A two-phase anaerobic reactor fed with glucose substrate（3 g chemical oxygen demand（COD）/L） was used to investigate the effects of toxic metals on the degradation of organics and the soluble microbial product（SMP...A two-phase anaerobic reactor fed with glucose substrate（3 g chemical oxygen demand（COD）/L） was used to investigate the effects of toxic metals on the degradation of organics and the soluble microbial product（SMP） formation. Low concentrations of Ni（II）（5 and10 mg/L） promoted the acid phase, whereas high concentrations（15, 20, and 25 mg/L）exhibited an inhibitory effect on, but did not alter the fermentative method, which mainly involved the fermentation of propionic acid. The methanogenic microorganism exhibited a strong capability adapting constantly increased Ni（II） levels. The acid phase was an accumulation stage of SMP. In the absence of Ni（II）, the high-molecular-weight material in the effluent SMP mainly contained polysaccharide, tryptophan, and casein. Methanogens metabolized most of the polysaccharide, the whole tryptophan content, and part of the casein, leading to the presence of humic acid and protein in effluent. After Ni（II） dosage, the protein and polysaccharide of the acid phase increased, and tryptophan changed, while casein remained stable. More protein than polysaccharide was produced, suggesting the prominent function of protein when addressing the negative effect of toxic metals. The analysis of DNA confirmed the change of bacterial activity.展开更多
A two-stage UASB reactor was employed to remove sulfate from acrylic fiber manufacturing wastewater.Mesophilic operation（35±0.5℃） was performed with hydraulic retention time（HRT） varied between 28 and 40 hr....A two-stage UASB reactor was employed to remove sulfate from acrylic fiber manufacturing wastewater.Mesophilic operation（35±0.5℃） was performed with hydraulic retention time（HRT） varied between 28 and 40 hr.Mixed liquor suspended solids（MLSS） in the reactor was maintained about 8000 mg/L.The results indicated that sulfate removal was enhanced with increasing the ratio of COD/SO24-.At low COD/SO42-,the growth of the sulfate-reducing bacteria（SRB） was carbon-limited.The optimal sulfate removal efficiencies were 75% when the HRT was no less than 38 hr.Sulfidogenesis mainly happened in the sulfate-reducing stage,while methanogenesis in the methane-producing stage.Microbes in sulfate-reducing stage performed granulation better than that in methaneproducing stage.Higher extracellular polymeric substances（EPS） content in sulfate-reducing stage helped to adhere and connect the flocculent sludge particles together.SRB accounted for about 31% both in sulfate-reducing stage and methane-producing stage at COD/SO42-ratio of 0.5,while it dropped dramatically from 34% in sulfate-reducing stage to 10% in methane-producing stage corresponding to the COD/SO42-ratio of 4.7.SRB and MPA were predominant in sulfate-reducing stage and methane-producing stage respectively.展开更多
On the basis of continuous tests and batch tests, conversion regular patterns of acetate, propionate and butyrate in activated sludge at different heights of the UASB reactor were conducted. Results indicated that the...On the basis of continuous tests and batch tests, conversion regular patterns of acetate, propionate and butyrate in activated sludge at different heights of the UASB reactor were conducted. Results indicated that the conversion capacity of the microbe is decided by the substrate characteristic when sole VFA is used as the only substrate. But when mixed substrates are used,the conversion regulations would have changed accordingly. Relationships of different substrates vary according to their locations. In the whole reactor, propionate's conversion is restrained by acetate and butyrate of high concentration. On the top and at the bottom of the reactor, conversion of acetate, but butyrate, is restrained by propionate. And in the midst, acetate's conversion is accelerated by propionate while that of butyrate is restrained. It is proved, based on the analysis of specific conversion rate, that the space distribution of the microbe is the main factor that affects substrates' conversion. The ethanol type fermentation of the acidogenic phase is the optimal acid type fermentation for the two phase anaerobic process.展开更多
A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and...A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.展开更多
The UASB reactor was used to reconstruct leachate treatment project of Beijing Asuwei Waste Sanitary Landfill Site,and the commissioning with the UASB reactor was executed.Water quality indicators were determined in t...The UASB reactor was used to reconstruct leachate treatment project of Beijing Asuwei Waste Sanitary Landfill Site,and the commissioning with the UASB reactor was executed.Water quality indicators were determined in the debugging process,and the results showed that the VFA content in the anaerobic tank was controlled within 600 mg/L,which indicated that the water quality did not have the acidified phenomenon.The COD removal efficiency was 50%approximately and NH_3-N concentration showed as light decline when operation stability in anaerobic system.展开更多
Three UASB reactors were operated to investigate the population dynamics of anaerobic sludge granulation. It is found that the increase of bacterial population relates to the bacterial status in anaerobic food chain a...Three UASB reactors were operated to investigate the population dynamics of anaerobic sludge granulation. It is found that the increase of bacterial population relates to the bacterial status in anaerobic food chain and relates to sludge organic loading rates. In order to form granular sludge, it is necessary to have sufficient amount of different groups of bacteria in the sludge. In our experiment, the population of fermentative bacteria, propionate degraders, butyrate degraders and methanogens is about 107-8, 105-7, 105-7 and 105-7 cells/ml respectively at the appearance of granular sludge. Filamentous methanogenic bacteria are found to be the important species in sludge granulation. Based on the results obtained, a descriptive model is proposed to describe the microbial characteristics of granulation.展开更多
This paper concerns with the treatment of bagasse wash water, which is generated after washing the stored bagasse before its use in the paper manufacture. The bagasse wash water, treated earlier in open lagoons, is no...This paper concerns with the treatment of bagasse wash water, which is generated after washing the stored bagasse before its use in the paper manufacture. The bagasse wash water, treated earlier in open lagoons, is now treated by the anaerobic process using UASB reactor. This study, based upon an operating unit, shows that the UASB reactor reduces COD of wash water by 85% - 90%, and results in significant emission reductions. Economic analysis carried out by using financial indicators such as DSCR, Payback period and IRR reveals very attractive rate of returns and thus, greatly reduces the risks in financing such projects by the financial institutions.展开更多
The two-stage and two-phase anaerobic process (TSTP) composed of hydrolytic acidification reactor,first-order and second-order external circulation anaerobic reactors (EC) was taken to treat methanol wastewater. Test ...The two-stage and two-phase anaerobic process (TSTP) composed of hydrolytic acidification reactor,first-order and second-order external circulation anaerobic reactors (EC) was taken to treat methanol wastewater. Test results show that TSTP process is quick start-up in 51 d, and the maximum VFA of hydrolytic acidification reactor effluent reaches 876 mg/L. Under the condition of volume loading of 6.56 kgCOD/m3·d, COD removal rate of the first-order EC reactor is about 85%, and under the condition of volume loading of 1.02 kgCOD/m3·d, COD removal rate of the second-order EC reactor is about 50%. When the inflow COD of TSTP process is between 7000-11000 mg/L, its effluent COD is lower than 600 mg/L. In the biological conversion process of methanol into methane,the production of acetic acids as an intermediate product can be ignored and the direct production of methane from methanol is predominant.展开更多
Vinasse poses considerable environmental problems due to its complex composition of organic matter,minerals,and toxic compounds.If discharged into the environment without treatment,it can cause adverse impacts on ecos...Vinasse poses considerable environmental problems due to its complex composition of organic matter,minerals,and toxic compounds.If discharged into the environment without treatment,it can cause adverse impacts on ecosystems.This research investigated the effectiveness of an integrated treatment system involving an upflow anaerobic sludge blanket(UASB)reactor and the modified Bardenpho process(MBP)for purifying synthetic vinasse.The study lasted for 167 days,during which the integrated UASB-MBP system processed untreated synthetic vinasse with organic loading rates(OLR)ranging from 1.6 to 12.5 kgCOD/m3 day.The UASB-MBP system impressively achieved a COD removal efficiency of 99.41%.Removal efficiencies of approximately 98.14,99.91,and 99.63%were also achieved for total nitrogen(TN),total phosphorus(TP)and total ammonium(NH4+-N),respectively.The final discharge was 51.06 mg/L.The concentrations of NH4+-N and TN in the outflow of the settlement tank were 0.8-1.2 mg/L and 5.1-7.9 mg/L,respectively.Optimal performance was achieved when the HRT and nitrate recycle ratio were 15.5 h and 200%,respectively.The temperature was kept in the mesophilic range(33-35°C)during the experiments.These results underscores the potential of the integrated UASB reactor and modified Bardenpho process to provide an effective and eco-friendly approach for concurrent removal of COD and nutrients from vinasse treatment,offering broad prospects for implementation in wastewater treatment.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51178215 and 51378251)the Jiangsu Nature Science Fund (No. BK2011032)+2 种基金Open Science Foundation of Jiangsu (No. 50808121)the National Science and Technology Major Project for Water Pollution Control and Treatment (No. 2012ZX07301-005)the 2012 Scientific Research Open Found of Jiangsu Key Laboratory of Environmental Engineering
文摘A two-phase anaerobic reactor fed with glucose substrate（3 g chemical oxygen demand（COD）/L） was used to investigate the effects of toxic metals on the degradation of organics and the soluble microbial product（SMP） formation. Low concentrations of Ni（II）（5 and10 mg/L） promoted the acid phase, whereas high concentrations（15, 20, and 25 mg/L）exhibited an inhibitory effect on, but did not alter the fermentative method, which mainly involved the fermentation of propionic acid. The methanogenic microorganism exhibited a strong capability adapting constantly increased Ni（II） levels. The acid phase was an accumulation stage of SMP. In the absence of Ni（II）, the high-molecular-weight material in the effluent SMP mainly contained polysaccharide, tryptophan, and casein. Methanogens metabolized most of the polysaccharide, the whole tryptophan content, and part of the casein, leading to the presence of humic acid and protein in effluent. After Ni（II） dosage, the protein and polysaccharide of the acid phase increased, and tryptophan changed, while casein remained stable. More protein than polysaccharide was produced, suggesting the prominent function of protein when addressing the negative effect of toxic metals. The analysis of DNA confirmed the change of bacterial activity.
基金supported by the National Science and Technology Major Project (No. 2009ZX07529-004-2)the National High Technology Research and Development Program (863) of China (No. 2009AA063901)
文摘A two-stage UASB reactor was employed to remove sulfate from acrylic fiber manufacturing wastewater.Mesophilic operation（35±0.5℃） was performed with hydraulic retention time（HRT） varied between 28 and 40 hr.Mixed liquor suspended solids（MLSS） in the reactor was maintained about 8000 mg/L.The results indicated that sulfate removal was enhanced with increasing the ratio of COD/SO24-.At low COD/SO42-,the growth of the sulfate-reducing bacteria（SRB） was carbon-limited.The optimal sulfate removal efficiencies were 75% when the HRT was no less than 38 hr.Sulfidogenesis mainly happened in the sulfate-reducing stage,while methanogenesis in the methane-producing stage.Microbes in sulfate-reducing stage performed granulation better than that in methaneproducing stage.Higher extracellular polymeric substances（EPS） content in sulfate-reducing stage helped to adhere and connect the flocculent sludge particles together.SRB accounted for about 31% both in sulfate-reducing stage and methane-producing stage at COD/SO42-ratio of 0.5,while it dropped dramatically from 34% in sulfate-reducing stage to 10% in methane-producing stage corresponding to the COD/SO42-ratio of 4.7.SRB and MPA were predominant in sulfate-reducing stage and methane-producing stage respectively.
文摘On the basis of continuous tests and batch tests, conversion regular patterns of acetate, propionate and butyrate in activated sludge at different heights of the UASB reactor were conducted. Results indicated that the conversion capacity of the microbe is decided by the substrate characteristic when sole VFA is used as the only substrate. But when mixed substrates are used,the conversion regulations would have changed accordingly. Relationships of different substrates vary according to their locations. In the whole reactor, propionate's conversion is restrained by acetate and butyrate of high concentration. On the top and at the bottom of the reactor, conversion of acetate, but butyrate, is restrained by propionate. And in the midst, acetate's conversion is accelerated by propionate while that of butyrate is restrained. It is proved, based on the analysis of specific conversion rate, that the space distribution of the microbe is the main factor that affects substrates' conversion. The ethanol type fermentation of the acidogenic phase is the optimal acid type fermentation for the two phase anaerobic process.
基金Project supported by the National Natural Science Foundation of China(No. 50278036)the Natural Science Foundation of Guangdong Province (No. 04105951)
文摘A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.
文摘The UASB reactor was used to reconstruct leachate treatment project of Beijing Asuwei Waste Sanitary Landfill Site,and the commissioning with the UASB reactor was executed.Water quality indicators were determined in the debugging process,and the results showed that the VFA content in the anaerobic tank was controlled within 600 mg/L,which indicated that the water quality did not have the acidified phenomenon.The COD removal efficiency was 50%approximately and NH_3-N concentration showed as light decline when operation stability in anaerobic system.
文摘Three UASB reactors were operated to investigate the population dynamics of anaerobic sludge granulation. It is found that the increase of bacterial population relates to the bacterial status in anaerobic food chain and relates to sludge organic loading rates. In order to form granular sludge, it is necessary to have sufficient amount of different groups of bacteria in the sludge. In our experiment, the population of fermentative bacteria, propionate degraders, butyrate degraders and methanogens is about 107-8, 105-7, 105-7 and 105-7 cells/ml respectively at the appearance of granular sludge. Filamentous methanogenic bacteria are found to be the important species in sludge granulation. Based on the results obtained, a descriptive model is proposed to describe the microbial characteristics of granulation.
文摘This paper concerns with the treatment of bagasse wash water, which is generated after washing the stored bagasse before its use in the paper manufacture. The bagasse wash water, treated earlier in open lagoons, is now treated by the anaerobic process using UASB reactor. This study, based upon an operating unit, shows that the UASB reactor reduces COD of wash water by 85% - 90%, and results in significant emission reductions. Economic analysis carried out by using financial indicators such as DSCR, Payback period and IRR reveals very attractive rate of returns and thus, greatly reduces the risks in financing such projects by the financial institutions.
基金Sponsored by the National Hi-Tech Research and Development Program of China (Grant No.2003AA601090)Projects of Development Plan of the State Key Fundamental Research of China (Grant No.2004CB4185)
文摘The two-stage and two-phase anaerobic process (TSTP) composed of hydrolytic acidification reactor,first-order and second-order external circulation anaerobic reactors (EC) was taken to treat methanol wastewater. Test results show that TSTP process is quick start-up in 51 d, and the maximum VFA of hydrolytic acidification reactor effluent reaches 876 mg/L. Under the condition of volume loading of 6.56 kgCOD/m3·d, COD removal rate of the first-order EC reactor is about 85%, and under the condition of volume loading of 1.02 kgCOD/m3·d, COD removal rate of the second-order EC reactor is about 50%. When the inflow COD of TSTP process is between 7000-11000 mg/L, its effluent COD is lower than 600 mg/L. In the biological conversion process of methanol into methane,the production of acetic acids as an intermediate product can be ignored and the direct production of methane from methanol is predominant.
文摘Vinasse poses considerable environmental problems due to its complex composition of organic matter,minerals,and toxic compounds.If discharged into the environment without treatment,it can cause adverse impacts on ecosystems.This research investigated the effectiveness of an integrated treatment system involving an upflow anaerobic sludge blanket(UASB)reactor and the modified Bardenpho process(MBP)for purifying synthetic vinasse.The study lasted for 167 days,during which the integrated UASB-MBP system processed untreated synthetic vinasse with organic loading rates(OLR)ranging from 1.6 to 12.5 kgCOD/m3 day.The UASB-MBP system impressively achieved a COD removal efficiency of 99.41%.Removal efficiencies of approximately 98.14,99.91,and 99.63%were also achieved for total nitrogen(TN),total phosphorus(TP)and total ammonium(NH4+-N),respectively.The final discharge was 51.06 mg/L.The concentrations of NH4+-N and TN in the outflow of the settlement tank were 0.8-1.2 mg/L and 5.1-7.9 mg/L,respectively.Optimal performance was achieved when the HRT and nitrate recycle ratio were 15.5 h and 200%,respectively.The temperature was kept in the mesophilic range(33-35°C)during the experiments.These results underscores the potential of the integrated UASB reactor and modified Bardenpho process to provide an effective and eco-friendly approach for concurrent removal of COD and nutrients from vinasse treatment,offering broad prospects for implementation in wastewater treatment.
