The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste c...The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste collected in Shanghai, China, which was characterized by high food waste content. The NH + 4 removal efficiency in the system of SBR nitrifying reactor followed by fresh and matured landfilled waste layer in series was studied. In the nitrifying reactor, above 90% of NH + 4 in leachate was oxidized to NO - 2 and NO - 3. Then high concentrated NO - 2 and NO - 3 were removed in the way of denitrification process in fresh landfilled waste layer. At the same time, degradation of fresh landfilled waste was accelerated. Up to the day 120, 136.5 gC/(kg dry waste) and 17.9 gN/(kg dry waste) were converted from waste layer. It accounted for 50.15% and 86.89% of the total carbon and nitrogen content of preliminary fresh waste, which was 4.42 times and 5.17 times higher than that of reference column respectively. After filtering through matured landfilled waste, BOD 5 concentration in leachate dropped to below 100 mg/L, which would not affect following nitrification adversely. Because the matured landfilled waste acted as a well methanogenic reactor, 23% of carbon produced accumulatively from fresh landfilled waste degradation was converted into CH 4.展开更多
Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^...Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.展开更多
The removal of biological nutrient from mature landfill leachate with a high nitrogen load by an internal circulation upflow sludge blanket （ICUSB） reactor was studied. The reactor is a set of anaerobic-anoxic-aerob...The removal of biological nutrient from mature landfill leachate with a high nitrogen load by an internal circulation upflow sludge blanket （ICUSB） reactor was studied. The reactor is a set of anaerobic-anoxic-aerobic （A^2/O） bioreactors, developed on the basis of an expended granular sludge blanket （EGSB）, granular sequencing batch reactor （GSBR） and intermittent cycle extended aeration system （ICEAS）. Leachate was subjected to stripping by agitation process and poly ferric sulfate coagulation as a pretreatment process, in order to reduce both ammonia toxicity to microorganisms and the organic contents. The reactor was operated under three different operating systems, consisting of recycling sludge with air （A^2/O）, recycling sludge without air （low oxygen） and a combination of both （A^2/O and low oxygen）. The lowest effluent nutrient levels were realised by the combined system of A^2/O and low oxygen, which resulted in effluent of chemical oxygen demand （COD）, NH3-N and biological oxygen demand （BOD5） concentrations of 98.20, 13.50 and 22.50 mg/L. The optimal operating conditions for the efficient removal of biological nutrient using the ICUSB reactor were examined to evaluate the influence of the parameters on its performance. The results showed that average removal efflciencies of COD and NH3- N of 96.49% and 99.39%, respectively were achieved under the condition of a hydraulic retention time of 12 hr, including 4 hr of pumping air into the reactor, with dissolved oxygen at an rate of 4 mg/L and an upflow velocity 2 m/hr. These combined processes were successfully employed and effectively decreased pollutant loading.展开更多
Both “two-stage upflow anaerobic sludge blanket (UASB) +anoxic/oxic(A/O)” system and “one stage UASB+A/O” system were successively introduced to treat a leachate containing relatively low concentration of organics...Both “two-stage upflow anaerobic sludge blanket (UASB) +anoxic/oxic(A/O)” system and “one stage UASB+A/O” system were successively introduced to treat a leachate containing relatively low concentration of organics and high concentration of ammonia from a mature landfill site.The “two-stage UASB+A/O” system was used firstly.The denitrification of the return effluent was carried out in the first stage UASB (UASB1).The nitrification took place in the A/O reactor.The results showed that most biodegradable organic matter was removed in the UASB1,so “one stage UASB+A/O” system was used in the second phase experiment.The NH+4-N loading rate of A/O reactor and operation temperature were 0.28—0.60 kg NH+4-N·m-3·d-1 and 17—29℃,respectively.The COD removal efficiency and the final effluent COD were 50%—70%,1000—1500 mg·L-1,respectively.Short-cut nitrification with 90%—99% of nitrite accumulation efficiency took place in the system.The NH+4-N removal efficiency varied between 90% and 100%.When NH+4-N loading rate was less than 0.45 kg NH+4-N·m-3·d-1,the NH+4-N removal efficiency was more than 98%,and effluent NH+4-N was below 15 mg·L-1.When the ratio of the feed COD to feed NH+4-N concentrations was 2—3,the total inorganic nitrogen (TIN) removal efficiency was 70%—80%.The sludge samples from A/O reactor were analyzed by using fluoresence in situ hybridization (FISH).The FISH analysis showed that ammonia oxidation bacteria (AOB) were 4% of the eubacteria,meanwhile nitrite oxidation bacteria (NOB) were less than 0.2% of the eubacteria.展开更多
文摘The landfill of municipal solid waste(MSW) could be regarded as denitrification reactor and involved in ammonia nitrogen biological removal process. In this research, the process was applied to municipal solid waste collected in Shanghai, China, which was characterized by high food waste content. The NH + 4 removal efficiency in the system of SBR nitrifying reactor followed by fresh and matured landfilled waste layer in series was studied. In the nitrifying reactor, above 90% of NH + 4 in leachate was oxidized to NO - 2 and NO - 3. Then high concentrated NO - 2 and NO - 3 were removed in the way of denitrification process in fresh landfilled waste layer. At the same time, degradation of fresh landfilled waste was accelerated. Up to the day 120, 136.5 gC/(kg dry waste) and 17.9 gN/(kg dry waste) were converted from waste layer. It accounted for 50.15% and 86.89% of the total carbon and nitrogen content of preliminary fresh waste, which was 4.42 times and 5.17 times higher than that of reference column respectively. After filtering through matured landfilled waste, BOD 5 concentration in leachate dropped to below 100 mg/L, which would not affect following nitrification adversely. Because the matured landfilled waste acted as a well methanogenic reactor, 23% of carbon produced accumulatively from fresh landfilled waste degradation was converted into CH 4.
基金Project supported by the National Natural Science Foundation of China (No. 50238050)the Hi-Tech Research and Development Program (863) of China (No. 2002AA649250).
文摘Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the effluent.The impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.
基金supported by the Hubei Provincial Science and Technology Department(No.2006AA305A05)the China Scholarship Council (CSC)China University of Geosciences (CUG) for the financial support of this research
文摘The removal of biological nutrient from mature landfill leachate with a high nitrogen load by an internal circulation upflow sludge blanket （ICUSB） reactor was studied. The reactor is a set of anaerobic-anoxic-aerobic （A^2/O） bioreactors, developed on the basis of an expended granular sludge blanket （EGSB）, granular sequencing batch reactor （GSBR） and intermittent cycle extended aeration system （ICEAS）. Leachate was subjected to stripping by agitation process and poly ferric sulfate coagulation as a pretreatment process, in order to reduce both ammonia toxicity to microorganisms and the organic contents. The reactor was operated under three different operating systems, consisting of recycling sludge with air （A^2/O）, recycling sludge without air （low oxygen） and a combination of both （A^2/O and low oxygen）. The lowest effluent nutrient levels were realised by the combined system of A^2/O and low oxygen, which resulted in effluent of chemical oxygen demand （COD）, NH3-N and biological oxygen demand （BOD5） concentrations of 98.20, 13.50 and 22.50 mg/L. The optimal operating conditions for the efficient removal of biological nutrient using the ICUSB reactor were examined to evaluate the influence of the parameters on its performance. The results showed that average removal efflciencies of COD and NH3- N of 96.49% and 99.39%, respectively were achieved under the condition of a hydraulic retention time of 12 hr, including 4 hr of pumping air into the reactor, with dissolved oxygen at an rate of 4 mg/L and an upflow velocity 2 m/hr. These combined processes were successfully employed and effectively decreased pollutant loading.
文摘Both “two-stage upflow anaerobic sludge blanket (UASB) +anoxic/oxic(A/O)” system and “one stage UASB+A/O” system were successively introduced to treat a leachate containing relatively low concentration of organics and high concentration of ammonia from a mature landfill site.The “two-stage UASB+A/O” system was used firstly.The denitrification of the return effluent was carried out in the first stage UASB (UASB1).The nitrification took place in the A/O reactor.The results showed that most biodegradable organic matter was removed in the UASB1,so “one stage UASB+A/O” system was used in the second phase experiment.The NH+4-N loading rate of A/O reactor and operation temperature were 0.28—0.60 kg NH+4-N·m-3·d-1 and 17—29℃,respectively.The COD removal efficiency and the final effluent COD were 50%—70%,1000—1500 mg·L-1,respectively.Short-cut nitrification with 90%—99% of nitrite accumulation efficiency took place in the system.The NH+4-N removal efficiency varied between 90% and 100%.When NH+4-N loading rate was less than 0.45 kg NH+4-N·m-3·d-1,the NH+4-N removal efficiency was more than 98%,and effluent NH+4-N was below 15 mg·L-1.When the ratio of the feed COD to feed NH+4-N concentrations was 2—3,the total inorganic nitrogen (TIN) removal efficiency was 70%—80%.The sludge samples from A/O reactor were analyzed by using fluoresence in situ hybridization (FISH).The FISH analysis showed that ammonia oxidation bacteria (AOB) were 4% of the eubacteria,meanwhile nitrite oxidation bacteria (NOB) were less than 0.2% of the eubacteria.
