A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing...A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.展开更多
To investigate feasibility of pathogen free industrial organics with higher agronomic value, the industrial organic wastes were subjected to vermistabilization. The body of earthworm work as ＂biofilter＂ and they can...To investigate feasibility of pathogen free industrial organics with higher agronomic value, the industrial organic wastes were subjected to vermistabilization. The body of earthworm work as ＂biofilter＂ and they can ＂purify＂ and also ＂disinfect＂ and ＂detoxify＂ municipal and industrial organics. The microbiomics of gut and cast of earthworm （Eisenia foetida Savigny） and their association with vermistabilization was studied to determine the microbial quantification in reactors （industrial organics）. Worm were reared in five reactors viz. Sewage sludge （SS）, Paper mill industry sludge （PS）, Vegetable processing industry （VP）, Tannery waste （TW） and Meat process industrial sludge （MP） for ninety days. The microbial load （Salmonella, Shigella, Escherichia, Mycobacterium, Streptococcus） in gut and cast, biomass, recovery of cast in different reactors were determined, periodically. The microbiomics of worms gut revealed the removal of Salmonella （12-18 × 10^8±0.02 to 0-4 × 10^3 ＋ 0.05 CFU/g）, Shigella （14-23 × 10^8 ± 0.04 to 0-4 × 10^3 ± 0.05 CFU/g）, Escherichia （4-16 × 10^8 ± 0.02 to 0-4 × 10^2 ± 0.05 CFU/g）, Mycobacterium （3-16 × 10^8 ± 0.02 to 0-3 × 10^2 ± 0.05 CFU/g）, Streptococcus （6-16 × 10^8 ± 0.02 to 0-4 × 10^3 ± 0.05 CFU/g） during stabilization of industrial organics. Similarly, reduction in pathogens Salmonella （12-19 × 10^8 ± 0.02 to 0-8 ×10^3 ± 0.05 CFU/g）, Shigella （7-20× 10^8 ± 0.04 to 0-2 ×10^3 ± 0.05 CFU/g）, Escherichia （2-20 × 10^8 ± 0.02 to 0.0-2 × 10^3 ± 0.05）, Mycobacterium （1-8 × 10^8 ±0.05 to 0.0-5 × 10^2 ± 0.05 CFU/g）, Streptococcus （8-18 × 10^8 ± 0.02 to 0-7 × 10^3 ± 0.05 CFU/g） in castings of industrial organics indicates the selective nature of feeding of worm. This amply demonstrates that these pathogens have been eliminated as they entered in food chain of worms. However, it may not be possible to remove pathogens completely, but at least worms change the ＂microbial make-up＂ of industrial organics to make it harmless to the soil and enable its use as a nutritive organic fertilizer.展开更多
Two lab-scale reactors, suspended-sludge and fluidized.bed, were conducted with the feed of ammonium-rich synthetic wastewater devoid of COD. Completely autotrophic nitrogen-removal process was fulfilled in both react...Two lab-scale reactors, suspended-sludge and fluidized.bed, were conducted with the feed of ammonium-rich synthetic wastewater devoid of COD. Completely autotrophic nitrogen-removal process was fulfilled in both reactors and the maximum efficiencies of nitrogen removal were achieved, 65% in the suspended-sludge reactor and 73% in the fluidized-bed reactor respectively. Different from the steady performance of the fluldized-bed reactor, the suspended-sludge reactor came to deteriorate constantly after a period of stable operation, resulting in almost complete loss of the N-removal ability in the suspending system. Molecular methods such as PCR and FISH were employed for describing the microbial characteristics in two systems. This study suggests that a biofllm system is a suitable configuration for completely autotrophic N-removal with more feasibility and stability than a suspending system.展开更多
Performance of biological phosphorus removal in the oxic-settling-anaerobic(OSA) process was investigated. Cell staining and fluorescent in situ hybridization(FISH) were used to analyze characteristics and microbial c...Performance of biological phosphorus removal in the oxic-settling-anaerobic(OSA) process was investigated. Cell staining and fluorescent in situ hybridization(FISH) were used to analyze characteristics and microbial community of sludge. Experimental results showed that phosphorus removal efficiency was near 60% and the amount of biological phosphorus accumulation in aerobic sludge of the OSA system was up to 26.9 mg/g. Biological phosphorus removal efficiency was partially inhibited by carbon sources in the continuous OSA system. Contrasted to the OSA system,biological phosphorus removal efficiency was enhanced by 14% and the average total phosphorus(TP) contents of aerobic sludge were increased by 0.36 mg/g when sufficient carbon sources were supplied in batch experiments. Staining methods indicated that about 35% of microorganisms had typical characteristics of phosphorus accumulating organisms(PAOs) . FISH analysis demonstrated that PAOMIX-binding bacteria were predominant microbial communities in the OSA system,which accounted for around 28% of total bacteria.展开更多
In this study,four sequencing batch reactors(SBR),with the sludge retention time(SRT)of 5,10,20 and 40 d,were used to treat domestic wastewater,and the effect of SRT on nitrite accumulation in the biological nitrogen ...In this study,four sequencing batch reactors(SBR),with the sludge retention time(SRT)of 5,10,20 and 40 d,were used to treat domestic wastewater,and the effect of SRT on nitrite accumulation in the biological nitrogen removal SBR was investigated.The real-time control strategy based on online parameters,such as pH,dissolved oxygen(DO)and oxidation reduction potential(ORP),was used to regulate the nitrite accumulation in SBR. The model-based simulation and experimental results showed that with the increase of SRT,longer time was needed to achieve high level of nitritation.In addition,the nitrite accumulation rate(NAR)was higher when the SRT was relatively shorter during a 112-day operation.When the SRT was 5 d,the system was unstable with the mixed liquor suspended solids(MLSS)decreased day after day.When the SRT was 40 d,the nitrification process was significantly inhibited.SRT of 10 to 20 d was more suitable in this study.The real-time control strategy combined with SRT control in SBR is an effective method for biological nitrogen removal via nitrite from wastewater.展开更多
The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite ...The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.展开更多
Sludge production is an avoidable problem arising from the treatment of wastewater. The sludge remained after municipal wastewater treatment contains considerable amounts of various contaminants and if is not properly...Sludge production is an avoidable problem arising from the treatment of wastewater. The sludge remained after municipal wastewater treatment contains considerable amounts of various contaminants and if is not properly handled and disposed, it may produce extensive health hazards. On the other hand, this sludge has benefit for plants and soils. Sludge samples were collected over a 12 month period from sewage treatment plants （STP＇s）, i.e, Khairathabad and Meeralam Tank, Hyderabad, India and analyzed for C, H, N, S by elementar analyzer, P, K, Ca, Mg by spectrophotometer and heavy metals like Zn, Pb, Ni, Cu, Cd by atomic absorption spectrophotometer. The sludge contained approximately 50% organic matter and 1-4% inorganic carbon. Organic and inorganic carbon, organic nitrogen, inorganic phosphorous, Ca and Mg were found to be present in sludge at a relatively constant concentration with respect to sampling time. Inorganic N, organic P, K, and all metals were found to be quite variable with time when sludge produced from different STP＇s.展开更多
基金Supported by the Major Science and Technology Program for Water Pollution Control and Treatment (2008ZX07316)
文摘A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.
文摘To investigate feasibility of pathogen free industrial organics with higher agronomic value, the industrial organic wastes were subjected to vermistabilization. The body of earthworm work as ＂biofilter＂ and they can ＂purify＂ and also ＂disinfect＂ and ＂detoxify＂ municipal and industrial organics. The microbiomics of gut and cast of earthworm （Eisenia foetida Savigny） and their association with vermistabilization was studied to determine the microbial quantification in reactors （industrial organics）. Worm were reared in five reactors viz. Sewage sludge （SS）, Paper mill industry sludge （PS）, Vegetable processing industry （VP）, Tannery waste （TW） and Meat process industrial sludge （MP） for ninety days. The microbial load （Salmonella, Shigella, Escherichia, Mycobacterium, Streptococcus） in gut and cast, biomass, recovery of cast in different reactors were determined, periodically. The microbiomics of worms gut revealed the removal of Salmonella （12-18 × 10^8±0.02 to 0-4 × 10^3 ＋ 0.05 CFU/g）, Shigella （14-23 × 10^8 ± 0.04 to 0-4 × 10^3 ± 0.05 CFU/g）, Escherichia （4-16 × 10^8 ± 0.02 to 0-4 × 10^2 ± 0.05 CFU/g）, Mycobacterium （3-16 × 10^8 ± 0.02 to 0-3 × 10^2 ± 0.05 CFU/g）, Streptococcus （6-16 × 10^8 ± 0.02 to 0-4 × 10^3 ± 0.05 CFU/g） during stabilization of industrial organics. Similarly, reduction in pathogens Salmonella （12-19 × 10^8 ± 0.02 to 0-8 ×10^3 ± 0.05 CFU/g）, Shigella （7-20× 10^8 ± 0.04 to 0-2 ×10^3 ± 0.05 CFU/g）, Escherichia （2-20 × 10^8 ± 0.02 to 0.0-2 × 10^3 ± 0.05）, Mycobacterium （1-8 × 10^8 ±0.05 to 0.0-5 × 10^2 ± 0.05 CFU/g）, Streptococcus （8-18 × 10^8 ± 0.02 to 0-7 × 10^3 ± 0.05 CFU/g） in castings of industrial organics indicates the selective nature of feeding of worm. This amply demonstrates that these pathogens have been eliminated as they entered in food chain of worms. However, it may not be possible to remove pathogens completely, but at least worms change the ＂microbial make-up＂ of industrial organics to make it harmless to the soil and enable its use as a nutritive organic fertilizer.
文摘Two lab-scale reactors, suspended-sludge and fluidized.bed, were conducted with the feed of ammonium-rich synthetic wastewater devoid of COD. Completely autotrophic nitrogen-removal process was fulfilled in both reactors and the maximum efficiencies of nitrogen removal were achieved, 65% in the suspended-sludge reactor and 73% in the fluidized-bed reactor respectively. Different from the steady performance of the fluldized-bed reactor, the suspended-sludge reactor came to deteriorate constantly after a period of stable operation, resulting in almost complete loss of the N-removal ability in the suspending system. Molecular methods such as PCR and FISH were employed for describing the microbial characteristics in two systems. This study suggests that a biofllm system is a suitable configuration for completely autotrophic N-removal with more feasibility and stability than a suspending system.
基金Project (No. 2006BAC19B04) supported by the National Key Technology R&D Program of China
文摘Performance of biological phosphorus removal in the oxic-settling-anaerobic(OSA) process was investigated. Cell staining and fluorescent in situ hybridization(FISH) were used to analyze characteristics and microbial community of sludge. Experimental results showed that phosphorus removal efficiency was near 60% and the amount of biological phosphorus accumulation in aerobic sludge of the OSA system was up to 26.9 mg/g. Biological phosphorus removal efficiency was partially inhibited by carbon sources in the continuous OSA system. Contrasted to the OSA system,biological phosphorus removal efficiency was enhanced by 14% and the average total phosphorus(TP) contents of aerobic sludge were increased by 0.36 mg/g when sufficient carbon sources were supplied in batch experiments. Staining methods indicated that about 35% of microorganisms had typical characteristics of phosphorus accumulating organisms(PAOs) . FISH analysis demonstrated that PAOMIX-binding bacteria were predominant microbial communities in the OSA system,which accounted for around 28% of total bacteria.
基金Supported by the National Key Technologies Research and Development Program of China during the Eleventh Five-year Plan Period(2006BAC19B03)the Project of Scientific Research Base and Scientific Innovation Platform of Beijing Municipal Education Commission(PXM2008_014204_050843the State Key Laboratory of Urban Water Resource and Environment(HIT)(QAK201006)
文摘In this study,four sequencing batch reactors(SBR),with the sludge retention time(SRT)of 5,10,20 and 40 d,were used to treat domestic wastewater,and the effect of SRT on nitrite accumulation in the biological nitrogen removal SBR was investigated.The real-time control strategy based on online parameters,such as pH,dissolved oxygen(DO)and oxidation reduction potential(ORP),was used to regulate the nitrite accumulation in SBR. The model-based simulation and experimental results showed that with the increase of SRT,longer time was needed to achieve high level of nitritation.In addition,the nitrite accumulation rate(NAR)was higher when the SRT was relatively shorter during a 112-day operation.When the SRT was 5 d,the system was unstable with the mixed liquor suspended solids(MLSS)decreased day after day.When the SRT was 40 d,the nitrification process was significantly inhibited.SRT of 10 to 20 d was more suitable in this study.The real-time control strategy combined with SRT control in SBR is an effective method for biological nitrogen removal via nitrite from wastewater.
基金Supported by the National Natural Science Foundation of China （50978003）, the Natural Science Foundation of Beijing （8091001）, the Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality （PHR 20090502）, and the State Key Laboratory of Urban Water Resource and Environment （HIT） （QAK200802）.
文摘The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.
文摘Sludge production is an avoidable problem arising from the treatment of wastewater. The sludge remained after municipal wastewater treatment contains considerable amounts of various contaminants and if is not properly handled and disposed, it may produce extensive health hazards. On the other hand, this sludge has benefit for plants and soils. Sludge samples were collected over a 12 month period from sewage treatment plants （STP＇s）, i.e, Khairathabad and Meeralam Tank, Hyderabad, India and analyzed for C, H, N, S by elementar analyzer, P, K, Ca, Mg by spectrophotometer and heavy metals like Zn, Pb, Ni, Cu, Cd by atomic absorption spectrophotometer. The sludge contained approximately 50% organic matter and 1-4% inorganic carbon. Organic and inorganic carbon, organic nitrogen, inorganic phosphorous, Ca and Mg were found to be present in sludge at a relatively constant concentration with respect to sampling time. Inorganic N, organic P, K, and all metals were found to be quite variable with time when sludge produced from different STP＇s.
