Choah; Kim, Hee Jun; Cho, Jinwoo

    2015-06-01

    ATP measurement provides an overview of the general state of microbial activity, and thus it has proven useful for the evaluation of nanoparticle toxicity in activated sludge. ATP bioluminescence assay, however, is susceptible to interference by the components of activated sludge other than biomass. This paper presents the interference identified specific to the use of this assay after activated sludge respiration inhibition test of silica nanoparticles (OECD 209). We observed a high degree of interference (90%) in the presence of 100 mg/L silica nanoparticles and a low level of ATP being measured (0.01 μM); and 30% interference by the synthetic medium regardless of silica nanoparticle concentration and ATP level in the samples. ATP measurement in activated sludge with different MLSS concentrations revealed interference of high biomass content. In conclusion, silica nanoparticles, synthetic medium and activated sludge samples themselves interfere with ATP bioluminescence; this will need to be considered in the evaluation of silica nanoparticle toxicity to activated sludge when this type of assay is used.

  2. Effect of sewage sludge content on gas quality and solid residues produced by cogasification in an updraft gasifier

    SciTech Connect

    Seggiani, Maurizia; Puccini, Monica; Raggio, Giovanni

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Cogasification of sewage sludge with wood pellets in updraft gasifier was analysed. Black-Right-Pointing-Pointer The effects of sewage sludge content on the gasification process were examined. Black-Right-Pointing-Pointer Sewage sludge addition up to 30 wt.% reduces moderately the process performance. Black-Right-Pointing-Pointer At high sewage sludge content slagging and clinker formation occurred. Black-Right-Pointing-Pointer Solid residues produced resulted acceptable at landfills for non-hazardous waste. - Abstract: In the present work, the gasification with air of dehydrated sewage sludge (SS) with 20 wt.% moisture mixed with conventional woody biomass was investigated using a pilot fixed-bed updraft gasifier. Attention was focused on the effect of the SS content on the gasification performance and on the environmental impact of the process. The results showed that it is possible to co-gasify SS with wood pellets (WPs) in updraft fixed-bed gasification installations. However, at high content of sewage sludge the gasification process can become instable because of the very high ash content and low ash fusion temperatures of SS. At an equivalent ratio of 0.25, compared with wood pellets gasification, the addition of sewage sludge led to a reduction of gas yield in favor of an increase of condensate production with consequent cold gas efficiency decrease. Low concentrations of dioxins/furans and PAHs were measured in the gas produced by SS gasification, well below the limiting values for the exhaust gaseous emissions. NH{sub 3}, HCl and HF contents were very low because most of these compounds were retained in the wet scrubber systems. On the other hand, high H{sub 2}S levels were measured due to high sulfur content of SS. Heavy metals supplied with the feedstocks were mostly retained in gasification solid residues. The leachability tests performed according to European regulations showed that metals leachability was

  3. Activated-sludge nitrification in the presence of linear and branched-chain alkyl benzene sulfonates.

    PubMed

    Baillod, C R; Boyle, W C

    1968-01-01

    The effects of biodegradable linear alkyl benzene sulfonate and branched-chain alkyl benzene sulfonate detergents on activated-sludge nitrification were investigated by administering a synthetic waste containing up to 23 mg of each detergent per liter to eight bench-scale, batch, activated-sludge units. It was found that both detergents tended to promote complete oxidation of ammonia to nitrate, whereas control units produced approximately equal amounts of nitrite and nitrate. Various hypotheses are offered to explain the phenomenon.

  4. Fate of tetracycline resistant bacteria as a function of activated sludge process organic loading and growth rate.

    PubMed

    Kim, S; Jensen, J N; Aga, D S; Weber, A S

    2007-01-01

    The objective of this research was to elucidate the fate of tetracycline resistant bacteria as a function of activated sludge organic loading rate and growth rate. Techniques employed to evaluate the effect of these factors on the fate of tetracycline resistant bacteria were: (1) resistant bacteria concentrations in the SBR biomass; (2) production of tetracycline resistant bacteria as measured by a combination of effluent efflux and intentional solids wasting; (3) net specific growth rates as determined by an SBR population balance; and (4) percentage of resistance as determined by normalising resistant concentrations to total concentrations. Based on these evaluation parameters, increases in organic loading and growth rate both resulted in amplification of tetracycline resistance. These trends were observed for activated sludge reactors loaded with typical municipal background tetracycline concentrations (approximately 1 microg/L) and those receiving influent augmented with 250 microg/L tetracycline. Accordingly, biological wastewater treatment plants, such as the activated sludge process, may be significant sources of antibiotic resistance to the environment.

  5. A study on torrefaction of sewage sludge to enhance solid fuel qualities

    SciTech Connect

    Poudel, Jeeban; Ohm, Tae-In; Lee, Sang-Hoon; Oh, Sea Cheon

    2015-06-15

    Highlights: • The physio chemical variation of sewage sludge during torrefaction was studied. • Compounds with oxygen were emitted at a temperature lower than that for C{sub x}H{sub y}. • Sewage sludge torrefaction range was defined between 300 and 350 °C. - Abstract: Torrefaction is a treatment which serves to improve the properties of biomass in relation to thermochemical processing techniques for energy generation. In this study, the torrefaction of sewage sludge, which is a non-lignocellulosic waste was investigated in a horizontal tubular reactor under nitrogen flow at temperature ranging from 150 to 400 °C, for torrefaction residence time varying from 0 to 50 min. The torrefaction kinetics of sewage sludge was studied to obtain the kinetic parameters. The torrefied sewage sludge products were characterized in terms of their elemental composition, energy yield, ash content and volatile fraction. The energy and mass yields decreased with an increase in the torrefaction temperature. From an elemental analysis, the weight percentage of carbon in the sewage sludge increased with an increase in the torrefaction temperature. On the other hand, the weight percentages of hydrogen and oxygen tended to decrease. The gaseous products from torrefaction of sewage sludge were also analyzed. From this work, it was found that the compounds with oxygen were emitted at a temperature lower than that for hydrocarbon gases and the temperatures of 300–350 °C were the optimum torrefaction temperatures for sewage sludge.

  6. Extracellular polymeric substances (EPS) and surface properties of activated sludges: effect of organic carbon sources.

    PubMed

    Geyik, Ayse Gul; Kılıç, Başak; Çeçen, Ferhan

    2016-01-01

    The study aims to clarify how the type of organic substrate in a wastewater affects the production and composition of extracellular polymeric substances (EPS) and hydrophobicity and surface charge of activated sludges. For this purpose, three activated sludge reactors were operated in parallel with feeds composed of the organics (i) peptone, glucose, and acetate and (ii) peptone and (iii) glucose. EPS extracted from sludges were fractionated into very loosely bound, loosely bound, and tightly bound fractions and analyzed for protein and polysaccharide. Also, molecular weight distribution of proteins was determined by using high-pressure size exclusion chromatography (HPSEC). Regardless of the type of organic substrate, in each sludge, tightly bound EPS (TB-EPS) prevailed. The type of organic substrate affected the relative proportion of protein and polysaccharide and had an impact on hydrophobicity and surface charge. The sludge fed with peptone was distinctly more hydrophobic and had a lower negative surface charge than others. HPSEC fingerprints revealed that the variety and size of proteins were dependent on the type of feed. HPSEC also pointed to a shift of high molecular weight (MW) proteins from TB-EPS to others. In addition, results of a parallel study examining the inhibitory effect of Ag(+) on three sludges were interpreted along with feed composition, EPS, and surface measurements. The response of each sludge to toxic Ag(+) ion seemed to change with the type of feed. PMID:26381789

  7. Biodegradation of imidazolium ionic liquids by activated sludge microorganisms.

    PubMed

    Liwarska-Bizukojc, Ewa; Maton, Cedric; Stevens, Christian V

    2015-11-01

    Biological properties of ionic liquids (ILs) have been usually tested with the help of standard biodegradation or ecotoxicity tests. So far, several articles on the identification of intermediate metabolites of microbiological decay of ILs have been published. Simultaneously, the number of novel ILs with unrecognized characteristics regarding biodegradability and effect on organisms and environment is still increasing. In this work, seven imidazolium ionic liquids of different chemical structure were studied. Three of them are 1-alkyl-3-methyl-imidazolium bromides, while the other four are tetra- or completely substituted imidazolium iodides. This study focused on the identification of intermediate metabolites of the aforementioned ionic liquids subjected to biodegradation in a laboratory activated sludge system. Both fully substituted ionic liquids and 1-ethyl-3-methyl-imidazolium bromide were barely biodegradable. In the case of two of them, no biotransformation products were detected. The elongation of the alkyl side chain made the IL more susceptible for microbiological decomposition. 1-Decyl-3-methyl-imidazolium bromide was biotransformed most easily. Its primary biodegradation up to 100 % could be achieved. Nevertheless, the cleavage of the imidazolium ring has not been observed.

  8. A hundred years of activated sludge: time for a rethink

    PubMed Central

    Sheik, Abdul R.; Muller, Emilie E. L.; Wilmes, Paul

    2014-01-01

    Biological wastewater treatment plants (BWWTPs) based on the activated sludge (AS) process have dramatically improved worldwide water sanitation despite increased urbanization and industrialization. However, current AS-based operations are considered economically and environmentally unsustainable. In this Perspective, we discuss our current understanding of microbial populations and their metabolic transformations in AS-based BWWTPs in view of developing more sustainable processes in the future. In particular, much has been learned over the course of the past 25 years about specialized microorganisms, which could be more comprehensively leveraged to recover energy and/or nutrients from wastewater streams. To achieve this, we propose a bottom-up design approach, focused around the concept of a “wastewater biorefinery column”, which would rely on the engineering of distinct ecological niches into a BWWTP in order to guarantee the targeted enrichment of specific organismal groups which in turn will allow the harvest of high-value resources from wastewater. This concept could be seen as a possible grand challenge to microbial ecologists and engineers alike at the centenary of the discovery of the AS process. PMID:24624120

  9. [Study on dewatering of activated sludge under applied electric field].

    PubMed

    Ji, Xue-Yuan; Wang, Yi-Li; Feng, Jing

    2012-12-01

    For an electro-dewatering process of activated sludge (AS), the effect of pH and conductivity of AS, flocculation conditioning and operation factors of horizontal electric field (voltage magnitude, method of applying electric field and distance between plates) were investigated, and the corresponding optimum electro-dewatering conditions were also obtained. The results showed that the best electro-dewatering effect was achieved for AS without change of its pH value (6.93) and conductivity (1.46 mS x cm(-1)). CPAM conditioning could lead to the increase of 30%-40% in the dewatering rate and accelerate the dewatering process, whereas a slight increase in the electro-dewatering rate. The electro-dewatering rate for conditioned AS reached 83.12% during an electric field applied period of 60 minutes, while this rate for original AS could be 75.31% even the electric field applied period extended to 120 minutes. The delay of applying the electric field had an inhibition effect on the AS electro-dewatering rate. Moreover, the optimum conditions for AS electro-dewatering were followed: CPAM dose of 9 g x kg(-1), electric field strength of 600 V x m(-1), distance between the two plates of 40 mm, dehydration time of 60 minutes. Under above optimum conditions the AS electro-dewatering rate could approach to 85.33% and the moisture content in AS decreased from 99.30% to 95.15% accordingly.

  10. Immobilised activated sludge based biosensor for biochemical oxygen demand measurement.

    PubMed

    Liu, J; Björnsson, L; Mattiasson, B

    2000-02-01

    A biochemical oxygen demand (BOD) sensor, based on an immobilised mixed culture of microorganisms in combination with a dissolved oxygen electrode, has been developed for the purpose of on-line monitoring of the biological treatment process for waste and wastewater. The sensor was designed for easy replacement of the biomembrane, thereby making it suitable for short-term use. The drawbacks of activated sludge based sensor, such as short sensor lifetime, were thereby circumvented. The sensor BOD measurements were carried out in the kinetic mode using a flow injection system, resulting in 25 s for one measurement followed by 4-8 min recovery time. Based on the results of normalised sensor responses, the OECD synthetic wastewater was considered to be a more suitable calibration solution in comparison with the GGA solution. Good agreement was achieved between the results of the sensor BOD measurement and those obtained from BOD5 analysis of a wastewater sample from a food-processing factory. Reproducibility of responses using one sensor was below +/- 5.6%, standard deviation. Reproducibility of responses using different sensors was within acceptable bias limits, viz. +/- 15% standard deviation.

  11. Aerobic activated sludge transformation of methotrexate: identification of biotransformation products.

    PubMed

    Kosjek, Tina; Negreira, Noelia; de Alda, Miren López; Barceló, Damià

    2015-01-01

    This study describes the biotransformation of cytostatic and immunosuppressive pharmaceutical methotrexate. Its susceptibility to microbiological breakdown was studied in a batch biotransformation system, in presence or absence of carbon source and at two activated sludge concentrations. The primary focus of the present study are methotrexate biotransformation products, which were tentatively identified by the ultra-high performance liquid chromatography-quadrupole--Orbitrap-MS. Data-dependent experiments, combining full-scan MS data with product ion spectra were acquired, in order to identify the molecular ions of methotrexate transformation products, to propose the molecular formulae and to elucidate their chemical structures. Among the identified transformation products 2,4-diamino-N10-methyl-pteroic acid is most abundant and persistent. Other biotransformation reactions involve demethylation, oxidative cleavage of amine, cleavage of C-N bond, aldehyde to carboxylate transformation and hydroxylation. Finally, a breakdown pathway is proposed, which shows that most of methotrexate breakdown products retain the diaminopteridine structural segment. In total we propose nine transformation products, among them eight are described as methotrexate transformation products for the first time.

  12. Solid Waste Activity Packet for Teachers.

    ERIC Educational Resources Information Center

    Illinois Univ., Urbana. Cooperative Extension Service.

    This solid waste activity packet introduces students to the solid waste problem in Illinois. Topics explore consumer practices in the market place, packaging, individual and community garbage generation, and disposal practices. The activities provide an integrated approach to incorporating solid waste management issues into subject areas. The…

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

    PubMed

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

    2015-01-01

    Many wastewater treatment plants in the USA, which were originally designed as secondary treatment systems with no or partial nitrification requirements, are facing increased flows, loads, and more stringent ammonia discharge limits. Plant expansion is often not cost-effective due to either high construction costs or lack of land. Under these circumstances, integrated fixed-film activated sludge (IFAS) systems using both suspended growth and biofilms that grow attached to a fixed plastic structured sheet media are found to be a viable solution for solving the challenges. Multiple plants have been retrofitted with such IFAS systems in the past few years. The system has proven to be efficient and reliable in achieving not only consistent nitrification, but also enhanced bio-chemical oxygen demand removal and sludge settling characteristics. This paper presents long-term practical experiences with the IFAS system design, operation and maintenance, and performance for three full-scale plants with distinct processes; that is, a trickling filter/solids contact process, a conventional plug flow activated sludge process and an extended aeration process. PMID:25746646

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

    PubMed

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

    2015-01-01

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

  15. Relationship between flocculation of activated sludge and composition of extracellular polymeric substances.

    PubMed

    Wilén, B M; Jin, B; Lant, P

    2003-01-01

    Activated sludge flocs are a flocculated mass of microorganisms, extracellular polymeric substances (EPS) and adsorbed organic and inorganic material. The structure of the floc is very heterogeneous and flocs with very different properties and morphologies may occur, depending on the conditions in the activated sludge treatment plant and wastewater composition. Present thinking suggest that cations, such as calcium, create cationic bridges with EPS excreted by the bacteria and thereby hold the various floc constituents together. However, due to the complex and heterogeneous nature of activated sludge, the mechanisms have neither been thoroughly investigated nor successfully quantified. A better understanding and description of the biological flocculation process is necessary in order to establish more efficient operational strategies. The main aim of this study was to get a comprehensive and unique insight into the floc properties of activated sludge and to assess the relative impact of chemical and physical parameters. A variety of sludges from full scale treatment plants with different settling properties were characterised. The interrelationships between floc parameters such as composition of EPS, surface properties and floc structure, and their effect on the flocculation and separation properties were assessed. The results indicate that the EPS, both in terms of quantity and quality, are very important for the floc properties of the activated sludge. However, presence of filaments may alter the physical properties of the flocs considerably. The EPS showed positive correlations to sludge volume index (SVI) if only sludges with low or moderate numbers of filaments were included. The surface properties were more affected by the composition of the EPS than by the number of filaments. The EPS showed positive correlation to negative surface charge and a negative correlation to relative hydrophobicity and flocculation ability. The negative correlation between

  16. The effect of malathion on the activity, performance, and microbial ecology of activated sludge.

    PubMed

    Rauglas, Erik; Martin, Seth; Bailey, Kandace; Magnuson, Matthew; Phillips, Rebecca; Harper, Willie F

    2016-12-01

    This study evaluated the effect of a VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) surrogate (malathion) on the activity, performance, and ecology of activated sludge bioreactors. In the presence of malathion, the maximum observed respiration rates varied between 43 and 53 μg/O2 min, generally similar to the 49 μg O2/min rates observed in controls. Malathion did not alter the respiration ratio of O2 consumed-to-CO2 produced nor did it impact the shape of the oxygen consumption curves during respirometry. Shorter term (12 h) batch tests showed that both chemical oxygen demand (COD) and ammonia removal were not negatively impacted by the presence of 0.1-3 mg/L malathion. Longer term continuous addition (i.e. 40 days) of 0.1 mg/L of malathion also had no effect on COD and ammonia removal. In contrast to shorter term exposures, longer term continuous addition of 3 mg/L of malathion negatively impacted both COD and nitrogen removal and was associated with shifts in the abundance of species that are common to activated sludge. These results illustrate the impact that chemicals like malathion may have on COD removal, and nitrification, as well as the robustness of activated sludge microbial communities.

  17. The effect of malathion on the activity, performance, and microbial ecology of activated sludge.

    PubMed

    Rauglas, Erik; Martin, Seth; Bailey, Kandace; Magnuson, Matthew; Phillips, Rebecca; Harper, Willie F

    2016-12-01

    This study evaluated the effect of a VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) surrogate (malathion) on the activity, performance, and ecology of activated sludge bioreactors. In the presence of malathion, the maximum observed respiration rates varied between 43 and 53 μg/O2 min, generally similar to the 49 μg O2/min rates observed in controls. Malathion did not alter the respiration ratio of O2 consumed-to-CO2 produced nor did it impact the shape of the oxygen consumption curves during respirometry. Shorter term (12 h) batch tests showed that both chemical oxygen demand (COD) and ammonia removal were not negatively impacted by the presence of 0.1-3 mg/L malathion. Longer term continuous addition (i.e. 40 days) of 0.1 mg/L of malathion also had no effect on COD and ammonia removal. In contrast to shorter term exposures, longer term continuous addition of 3 mg/L of malathion negatively impacted both COD and nitrogen removal and was associated with shifts in the abundance of species that are common to activated sludge. These results illustrate the impact that chemicals like malathion may have on COD removal, and nitrification, as well as the robustness of activated sludge microbial communities. PMID:27594690

  18. Is anaerobic digestion effective for the removal of organic micropollutants and biological activities from sewage sludge?

    PubMed

    Gonzalez-Gil, L; Papa, M; Feretti, D; Ceretti, E; Mazzoleni, G; Steimberg, N; Pedrazzani, R; Bertanza, G; Lema, J M; Carballa, M

    2016-10-01

    The occurrence of emerging organic micropollutants (OMPs) in sewage sludge has been widely reported; nevertheless, their fate during sludge treatment remains unclear. The objective of this work was to study the fate of OMPs during mesophilic and thermophilic anaerobic digestion (AD), the most common processes used for sludge stabilization, by using raw sewage sludge without spiking OMPs. Moreover, the results of analytical chemistry were complemented with biological assays in order to verify the possible adverse effects (estrogenic and genotoxic) on the environment and human health in view of an agricultural (re)use of digested sludge. Musk fragrances (AHTN, HHCB), ibuprofen (IBP) and triclosan (TCS) were the most abundant compounds detected in sewage sludge. In general, the efficiency of the AD process was not dependent on operational parameters but compound-specific: some OMPs were highly biotransformed (e.g. sulfamethoxazole and naproxen), while others were only slightly affected (e.g. IBP and TCS) or even unaltered (e.g. AHTN and HHCB). The MCF-7 assay evidenced that estrogenicity removal was driven by temperature. The Ames test did not show point mutation in Salmonella typhimurium while the Comet test exhibited a genotoxic effect on human leukocytes attenuated by AD. This study highlights the importance of combining chemical analysis and biological activities in order to establish appropriate operational strategies for a safer disposal of sewage sludge. Actually, it was demonstrated that temperature has an insignificant effect on the disappearance of the parent compounds while it is crucial to decrease estrogenicity. PMID:27344252

  19. Petroleum refinery stripped sour water treatment using the activated sludge process.

    PubMed

    Merlo, Rion; Gerhardt, Matthew B; Burlingham, Fran; De Las Casas, Carla; Gill, Everett; Flippin, T Houston

    2011-11-01

    A pilot study was performed over 91 days to determine if the activated sludge process could treat a segregated stripped sour water (SSW) stream from a petroleum refinery. The study was performed in two periods. The first period was terminated after 19 days, as a result of excessive sludge bulking. The elimination of sludge bulking during the 70-day second period is attributed to operational changes, which included aerating the influent to oxidize reduced sulfur, adjusting the influent pH, and adding micronutrients to satisfy biological requirements. The pilot plant provided a chemical oxygen demand (COD) removal of up to 93%. Nitrification was achieved, with effluent ammonia values < 1 mg-N/L. These results indicate that direct treatment of SSW with the activated sludge process is possible and has direct application to full-scale petroleum refinery wastewater plant upgrades.

  20. Adaptation of microbial communities in activated sludge to 1-decyl-3-methylimidazolium bromide.

    PubMed

    Gendaszewska, Dorota; Liwarska-Bizukojc, Ewa

    2016-01-01

    The effects of 1-decyl-3-methylimidazolium bromide on activated sludge process and microbial composition were investigated. Ionic liquid (IL) was dosed continuously to the laboratory activated sludge system at an influent concentration from 1 to 20 mg l(-1) for about 1 month. As compared to the control test, mean values of degree of chemical oxygen demand removal and degree of biochemical oxygen demand removal were almost remaining constant at a high level, equaling 92.6% and 98.1%, respectively. In addition, no influence of IL on size and shape of flocs was observed. The values of the sludge biotic index indicate that sludge exposed on IL was stable and very well colonized with good biological activity. Increases in Proteobacteria (mainly Variovorax sp., Vogesella sp., Hydrogenophaga sp.), Bacteroidetes (mainly Lewinella sp., Haliscomenobacter sp., Runella sp.) and Nitrospirae were detected in sludge adapted to IL compared to the control system. The results showed that activated sludge can adapt to IL present in wastewater. PMID:27642842

  1. Total nitrogen removal in a hybrid, membrane-aerated activated sludge process.

    PubMed

    Downing, Leon S; Nerenberg, Robert

    2008-08-01

    The hybrid (suspended and attached growth) membrane biofilm process (HMBP) is a novel method to achieve total nitrogen removal from wastewater. Air-filled hollow-fiber membranes are incorporated into an activated sludge tank, and a nitrifying biofilm develops on the membranes, producing nitrite and nitrate. By suppressing bulk aeration, the bulk liquid becomes anoxic, and the nitrate/nitrite can be reduced with influent BOD. The key feature that distinguishes the HMBP from other membrane-aerated processes is that it is hybrid; heterotrophic bacteria are kept mainly in suspension by maintaining low bulk liquid BOD concentrations. We investigated the HMBP's performance under a variety of BOD and ammonium loadings, and determined the dominant mechanisms of nitrogen removal. Suspended solids increased with the BOD loadings, maintaining low bulk liquid BOD concentrations. As a result, nitrification rates were insensitive to the BOD loadings, remaining at 1gNm(-2)day(-1) for BOD loadings ranging from 4 to 17gBODm(-2)day(-1). Nitrification rates decreased during short-term spikes in bulk liquid BOD concentrations. Shortcut nitrogen removal was confirmed using microsensor measurements, showing that nitrite was the dominant form of oxidized nitrogen produced by the biofilm. Fluorescence in situ hybridization (FISH) showed that ammonia oxidizing bacteria (AOB) were dominant throughout the biofilm, while nitrite oxidizing bacteria (NOB) were only present in the deeper regions of the biofilm, where the oxygen concentration was above 2mg/L. Denitrification occurred mainly in the suspended phase, instead of in the biofilm, decreasing the potential for biofouling. When influent BOD concentrations were sufficiently high, full denitrification occurred, with total nitrogen (TN) removal approaching 100%. These results suggest that the process is well-suited for achieving concurrent BOD and TN removal in activated sludge.

  2. Modeling of organic substrate transformation in the high-rate activated sludge process.

    PubMed

    Nogaj, Thomas; Randall, Andrew; Jimenez, Jose; Takacs, Imre; Bott, Charles; Miller, Mark; Murthy, Sudhir; Wett, Bernhard

    2015-01-01

    This study describes the development of a modified activated sludge model No.1 framework to describe the organic substrate transformation in the high-rate activated sludge (HRAS) process. New process mechanisms for dual soluble substrate utilization, production of extracellular polymeric substances (EPS), absorption of soluble substrate (storage), and adsorption of colloidal substrate were included in the modified model. Data from two HRAS pilot plants were investigated to calibrate and to validate the proposed model for HRAS systems. A subdivision of readily biodegradable soluble substrate into a slow and fast fraction were included to allow accurate description of effluent soluble chemical oxygen demand (COD) in HRAS versus longer solids retention time (SRT) systems. The modified model incorporates production of EPS and storage polymers as part of the aerobic growth transformation process on the soluble substrate and transformation processes for flocculation of colloidal COD to particulate COD. The adsorbed organics are then converted through hydrolysis to the slowly biodegradable soluble fraction. Two soluble substrate models were evaluated during this study, i.e., the dual substrate and the diauxic models. Both models used two state variables for biodegradable soluble substrate (SBf and SBs) and a single biomass population. The A-stage pilot typically removed 63% of the soluble substrate (SB) at an SRT <0.13 d and 79% at SRT of 0.23 d. In comparison, the dual substrate model predicted 58% removal at the lower SRT and 78% at the higher SRT, with the diauxic model predicting 32% and 70% removals, respectively. Overall, the dual substrate model provided better results than the diauxic model and therefore it was adopted during this study. The dual substrate model successfully described the higher effluent soluble COD observed in the HRAS systems due to the partial removal of SBs, which is almost completely removed in higher SRT systems.

  3. Zinc chloride as a coagulant for textile dyes and treatment of generated dye sludge under the solid state fermentation: hybrid treatment strategy.

    PubMed

    Kadam, Avinash A; Lade, Harshad S; Lee, Dae Sung; Govindwar, Sanjay P

    2015-01-01

    Dye sludge generation is major drawback of coagulation process. Efficient hybrid technology by combining coagulation and solid state fermentation (SSF) has capacity to solve generated dye sludge problem. Coagulation of 100mg/L Reactive Red 120 (RR120) using ZnCl2 showed 99% color removal. Mixture of textile dyes (MTD) and textile wastewater (TW) showed 96% and 98% ADMI (American Dye Manufacturing Institute) removal after coagulation by ZnCl2. 92% and 94% ADMI removal from MTD and TW dye sludge and 96% decolorization of RR120 sludge was observed respectively by developed microbial consortium (DCM) in 72h under SSF. Scale up of coagulation process by coagulation reactor (CR) having 50L capacity operated for 30min/cycle. CR showed average 94% ADMI removal from TW in 10 successive cycles. Scale up of SSF composting bioreactor (CB) showed complete dye removal from dye sludge obtained from CR (500L of TW) in 30days.

  4. The influence of hydrolysis induced biopolymers from recycled aerobic sludge on specific methanogenic activity and sludge filterability in an anaerobic membrane bioreactor.

    PubMed

    Buntner, D; Spanjers, H; van Lier, J B

    2014-03-15

    The objective of the present study was to evaluate the impact of excess aerobic sludge on the specific methanogenic activity (SMA), in order to establish the maximum allowable aerobic sludge loading. In batch tests, different ratios of aerobic sludge to anaerobic inoculum were used, i.e. 0.03, 0.05, 0.10 and 0.15, showing that low ratios led to an increased SMA. However, the ratio 0.15 caused more than 20% SMA decrease. In addition to the SMA tests, the potential influence of biopolymers and extracellular substances, that are generated as a result of excess aerobic sludge hydrolysis, on membrane performance was determined by assessing the fouling potential of the liquid broth, taking into account parameters such as specific resistance to filtration (SRF) and supernatant filterability (SF). Addition of aerobic sludge to the anaerobic biomass resulted in a high membrane fouling potential. The increase in biopolymers could be ascribed to aerobic sludge hydrolysis. A clear positive correlation between the concentration of the colloidal fraction of biopolymer clusters (cBPC) and the SRF was observed and a negative correlation between the cBPC and the SF measured at the end of the above described SMA tests. The latter implies that sludge filtration resistance increases when more aerobic sludge is hydrolyzed, and thus more cBPC is released. During AnMBR operation, proteins significantly contributed to sludge filterability decrease expressed as SRF and SF, whereas the carbohydrate fraction of SMP was of less importance due to low concentrations. On the contrary, carbohydrates seemed to improve filterability and diminish SRF of the sludge. Albeit, cBPC increase caused an increase in mean TMP during the AnMBR operation, confirming that cBPC is positively correlated to membrane fouling.

  5. A critical review of the bioavailability and impacts of heavy metals in municipal solid waste composts compared to sewage sludge.

    PubMed

    Smith, Stephen R

    2009-01-01

    The content, behaviour and significance of heavy metals in composted waste materials is important from two potentially conflicting aspects of environmental legislation in terms of: (a) defining end-of-waste criteria and increasing recycling of composted residuals on land and (b) protecting soil quality by preventing contamination. This review examines the effects of heavy metals in compost and amended soil as a basis for achieving a practical and sustainable balance between these different policy objectives, with particular emphasis on agricultural application. All types of municipal solid waste (MSW) compost contain more heavy metals than the background concentrations present in soil and will increase their contents in amended soil. Total concentrations of heavy metals in source-segregated and greenwaste compost are typically below UK PAS100 limits and mechanical segregated material can also comply with the metal limits in UK PAS100, although this is likely to be more challenging. Zinc and Pb are numerically the elements present in the largest amounts in MSW-compost. Lead is the most limiting element to use of mechanically-segregated compost in domestic gardens, but concentrations are typically below risk-based thresholds that protect human health. Composted residuals derived from MSW and greenwaste have a high affinity for binding heavy metals. There is general consensus in the scientific literature that aerobic composting processes increase the complexation of heavy metals in organic waste residuals, and that metals are strongly bound to the compost matrix and organic matter, limiting their solubility and potential bioavailability in soil. Lead is the most strongly bound element and Ni the weakest, with Zn, Cu and Cd showing intermediate sorption characteristics. The strong metal sorption properties of compost produced from MSW or sewage sludge have important benefits for the remediation of metal contaminated industrial and urban soils. Compost and sewage sludge

  6. Identical full-scale biogas-lift reactors (Blrs) with anaerobic granular sludge and residual activated sludge for brewery wastewater treatment and kinetic modeling.

    PubMed

    Xu, Fu; Huang, Zhenxing; Miao, Hengfeng; Ren, Hongyan; Zhao, Mingxing; Ruan, Wenquan

    2013-10-01

    Two identical full-scale biogas-lift reactors treating brewery wastewater were inoculated with different types of sludge to compare their operational conditions, sludge characteristics, and kinetic models at a mesophilic temperature. One reactor (R1) started up with anaerobic granular sludge in 12 weeks and obtained a continuously average organic loading rate (OLR) of 7.4 kg chemical oxygen demand (COD)/(m3 x day), COD removal efficiency of 80%, and effluent COD of 450 mg/L. The other reactor (R2) started up with residual activated sludge in 30 weeks and granulation accomplished when the reactor reached an average OLR of 8.3 kg COD/(m3 x day), COD removal efficiency of 90%, and effluent COD of 240 mg/L. Differences in sludge characteristics, biogas compositions, and biogas-lift processes may be accounted for the superior efficiency of the treatment performance of R2 over R1. Grau second-order and modified StoverKincannon models based on influent and effluent concentrations as well as hydraulic retention time were successfully used to develop kinetic parameters of the experimental data with high correlation coefficients (R2 > 0.95), which further showed that R2 had higher treatment performance than R1. These results demonstrated that residual activated sludge could be used effectively instead of anaerobic granular sludge despite the need for a longer time.

  7. Particle counting as a tool to predict filterability in membrane bioreactors activated sludge?

    PubMed

    Lousada-Ferreira, M; Moreau, A; van Lier, J B; van der Graaf, J H J M

    2011-01-01

    Activated sludge quality is one of the major factors influencing flux decline in membrane bioreactors (MBRS). Sludge filterability is a recognized parameter to characterize the physical properties of activated sludge. Decrease in filterability is linked to a higher number of submicron particles. In our present research we studied whether particle counting techniques can be used to indicate deflocculation of the sludge suspended fraction to submicron particles, causing the aforementioned filterability decrease. A total number of 105 activated sludge samples were collected in four full scale municipal MBRS. Samples were tested for filterability and particle counting in the range 2-100 microm. In 88% of the membrane tank samples the filterability varied between good and poor, characterized by the deltaR20, being 0 < deltaR20 < 1. Filterability varied following the season of the year, stability of the MBR operation and recirculation ratio. The membrane tank filterability can be improved by applying low recirculation ratio between MBR tanks. The applied particle counting methodology generated reproducible and reliable results in the range 10-100 microm. Results show that differences in filterability cannot be explained by variations in particle size distribution in the range 10-100 microm. However, measurable deflocculation might be masked by the large numbers of particles present. Therefore, we cannot exclude the suspended particles as a possible source of submicron particles that are subsequently responsible for MBR sludge filterability deterioration.

  8. The effect of wastewater cations on activated sludge characteristics: effects of aluminum and iron in floc.

    PubMed

    Park, Chul; Muller, Christopher D; Abu-Orf, Mohammad M; Novak, John T

    2006-01-01

    Wastewater samples collected from seven wastewater treatment plants (WWTPs) were characterized to assess the impacts of wastewater cations on the activated sludge process. The cations included in this study were sodium (Na+), potassium, ammonium, calcium, magnesium, aluminum (Al), and iron (Fe). Among the selected cations, Al and Fe were of most interest to this study because their role in bioflocculation has not been extensively studied and remains largely unknown. The data showed that WWTPs contained highly varying concentrations of Na+, Al, and Fe in the wastewater and that these cations were responsible for differences between WWTPs as to sludge dewatering rates and effluent quality. In general, a high influent Na+ concentration caused poor sludge dewatering and effluent characteristics. However, when sufficient Al and Fe were present in floc, the deleterious effects of Na+ were offset. The data associated with Al further revealed that waste activated sludge with low Al contained high concentrations of soluble and colloidal biopolymer (protein + polysaccharide), resulting in a high effluent chemical oxygen demand, high conditioning chemical requirements, and poor sludge dewatering properties. These results suggest that Al will improve activated sludge effluent quality by scavenging organic compounds from solution and binding them to floc. PMID:16553164

  9. Simultaneous precipitation of orthophosphate in activated sludge systems with Al(III)

    SciTech Connect

    Gates, D.D.

    1991-01-01

    This dissertation examines the simultaneous precipitation of soluble orthophosphate (SOP) when alum is dosed to an activated sludge aeration basin. The results of batch and continuous flow experimental studies were used to develop a model of this process. This research identified three regions of chemical phosphorus removal, in each of which a different SOP removal mechanism appeared to apply: Region 1 extends to SOP residual concentrations as low as 1.0 mg P/1. In this region the stoichiometric precipitation of Al{sub 0.91}H{sub 2}PO{sub 4} (OH){sub 1.73(s)} is the predominate phosphate removal mechanism. Region 2 includes SOP residual concentrations in the range 0.1-1.0 mg P/1. Phosphate removal in this region is described on the basis of the adsorption of SOP on to aluminum hydroxide solid surfaces. Region 3 includes SOP residual concentrations as low as 0.02 mg P/1. The minimum SOP phosphate concentration that can be reached in this region is controlled by the presence of both aluminum-hydroxyphosphate and aluminum hydroxide solids.

  10. Cultivation of phagotrophic algae with waste activated sludge as a fast approach to reclaim waste organics.

    PubMed

    Li, Cong; Xiao, Suo; Ju, Lu-Kwang

    2016-03-15

    Substantial energy is reserved in waste activated sludge (WAS) organics but much of it is difficult to recover because the solid organics require long time to solubilize. In this work we introduced the new approach of recovering WAS organics into the biomass of phagotrophic algae. Phagotrophic algae have the unique ability to grow by ingesting insoluble organic particles including microbial cells. This phagotrophic ability renders the solubilization of WAS organics unnecessary and makes this approach remarkably fast. The approach consists of two stages: a short anaerobic digestion treatment followed by the algal growth on treated WAS. The short anaerobic digestion was exploited to release discrete bacteria from WAS flocs. Phagotrophic algae could then grow rapidly with the released bacteria as well as the solubilized nutrients in the treated WAS. The results showed that WAS organics could be quickly consumed by phagotrophic algae. Among all studied conditions the highest WAS volatile solids (VS) reduction was achieved with 72 h anaerobic digestion and 24 h algal growth. In this optimal process, 28% of WAS VS was reduced, and 41% and 20% of the reduced VS were converted into algal biomass and lipids, respectively. In comparison, only 18% WAS VS were reduced after the same time of aerobic digestion without algae addition. Through this approach, the amount of WAS organics requiring further treatment for final disposal is significantly reduced. With the production of significant amounts of algal biomass and lipids, WAS treatment is expected to be more economical and sustainable in material recycling.

  11. [Characteristics of municipal sludge and vacuum filtration thickening process].

    PubMed

    Qiao, Wei; Wang, Wei; Yin, Ke-qing

    2008-04-01

    It was found that sludge total solid (TS) concentration was equal to chemical oxygen demand (COD), while volatile solid (VS) was 1.5 times of COD concentration. R2 of linear regression of TS and VS with COD was 0.9314 and 0.9228 respectively. Total COD in sludge was approximately 60% of that removed in water treatment process. Sludge contained high level protein and low fat. The TS of present gravity thickening sludge was universally lower than 3.3%. Efficiency of vacuum filtration process was determined by sludge type, sludge solid concentration, PAM molecular weight and PAM addition dose. Under - 34.7 kPa pressure, sludge dry solid filtration thickening rate of primary sludge was up to 31 kg/(m2 x h). While, for wasted actived sludge the rate was lower than 15 kg/(m2 x h). Rate of gravity thickening sludge was up to 43 kg/(m2 x h). TS of vacuum filtrate were lower than 1.5 g/L.

  12. WWTP design in warm climates - guideline comparison and parameter adaptation for a full-scale activated sludge plant using mass balancing.

    PubMed

    Walder, C; Lindtner, S; Proesl, A; Klegraf, F; Weissenbacher, N

    2013-01-01

    The ATV-A-131 guideline and the design approach published in 'Wastewater Engineering, Treatment and Reuse (WE)' are widely used for the design of activated sludge plants. They are both based on simplified steady-state assumptions tailored to the boundary conditions of temperate climates. Using design guidelines beyond the designated temperature range may lead to inappropriate results. The objectives of this paper are (1) to summarise temperature relevant differences between ATV-A-131 and WE; (2) to show the related design components; and (3) to demonstrate a procedure for design parameter adaptation for a full-scale activated sludge plant located in a warm climate region. To gain steady-state data required for wastewater treatment plant (WWTP) design according to ATV-A-131 and WE, full-scale plant data were acquired for a period of 6 months as a basis for analyses and adaptation. Mass balances were calculated for the verification of the measurements and for analysing excess sludge production. The two approaches showed relevant temperature related differences. WE default application resulted in lower deviation in the mass balance results for excess sludge production. However, with the adaptation of the heterotrophic decay rates for both approaches and the inert organic and mineral solids fraction additionally for ATV-A-131, a good fit to the observed excess sludge production could be achieved.

  13. [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. PMID:23323416

  14. Roseomonas eburnea sp. nov., isolated from activated sludge.

    PubMed

    Wang, Chenghong; Deng, Shikai; Liu, Xin; Yao, Li; Shi, Chao; Jiang, Jin; Kwon, Soon-Wo; He, Jian; Li, Jiayou

    2016-01-01

    A Gram-stain-negative, aerobic, short rod-shaped, non-endospore-forming, ivory-pigmented and non-motile bacterium, designated strain BUT-5T, was isolated from activated sludge of an herbicides-manufacturing wastewater treatment facility in Jiangsu Province, China. The major fatty acids (>5 % of total fatty acids) were C16 : 0, C18 : 1 2-OH and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The predominant respiratory quinone was ubiquinone Q-10. The polar lipids profile of strain BUT-5T included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and two unknown aminolipids. The DNA G+C content was 67.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BUT-5T showed the highest sequence similarities to Roseomonas soli 5N26T (97.5 % 16S rRNA gene sequence similarity), followed by Roseomonas lacus TH-G33T (97.3 %) and Roseomonas terrae DS-48T (97.1 %). Strain BUT-5T showed low DNA-DNA relatedness with Roseomonas soli KACC 16376T (41 %), Roseomonas lacus KACC 11678T (46 %) and Roseomonas terrae KACC 12677T (42 %), respectively. On the basis of phenotypic and genotypic properties, as well as chemotaxonomic data, strain BUT-5T represents a novel species of the genus Roseomonas, for which the name Roseomonas eburnea sp. nov. is proposed. The type strain is BUT-5T ( = CCTCC AB2013276T = KACC 17166T).

  15. Quantitative mapping of suspended solids in wastewater sludge plumes in the New York Bight apex

    NASA Technical Reports Server (NTRS)

    Johnson, R. W.; Duedall, I. W.; Glasgow, R. M.; Proni, J. R.; Nelsen, T. A.

    1977-01-01

    The purpose of this investigation was to apply the previously reported methodology to remotely sensed data that were collected over wastewater sludge plumes in the New York Bight apex on September 22, 1975. Spectral signatures were also determined during this study. These signatures may be useful in the specific identification of sludge plumes, as opposed to other plumes such as those created by the disposal of industrial acid wastes.

  16. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    PubMed

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction.

  17. Influence of different anoxic time exposures on active biomass, protozoa and filamentous bacteria in activated sludge.

    PubMed

    Rodriguez-Perez, S; Fermoso, F G; Arnaiz, C

    2016-01-01

    Medium-sized wastewater treatment plants are considered too small to implement anaerobic digestion technologies and too large for extensive treatments. A promising option as a sewage sludge reduction method is the inclusion of anoxic time exposures. In the present study, three different anoxic time exposures of 12, 6 and 4 hours have been studied to reduce sewage sludge production. The best anoxic time exposure was observed under anoxic/oxic cycles of 6 hours, which reduced 29.63% of the biomass production compared with the oxic control conditions. The sludge under different anoxic time exposures, even with a lower active biomass concentration than the oxic control conditions, showed a much higher metabolic activity than the oxic control conditions. Microbiological results suggested that both protozoa density and abundance of filamentous bacteria decrease under anoxic time exposures compared to oxic control conditions. The anoxic time exposures 6/6 showed the highest reduction in both protozoa density, 37.5%, and abundance of filamentous bacteria, 41.1%, in comparison to the oxic control conditions. The groups of crawling ciliates, carnivorous ciliates and filamentous bacteria were highly influenced by the anoxic time exposures. Protozoa density and abundance of filamentous bacteria have been shown as promising bioindicators of biomass production reduction. PMID:27508364

  18. Enhancing waste activated sludge digestion and power production using hypochlorite as catholyte in clayware microbial fuel cell.

    PubMed

    Ghadge, Anil N; Jadhav, Dipak A; Pradhan, Harapriya; Ghangrekar, Makarand M

    2015-04-01

    Waste activated sludge was digested in anodic compartment of dual chambered clayware microbial fuel cell (MFC). Performance of MFC was evaluated using oxygen (MFC-1) and hypochlorite (MFC-2) as cathodic electron acceptors. Power production of 8.7 W/m(3) was achieved using hypochlorite as catholyte, which was two times higher than using oxygen (4.2 W/m(3)). Total chemical oxygen demand of sludge was reduced by 65.4% and 84.7% in MFC-1 and MFC-2, respectively. Total and volatile suspended solids reductions were higher in MFC-2 (75.8% and 80.2%, respectively) as compared to MFC-1 (66.7% and 76.4%, respectively). Use of hypochlorite demonstrated 3.8 times higher Coulombic efficiency (13.8%) than oxygen. Voltammetric and impedance analysis revealed increase in reduction peak (from 8 to 24 mA) and decreased polarization resistance (from 42.6 to 26.5 Ω). Hypochlorite proved to be better cathodic electron acceptor, supporting rapid sludge digestion within 8 days of retention time and improved power production in MFC. PMID:25700342

  19. Sorption and biodegradation of selected benzotriazoles and hydroxybenzothiazole in activated sludge and estimation of their fate during wastewater treatment.

    PubMed

    Mazioti, Aikaterini A; Stasinakis, Athanasios S; Gatidou, Georgia; Thomaidis, Nikolaos S; Andersen, Henrik R

    2015-07-01

    Biodegradation of benzotriazole (BTR), 5-chlorobenzotriazole (CBTR), xylytriazole (XTR), 4-methyl-1H-benzotriazole (4TTR), 5-methy-1H-lbenzotriazole (5TTR) and 2-hydroxybenzothiazole (OHBTH) was studied in activated sludge batch experiments under aerobic and anoxic conditions, presence of organic substrate and different sludge residence times (SRTs). Their sludge-water distribution coefficients were also calculated in sorption experiments and ranged between 87 and 220 L kg(-1). Significant biodegradation of BTR, CBTR, XTR and OHBTH was observed in all biotic experiments. Half-life values ranged between 23 and 45 h (BTR), 18 and 47 h (CBTR), 14 and 26 h (XTR), 6.5 and 24 h (OHBTH). The addition of substrate did not suppress biodegradation kinetics; whereas in some cases accelerated biodegradation of microcontaminants. Except for CBTR, no effect of SRT on biodegradation constants was observed. Prediction of micropollutants removal in Sewage Treatment Plants (STPs) indicated that they will be partially removed, mainly due to aerobic biodegradation. Higher removal is expected at STPs operating at higher SRT and higher suspended solids concentrations. PMID:25828067

  20. Investigation into cyclic utilization of carbon source in an advanced sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal (SIPER) wastewater treatment process.

    PubMed

    Yan, Peng; Ji, Fang-Ying; Wang, Jing; Chen, You-Peng; Shen, Yu; Fang, Fang; Guo, Jin-Song

    2015-01-01

    An advanced wastewater treatment process (SIPER) was developed to simultaneously reduce sludge production, prevent the accumulation of inorganic solids, recover phosphorus, and enhance nutrient removal. The ability to recover organic substance from excess sludge to enhance nutrient removal (especially nitrogen) and its performance as a C-source were evaluated in this study. The chemical oxygen demand/total nitrogen (COD/TN) and volatile fatty acids/total phosphorus (VFA/TP) ratios for the supernatant of the alkaline-treated sludge were 3.1 times and 2.7 times those of the influent, respectively. The biodegradability of the supernatant was much better than that of the influent. The system COD was increased by 91 mg/L, and nitrogen removal was improved by 19.6% (the removal rate for TN reached 80.4%) after the return of the alkaline-treated sludge as an internal C-source. The C-source recovered from the excess sludge was successfully used to enhance nitrogen removal. The internal C-source contributed 24.1% of the total C-source, and the cyclic utilization of the system C-source was achieved by recirculation of alkaline-treated sludge in the sludge reduction, inorganic solids separation, phosphorus recovery (SIPER) process.

  1. Investigation into cyclic utilization of carbon source in an advanced sludge reduction, inorganic solids separation, phosphorus recovery, and enhanced nutrient removal (SIPER) wastewater treatment process.

    PubMed

    Yan, Peng; Ji, Fang-Ying; Wang, Jing; Chen, You-Peng; Shen, Yu; Fang, Fang; Guo, Jin-Song

    2015-01-01

    An advanced wastewater treatment process (SIPER) was developed to simultaneously reduce sludge production, prevent the accumulation of inorganic solids, recover phosphorus, and enhance nutrient removal. The ability to recover organic substance from excess sludge to enhance nutrient removal (especially nitrogen) and its performance as a C-source were evaluated in this study. The chemical oxygen demand/total nitrogen (COD/TN) and volatile fatty acids/total phosphorus (VFA/TP) ratios for the supernatant of the alkaline-treated sludge were 3.1 times and 2.7 times those of the influent, respectively. The biodegradability of the supernatant was much better than that of the influent. The system COD was increased by 91 mg/L, and nitrogen removal was improved by 19.6% (the removal rate for TN reached 80.4%) after the return of the alkaline-treated sludge as an internal C-source. The C-source recovered from the excess sludge was successfully used to enhance nitrogen removal. The internal C-source contributed 24.1% of the total C-source, and the cyclic utilization of the system C-source was achieved by recirculation of alkaline-treated sludge in the sludge reduction, inorganic solids separation, phosphorus recovery (SIPER) process. PMID:26524455

  2. 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.

  3. A study on torrefaction of sewage sludge to enhance solid fuel qualities.

    PubMed

    Poudel, Jeeban; Ohm, Tae-In; Lee, Sang-Hoon; Oh, Sea Cheon

    2015-06-01

    Torrefaction is a treatment which serves to improve the properties of biomass in relation to thermochemical processing techniques for energy generation. In this study, the torrefaction of sewage sludge, which is a non-lignocellulosic waste was investigated in a horizontal tubular reactor under nitrogen flow at temperature ranging from 150 to 400°C, for torrefaction residence time varying from 0 to 50 min. The torrefaction kinetics of sewage sludge was studied to obtain the kinetic parameters. The torrefied sewage sludge products were characterized in terms of their elemental composition, energy yield, ash content and volatile fraction. The energy and mass yields decreased with an increase in the torrefaction temperature. From an elemental analysis, the weight percentage of carbon in the sewage sludge increased with an increase in the torrefaction temperature. On the other hand, the weight percentages of hydrogen and oxygen tended to decrease. The gaseous products from torrefaction of sewage sludge were also analyzed. From this work, it was found that the compounds with oxygen were emitted at a temperature lower than that for hydrocarbon gases and the temperatures of 300-350°C were the optimum torrefaction temperatures for sewage sludge.

  4. Structure-function dynamics and modeling analysis of the micro-environment of activated sludge floc.

    PubMed

    Li, B; Bishop, P

    2003-01-01

    Biodegradation by microorganisms and mass transfer resistance in the micro-environment of activated sludge floc can cause changes in substrate and dissolved oxygen concentrations within the floc and can contribute to stratification of microbial processes inside the flocs. In this study, an integrated model of the microenvironment of the activated sludge floc was developed for floc from wastewaters from several sources and of varying strengths for dynamic simulation of the combined biological processes of COD and nitrogen removal. The model simulation results and measured profiles show the heterogeneous and gradient-governed microenvironment of activated sludge floc under different substrate and bulk oxygen concentrations. The substrate concentration increase zones inside the floc were present in all activated sludge floc from the Miller Brewing Co. wastewater treatment facility (high pollutant strength), with an oxygen penetration depth of only 0.15 mm into the outer layer. The anoxic and substrate concentration increase zones also dominated in the activated sludge floc from the Mill Creek Plant influent (medium pollutant strength), with the outer layer (0.20 mm) participating in the metabolism of the pollutants. The radius of the substrate concentration increase zone inside the sludge floc decreased with pollutant removal along the length of the tank. When the pollutant concentration in the bulk wastewater was low (Muddy Creek Plant), the substrate concentration increase zone disappeared; the whole floc was aerobic and in a high redox status. Our experiments and model analyses demonstrate that the microorganisms' structure-functions inside activated sludge floc change with the bulk substrate concentration and dissolved oxygen concentration. PMID:12906299

  5. 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.

  6. Biomass density and filament length synergistically affect activated sludge settling: systematic quantification and modeling.

    PubMed

    Jassby, D; Xiao, Y; Schuler, A J

    2014-01-01

    Settling of the biomass produced during biological treatment of wastewater is a critical and often problematic process. Filamentous bacteria content is the best-known factor affecting biomass settleability in activated sludge wastewater treatment systems, and varying biomass density has recently been shown to play an important role as well. The objective of this study was to systematically determine how filament content and biomass density combine to affect microbial biomass settling, with a focus on density variations over the range found in full-scale systems. A laboratory-scale bioreactor system was operated to produce biomass with a range of filamentous bacterium contents. Biomass density was systematically varied in samples from this system by addition of synthetic microspheres to allow separation of filament content and density effects on settleability. Fluorescent in-situ hybridization indicated that the culture was dominated by Sphaerotilus natans, a common contributor to poor settling in full-scale systems. A simple, image-based metric of filament content (filament length per floc area) was linearly correlated with the more commonly used filament length per dry biomass measurement. A non-linear, semi-empirical model of settleability as a function of filament content and density was developed and evaluated, providing a better understanding of how these two parameters combine to affect settleability. Filament content (length per dry biomass weight) was nearly linearly related to sludge volume index (SVI) values, with a slightly decreasing differential, and biomass density exhibited an asymptotic relationship with SVI. The filament content associated with bulking was shown to be a function of biomass density. The marginal effect of filament content on settleability increased with decreasing biomass density (low density biomass was more sensitive to changes in filament content than was high density biomass), indicating a synergistic relationship between these

  7. Detection of enteric viruses in activated sludge by feasible concentration methods

    PubMed Central

    Prado, Tatiana; Gaspar, Ana Maria Coimbra; Miagostovich, Marize Pereira

    2014-01-01

    Human enteric viruses are responsible to cause several diseases, including gastroenteritis and hepatitis, and can be present in high amounts in sewage sludge. This study compared virus recovery efficiency of two feasible concentration methods used for detecting human adenovirus (HAdV), rotavirus species A (RV-A), norovirus genogroup II (NoV GII) and hepatitis A virus (HAV) in sewage sludge from an activated sludge process. Twelve sewage sludge samples were collected bi-monthly from January to July, 2011. Ultracentrifugation was compared with a simplified protocol based on beef extract elution for recovering enteric viruses. Viruses were quantified by quantitative real-time PCR assays and virus recovery efficiency and limits of detection were determined. Methods showed mean recovery rates lower than 7.5%, presenting critical limits of detection (higher than 102 – 103 genome copies - GC L−1 for all viruses analyzed). Nevertheless, HAdV were detected in 90% of the analyzed sewage sludge samples (range: 1.8 × 104 to 1.1 × 105 GC L−1), followed by RV-A and NoV (both in 50%) and HAV (8%). Results suggesting that activated sludge is contaminated with high viral loads and HAdV are widely disseminated in these samples. The low virus recovery rates achieved, especially for HAV, indicate that other feasible concentration methods could be developed to improve virus recovery efficiency in these environmental matrices. PMID:24948954

  8. ACTIVE PEC APPLICATIONS, THE PEC WEBSITE, AND SLUDGE STABILITY RESEARCH

    EPA Science Inventory

    Since it's creation in 1985, the Pathogen Equivalency Committee (PEC) has been reviewing novel sludge disinfection technologies with regards to their abilities to protect human health and the environment. The PEC is charged to make recommendations on whether these novel technolog...

  9. The impact of sea water flushing on biological nitrification-denitrification activated sludge sewage treatment process.

    PubMed

    Yu, S M; Leung, W Y; Ho, K M; Greenfield, P F; Eckenfelder, W W

    2002-01-01

    The process performance of the two largest activated sludge processes in Hong Kong, the Sha Tin and the Tai Po Sewage Treatment Works (STW), deteriorated in the initial period after the introduction of seawater flushing in 1995 and 1996, respectively. High effluent ammonia nitrogen (NH4-N) and total suspended solids (TSS) in excess of the discharge standards resulted from incomplete nitrification and changes in floc characteristics. A desktop study on the inhibitory effects of salinity, particularly on nitrification, was subsequently conducted using the Tai Po STW operating data. To assist the upgrade of the Sha Tin STW a five-month extensive bench-scale investigation on a simple but flexible modified Ludzack-Ettinger configuration with bio-selector was conducted to quantify the inhibitory effects due to the saline concentration. The Sha Tin STW upgrade consists of restoration of its original design capacity (conventional process) of 205,000 m3/day from its currently much reduced capacity as a Bardenpho process. Only the volume of the existing biological process and clarifier is to be utilized. The saline concentration ranges from 3,500 up to 6,500 mg Cl-/L, both daily and seasonally. High and greatly fluctuating saline concentrations have been known to inhibit nitrification. Design consideration should also be given to the peak daily and seasonal TKN loading of up to three times the average. Although the nitrifiers maximum specific growth rate was significantly reduced to a low 0.25 day(-1), the inhibition was considered to be tolerable with effluent NH4-N and NO3-N consistently at < 1 and < 6 mg/L. The bio-selector was demonstrated to be efficient in control of sludge foaming and bulking with SVI consistently < or = 125 mL/g. Results from the IAWO Model No. 1 and the hydraulic model of the secondary clarifiers allowed overall process capacity maximization. With an anoxic mass fraction of 25-30%, operating sludge age of 9-14 days and SVI < or = 125 mL/g, both the

  10. Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste.

    PubMed

    Liu, Chuanyang; Li, Huan; Zhang, Yuyao; Liu, Can

    2016-11-01

    Anaerobic co-digestion of sewage sludge and food waste was tested at two different total solid (TS) concentrations. In the low-solids group with TS 4.8%, the biogas production increased linearly as the ratio of food waste in substrate increased from 0 to 100%, but no synergetic effect was found between the two substrates. Moreover, the additive food waste resulted in the accumulation of volatile fatty acids and decelerated biogas production. Thus, the blend ratio of food waste should be lower than 50%. While in the high-solids group with TS 14%, the weak alkaline environment with pH 7.5-8.5 avoided excessive acidification but high concentration of free ammonia was a potential risk. However, good synergetic effect was found between the two substrates because the added food waste improved mass transfer in sludge cake. Thus, 50% was recommended as the optimum ratio of food waste in substrate because of the best synergetic effect. PMID:27497086

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

    PubMed

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

    2014-12-01

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

  12. A comparative adsorption study: 17β-estradiol onto aerobic granular sludge and activated sludge.

    PubMed

    Zheng, Xiao-ying; He, Yu-jie; Chen, Wei; Wang, Ming-yang; Cao, Su-lan; Ni, Ming; Chen, Yu

    2016-01-01

    Adsorption plays a significant role in removing hydrophobic 17β-estradiol (E2) from wastewater. Batch experiments were conducted to compare the adsorption of E2 onto activated aerobic granular sludge (AGS) and activated sludge (AS), and features evaluated included the adsorption kinetics, thermodynamics, and influence of other environmental factors. By using a non-chemical wet-heat technique, both AGS and AS were treated to inactivated status. Then, after loading E2, the adsorption equilibrium capacity of the AGS was found to be greater than that of the AS at the same initial concentration of E2. Moreover, both the adsorption processes corresponded to a pseudo-second-order kinetic model; the adsorption rate constant of AGS was found to be higher and the half-adsorption time was shorter than that of AS. Next, evaluations of adsorption isotherms and thermodynamics indicated that the adsorption process was mainly a physical process. Lower temperatures facilitated a higher equilibrium adsorption capacity. However, the adsorption binding sites of AGS were distributed more uniformly at higher temperature, in contrast to the distribution found for AS. Finally, acidic conditions and an appropriate ionic strength (0.4 mol/L) were found to be particularly conducive to the adsorption process. Overall, the results showed that AGS has the potential to adsorb E2 with significant efficiency, thereby offering a new and more efficient means of treating E2 and trace oestrogens in wastewater.

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

    SciTech Connect

    Mondala, Andro; Hernandez, Rafael; French, Todd; McFarland, Linda; Sparks, Darrell; Holmes, William; Haque, Monica

    2012-01-01

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

  14. Diversity of dominant bacterial taxa in activated sludge promotes functional resistance following toxic shock loading.

    PubMed

    Saikaly, Pascal E; Oerther, Daniel B

    2011-04-01

    Examining the relationship between biodiversity and functional stability (resistance and resilience) of activated sludge bacterial communities following disturbance is an important first step towards developing strategies for the design of robust biological wastewater treatment systems. This study investigates the relationship between functional resistance and biodiversity of dominant bacterial taxa by subjecting activated sludge samples, with different levels of biodiversity, to toxic shock loading with cupric sulfate (Cu[II]), 3,5-dichlorophenol (3,5-DCP), or 4-nitrophenol (4-NP). Respirometric batch experiments were performed to determine the functional resistance of activated sludge bacterial community to the three toxicants. Functional resistance was estimated as the 30 min IC(50) or the concentration of toxicant that results in a 50% reduction in oxygen utilization rate compared to a referential state represented by a control receiving no toxicant. Biodiversity of dominant bacterial taxa was assessed using polymerase chain reaction-terminal restriction fragment length polymorphism (PCR-T-RFLP) targeting the 16S ribosomal RNA (16S rRNA) gene. Statistical analysis of 30 min IC(50) values and PCR-T-RFLP data showed a significant positive correlation (P < 0.05) between functional resistance and microbial diversity for each of the three toxicants tested. To our knowledge, this is the first study showing a positive correlation between biodiversity of dominant bacterial taxa in activated sludge and functional resistance. In this system, activated sludge bacterial communities with higher biodiversity are functionally more resistant to disturbance caused by toxic shock loading.

  15. Study of kinetics of degradation of cyclohexane carboxylic acid by acclimated activated sludge.

    PubMed

    Wang, Chunhua; Shi, Shuian; Chen, Hongyan

    2016-01-01

    Activated sludge contains complex microorganisms, which are highly effective biodegrading agents. In this study, the kinetics of biodegradation of cyclohexane carboxylic acid (CHCA) by an acclimated aerobic activated sludge were investigated. The results showed that after 180 days of acclimation, the activated sludge could steadily degrade >90% of the CHCA in 120 h. The degradation of CHCA by the acclimated activated sludge could be modeled using a first-order kinetics equation. The equations for the degradation kinetics for different initial CHCA concentrations were also obtained. The kinetics constant, kd, decreased with an increase in the CHCA concentration, indicating that, at high concentrations, CHCA had an inhibiting effect on the microorganisms in the activated sludge. The effects of pH on the degradation kinetics of CHCA were also investigated. The results showed that a pH of 10 afforded the highest degradation rate, indicating that basic conditions significantly promoted the degradation of CHCA. Moreover, it was found that the degradation efficiency for CHCA increased with an increase in temperature and concentration of dissolved oxygen under the experimental conditions.

  16. Removal of endocrine-disrupting chemicals in activated sludge treatment works.

    PubMed

    Johnson, A C; Sumpter, J P

    2001-12-15

    The release of endocrine-disrupting chemicals into the aquatic environment has raised the awareness of the central role played by sewage treatment in lowland water quality. This review focuses on the activated sludge process, which is commonly used to treat sewage in large towns and cities and which successfully removes the bulk of the organic compounds that enter the works. However, not all compounds are completely broken down or converted to biomass. For example, the estrogenic alkylphenols and steroid estrogens found in effluent are the breakdown products of incomplete breakdown of their respective parent compounds. Batch microcosm studies have indicated that estrone, ethinylestradiol, and alkylphenols will not be completely eliminated in activated sludge over typical treatment times. Field data suggest that the activated sludge treatment process can consistently remove over 85% of estradiol, estriol, and ethinylestradiol. The removal performance for estrone appears to be less and is more variable. Because of its relatively high hydrophobicity, the accumulation of alkylphenol in sludge has been observed. Although it has not been examined, accumulation of ethinylestradiol in sludge is a possibility due to its recalcitrance and hydrophobicity. A comparison between the concentrations of some of the major endocrine-active chemicals in effluents and their biological potencies has been made, to direct attention to the chemicals of most concern. While water purification techniques such as UV or activated charcoal could significantly remove these microorganic contaminants, the high costs involved suggest that research into the potential for treatment optimization should receive more attention. PMID:11775141

  17. Analytical methodologies based on LC–MS/MS for monitoring selected emerging compounds in liquid and solid phases of the sewage sludge

    PubMed Central

    Boix, C.; Ibáñez, M.; Fabregat-Safont, D.; Morales, E.; Pastor, L.; Sancho, J.V.; Sánchez-Ramírez, J.E.; Hernández, F.

    2016-01-01

    In this work, two analytical methodologies based on liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) were developed for quantification of emerging pollutants identified in sewage sludge after a previous wide-scope screening. The target list included 13 emerging contaminants (EC): thiabendazole, acesulfame, fenofibric acid, valsartan, irbesartan, salicylic acid, diclofenac, carbamazepine, 4-aminoantipyrine (4-AA), 4-acetyl aminoantipyrine (4-AAA), 4-formyl aminoantipyrine (4-FAA), venlafaxine and benzoylecgonine. The aqueous and solid phases of the sewage sludge were analyzed making use of Solid-Phase Extraction (SPE) and UltraSonic Extraction (USE) for sample treatment, respectively. The methods were validated at three concentration levels: 0.2, 2 and 20 μg L−1 for the aqueous phase, and 50, 500 and 2000 μg kg−1 for the solid phase of the sludge. In general, the method was satisfactorily validated, showing good recoveries (70–120%) and precision (RSD < 20%). Regarding the limit of quantification (LOQ), it was below 0.1 μg L−1 in the aqueous phase and below 50 μg kg−1 in the solid phase for the majority of the analytes. The method applicability was tested by analysis of samples from a wider study on degradation of emerging pollutants in sewage sludge under anaerobic digestion. The key benefits of these methodologies are: • SPE and USE are appropriate sample procedures to extract selected emerging contaminants from the aqueous phase of the sewage sludge and the solid residue. • LC–MS/MS is highly suitable for determining emerging contaminants in both sludge phases. • Up to our knowledge, the main metabolites of dipyrone had not been studied before in sewage sludge. PMID:27222823

  18. Analytical methodologies based on LC-MS/MS for monitoring selected emerging compounds in liquid and solid phases of the sewage sludge.

    PubMed

    Boix, C; Ibáñez, M; Fabregat-Safont, D; Morales, E; Pastor, L; Sancho, J V; Sánchez-Ramírez, J E; Hernández, F

    2016-01-01

    In this work, two analytical methodologies based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) were developed for quantification of emerging pollutants identified in sewage sludge after a previous wide-scope screening. The target list included 13 emerging contaminants (EC): thiabendazole, acesulfame, fenofibric acid, valsartan, irbesartan, salicylic acid, diclofenac, carbamazepine, 4-aminoantipyrine (4-AA), 4-acetyl aminoantipyrine (4-AAA), 4-formyl aminoantipyrine (4-FAA), venlafaxine and benzoylecgonine. The aqueous and solid phases of the sewage sludge were analyzed making use of Solid-Phase Extraction (SPE) and UltraSonic Extraction (USE) for sample treatment, respectively. The methods were validated at three concentration levels: 0.2, 2 and 20 μg L(-1) for the aqueous phase, and 50, 500 and 2000 μg kg(-1) for the solid phase of the sludge. In general, the method was satisfactorily validated, showing good recoveries (70-120%) and precision (RSD < 20%). Regarding the limit of quantification (LOQ), it was below 0.1 μg L(-1) in the aqueous phase and below 50 μg kg(-1) in the solid phase for the majority of the analytes. The method applicability was tested by analysis of samples from a wider study on degradation of emerging pollutants in sewage sludge under anaerobic digestion. The key benefits of these methodologies are: • SPE and USE are appropriate sample procedures to extract selected emerging contaminants from the aqueous phase of the sewage sludge and the solid residue. • LC-MS/MS is highly suitable for determining emerging contaminants in both sludge phases. • Up to our knowledge, the main metabolites of dipyrone had not been studied before in sewage sludge.

  19. Mechanisms for Reduced Excess Sludge Production in the Cannibal Process.

    PubMed

    Labelle, Marc-André; Dold, Peter L; Comeau, Yves

    2015-08-01

    Reducing excess sludge production is increasingly attractive as a result of rising costs and constraints with respect to sludge treatment and disposal. A technology in which the mechanisms remain not well understood is the Cannibal process, for which very low sludge yields have been reported. The objective of this work was to use modeling as a means to characterize excess sludge production at a full-scale Cannibal facility by providing a long sludge retention time and removing trash and grit by physical processes. The facility was characterized by using its historical data, from discussion with the staff and by conducting a sampling campaign to prepare a solids inventory and an overall mass balance. At the evaluated sludge retention time of 400 days, the sum of the daily loss of suspended solids to the effluent and of the waste activated sludge solids contributed approximately equally to the sum of solids that are wasted daily as trash and grit from the solids separation module. The overall sludge production was estimated to be 0.14 g total suspended solids produced/g chemical oxygen demand removed. The essential functions of the Cannibal process for the reduction of sludge production appear to be to remove trash and grit from the sludge by physical processes of microscreening and hydrocycloning, respectively, and to provide a long sludge retention time, which allows the slow degradation of the "unbiodegradable" influent particulate organics (XU,Inf) and the endogenous residue (XE). The high energy demand of 1.6 kWh/m³ of treated wastewater at the studied facility limits the niche of the Cannibal process to small- to medium-sized facilities in which sludge disposal costs are high but electricity costs are low.

  20. Mechanisms for Reduced Excess Sludge Production in the Cannibal Process.

    PubMed

    Labelle, Marc-André; Dold, Peter L; Comeau, Yves

    2015-08-01

    Reducing excess sludge production is increasingly attractive as a result of rising costs and constraints with respect to sludge treatment and disposal. A technology in which the mechanisms remain not well understood is the Cannibal process, for which very low sludge yields have been reported. The objective of this work was to use modeling as a means to characterize excess sludge production at a full-scale Cannibal facility by providing a long sludge retention time and removing trash and grit by physical processes. The facility was characterized by using its historical data, from discussion with the staff and by conducting a sampling campaign to prepare a solids inventory and an overall mass balance. At the evaluated sludge retention time of 400 days, the sum of the daily loss of suspended solids to the effluent and of the waste activated sludge solids contributed approximately equally to the sum of solids that are wasted daily as trash and grit from the solids separation module. The overall sludge production was estimated to be 0.14 g total suspended solids produced/g chemical oxygen demand removed. The essential functions of the Cannibal process for the reduction of sludge production appear to be to remove trash and grit from the sludge by physical processes of microscreening and hydrocycloning, respectively, and to provide a long sludge retention time, which allows the slow degradation of the "unbiodegradable" influent particulate organics (XU,Inf) and the endogenous residue (XE). The high energy demand of 1.6 kWh/m³ of treated wastewater at the studied facility limits the niche of the Cannibal process to small- to medium-sized facilities in which sludge disposal costs are high but electricity costs are low. PMID:26237684

  1. The re-use of Waste-Activated Sludge as part of a "zero-sludge" strategy for wastewater treatments in the pulp and paper industry.

    PubMed

    Kaluža, Leon; Suštaršič, Matej; Rutar, Vera; Zupančič, Gregor D

    2014-01-01

    The possibility of introducing the thermo-alkali hydrolysis of Waste-Activated Sludge (WAS) was investigated, in order to enable the use of its solid residue as a raw material in cardboard production and the use of its liquid portion for anaerobic digestion in an UASB reactor. The evaluation of the hydrolysis at pH>12 and T=70°C showed that the microbe cells were disrupted with more than 90% efficiency in less than 2h. The solid portion was hygienised, therefore making it possible to integrate it into the cardboard production as a raw material for less demanding cardboards. Up to 6% addition of the liquid portion of hydrolysed WAS to wastewater decreased the specific biogas production in a pilot-scale UASB from 0.236 to 0.212 m(3)/kg(COD), while the efficiency of the COD removal decreased from 80.4% to 76.5%. These values still guarantee an adequate treatment of the wastewater and an increased biogas production by 16%.

  2. Role of oxidants in enhancing dewaterability of anaerobically digested sludge through Fe (II) activated oxidation processes: hydrogen peroxide versus persulfate

    PubMed Central

    Song, Kang; Zhou, Xu; Liu, Yiqi; Gong, Yanyan; Zhou, Beibei; Wang, Dongbo; Wang, Qilin

    2016-01-01

    Improving dewaterability of sludge is important for the disposal of sludge in wastewater treatment plants (WWTPs). This study, for the first time, investigated the Fe(II) activated oxidization processes in improving anaerobically digested sludge (ADS) dewaterability. The combination of Fe(II) (0–100 mg/g total solids (TS)) and persulfate (0–1,000 mg/g TS) under neutral pH as well as the combination of Fe(II) (0–100 mg/g TS) and hydrogen peroxide (HP) (0–1,000 mg/g TS) under pH 3.0 were used to examine and compare their effect on the ADS dewaterability enhancement. The highest ADS dewaterability enhancement was attained at 25 mg Fe(II)/g TS and 50 mg HP/g TS, when the CST (CST: the capillary suction time, a sludge dewaterability indicator) was reduced by 95%. In contrast, the highest CST reduction in Fe(II)-persulfate conditioning was 90%, which was obtained at 50 mg Fe(II)/g TS and 250 mg persulfate/g TS. The results showed that Fe(II)-HP conditioning was comparable with Fe(II)-persulfate conditioning in terms of highest CST reduction. Economic analysis suggested that the Fe(II)-HP conditioning was more promising for improving ADS dewaterability compared with Fe(II)-persulfate conditioning, with the saving being up to $65,000 per year in a WWTP with a population equivalent of 100,000. PMID:27109500

  3. The Impact of Oxone on Disintegration and Dewaterability of Waste Activated Sludge.

    PubMed

    Wacławek, Stanisław; Grübel, Klaudiusz; Chłąd, Zuzanna; Dudziak, Mariusz; Černík, Miroslav

    2016-02-01

    Biochemical parameters such as soluble chemical oxygen demand (SCOD), phosphate, ammonium nitrogen and proteins are often used to characterize the efficiency of disintegration of waste activated sludge (WAS) flocs and microorganism cells. In this study, the chemical disintegration using peroxymonosulfate (MPS, Oxone) and thermally activated MPS, were evaluated for the destruction of WAS. Our study was conducted for chemical disintegration of WAS by MPS in doses between 84.7 - 847.5 mg/g(TS) activated by temperatures of 50, 70 and 90 °C over 30 minutes. The application of these methods causes an increase in the soluble COD value and protein concentration in the supernatant. Also, they positively influence the sludge volume index (SVI) which decreased from 89.8 to 17.2 ml/g. Our research work confirmed that the application of thermally activated MPS may become a new effective way of improving sewage treatment and sewage sludge processing. PMID:26803102

  4. Effect of deflocculation on the efficiency of disperser induced dairy waste activated sludge disintegration and treatment cost.

    PubMed

    Devi, T Poornima; Ebenezer, A Vimala; Kumar, S Adish; Kaliappan, S; Banu, J Rajesh

    2014-09-01

    Excess sludge disintegration by energy intensive processes like mechanical pretreatment is considered to be high in cost. In this study, an attempt has been made to disintegrate excess sludge by disperser in a cost effective manner by deflocculating the sludge using sodium dodecyl sulphate (SDS) at a concentration of 0.04 g/g SS. The disperser pretreatment was effective at a specific energy input of 5013 kJ/kg TS where deflocculated sludge showed higher chemical oxygen demand solubilisation and suspended solids reduction of 26% and 22.9% than flocculated sludge and was found to be 18.8% and 18.6% for former and latter respectively. Higher accumulation of volatile fatty acid (700 mg/L) in deflocculated sludge indicates better hydrolysis of sludge by proposed method. The anaerobic biodegradability resulted in higher biogas production potential of 0.522 L/(g VS) for deflocculated sludge. Cost analysis of the study showed 43% net energy saving in deflocculated sludge. PMID:24976494

  5. Activated carbons obtained from sewage sludge by chemical activation: gas-phase environmental applications.

    PubMed

    Boualem, T; Debab, A; Martínez de Yuso, A; Izquierdo, M T

    2014-07-01

    The objective of this study was to evaluate the adsorption capacity for toluene and SO2 of low cost activated carbons prepared from sewage sludge by chemical activation at different impregnation ratios. Samples were characterized by proximate and ultimate analyses, thermogravimetry, infrared spectroscopy and N2 adsorption. Because of the low carbon content of the raw material, the development of porosity in the activated carbons was mainly of a mesoporous nature, with surface areas lower than 300 m(2)/g. The study of gas-phase applications for activated carbons from sewage sludge was carried out using both an organic and an inorganic compound in order to screen for possible applications. Toluene adsorption capacity at saturation was around 280 mg/g, which is a good level of performance given the high ash content of the activated carbons. However, dynamic experiments at low toluene concentration presented diffusion problems resulting from low porosity development. SO2 adsorption capacity is associated with average micropore size, which can be controlled by the impregnation ratio used to prepare the activated carbons.

  6. Long-term effects of the ozonation of the sludge recycling stream on excess sludge reduction and biomass activity at full-scale.

    PubMed

    Gardoni, D; Ficara, E; Fornarelli, R; Parolini, M; Canziani, R

    2011-01-01

    This paper presents a full-scale experience of sludge minimization by means of short contact time ozonation in a wastewater treatment plant (WWTP) mainly fed on textile wastewater. The WWTP performance over a 3-year operational data series was analysed and compared with a two-year operation with sludge ozonation. Lab-scale respirometric tests were also performed to characterize biomass activity upstream and downstream of the ozone contact reactor. Results suggest that sludge ozonation: (1) is capable of decreasing excess sludge production by 17%; (2) partially decreases both N removal, by lowering the denitrification capacity, and P removal, by reducing biomass synthesis; (3) increases the decay rate from the typical value of 0.62 d(-1) to 1.3 d(-1); (4) decreases the heterotrophic growth yield from the typical value of 0.67 to 0.58 gCOD/gCOD.

  7. Organochlorine pesticides removal from wastewater by pine bark adsorption after activated sludge treatment.

    PubMed

    Sousa, Sérgio; Jiménez-Guerrero, Pedro; Ruiz, Antonio; Ratola, Nuno; Alves, Arminda

    2011-04-01

    Pesticides have been responsible for strong environmental impacts, mainly due to their persistence in the environment. Removal technologies are usually combined, because degradation of organic matter is needed prior to a tertiary treatment to guarantee pesticides elimination to levels below legal limits (normally 0.1 microg L(-1)). Pine bark was studied as an alternative to activated carbon, for organochlorine pesticides removal. A combination of technologies based on biodegradation with activated sludge followed by pine bark adsorption treatment was used for lindane (LIN) and heptachlor (HEP) removal from contaminated waters. Pesticides were quantified throughout the process by GC-ECD preceded by solid-phase microextraction (SPME). An experimental set-up was maintained for 4 months, by feeding a standard solution with pesticides concentration of 1 microg L(-1) each and known organic matter (Chemical Oxygen Demand, COD, -563 mg O2 L(-1)) on a daily basis. COD suffered a reduction of about 81% in the biological step and no increase was detected in the subsequent adsorption treatment. Overall removal efficiency was 76.6% and above 77.7% for LIN and HEP, respectively.

  8. Shifts in Nitrification Kinetics and Microbial Community during Bioaugmentation of Activated Sludge with Nitrifiers Enriched on Sludge Reject Water

    PubMed Central

    Yu, Lifang; Peng, Dangcong; Pan, Ruiling

    2012-01-01

    This study used two laboratory-scale sequencing batch reactors (SBRs) to evaluate the shifts in nitrification kinetics and microbial communities of an activated sludge sewage treatment system (main stream) during bioaugmentation with nitrifiers cultivated on real sludge reject water (side stream). Although bioaugmentation exerted a strong influence on the microbial community and the nitrification kinetics in the main stream, there was 58% of maximum ammonia uptake rate (AUR) and 80% of maximum nitrite uptake rate (NUR) loss of the seed source after bioaugmentation. In addition, nitrite accumulation occurred during bioaugmentation due to the unequal and asynchronous increase of the AUR (from 2.88 to 13.36 mg N/L·h) and NUR (from 0.76 to 4.34 mg N/L·h). FISH results showed that ammonia oxidizing bacteria (AOB) was inclined to be washed out with effluent in contrast to nitrite oxidizing bacteria (NOB), and Nitrosococcus mobilis lineage was the dominant AOB, while the dominant NOB in the main stream gradually transferred from Nitrospira to Nitrobacter. Nitrospina and Nitrococcus which existed in the seed source could not be detected in the main stream. It can be inferred that nitrite accumulation occurred due to the mismatch of NOB structure but washed out with effluent. PMID:23091354

  9. Energy demand in sludge dewatering.

    PubMed

    Chu, C P; Lee, D J; Chang, C Y

    2005-05-01

    This work investigates the energy required to dewater a suspension, i.e., activated sludge dewatered by centrifugation or consolidation. Total energy input to the suspension from the dewatering device, bond strength between adjacent water and solid surface, and intra-cake friction loss were evaluated for original and flocculated sludges. In centrifugal dewatering, most energy input during the initial stage was consumed by overcoming process irreversibility other than intra-cake friction, and, thereby, had a low energy efficiency. To increase centrifuge speed or to flocculate the sludge at optimal flocculant dosage would yield a high-energy input. In the consolidation test, most energy input at the initial stage was consumed in breaking down the bond strength until the moisture content reduced to less than the critical content. During subsequent dewatering stages, friction loss became the dominant source of energy loss. Dewatering sludge with high-energy efficiency is beneficial to optimally operate a dewatering process.

  10. Effect of magnetic nanoparticles on the performance of activated sludge treatment system.

    PubMed

    Ni, Shou-Qing; Ni, Jianyuan; Yang, Ning; Wang, Juan

    2013-09-01

    Both short-term and long-term exposure experiments were carried out to investigate the influence of magnetic nanoparticles (NPs) on activated sludge. The short-term presence of 50-200 mg/L of NPs decreased total nitrogen (TN) removal efficiencies, resulted from the acute toxicity of a shock load of NPs. However, long-term exposure of 50 mg/L magnetic NPs were observed to significantly improve TN removal efficiency, partially due to the self-repair function of activated sludge and magnetic-induced bio-effect. Sludge properties and extracellular polymer substrates secretion were affected. Additional investigations with enzyme and FISH assays indicated that short-term exposure of 50 mg/L magnetic NPs led to the abatement of nitrifying bacteria. However, the activities of the enzyme nitrite oxidoreductase and key denitrifying enzymes were increased after long-term exposure. PMID:23835260

  11. Effect of oxygen concentration on nitrification and denitrification in single activated sludge flocs.

    PubMed

    Satoh, Hisashi; Nakamura, Yoshiyuki; Ono, Hideki; Okabe, Satoshi

    2003-09-01

    Simultaneous nitrification and denitrification (SND) was investigated in the single aeration tank of a municipal wastewater treatment plant. Microelectrode measurements and batch experiments were performed to test for the presence of SND. Microelectrodes recorded the presence of O(2) concentration gradients in individual activated sludge flocs. When the O(2) concentration in the bulk liquid was <45 microM, anoxic zones were detected within flocs with a larger diameter (approximately 3000 microm). The O(2) penetration depth in the floc was found to be dependent on the O(2) concentration in the bulk liquid. Nitrification was restricted to the oxic zones, whereas denitrification occurred mainly in the anoxic zones. The nitrification rate of the activated sludge increased with increasing O(2) concentration in the bulk liquid, up to 40 microM, and remained constant thereafter. SND was observed in the aerated activated sludge when O(2) concentration was in the range of 10 to 35 microM.

  12. Use of metagenomic approaches to isolate lipolytic genes from activated sludge.

    PubMed

    Liaw, Ren-Bao; Cheng, Mei-Ping; Wu, Ming-Che; Lee, Chia-Yin

    2010-11-01

    The aims of this study were to access the bacterial diversity and isolate lipolytic genes using the metagenomic approach in activated sludge of a swine wastewater treatment facility. On the basis of BLASTN analysis of 16S rRNA gene clones, most of these communities (90%) were of uncultivated bacteria. The metagenomic library was constructed using a plasmid vector and DNA extracted directly from activated sludge samples. The average insert size was approximately 5.1 kb. A total of 12 unique and lipolytic clones were obtained using the tributyrin plate assay. The rate of discovering a lipolytic clone in this study was as high as 0.31%. Molecular analysis revealed that most of the 16 putative lipolytic enzymes showed 28-55% identity with non-redundant protein sequences in the database. Briefly, this study demonstrates that activated sludge is an ideal bioresource for isolating new lipolytic enzymes. PMID:20639117

  13. Activated sludge pilot plant: comparison between experimental and predicted concentration profiles using three different modelling approaches.

    PubMed

    Le Moullec, Y; Potier, O; Gentric, C; Leclerc, J P

    2011-05-01

    This paper presents an experimental and numerical study of an activated sludge channel pilot plant. Concentration profiles of oxygen, COD, NO(3) and NH(4) have been measured for several operating conditions. These profiles have been compared to the simulated ones with three different modelling approaches, namely a systemic approach, CFD and compartmental modelling. For these three approaches, the kinetics model was the ASM-1 model (Henze et al., 2001). The three approaches allowed a reasonable simulation of all the concentration profiles except for ammonium for which the simulations results were far from the experimental ones. The analysis of the results showed that the role of the kinetics model is of primary importance for the prediction of activated sludge reactors performance. The fact that existing kinetics parameters in the literature have been determined by parametric optimisation using a systemic model limits the reliability of the prediction of local concentrations and of the local design of activated sludge reactors. PMID:21489593

  14. Characteristics of PAHs adsorption on inorganic particles and activated sludge in domestic wastewater treatment.

    PubMed

    Liu, J J; Wang, X C; Fan, B

    2011-05-01

    The occurrence of polycyclic aromatic hydrocarbons (PAHs) in a domestic wastewater treatment plant (WWTP) was investigated in a 1 year period. In order to understand how PAHs were removed at different stages of the treatment process, adsorption experiments were conducted using quartz sand, kaolinite, and natural clay as inorganic adsorbents and activated sludge as organic adsorbent for adsorbing naphthalene, phenanthrene, and pyrene. As a result, the adsorption of PAHs by the inorganic adsorbents well followed the Langmuir isotherm while that by the activated sludge well followed the Freundlich isotherm. By bridging equilibrium partitioning coefficient with the parameters of adsorption isotherm, a set of mathematical models were developed. Under an assumption that in the primary settler PAHs removal was by adsorption onto inorganic particles and in the biological treatment unit it was by adsorption onto activated sludge, the model calculation results fairly reflected the practical condition in the WWTP.

  15. IASON - Intelligent Activated Sludge Operated by Nanotechnology - Hydrogel Microcarriers in Wastewater Treatment

    NASA Astrophysics Data System (ADS)

    Fleit, E.; Melicz, Z.; Sándor, D.; Zrínyi, M.; Filipcsei, G.; László, K.; Dékány, I.; Király, Z.

    Performance of biological wastewater treatment depends to a large extent on mechanical strength, size distribution, permeability and other textural properties of the activated sludge flocs. A novel approach was developed in applying synthetic polymer materials to organize floc architecture instead of spontaneously formed activated sludge floc. Developed microcarrier polymer materials were used in our experiments to mitigate technological goals. Preliminary results suggest that the PVA-PAA (polyvinyl alcohol-polyacrylic acid copolymer) is a feasible choice for skeleton material replacing "traditional" activated sludge floc. Use of PVA-PAA hydrogel material as microreactors and methods for biofilm formation of wastewater bacteria on the carrier material are described. Laboratory scale experimental results with microscopic size bioreactors and their potential application for simultaneous nitrification and denitrification are presented.

  16. Effect of membrane bioreactor configurations on sludge structure and microbial activity.

    PubMed

    Clouzot, L; Roche, N; Marrot, B

    2011-01-01

    The aim of this paper was to determine the effect of two different membrane bioreactor (MBR) configurations (external/immersed) on sludge structure and microbial activity. Sludge structure was deduced from rheological measurements. The high shear stress induced by the recirculation pump in the external MBR was shown to result in decreasing viscosity due to activated sludge (AS) deflocculation. Besides, soluble microbial products (SMP) release was higher in the external MBR (5 mgCOD gMLVSS(-1)) than in the immersed configuration (2 mgCOD gMLVSS(-1)). Microbial activity was followed from respirometry tests by focusing on the distinction between heterotrophs and autotrophs. An easier autotrophic microbe development was then observed in the immersed MBR compared to the external one. However, the external MBR was shown to allow better heterotrophic microbe development. PMID:20947340

  17. [Comparative Metagenomics of BIOLAK and A2O Activated Sludge Based on Next-generation Sequencing Technology].

    PubMed

    Tian, Mei; Liu, Han-hu; Shen, Xin

    2016-02-15

    This is the first report of comparative metagenomic analyses of BIOLAK sludge and anaerobic/anoxic/oxic (A2O) sludge. In the BIOLAK and A2O sludge metagenomes, 47 and 51 phyla were identified respectively, more than the numbers of phyla identified in Australia EBPR (enhanced biological phosphorus removal), USA EBPR and Bibby sludge. All phyla found in the BIOLAK sludge were detected in the A2O sludge, but four phyla were exclusively found in the A20 sludge. The proportion of the phylum Ignavibacteriae in the A2O sludge was 2.0440%, which was 3.2 times as much as that in the BIOLAK sludge (0.6376%). Meanwhile, the proportion of the bacterial phylum Gemmatimonadetes in the BIOLAK sludge was 2.4673%, which was >17 times as much as that in the A2O sludge (0.1404%). The proportion of the bacterial phylum Chlamydiae in the BIOLAK metagenome (0.2192%) was >6 times higher than that in the A2O (0.0360%). Furthermore, 167 genera found in the A20 sludge were not detected in the BIOLAK sludge. And 50 genera found in the BIOLAK sludge were not detected in the A20 sludge. From the analyses of both the phylum and genus levels, there were huge differences between the two biological communities of A2O and BIOLAK sludge. However, the proportions of each group of functional genes associated with metabolism of nitrogen, phosphor, sulfur and aromatic compounds in BIOLAK were very similar to those in A2O sludge. Moreover, the rankings of all six KEGG (Kyoto Encyclopedia for Genes and Genomes) categories were identical in the two sludges. In addition, the analyses of functional classification and pathway related nitrogen metabolism showed that the abundant enzymes had identical ranking in the BIOLAK and A2O metagenomes. Therefore, comparative metagenomics of BIOLAK and A2O activated sludge indicated similar function assignments from the two different biological communities. PMID:27363155

  18. Micropollutant removal by attached and suspended growth in a hybrid biofilm-activated sludge process.

    PubMed

    Falås, P; Longrée, P; la Cour Jansen, J; Siegrist, H; Hollender, J; Joss, A

    2013-09-01

    Removal of organic micropollutants in a hybrid biofilm-activated sludge process was investigated through batch experiments, modeling, and full-scale measurements. Batch experiments with carriers and activated sludge from the same full-scale reactor were performed to assess the micropollutant removal rates of the carrier biofilm under oxic conditions and the sludge under oxic and anoxic conditions. Clear differences in the micropollutant removal kinetics of the attached and suspended growth were demonstrated, often with considerably higher removal rates for the biofilm compared to the sludge. For several micropollutants, the removal rates were also affected by the redox conditions, i.e. oxic and anoxic. Removal rates obtained from the batch experiments were used to model the micropollutant removal in the full-scale process. The results from the model and plant measurements showed that the removal efficiency of the process can be predicted with acceptable accuracy (± 25%) for most of the modeled micropollutants. Furthermore, the model estimations indicate that the attached growth in hybrid biofilm-activated sludge processes can contribute significantly to the removal of individual compounds, such as diclofenac. PMID:23764599

  19. [Effect of ultrasonic energy on the characteristics of waste activated sludge].

    PubMed

    Feng, Xin; Deng, Jin-Chuan; Li, Bi-Qing; Luo, Gang; Lei, Heng-Yi

    2011-10-01

    Seven ultrasonic energy levels ranging from 0 to 26 000 kJ x kg(-1) were used to disintegrate excess sludge to investigate the changes in physical characteristics. The results indicated that the ultrasonication process destroys floc structure, facilitates the transfer of matter into the aqueous phase, and breaks up cell walls, which facilitated the improvement of settleability and biodegradability. Low ultrasonic energies could improve the settleability and supernatant turbidity. When the energy of 1 000 kJ x kg(-1) was applied into the sludge, the maximal settling velocity of sludge at 45 min was increased by 18.58% and the supernatant turbidity at 24 h was decreased by 43.52%, compared to the control. However, high ultrasonic energies deteriorated the characteristics. The maximal settling velocity was reduced by 37.03% and the supernatant turbidity was increased by 10 times in comparison to the control when the energy dose of 26 000 kJ x kg(-1) was applied. With the increases in ultrasonic energies, the particle size was significantly decreased, the soluble solids increased and the floc clusters dispersed. These changes in sludge characteristics were directly dependent upon the amount of ultrasonic energy applied. Furthermore, these characteristics correlated significantly to the ultrasonic energy. 1000 kJ x kg(-1) was the optimal energy that improved the settleability and the supernatant turbidity, and that destructed the floc structure of sludge. On the other hand, particle size was an important factor affecting sludge settleability and supernatant turbidity. The optimal values led to best settleability and turbidity.

  20. 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.

  1. Simultaneous organic carbon and nitrogen removal in an anoxic-oxic activated sludge system under various operating conditions.

    PubMed

    Rasool, Kashif; Ahn, Dae Hee; Lee, Dae Sung

    2014-06-01

    This study investigated a bench-scale anoxic-oxic activated sludge system for integrated removal of COD and nitrogen. The experimental unit includes four chambers and continuous feeding in first chamber without recycle of nitrified liquid from aerobic to anoxic chamber unlike the conventional anoxic-oxic process. Recycled excessive sludge was used for the purpose of recycling nitrified mixed liquor. Synthetic wastewater with average loading rates of 0.53 kg COD/m(3)/d and 0.067 kg NH4(+)-N/m(3)/d was fed to the reactor system at hydraulic residence times (HRT) of 24 and 18 h. The results of 100 days operation showed high removal efficiencies of organic matter of about 97% as total COD and more than 99% removal of ammonia-nitrogen. In anoxic-oxic operation phase, total inorganic nitrogen (TIN) removal was about 66% by pre-denitrification. Moreover, the solid liquid separation through final clarifier was excellent without any suspended solid in the effluent.

  2. Comparison of microbial communities of activated sludge and membrane biofilm in 10 full-scale membrane bioreactors.

    PubMed

    Jo, Sung Jun; Kwon, Hyeokpil; Jeong, So-Yeon; Lee, Chung-Hak; Kim, Tae Gwan

    2016-09-15

    Operation of membrane bioreactors (MBRs) for wastewater treatment is hampered by the membrane biofouling resulting from microbial activities. However, the knowledge of the microbial ecology of both biofilm and activated sludge in MBRs has not been sufficient. In this study, we scrutinized microbial communities of biofilm and activated sludge from 10 full-scale MBR plants. Overall, Flavobacterium, Dechloromonas and Nitrospira were abundant in order of abundance in biofilm, whereas Dechloromonas, Flavobacterium and Haliscomenobacter in activated sludge. Community structure was analyzed in either biofilm or activated sludge. Among MBRs, as expected, not only diversity of microbial community but also its composition was different from one another (p < 0.05). Between the biofilm and activated sludge, community composition made significant difference, but its diversity measures (i.e., alpha diversity, e.g., richness, diversity and evenness) did not (p > 0.05). Effects of ten environmental factors on community change were investigated using Spearman correlation. MLSS, HRT, F/M ratio and SADm explained the variation of microbial composition in the biofilm, whereas only MLSS did in the activated sludge. Microbial networks were constructed with the 10 environmental factors. The network results revealed that there were different topological characteristics between the biofilm and activated sludge networks, in which each of the 4 factors had different associations with microbial nodes. These results indicated that the different microbial associations were responsible for the variation of community composition between the biofilm and activated sludge.

  3. [The effect of selected tannery chemical compounds on selected bacteria of activated sludge].

    PubMed

    Mendrycka, M; Mierzejewski, J; Lidacki, A; Smiechowski, K

    2000-01-01

    Influence of tannery chemical compounds on the selected bacteria of the activated sludge was investigated. The chromium compounds must be diluted to 1:15-1:20 to loss its activity on the bacteria. Other compounds like: natrium chloratum, natrium formate and greased oils have any influence on the growth of the selected bacteria. PMID:11286092

  4. Activated sludge as inoculum for ready biodegradability testing: effect of source.

    PubMed

    Vazquez-Rodriguez, G; Goma, G; Rols, J L

    2003-08-01

    Results of ready biodegradability tests (RBT) are barely reproducible owing to a well-known lack of definition in inoculum source and quality. In this study, the degree of variability expected when only activated sludges are used as inoculum source was investigated. For this, the characteristics of activated sludges collected in municipal wastewater treatment plants operating at various massic loading rates (MLR; 0.1, 0.5 and 0.9 kgBOD5 kgVSS(-1) d(-1)) were compared. In order to provide suitable cellular densities for RBT, inocula were obtained after settling of activated sludges and analyzed in terms of active and cultivable cell densities, dehydrogenasic activity, BOD5 and a general profile of hydrolytic enzymes. In our analysis, biomass obtained from the High-MLR treatment plant constituted the inoculum having the highest biodegradation potential both with respect to microbial densities and to enzyme activities. This biomass also yielded the fastest biodegradation kinetics in dodecyl benzene sulfonate RBT. An attempt of biomass homogenization of inocula on the basis of cultivable cell density and dehydrogenasic activity gave negative results with this chemical compound. Since, in practice, restriction of activated sludge sources may be difficult, our results emphasize the importance of further studies aimed at homogenization of inoculum quality and quantity. PMID:14509389

  5. Degradation of PPCPs in activated sludge from different WWTPs in Denmark.

    PubMed

    Chen, Xijuan; Vollertsen, Jes; Nielsen, Jeppe Lund; Dall, Agnieszka Gieraltowska; Bester, Kai

    2015-12-01

    Pharmaceuticals and Personal care products (PPCPs) are often found in effluents from wastewater treatment plants (WWTPs) due to insufficient removal during wastewater treatment processes. To understand the factors affecting the removal of PPCPs in classical activated sludge WWTPs, the present study was performed to assess the removal of frequently occurring pharmaceuticals (Naproxen, Fenoprofen, Ketoprofen, Dichlofenac, Carbamazepine) and the biocide Triclosan in activated sludge from four different Danish WWTPs. The respective degradation constants were compared to operational parameters previous shown to be of importance for degradation of micropollutants such as biomass concentration, and sludge retention time (SRT). The most rapid degradation, was observed for NSAID pharmaceuticals (55-90% for Fenoprofen, 77-94% for Ketoprofen and 46-90% for Naproxen), followed by Triclosan (61-91%), while Dichlofenac and Carbamazepine were found to be persistent in the systems. Degradation rate constants were calculated as 0.0026-0.0407 for NSAID pharmaceuticals and 0.0022-0.0065 for triclosan. No relationships were observed between degradation rates and biomass concentrations in the diverse sludges. However, for the investigated PPCPs, the optimal SRT was within 14-20 days (for these values degradation of these PPCPs was the most efficient). Though all of these parameters influence the degradation rate, none of them seems to be overall decisive. These observations indicate that the biological composition of the sludge is more important than the design parameters of the respective treatment plant.

  6. Proposal for a screening test to evaluate the fate of organic micropollutants in activated sludge.

    PubMed

    Salvetti, Roberta; Vismara, Renato; Dal Ben, Ilaria; Gorla, Elena; Romele, Laura

    2011-04-01

    The concentrations of organic micropollutants are usually low in wastewaters (order of magnitude of mg L(-1)). However, their emission standards, especially in the case of carcinogenic and bioaccumulating substances, are often much lower (order of magnitude of microg L(-1)). Since these substances, in some cases, can be adsorbable or volatile, their removal via volatilization, biodegradation or sludge adsorption in a wastewater treatment plant (WWTP) becomes a significant feature to include in the usual design process, in order to verify the emission standards in gas and sludge too. In this study a simple screening batch test for the evaluation of the fate of organic micropollutants in water, air and sludge is presented. The test is set up by means of simple laboratory instruments and simulates an activated sludge tank process. In this study the results obtained for four substances with different chemical properties (i.e. toluene, benz(a)anthracene, phenol and benzene) are presented. The screening test proposed can be a useful tool to assess in about one month the fate of organic micropollutants in an activated sludge tank of a WWTP. Moreover, the test can constitute a useful support in the use of mathematical models, since it allows the verification of model results and the calibration of the reactions involved in the removal process. PMID:21877546

  7. The abundance and diversity of ammonia-oxidizing bacteria in activated sludge under autotrophic domestication.

    PubMed

    Li, Qiang; Ma, Chao; Sun, Shifang; Xie, Hui; Zhang, Wei; Feng, Jun; Song, Cunjiang

    2013-04-01

    Ammonia-oxidizing bacteria (AOB) play a key role in nitrogen-removal wastewater treatment plants (WWTPs) as they can transform ammonia into nitrite. AOB can be enriched in activated sludge through autotrophic domestication although they are difficult to be isolated. In this study, autotrophic domestication was carried out in a lab-scale sequencing-batch-reactor (SBR) system with two activated sludge samples. The ammonia removal capacity of the sludge samples increased during the domestication, and pH exhibited a negative correlation with the ammonia removal amount, which indicated that it was one important factor of microbial ammonia oxidation. The count of AOB, measured by the most probable number (MPN) method, increased significantly during autotrophic domestication as ammonia oxidation efficiency was enhanced. We investigated the changes in the community structure of AOB before and after domestication by amoA clone library and T-RFLP profile. It showed that AOB had been successfully enriched and the community structure significantly shifted during the domestication. Two groups of AOB were found in sludge samples: Nitrosomonas-like group remained predominant all the time and Nitrosospira-like group changed obviously. Simultaneously, the total heterotrophic bacteria were investigated by MPN and Biolog assay. The metabolic diversity of heterotrophs had changed minutely, although the count of them decreased significantly and lost superiority of microbial communities in the sludge.

  8. Degradation of PPCPs in activated sludge from different WWTPs in Denmark.

    PubMed

    Chen, Xijuan; Vollertsen, Jes; Nielsen, Jeppe Lund; Dall, Agnieszka Gieraltowska; Bester, Kai

    2015-12-01

    Pharmaceuticals and Personal care products (PPCPs) are often found in effluents from wastewater treatment plants (WWTPs) due to insufficient removal during wastewater treatment processes. To understand the factors affecting the removal of PPCPs in classical activated sludge WWTPs, the present study was performed to assess the removal of frequently occurring pharmaceuticals (Naproxen, Fenoprofen, Ketoprofen, Dichlofenac, Carbamazepine) and the biocide Triclosan in activated sludge from four different Danish WWTPs. The respective degradation constants were compared to operational parameters previous shown to be of importance for degradation of micropollutants such as biomass concentration, and sludge retention time (SRT). The most rapid degradation, was observed for NSAID pharmaceuticals (55-90% for Fenoprofen, 77-94% for Ketoprofen and 46-90% for Naproxen), followed by Triclosan (61-91%), while Dichlofenac and Carbamazepine were found to be persistent in the systems. Degradation rate constants were calculated as 0.0026-0.0407 for NSAID pharmaceuticals and 0.0022-0.0065 for triclosan. No relationships were observed between degradation rates and biomass concentrations in the diverse sludges. However, for the investigated PPCPs, the optimal SRT was within 14-20 days (for these values degradation of these PPCPs was the most efficient). Though all of these parameters influence the degradation rate, none of them seems to be overall decisive. These observations indicate that the biological composition of the sludge is more important than the design parameters of the respective treatment plant. PMID:26407712

  9. Granulation of activated sludge in a pilot-scale sequencing batch reactor for the treatment of low-strength municipal wastewater.

    PubMed

    Ni, Bing-Jie; Xie, Wen-Ming; Liu, Shao-Gen; Yu, Han-Qing; Wang, Ying-Zhe; Wang, Gan; Dai, Xian-Liang

    2009-02-01

    Aerobic granulation of activated sludge was achieved in a pilot-scale sequencing batch reactor (SBR) for the treatment of low-strength municipal wastewater (<200 mg L(-1) of COD, chemical oxygen demand). The volume exchange ratio and settling time of an SBR were found to be two key factors in the granulation of activated sludge grown on the low-strength municipal wastewater. After operation of 300 days, the mixed liquor suspended solids (MLSS) concentration in the SBR reached 9.5 g L(-1) and consisted of approximate 85% granular sludge. The average total COD removal efficiency kept at 90% and NH4+-N was almost completely depleted (approximately 95%) after the formation of aerobic granules. The granules (with a diameter over 0.212 mm) had a diameter ranging from 0.2 to 0.8 mm and had good settling ability with a settling velocity of 18-40 m h(-1). Three bacterial morphologies of rod, coccus and filament coexisted in the granules. Mathematical modeling was performed to get insight into this pilot-scale granule-based reactor. The modified IWA activated sludge model No 3 (ASM3) was able to adequately describe the pilot-scale SBR dynamics during its cyclic operation.

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

    PubMed Central

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

    2016-01-01

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

  11. Process kinetics of an activated-sludge reactor system treating poultry slaughterhouse wastewater.

    PubMed

    Hsiao, Ting-Hsun; Huang, Ju-Sheng; Huang, Yu-I

    2012-01-01

    The principal objective was to generate the essential kinetic parameters for model simulation and operation management of an activated-sludge reactor (ASR) system treating poultry slaughterhouse wastewater. By varying four different mean cell residence times (theta(c) = 4.6-24.3 d), the ASR system (26 degrees C) removed effectively 93.5%-97.2% of chemical oxygen demand (COD) from wastewater. Ifa high COD removal efficiency and a low effluent volatile suspended solids (VSS) concentration are of great concern, a theta(c) of 15-24 d or a food to microorganism (F/M) ratio of 0.3-0.7 kg COD/kg VSS-d is suggested; if resource sustainability and enhanced operation of the ASR system are of great concern, a theta(c) of 9 d or an F/M ratio of 0.9 kg COD/kg VSS-d is suggested. The COD residual concentrations and COD removal efficiencies calculated by using the Monod model agreed well with the experimental results. When the parameters k and Ks (deltaP/P) were respectively varied from -100% to +100%, the parametric sensitivity analysis showed that the COD residual concentration change (deltaS/S) was highly sensitive to k in the deltaP/P range between 0% and -40%, causing a marked increase in COD residual concentration.

  12. Free nitrous acid (FNA)-based pretreatment enhances methane production from waste activated sludge.

    PubMed

    Wang, Qilin; Ye, Liu; Jiang, Guangming; Jensen, Paul D; Batstone, Damien J; Yuan, Zhiguo

    2013-10-15

    Anaerobic digestion of waste activated sludge (WAS) is currently enjoying renewed interest due to the potential for methane production. However, methane production is often limited by the slow hydrolysis rate and/or poor methane potential of WAS. This study presents a novel pretreatment strategy based on free nitrous acid (FNA or HNO2) to enhance methane production from WAS. Pretreatment of WAS for 24 h at FNA concentrations up to 2.13 mg N/L substantially enhanced WAS solubilization, with the highest solubilization (0.16 mg chemical oxygen demand (COD)/mg volatile solids (VS), at 2.13 mg HNO2-N/L) being six times that without FNA pretreatment (0.025 mg COD/mg VS, at 0 mg HNO2-N/L). Biochemical methane potential tests demonstrated methane production increased with increased FNA concentration used in the pretreatment step. Model-based analysis indicated FNA pretreatment improved both hydrolysis rate and methane potential, with the highest improvement being approximately 50% (from 0.16 to 0.25 d(-1)) and 27% (from 201 to 255 L CH4/kg VS added), respectively, achieved at 1.78-2.13 mg HNO2-N/L. Further analysis indicated that increased hydrolysis rate and methane potential were related to an increase in rapidly biodegradable substrates, which increased with increased FNA dose, while the slowly biodegradable substrates remained relatively static.

  13. A laboratory-scale test of anaerobic digestion and methane production after phosphorus recovery from waste activated sludge.

    PubMed

    Takiguchi, Noboru; Kishino, Machiko; Kuroda, Akio; Kato, Junichi; Ohtake, Hisao

    2004-01-01

    In enhanced biological phosphorus removal (EBPR) processes, activated sludge microorganisms accumulate large quantities of polyphosphate (polyP) intracellularly. We previously discovered that nearly all of polyP could be released from waste activated sludge simply by heating it at 70 degrees C for about 1 h. We also demonstrated that this simple method was applicable to phosphorus (P) recovery from waste activated sludge in a pilot plant-scale EBPR process. In the present study, we evaluated the effect of this sludge processing (heat treatment followed by calcium phosphate precipitation) on anaerobic digestion in laboratory-scale experiments. The results suggested that the sludge processing for P recovery could improve digestive efficiency and methane productivity at both mesophilic (37 degrees C) and thermophilic (53 degrees C) temperatures. In addition, heat-treated waste sludge released far less P into the digested sludge liquor than did untreated waste sludge. It is likely that the P recovery step prior to anaerobic digestion has a potential advantage for controlling struvite (magnesium ammonium phosphate) deposit problems in sludge handling processes. PMID:16233643

  14. Bacterial community structures of phosphate-removing and non-phosphate-removing activated sludges from sequencing batch reactors.

    PubMed Central

    Bond, P L; Hugenholtz, P; Keller, J; Blackall, L L

    1995-01-01

    The bacterial community structures of phosphate- and non-phosphate-removing activated sludges were compared. Sludge samples were obtained from two sequencing batch reactors (SBRs), and 16S rDNA clone libraries of the bacterial sludge populations were established. Community structures were determined by phylogenetic analyses of 97 and 92 partial clone sequences from SBR1 (phosphate-removing sludge) and SBR2 (non-phosphate-removing sludge), respectively. For both sludges, the predominant bacterial group with which clones were affiliated was the beta subclass of the proteobacteria. Other major groups represented were the alpha proteobacterial subclass, planctomycete group, and Flexibacter-Cytophaga-Bacteroides group. In addition, several clone groups unaffiliated with known bacterial assemblages were identified in the clone libraries. Acinetobacter spp., thought to be important in phosphate removal in activated sludge, were poorly represented by clone sequences in both libraries. Differences in community structure were observed between the phosphate- and non-phosphate-removing sludges; in particular, the Rhodocyclus group within the beta subclass was represented to a greater extent in the phosphate-removing community. Such differences may account for the differing phosphate-removing capabilities of the two activated sludge communities. PMID:7544094

  15. Effects of earthworm activity on fertility and heavy metal bioavailability in sewage sludge.

    PubMed

    Liu, Xiaoli; Hu, Chengxiao; Zhang, Shuzhen

    2005-08-01

    The potential for using earthworms (Eisenia fetida) to improve fertility and reduce copper and cadmium availability in sewage sludge was tested by laboratory incubation experiments. Results comparing sewage sludge with and without earthworm treatment showed that earthworm activity decreased the contents of organic matter, total nitrogen, but increased the contents of available nitrogen and phosphorus and had no significant effect on the contents of total phosphorus, total potassium and available potassium. After incubation of the sewage sludge with earthworms for 60 days, the contents of Cu and Cd in the earthworms increased with the increase of additional Cu up to 250 mg kg(-1) and Cd up to 10 mg kg(-1). Bioconcentration factors (BCF) were higher than 1 only for Cd when the addition rate was lower than 5 mg kg(-1), which indicates that the earthworms can only accumulate Cd when the concentration of Cd is low in sewage sludge. Bioavailability of Cd and Cu was evaluated by applying sewage sludge with and without earthworm treatment to soil and then growing cabbage plants. The results showed that earthworm treatment increased the biomass of cabbage and decreased the bioaccumulation of Cd and Cu in the cabbage plants.

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

    PubMed

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

    2014-04-01

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

  17. [Effect of continual application of two kinds sludge on enzyme activities and heavy metal concentrations in alluvial soil].

    PubMed

    Tan, Qiling; Hu, Chengxiao; Zhao, Bin; Mclaren, R G; Cheng, Li; Wu, Lishu

    2004-03-01

    Pot culture experiments were conducted to study the effect of industrial and sewage sludge on some enzyme activities and heavy metal concentrations in alluvial soil. The results showed that the heavy metals in both industrial and sewage sludge were mainly non-exchangeable, and those in sewage sludge had a lower concentration but a higher bio-availability than in industrial sludge. The application of sludge could increase the activities of soil urease, polyphenol oxidase and neutral phosphatase, and the polyphenol oxidase and neutral phosphatase activities showed a reverse relationship with the concentrations of soil exchangeable Zn and Cu. Soil polyphenol oxidase and catalase activities could be used to indicate the Zn pollution in soil.

  18. Identification of Triclosan-O-Sulfate and other transformation products of Triclosan formed by activated sludge.

    PubMed

    Chen, Xijuan; Casas, Mònica Escolà; Nielsen, Jeppe Lund; Wimmer, Reinhard; Bester, Kai

    2015-02-01

    Aerobic degradation experiments of Triclosan were performed in activated sludge to identify possible transformation products for this compound. During 7 days, the formation of biotransformation products such as 2,4-Dichlorophenol, 4-Chlorocatechol, 5-Hydroxy-Triclosan and other Monohydroxy-Triclosan derivatives as well as Dihydroxy-Triclosan-derivatives were observed. The structure of 5-Hydroxy-Triclosan was elucidated by NMR data for the first time in sludge degradation experiments. Additionally the production of a hitherto unknown transformation product in sludge, i.e., Triclosan-O-Sulfate was detected. During the incubations, the concentrations of this transformation product changed from zero to 330 μg L(-1). Based on the analysis of the biodegradation products, three types of reactions were identified: 1) chemical scission of ether bond to form phenols and catechols, 2) addition of OH moieties to the aromatic ring, and 3) adding of methyl or sulfate groups to the original hydroxyl group.

  19. Free nitrous acid pretreatment of wasted activated sludge to exploit internal carbon source for enhanced denitrification.

    PubMed

    Ma, Bin; Peng, Yongzhen; Wei, Yan; Li, Baikun; Bao, Peng; Wang, Yayi

    2015-03-01

    Using internal carbon source contained in waste activated sludge (WAS) is beneficial for nitrogen removal from wastewater with low carbon/nitrogen ratio, but it is usually limited by sludge disintegration. This study presented a novel strategy based on free nitrous acid (FNA) pretreatment to intensify the release of organic matters from WAS for enhanced denitrification. During FNA pretreatment, soluble chemical oxygen demand (SCOD) production kept increasing when FNA increased from 0 to 2.04 mg HNO2-N/L. Compared with untreated WAS, the internal carbon source production increased by 50% in a simultaneous fermentation and denitrification reactor fed with WAS pretreated by FNA for 24 h at 2.04 mg HNO2-N/L. This also increased denitrification efficiency by 76% and sludge reduction by 87.5%. More importantly, greenhouse gas nitrous oxide production in denitrification was alleviated since more electrons could be provided by FNA pretreated WAS.

  20. Effects of pyrite sludge pollution on soil enzyme activities: ecological dose-response model.

    PubMed

    Hinojosa, M Belén; Carreira, José A; Rodríguez-Maroto, José M; García-Ruíz, Roberto

    2008-06-25

    A laboratory study was conducted to evaluate the response of soil enzyme activities (acid and alkaline phosphatase, beta-glucosidase, arylsulfatase, urease and dehydrogenase) to different levels of trace elements pollution in soils representative of the area affected by the pyrite sludge mining spill of Aznalcóllar (Guadiamar basin, SW Spain). Three uncontaminated soils from the study area were mixed with different loads of pyrite sludge to resemble field conditions and criteria applied for reclamation practices following the pollution incident: 0% ("reference" or background level), 1.3% ("attention level", further monitoring required), 4% ("intervention level", further cleaning and liming required) and 13% (ten times the "attention level"). Enzyme activities were analysed 4, 7, 14, 21, 34 and 92 days after pollutant addition and those measured after 92 days were used to calculate the ecological dose value (ED50). Soil enzyme activities and pH decreased after the pyrite sludge addition with respect to the "reference level" (0% pyrite sludge), whereas soil bioavailable (DTPA-extractable) trace elements concentration increased. Arylsulfatase, beta-glucosidase and phosphatase activities were reduced by more than 50% at 1.3% pyrite sludge dose. Arylsulfasate was the most sensitive soil enzyme (in average, ED50=0.99), whereas urease activity showed the lowest inhibition (in average, ED50=7.87) after pyrite sludge addition. Our results showed that the ecological dose concept, applied to enzyme activities, was satisfactory to quantify the effect of a multi-metalic pollutant (pyrite sludge) on soil functionality, and would provide manageable data to establish permissible limits of trace elements in polluted soils. Additionally, we evaluate the recovery of enzyme activities after addition of sugar-beet lime (calcium carbonate) to each experimentally polluted soil. The amount of lime added to each soil was enough to raise the pH to the original value (equal to control soil

  1. Effect of process variables on the production of Polyhydroxyalkanoates by activated sludge

    PubMed Central

    2012-01-01

    Polyhydroxyalkanoates are known to be temporarily stored by microorganisms in activated sludge, especially in anaerobic-aerobic processes. Due to the problems resulted from the disposals of plastic wastes and excess sludge of wastewater treatment plants, the production of polyhydroxyalkanoates by treating activated sludge and determining the effect of process variables were the main issues of this paper. In this research, an anaerobic-aerobic sequencing batch reactor was used to make microorganism adapted and a batch aerobic reactor was used for enriching them. The variables affecting polyhydroxyalkanoates production including aeration time, sludge retention time, and volatile fatty acids concentration of the influent in sequencing batch reactor, and also carbon to nitrogen ratio and cultivation time in polymer production reactor, were investigated using Taguchi statistical approach to determine optimum conditions. The maximum polymer production of 29% was achieved at sludge retention time of 5–10 days, aeration time of 2 hours, supplementation of 40% of volatile fatty acids in the influent and increasing of carbon to nitrogen ratio of polymer production reactor to above 25 g/g. Based on the results, in optimum conditions, the volatile fatty acids concentration which increased the production of polyhydroxyalkanoates up to 49% was the most effective variable. Carbon to nitrogen ratio, sludge retention time and aeration time were ranked as the next affecting parameters. Although the polyhydroxyalkanoates content achieved in present study is much lower than that by pure culture, but the proposed method may still serve well as an environmental friendly means to convert waste into valuable product. PMID:23369512

  2. Bioavailable and biodegradable dissolved organic nitrogen in activated sludge and trickling filter wastewater treatment plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A study was carried out to understand the fate of biodegradable dissolved organic nitrogen (BDON) and bioavailable dissolved organic nitrogen (ABDON) along the treatment trains of a wastewater treatment facility (WWTF) equipped with an activated sludge (AS) system and a WWTF equipped with a two-stag...

  3. An Operations Manual for Achieving Nitrification in an Activated Sludge Plant.

    ERIC Educational Resources Information Center

    Ontario Ministry of the Environment, Toronto.

    In Ontario, the attainment of nitrification (oxidation of ammonia) in activated sludge plants is receiving increased attention. Nitrification of waste water is a necessary requirement because it reduces plant discharge of nitrogenous oxygen demand and/or toxic ammonia. However, this new requirement will result in added responsibility for…

  4. Local adaptive approach toward segmentation of microscopic images of activated sludge flocs

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Burhan; Nisar, Humaira; Ng, Choon Aun; Lo, Po Kim; Yap, Vooi Voon

    2015-11-01

    Activated sludge process is a widely used method to treat domestic and industrial effluents. The conditions of activated sludge wastewater treatment plant (AS-WWTP) are related to the morphological properties of flocs (microbial aggregates) and filaments, and are required to be monitored for normal operation of the plant. Image processing and analysis is a potential time-efficient monitoring tool for AS-WWTPs. Local adaptive segmentation algorithms are proposed for bright-field microscopic images of activated sludge flocs. Two basic modules are suggested for Otsu thresholding-based local adaptive algorithms with irregular illumination compensation. The performance of the algorithms has been compared with state-of-the-art local adaptive algorithms of Sauvola, Bradley, Feng, and c-mean. The comparisons are done using a number of region- and nonregion-based metrics at different microscopic magnifications and quantification of flocs. The performance metrics show that the proposed algorithms performed better and, in some cases, were comparable to the state-of the-art algorithms. The performance metrics were also assessed subjectively for their suitability for segmentations of activated sludge images. The region-based metrics such as false negative ratio, sensitivity, and negative predictive value gave inconsistent results as compared to other segmentation assessment metrics.

  5. Operational Control Procedures for the Activated Sludge Process, Part I - Observations, Part II - Control Tests.

    ERIC Educational Resources Information Center

    West, Alfred W.

    This is the first in a series of documents developed by the National Training and Operational Technology Center describing operational control procedures for the activated sludge process used in wastewater treatment. Part I of this document deals with physical observations which should be performed during each routine control test. Part II…

  6. Effects of TiO2 and Ag nanoparticles on polyhydroxybutyrate biosynthesis by activated sludge bacteria.

    PubMed

    Priester, John H; Van De Werfhorst, Laurie C; Ge, Yuan; Adeleye, Adeyemi S; Tomar, Shivira; Tom, Lauren M; Piceno, Yvette M; Andersen, Gary L; Holden, Patricia A

    2014-12-16

    Manufactured nanomaterials (MNMs) are increasingly incorporated into consumer products that are disposed into sewage. In wastewater treatment, MNMs adsorb to activated sludge biomass where they may impact biological wastewater treatment performance, including nutrient removal. Here, we studied MNM effects on bacterial polyhydroxyalkanoate (PHA), specifically polyhydroxybutyrate (PHB), biosynthesis because of its importance to enhanced biological phosphorus (P) removal (EBPR). Activated sludge was sampled from an anoxic selector of a municipal wastewater treatment plant (WWTP), and PHB-containing bacteria were concentrated by density gradient centrifugation. After starvation to decrease intracellular PHB stores, bacteria were nutritionally augmented to promote PHB biosynthesis while being exposed to either MNMs (TiO2 or Ag) or to Ag salts (each at a concentration of 5 mg L(-1)). Cellular PHB concentration and PhyloChip community composition were analyzed. The final bacterial community composition differed from activated sludge, demonstrating that laboratory enrichment was selective. Still, PHB was synthesized to near-activated sludge levels. Ag salts altered final bacterial communities, although MNMs did not. PHB biosynthesis was diminished with Ag (salt or MNMs), indicating the potential for Ag-MNMs to physiologically impact EBPR through the effects of dissolved Ag ions on PHB producers. PMID:25409530

  7. Operational Control Procedures for the Activated Sludge Process, Part III-A: Calculation Procedures.

    ERIC Educational Resources Information Center

    West, Alfred W.

    This is the second in a series of documents developed by the National Training and Operational Technology Center describing operational control procedures for the activated sludge process used in wastewater treatment. This document deals exclusively with the calculation procedures, including simplified mixing formulas, aeration tank…

  8. Two-phased hyperthermophilic anaerobic co-digestion of waste activated sludge with kitchen garbage.

    PubMed

    Lee, Myungyeol; Hidaka, Taira; Tsuno, Hiroshi

    2009-11-01

    For co-digestion of waste activated sludge with kitchen garbage, hyperthermophilic digester systems that consisted of an acidogenic reactor operated at hyperthermophilic (70 degrees C) and a methanogenic reactor operated at mesophilic (35 degrees C), thermophilic (55 degrees C) or hyperthermophilic (65 degrees C) conditions in series were studied by comparing with a thermophilic digester system that consisted of thermophilic (55 degrees C) acidogenic and methanogenic reactors. Laboratory scale reactors were operated continuously fed with a substrate blend composed of concentrated waste activated sludge and artificial kitchen garbage. At the acidogenic reactor, solubilization efficiencies of chemical oxygen demand (COD), carbohydrate and protein at 70 degrees C were about 39%, 42% and 54%, respectively, and they were higher than those at 55 degrees C by around 10%. The system of acidogenesis at 70 degrees C and methanogenesis at 55 degrees C was stable and well-functioned in terms of treatment performances and low ammonium nitrogen concentrations. Microbial community analysis was conducted using a molecular biological method. The key microbe determined at the hyperthermophilic acidogenesis step was Coprothermobacter sp., which was possibly concerned with the degradation of protein in waste activated sludge. The present study proved that the hyperthermophilic system was advantageous for treating substrate blends containing high concentrations of waste activated sludge.

  9. Two-phased hyperthermophilic anaerobic co-digestion of waste activated sludge with kitchen garbage.

    PubMed

    Lee, Myungyeol; Hidaka, Taira; Tsuno, Hiroshi

    2009-11-01

    For co-digestion of waste activated sludge with kitchen garbage, hyperthermophilic digester systems that consisted of an acidogenic reactor operated at hyperthermophilic (70 degrees C) and a methanogenic reactor operated at mesophilic (35 degrees C), thermophilic (55 degrees C) or hyperthermophilic (65 degrees C) conditions in series were studied by comparing with a thermophilic digester system that consisted of thermophilic (55 degrees C) acidogenic and methanogenic reactors. Laboratory scale reactors were operated continuously fed with a substrate blend composed of concentrated waste activated sludge and artificial kitchen garbage. At the acidogenic reactor, solubilization efficiencies of chemical oxygen demand (COD), carbohydrate and protein at 70 degrees C were about 39%, 42% and 54%, respectively, and they were higher than those at 55 degrees C by around 10%. The system of acidogenesis at 70 degrees C and methanogenesis at 55 degrees C was stable and well-functioned in terms of treatment performances and low ammonium nitrogen concentrations. Microbial community analysis was conducted using a molecular biological method. The key microbe determined at the hyperthermophilic acidogenesis step was Coprothermobacter sp., which was possibly concerned with the degradation of protein in waste activated sludge. The present study proved that the hyperthermophilic system was advantageous for treating substrate blends containing high concentrations of waste activated sludge. PMID:19804865

  10. FATE OF WATER SOLUBLE AZO DYES IN THE ACTIVATED SLUDGE PROCESS

    EPA Science Inventory

    The objective of this study was to determine the partitioning of water soluble azo dyes in the activated sludge process (ASP). Azo dyes are of concern because some of the dyes, dye precursors , and/or their degradation products such as aromatic amines (which are also dye precurso...

  11. Microbial diversity in various types of paper mill sludge: identification of enzyme activities with potential industrial applications.

    PubMed

    Ghribi, Manel; Meddeb-Mouelhi, Fatma; Beauregard, Marc

    2016-01-01

    This study is the first comprehensive investigation of enzyme-producing bacteria isolated from four sludge samples (primary, secondary, press and machine) collected in a Kraft paper mill. Overall, 41 strains encompassing 11 different genera were identified by 16S rRNA gene analysis and biochemical testing. Both biodiversity and enzymatic activities were correlated with sludge composition. Press sludge hosted the largest variety of bacterial strains and enzymatic activities, which included hydrolytic enzymes and ligninolytic enzymes. In contrast, strains isolated from secondary sludge were devoid of several enzymatic activities. Most strains were found to metabolize Kraft liquor at its alkaline pH and to decolorize industrial lignin-mimicking dyes. Resistance to lignin or the ability to metabolize this substrate is a prerequisite to survival in any paper mill sludge type. We demonstrate here that the bacterial strains found in a typical Kraft paper mill represent a source of potential novel enzymes for both industrial applications and bioremediation.

  12. Microbial diversity in various types of paper mill sludge: identification of enzyme activities with potential industrial applications.

    PubMed

    Ghribi, Manel; Meddeb-Mouelhi, Fatma; Beauregard, Marc

    2016-01-01

    This study is the first comprehensive investigation of enzyme-producing bacteria isolated from four sludge samples (primary, secondary, press and machine) collected in a Kraft paper mill. Overall, 41 strains encompassing 11 different genera were identified by 16S rRNA gene analysis and biochemical testing. Both biodiversity and enzymatic activities were correlated with sludge composition. Press sludge hosted the largest variety of bacterial strains and enzymatic activities, which included hydrolytic enzymes and ligninolytic enzymes. In contrast, strains isolated from secondary sludge were devoid of several enzymatic activities. Most strains were found to metabolize Kraft liquor at its alkaline pH and to decolorize industrial lignin-mimicking dyes. Resistance to lignin or the ability to metabolize this substrate is a prerequisite to survival in any paper mill sludge type. We demonstrate here that the bacterial strains found in a typical Kraft paper mill represent a source of potential novel enzymes for both industrial applications and bioremediation. PMID:27652065

  13. Arsenic and chromium removal from water using biochars derived from rice husk, organic solid wastes and sewage sludge.

    PubMed

    Agrafioti, Evita; Kalderis, Dimitrios; Diamadopoulos, Evan

    2014-01-15

    Biochars derived from rice husk, the organic fraction of municipal solid wastes and sewage sludge, as well as a sandy loam soil, were used as adsorbents for As(V), Cr(III) and Cr(VI) removal from aqueous solutions. The kinetic study showed that sorption can be well described by the pseudo-second order kinetic model, while simulation of sorption isotherms gave better fit for the Freundlich model. The materials examined removed more than 95% of the initial Cr(III). However, removal rates for As(V) and Cr(VI) anions were significantly lower. Biochar derived from sewage sludge was efficient in removing 89% of Cr(VI) and 53% of As(V). Its ash high Fe2O3 content may have enhanced metal adsorption via precipitation. Soil was the most effective material for the removal of As(V), yet it could not strongly retain metal anions compared to biochars, as a significant amount of the adsorbed metal was released during desorption experiments. PMID:24412594

  14. Arsenic and chromium removal from water using biochars derived from rice husk, organic solid wastes and sewage sludge.

    PubMed

    Agrafioti, Evita; Kalderis, Dimitrios; Diamadopoulos, Evan

    2014-01-15

    Biochars derived from rice husk, the organic fraction of municipal solid wastes and sewage sludge, as well as a sandy loam soil, were used as adsorbents for As(V), Cr(III) and Cr(VI) removal from aqueous solutions. The kinetic study showed that sorption can be well described by the pseudo-second order kinetic model, while simulation of sorption isotherms gave better fit for the Freundlich model. The materials examined removed more than 95% of the initial Cr(III). However, removal rates for As(V) and Cr(VI) anions were significantly lower. Biochar derived from sewage sludge was efficient in removing 89% of Cr(VI) and 53% of As(V). Its ash high Fe2O3 content may have enhanced metal adsorption via precipitation. Soil was the most effective material for the removal of As(V), yet it could not strongly retain metal anions compared to biochars, as a significant amount of the adsorbed metal was released during desorption experiments.

  15. Co-composting as an oxygen stabilization of an organic fraction of municipal solid waste and industrial sewage sludge.

    PubMed

    Milczarek, M; Neczaj, E; Parkitna, K

    2013-01-01

    The purpose of this work is to study the characteristics of the co-composting of municipal solid waste (MSW), sewage sludge, grass and sawdust. Differing proportions of biodegradable waste were investigated through changes of temperature, oxygen consumption, organic matters, moisture content, carbon, nitrogen, C/N ratio as well as heavy metals and pathogen microorganisms content. The present study has shown that addition of MSW above 10% had a negative impact on the composting process. The initial C/N of the mixtures with a higher MSW content was below 18. Lower losses of organic matter occurred during composting for the mixture with the highest addition of MSW. Although studies have shown that composting is a good method for the disposal of organic waste additional research is required in order to optimize the organic and nitrogen compounds degradation during the co-composting process. In conclusion, a 1:4:4:1 mixture of MSW:sewage sludge:grass:sawdust is recommended because it can achieve high temperature as well as the highest organic matter degradation and highest N content in the final composting product. The concentration of heavy and light metals in all composts was within the limits of regulation of the Polish Minister of Agriculture and Rural Development. PMID:24185049

  16. [Transformation characteristics of carbon, nitrogen, phosphorus and sulfur during thermal hydrolysis pretreatment of sludge with high solid content].

    PubMed

    Zhuo, Yang; Han, Yun; Cheng, Yao; Peng, Dang-Cong; Li, Yu-You

    2015-03-01

    The transformation characteristics of carbon, nitrogen, phosphorus and sulfur in dewatering sludge from municipal wastewater treatment plant (WWTP) were investigated after thermal hydrolysis pretreatment at 165 degress C for 50 min. The results showed that the hydrolysis efficiency of VSS could reach as high as 43.35%, 54.36% of protein and 65.12% of carbohydrate were transferred to dissolved organics, respectively, and the main component of dissolved organic matter in hydrolysate was dissolved protein (52.18% ), 54.23% of insoluble organic nitrogen was turned into dissolved nitrogen and 22.13% of dissolved nitrogen in hydrolysate was converted to ammonia. The transformation rate of insoluble phosphorus was 30.52%. Dissolved phosphorus was mostly transformed to phosphate (79.84%) as phosphorus-accumulating bacteria cells were crushed. 50.03% of insoluble organic sulfur was hydrolyzed, and little change was detected in sulfide (0.50%). The analysis results of the organic compounds transformation are valuable for treatment of the thermal hydrolysis pretreated sludge with high solid content.

  17. Improvement of anaerobic digestion of sludge.

    PubMed

    Dohányos, M; Zábranská, J; Kutil, J; Jenícek, P

    2004-01-01

    Anaerobic digestion improvement can be accomplished by different methods. Besides optimization of the process conditions, pretreatment of input sludge and increase of process temperature is frequently used. The thermophilic process brings a higher solids reduction and biogas production, a high resistance to foaming, no problems with odour, better pathogens destruction and an improvement of the energy balance of the whole treatment plant. Disintegration of excess activated sludge in a lysate centrifuge was proved to cause increase of biogas production in full-scale conditions. The rapid thermal conditioning of digested sludge is an acceptable method of particulate matter disintegration and solubilization. PMID:15259942

  18. Influence of hydraulic retention time on indigenous microalgae and activated sludge process.

    PubMed

    Anbalagan, Anbarasan; Schwede, Sebastian; Lindberg, Carl-Fredrik; Nehrenheim, Emma

    2016-03-15

    Integration of the microalgae and activated sludge (MAAS) process in municipal wastewater treatment and biogas production from recovered MAAS was investigated by studying the hydraulic retention time (HRT) of semi-continuous photo-bioreactors. An average total nitrogen (TN) removal efficiency (RE) of maximum 81.5 ± 5.1 and 64.6 ± 16.2% was achieved at 6 and 4 days HRT. RE of total phosphorous (TP) increased slightly at 6 days (80 ± 12%) HRT and stabilized at 4 days (56 ± 5%) and 2 days (55.5 ± 5.5%) HRT due to the fluctuations in COD and N/P mass ratio of the periodic wastewater. COD and organic carbon were removed efficiently and a rapidly settleable MAAS with a sludge volume index (SVI_10) of less than 117 mL g(-1) was observed at all HRTs. The anaerobic digestion of the untreated MAAS showed a higher biogas yield of 349 ± 10 mL g VS(-1) with 2 days HRT due to a low solids retention time (SRT). Thermal pretreatment of the MAAS (120 °C, 120 min) did not show any improvement with biogas production at 6 days (269 ± 3 (untreated) and 266 ± 16 (treated) mL gVS(-1)), 4 days (258 ± 11(untreated) and 263 ± 10 (treated) mL gVS(-1)) and 2 days (308 ± 19 mL (treated) gVS(-1)) HRT. Hence, the biogas potential tests showed that the untreated MAAS was a feasible substrate for biogas production. Results from this proof of concept support the application of MAAS in wastewater treatment for Swedish conditions to reduce aeration, precipitation chemicals and CO2 emissions.

  19. Influence of hydraulic retention time on indigenous microalgae and activated sludge process.

    PubMed

    Anbalagan, Anbarasan; Schwede, Sebastian; Lindberg, Carl-Fredrik; Nehrenheim, Emma

    2016-03-15

    Integration of the microalgae and activated sludge (MAAS) process in municipal wastewater treatment and biogas production from recovered MAAS was investigated by studying the hydraulic retention time (HRT) of semi-continuous photo-bioreactors. An average total nitrogen (TN) removal efficiency (RE) of maximum 81.5 ± 5.1 and 64.6 ± 16.2% was achieved at 6 and 4 days HRT. RE of total phosphorous (TP) increased slightly at 6 days (80 ± 12%) HRT and stabilized at 4 days (56 ± 5%) and 2 days (55.5 ± 5.5%) HRT due to the fluctuations in COD and N/P mass ratio of the periodic wastewater. COD and organic carbon were removed efficiently and a rapidly settleable MAAS with a sludge volume index (SVI_10) of less than 117 mL g(-1) was observed at all HRTs. The anaerobic digestion of the untreated MAAS showed a higher biogas yield of 349 ± 10 mL g VS(-1) with 2 days HRT due to a low solids retention time (SRT). Thermal pretreatment of the MAAS (120 °C, 120 min) did not show any improvement with biogas production at 6 days (269 ± 3 (untreated) and 266 ± 16 (treated) mL gVS(-1)), 4 days (258 ± 11(untreated) and 263 ± 10 (treated) mL gVS(-1)) and 2 days (308 ± 19 mL (treated) gVS(-1)) HRT. Hence, the biogas potential tests showed that the untreated MAAS was a feasible substrate for biogas production. Results from this proof of concept support the application of MAAS in wastewater treatment for Swedish conditions to reduce aeration, precipitation chemicals and CO2 emissions. PMID:26803263

  20. Bacteriophages of wastewater foaming-associated filamentous Gordonia reduce host levels in raw activated sludge

    PubMed Central

    Liu, Mei; Gill, Jason J.; Young, Ry; Summer, Elizabeth J.

    2015-01-01

    Filamentous bacteria are a normal and necessary component of the activated sludge wastewater treatment process, but the overgrowth of filamentous bacteria results in foaming and bulking associated disruptions. Bacteriophages, or phages, were investigated for their potential to reduce the titer of foaming bacteria in a mixed-microbial activated sludge matrix. Foaming-associated filamentous bacteria were isolated from activated sludge of a commercial wastewater treatment plan and identified as Gordonia species by 16S rDNA sequencing. Four representative phages were isolated that target G. malaquae and two un-named Gordonia species isolates. Electron microscopy revealed the phages to be siphophages with long tails. Three of the phages - GordTnk2, Gmala1, and GordDuk1 - had very similar ~76 kb genomes, with >93% DNA identity. These genomes shared limited synteny with Rhodococcus equi phage ReqiDocB7 and Gordonia phage GTE7. In contrast, the genome of phage Gsput1 was smaller (43 kb) and was not similar enough to any known phage to be placed within an established phage type. Application of these four phages at MOIs of 5–15 significantly reduced Gordonia host levels in a wastewater sludge model by approximately 10-fold as compared to non-phage treated reactors. Phage control was observed for nine days after treatment. PMID:26349678

  1. Advanced steady-state model for the fate of hydrophobic and volatile compounds in activated sludge

    SciTech Connect

    Lee, K.C.; Rittmann, B.E.; Shi, J.; McAvoy, D.

    1998-09-01

    A steady-state, advanced, general fate model developed to study the fate of organic compounds in primary and activated-sludge systems. This model considers adsorption, biodegradation from the dissolved and adsorbed phases, bubble volatilization, and surface volatilization as removal mechanisms. A series of modeling experiments was performed to identify the key trends of these removal mechanisms for compounds with a range of molecular properties. With typical municipal wastewater treatment conditions, the results from the modeling experiments show that co-metabolic and primary utilization mechanisms give very different trends in biodegradation for the compounds tested. For co-metabolism, the effluent concentration increases when the influent concentration increases, while the effluent concentration remains unchanged when primary utilization occurs. For a highly hydrophobic compound, the fraction of compound removed from adsorption onto primary sludge can be very important, and the direct biodegradation of compound sorbed to the activated sludge greatly increases its biodegradation and reduces its discharge with the waste activated sludge. Volatilization from the surface of the primary and secondary systems is important for compounds with moderate to high volatilities, especially when these compounds are not biodegradable. Finally, bubble volatilization can be a major removal mechanism for highly volatile compounds even when they are highly biodegradable.

  2. Bacteriophages of wastewater foaming-associated filamentous Gordonia reduce host levels in raw activated sludge.

    PubMed

    Liu, Mei; Gill, Jason J; Young, Ry; Summer, Elizabeth J

    2015-09-09

    Filamentous bacteria are a normal and necessary component of the activated sludge wastewater treatment process, but the overgrowth of filamentous bacteria results in foaming and bulking associated disruptions. Bacteriophages, or phages, were investigated for their potential to reduce the titer of foaming bacteria in a mixed-microbial activated sludge matrix. Foaming-associated filamentous bacteria were isolated from activated sludge of a commercial wastewater treatment plan and identified as Gordonia species by 16S rDNA sequencing. Four representative phages were isolated that target G. malaquae and two un-named Gordonia species isolates. Electron microscopy revealed the phages to be siphophages with long tails. Three of the phages--GordTnk2, Gmala1, and GordDuk1--had very similar ~76 kb genomes, with >93% DNA identity. These genomes shared limited synteny with Rhodococcus equi phage ReqiDocB7 and Gordonia phage GTE7. In contrast, the genome of phage Gsput1 was smaller (43 kb) and was not similar enough to any known phage to be placed within an established phage type. Application of these four phages at MOIs of 5-15 significantly reduced Gordonia host levels in a wastewater sludge model by approximately 10-fold as compared to non-phage treated reactors. Phage control was observed for nine days after treatment.

  3. Enhancement of anaerobic biohydrogen/methane production from cellulose using heat-treated activated sludge.

    PubMed

    Lay, C H; Chang, F Y; Chu, C Y; Chen, C C; Chi, Y C; Hsieh, T T; Huang, H H; Lin, C Y

    2011-01-01

    Anaerobic digestion is an effective technology to convert cellulosic wastes to methane and hydrogen. Heat-treatment is a well known method to inhibit hydrogen-consuming bacteria in using anaerobic mixed cultures for seeding. This study aims to investigate the effects of heat-treatment temperature and time on activated sludge for fermentative hydrogen production from alpha-cellulose by response surface methodology. Hydrogen and methane production was evaluated based on the production rate and yield (the ability of converting cellulose into hydrogen and methane) with heat-treated sludge as the seed at various temperatures (60-97 degrees C) and times (20-60 min). Batch experiments were conducted at 55 degrees C and initial pH of 8.0. The results indicate that hydrogen and methane production yields peaked at 4.3 mmol H2/g cellulose and 11.6 mmol CH4/g cellulose using the seed activated sludge that was thermally treated at 60 degrees C for 40 min. These parameter values are higher than those of no-treatment seed (HY 3.6 mmol H2/g cellulose and MY 10.4 mmol CH4/g cellulose). The maximum hydrogen production rate of 26.0 mmol H2/L/d and methane production rate of 23.2 mmol CH4/L/d were obtained for the seed activated sludge that was thermally treated at 70 degrees C for 50 min and 60 degrees C for 40 min, respectively.

  4. Response of biodegradation characteristics of unacclimated activated sludge to moderate pressure in a batch reactor.

    PubMed

    Xu, Rui-Xiao; Li, Bing; Zhang, Yong; Si, Ling; Zhang, Xian-Qiu; Xie, Biao

    2016-04-01

    This study was aimed to investigate the effect of moderate pressure on unacclimated activated sludge. Process of organic degradation, variation of carbon dioxide (CO2) concentration of off-gas and characteristics of extracellular polymeric substances (EPS) of activated sludge were analyzed using pressure-atmospheric comparative experiments in bench-scale batch reactors. It was found that moderate pressure increased the degradation rate more dramatically when the biological process ran under a higher organic load with much more oxygen demand, which illuminated that applications of the pressurized method to high concentration organic wastewaters would be more reasonable and practicable. High oxygen transfer impetus increased utilization of oxygen which not only promoted the biodegradation of organics in wastewater, but also led to more EPS consumption in activated sludge. CO2 concentration of off-gas was lower in the earlier stage due to CO2 being pressed into the liquid phase and converted into inorganic carbon (IC). More CO2 emission was observed during the pressurized aerobic process 160 min later. EPS in pressurized reactor was much lower, which may be an important way of sludge reduction by pressurized technology.

  5. Effect of microbial activity on trace element release from sewage sludge.

    PubMed

    Qureshi, Shabnam; Richards, Brian K; Hay, Anthony G; Tsai, Christine C; McBride, Murray B; Baveye, Philippe; Steenhuis, Tammo S

    2003-08-01

    The microbial role in mobilization of trace elements from land-applied wastewater sludge is not well-defined. Our study examined the leachability of trace elements (Cd, Cr, Cu, Mo, Ni, P, Pb, S, and Zn) from dewatered sludge as affected by treatments designed to alter microbial activity. Different levels of microbial activity were achieved by incubating sludge columns at 4, 16, 28, and 37 degrees C and by the addition of AgNO3 biocide at each temperature. Columns (with inert glass bead support beds) were subjected to six consecutive incubation-leaching cycles, each consisting of 7.3-d incubation followed by 16-h leaching with synthetic acid rain. Glucose mineralization tests were used to assess overall microbial activity. Significant acidification and trace element leaching occurred when conditions favored microbial activity (16 and 28 degrees C). Extent of mobilization was element-specific with Zn, Ni, and Cu showing the greatest mobilization (99, 67, and 57%, respectively). Mobilization was reduced but still substantial at 4 degrees C. Conditions that best inhibited microbial activity (37 degrees C or biocide at any temperature) resulted in the least mobilization. Characterization of enrichments performed using thiosulfate as the sole energy source revealed the presence of both known and putative S-oxidizing bacteria in the sludge. The results suggest that microbial acidification via S oxidation can mobilize trace elements from sludge. Elemental mobility in field situations would also be governed by other factors, including the capacity of soil to buffer acidification and to adsorb mobilized elements.

  6. Microbial enhanced separation of oil from a petroleum refinery sludge.

    PubMed

    Joseph, P J; Joseph, Ammini

    2009-01-15

    Petroleum refineries around the world have adopted different technological options to manage the solid wastes generated during the refining process and stocking of crude oil. These include physical, chemical and biological treatment methods. In this investigation bacterial mediated oil separation is effected. Two strains of Bacillus were isolated from petroleum-contaminated soils, and inoculated into slurry of sludge, and sludge-sand combinations. The bacteria could effect the separation of oil so as to form a floating scum within 48h with an efficiency of 97% at < or =5% level of sludge in the sludge-sand mixture. The activity was traced to the production of biosurfactants by bacteria.

  7. Biodrying of sewage sludge: kinetics of volatile solids degradation under different initial moisture contents and air-flow rates.

    PubMed

    Villegas, Manuel; Huiliñir, Cesar

    2014-12-01

    This study focuses on the kinetics of the biodegradation of volatile solids (VS) of sewage sludge for biodrying under different initial moisture contents (Mc) and air-flow rates (AFR). For the study, a 3(2) factorial design, whose factors were AFR (1, 2 or 3L/minkgTS) and initial Mc (59%, 68% and 78% w.b.), was used. Using seven kinetic models and a nonlinear regression method, kinetic parameters were estimated and the models were analyzed with two statistical indicators. Initial Mc of around 68% increases the temperature matrix and VS consumption, with higher moisture removal at lower initial Mc values. Lower AFRs gave higher matrix temperatures and VS consumption, while higher AFRs increased water removal. The kinetic models proposed successfully simulate VS biodegradation, with root mean square error (RMSE) between 0.007929 and 0.02744, and they can be used as a tool for satisfactory prediction of VS in biodrying.

  8. Effects of long term irrigation with polluted water and sludge amendment on some soil enzyme activities

    SciTech Connect

    Topac, F.O.; Baskaya, H.S.; Alkan, U.; Katkat, A.V.

    2008-01-15

    The objective of this study was to determine the effects of wastewater sludge-fly ash mixtures on urease, dehydrogenase, alkaline phosphatase and beta-glucosidase activities in soils. In order to evaluate the probable effects of previous soil management practices (irrigation with polluted water) on soil enzymes, two different soil samples which were similar in physical properties, but different in irrigation practice were used. The application of wastewater sludges supplemented with varying doses of fly ash increased potential enzyme activities for a short period of time (3 months) in comparison to unamended soils. However, the activity levels generally showed a decreasing trend with increasing ash ratios indicating the inhibitory effect of fly ash. The urease and dehydrogenase activities were particularly lower in soils irrigated from a polluted stream, indicating the negative effects of the previous soil management on soil microbial activity.

  9. Optimization of Ozonation Process for the Reduction of Excess Sludge Production from Activated Sludge Process of Sago Industry Wastewater Using Central Composite Design

    PubMed Central

    Subha, B.; Muthukumar, M.

    2012-01-01

    Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction. PMID:22593666

  10. Optimization of ozonation process for the reduction of excess sludge production from activated sludge process of sago industry wastewater using central composite design.

    PubMed

    Subha, B; Muthukumar, M

    2012-01-01

    Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R(2)) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction.

  11. pH-dependent biotransformation of ionizable organic micropollutants in activated sludge.

    PubMed

    Gulde, Rebekka; Helbling, Damian E; Scheidegger, Andreas; Fenner, Kathrin

    2014-12-01

    Removal of micropollutants (MPs) during activated sludge treatment can mainly be attributed to biotransformation and sorption to sludge flocs, whereby the latter process is known to be of minor importance for polar organic micropollutants. In this work, we investigated the influence of pH on the biotransformation of MPs with cationic-neutral speciation in an activated sludge microbial community. We performed batch biotransformation, sorption control, and abiotic control experiments for 15 MPs with cationic-neutral speciation, one control MP with neutral-anionic speciation, and two neutral MPs at pHs 6, 7, and 8. Biotransformation rate constants corrected for sorption and abiotic processes were estimated from measured concentration time series with Bayesian inference. We found that biotransformation is pH-dependent and correlates qualitatively with the neutral fraction of the ionizable MPs. However, a simple speciation model based on the assumption that only the neutral species is efficiently taken up and biotransformed by the cells tends to overpredict the effect of speciation. Therefore, additional mechanisms such as uptake of the ionic species and other more complex attenutation mechanisms are discussed. Finally, we observed that the sorption coefficients derived from our control experiments were small and showed no notable pH-dependence. From this we conclude that pH-dependent removal of polar, ionizable organic MPs in activated sludge systems is less likely an effect of pH-dependent sorption but rather of pH-dependent biotransformation. The latter has the potential to cause marked differences in the removal of polar, ionizable MPs at different operational pHs during activated sludge treatment. PMID:25337862

  12. 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.

  13. In situ adaptation of activated sludge by shock leading to enhance treatment of high ammonia content petrochemical waste water

    SciTech Connect

    Thiem, L.T.; Alkhatib, E.A.

    1988-07-01

    A modified activated sludge process that includes both carbonaceous and nitrogenous oxidation to reduce high levels of ammonia in petrochemical waste water was studied in a pilot plant design. Dissolved oxygen, pH, temperature, and sludge age were controlled and measured. Ammonia concentration in the petrochemical waste water used as the influent waste to the pilot plant was maintained up to 390 mg/L. Adaptation of the activated sludge biomass to the influent was accomplished with step-function shock loading. Subsequently, operation in the zero sludge wasting mode resulted in a low excess sludge production rate and the minimization of nitrifier washout and high percentage removals of ammonia, COD, BOD, and sulfide were measured.

  14. Carbon source recovery from waste activated sludge by alkaline hydrolysis and gamma-ray irradiation for biological denitrification.

    PubMed

    Kim, Tak-Hyun; Nam, Youn-Ku; Park, Chulhwan; Lee, Myunjoo

    2009-12-01

    The recovery of an organic carbon source from a waste activated sludge by using alkaline hydrolysis and radiation treatment was studied, and the feasibility of the solubilized sludge carbon source for a biological denitrification was also investigated. The effects of an alkaline treatment and gamma-ray irradiation on a biodegradability enhancement of the sludge were also studied. A modified continuous bioreactor for a denitrification (MLE reactor) was operated by using a synthetic wastewater for 47 days. Alkaline treatment of pH 10 and gamma-ray irradiation of 20 kGy were found to be the optimum carbon source recovery conditions. COD removal of 84% and T-N removal of 51% could be obtained by using the solubilized sludge carbon source through the MLE denitrification process. It can be concluded that the carbon source recovered from the waste activated sludge was successfully employed as an alternative carbon source for a biological denitrification.

  15. Plasmid metagenome reveals high levels of antibiotic resistance genes and mobile genetic elements in activated sludge.

    PubMed

    Zhang, Tong; Zhang, Xu-Xiang; Ye, Lin

    2011-01-01

    The overuse or misuse of antibiotics has accelerated antibiotic resistance, creating a major challenge for the public health in the world. Sewage treatment plants (STPs) are considered as important reservoirs for antibiotic resistance genes (ARGs) and activated sludge characterized with high microbial density and diversity facilitates ARG horizontal gene transfer (HGT) via mobile genetic elements (MGEs). However, little is known regarding the pool of ARGs and MGEs in sludge microbiome. In this study, the transposon aided capture (TRACA) system was employed to isolate novel plasmids from activated sludge of one STP in Hong Kong, China. We also used Illumina Hiseq 2000 high-throughput sequencing and metagenomics analysis to investigate the plasmid metagenome. Two novel plasmids were acquired from the sludge microbiome by using TRACA system and one novel plasmid was identified through metagenomics analysis. Our results revealed high levels of various ARGs as well as MGEs for HGT, including integrons, transposons and plasmids. The application of the TRACA system to isolate novel plasmids from the environmental metagenome, coupled with subsequent high-throughput sequencing and metagenomic analysis, highlighted the prevalence of ARGs and MGEs in microbial community of STPs.

  16. Biological treatment of synthetic wastewater containing 2,4 dichlorophenol (DCP) in an activated sludge unit.

    PubMed

    Kargi, Fikret; Eker, Serkan; Uygur, Ahmet

    2005-08-01

    Chlorophenol compounds present in many chemical industry wastewaters are resistant to biological degradation because of the toxic effects of such compounds on microorganisms. Synthetic wastewater containing different concentrations of 2,4 dichlorophenol (DCP) was subjected to biological treatment in an activated sludge unit. Effects of feed DCP concentration on COD, DCP, and toxicity removals and on sludge volume index were investigated at a constant sludge age of 10 days and hydraulic residence time (HRT) of 25 h. The Resazurin method based on dehydrogenase activity was used for assessment of toxicity for the feed and effluent wastewater. Percent COD, DCP, and toxicity removals decreased and the effluent COD, DCP, and toxicity levels increased with increasing feed DCP concentrations above 150 mgl(-1) because of inhibitory effects of DCP. Biomass concentration in the aeration tank decreased and the sludge volume index (SVI) increased with feed DCP concentrations above 150 mgl(-1) resulting in lower COD and DCP removal rates. The system should be operated at feed DCP concentrations of less than 150 mgl(-1) in order to obtain high COD, DCP, and toxicity removals.

  17. Life cycle assessment comparison of activated sludge, trickling filter, and high-rate anaerobic-aerobic digestion (HRAAD).

    PubMed

    Postacchini, Leonardo; Lamichhane, Krishna M; Furukawa, Dennis; Babcock, Roger W; Ciarapica, F E; Cooney, Michael J

    2016-01-01

    This paper conducts a comparative assessment of the environmental impacts of three methods of treating primary clarifier effluent in wastewater treatment plants (WWTPs) through life cycle assessment methodology. The three technologies, activated sludge (AS), high rate anaerobic-aerobic digestion (HRAAD), and trickling filter (TF), were assessed for treatment of wastewater possessing average values of biochemical oxygen demand and total suspended solids of 90 mg L(-1) and 70 mg L(-1), respectively. The operational requirements to process the municipal wastewater to effluent that meets USEPA regulations have been calculated. The data for the AS system were collected from the East Honolulu WWTP (Hawaii, USA) while data for the HRAAD system were collected from a demonstration-scale system at the same plant. The data for the TF system were estimated from published literature. Two different assessment methods have been used in this study: IMPACT 2002+ and TRACI 2. The results show that TF had the smallest environmental impacts and that AS had the largest, while HRAAD was in between the two but with much reduced impacts compared with AS. Additionally, the study shows that lower sludge production is the greatest advantage of HRAAD for reducing environmental impacts compared with AS. PMID:27191555

  18. Characterization of activated sludge exocellular polymers using several cation-associated extraction methods.

    PubMed

    Park, Chul; Novak, John T

    2007-04-01

    Evaluation of prior research and preliminary investigations in our laboratory led to the development of an extraction strategy that can be used to target different cations in activated sludge floc and extract their associated extracellular polymeric substances (EPS). The methods we us