A membrane aerated biofilm reactor is a promising technology for wastewater treatment. In this study, a carbon-membrane aerated biofilm reactor （CMABR） has been developed, to remove carbon organics and nitrogen simu...A membrane aerated biofilm reactor is a promising technology for wastewater treatment. In this study, a carbon-membrane aerated biofilm reactor （CMABR） has been developed, to remove carbon organics and nitrogen simultaneously from one reactor. The results showed that CMABR has a high chemical oxygen demand （COD） and nitrogen removal efficiency, as it is operated with a hydraulic retention time （HRT） of 20 h, and it also showed a perfect performance, even if the HRT was shortened to 12 h. In this period, the removal efficiencies of COD, ammonia nitrogen （NH4^＋-N）, and total nitrogen （TN） reached 86%, 94%, and 84%, respectively. However, the removal efficiencies of NH4^＋-N and TN declined rapidly as the HRT was shortened to 8 h. This is because of the excessive growth of biomass on the nonwoven fiber and very high organic loading rate. The fluorescence in situ hybridization （FISH） analysis indicated that the ammonia oxidizing bacteria （AOB） were mainly distributed in the inner layer of the biofilm. The coexistence of AOB and eubacteria in one biofilm can enhance the simultaneous removal of COD and nitrogen.展开更多
The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membra...The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...展开更多
The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor(SMBR) is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applie...The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor(SMBR) is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules,improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held,and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased.This can improve scouring action of membrane surface on aeration and reduce energy consumption of strong aeration in SMBR.By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries,the relatively suitable incline angle θ under certain aeration place and in certain size rang of bubble can be obtained with the computer iterative calculation technology.Finally,for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR,some sugges-tions are offered:the interval distance of membrane modules is 8―15 mm,and aeration should be op-erated at 5―7 mm among membrane modules,and the optimal design angle of trapeziform membrane is 1.7°―2.5°.展开更多
A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants(POPs)in the Liao River.The model parameters,namely fugacity capacity,degradation rate,and transfe...A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants(POPs)in the Liao River.The model parameters,namely fugacity capacity,degradation rate,and transfer coefficient,are profoundly affected by tem-perature.This model is used to simulate the fate of γ-hexachlorocyclohexane(c-HCH)in the lower reaches of the Liao River from 1998 to 2008.Modeling results show that c-HCH fugacity capacities in air,water,and sediment increase as temperature decreases,and the transfer and transformation rate coefficients increase as temperature increases.The varia-tions of transfer and transformation parameter D values depend on fugacity capacities,and transfer and transformation coefficients simultaneously.The performance of the model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River.The predicted values agree well with the observed value in the order of magnitude,in most cases within the factor of 3.It is believed that the model is appropriate for simulating the long term fate of POPs in the Liao River.展开更多
The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and...The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and biodegradation of NH_(3)^(−)-N was analyzed in the reactor.Bacteria were isolated and determined from aerobic granules using selected media.The growth properties and morphology of bacteria colonies were observed by controlling aerobic or anaerobic conditions in the culture medium.It was found that bacteria in aerobic granules were diverse and some of them were facultative aerobes.The diversity of bacteria in aerobic granules was a premise of simultaneous nitrification and denitrification.展开更多
The paper discusses how to reach the equilibrium and optimization GI during the period of economic transformation. The market economy might not work because of its mechanism flaws, based on the assumption that the gov...The paper discusses how to reach the equilibrium and optimization GI during the period of economic transformation. The market economy might not work because of its mechanism flaws, based on the assumption that the government is the supplier and the market economy is the demander Of GI, there is an equilibrium and optimization issue. The theory suggests that GI could reach equilibrium through adjusting the government revenue, thus leads to the result of functional complement between the market economy and the GI, and the optimum economic efficiency.展开更多
基金This work was supported by the National Natural Science Foundation of China （No. 50578023）。
文摘A membrane aerated biofilm reactor is a promising technology for wastewater treatment. In this study, a carbon-membrane aerated biofilm reactor （CMABR） has been developed, to remove carbon organics and nitrogen simultaneously from one reactor. The results showed that CMABR has a high chemical oxygen demand （COD） and nitrogen removal efficiency, as it is operated with a hydraulic retention time （HRT） of 20 h, and it also showed a perfect performance, even if the HRT was shortened to 12 h. In this period, the removal efficiencies of COD, ammonia nitrogen （NH4^＋-N）, and total nitrogen （TN） reached 86%, 94%, and 84%, respectively. However, the removal efficiencies of NH4^＋-N and TN declined rapidly as the HRT was shortened to 8 h. This is because of the excessive growth of biomass on the nonwoven fiber and very high organic loading rate. The fluorescence in situ hybridization （FISH） analysis indicated that the ammonia oxidizing bacteria （AOB） were mainly distributed in the inner layer of the biofilm. The coexistence of AOB and eubacteria in one biofilm can enhance the simultaneous removal of COD and nitrogen.
文摘The effects of chemical oxygen demand and nitrogen(COD/N)ratio and dissolved oxygen concentration(DO)on simultaneous nitrification and denitrification(SND)were investigated using an airlift internal circulation membrane bioreactor(AIC-MBR)with synthetic wastewater.The results showed that the COD efficiencies were consistently greater than 90% regardless of changes in the COD/N ratio.At the COD/N ratio of 4.77 and 10.04,the system nitrogen removal efficiency became higher than 70%.However,the nitrogen remova...
文摘The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor(SMBR) is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules,improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held,and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased.This can improve scouring action of membrane surface on aeration and reduce energy consumption of strong aeration in SMBR.By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries,the relatively suitable incline angle θ under certain aeration place and in certain size rang of bubble can be obtained with the computer iterative calculation technology.Finally,for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR,some sugges-tions are offered:the interval distance of membrane modules is 8―15 mm,and aeration should be op-erated at 5―7 mm among membrane modules,and the optimal design angle of trapeziform membrane is 1.7°―2.5°.
基金This work was supported by the International Co-operation with Developing Countries of European Commission(INCO-DC Contract No.ERBIC 18CT970166).
文摘A QWASI model dependent on temperature is parameterized to describe the long-term fate of persistent organic pollutants(POPs)in the Liao River.The model parameters,namely fugacity capacity,degradation rate,and transfer coefficient,are profoundly affected by tem-perature.This model is used to simulate the fate of γ-hexachlorocyclohexane(c-HCH)in the lower reaches of the Liao River from 1998 to 2008.Modeling results show that c-HCH fugacity capacities in air,water,and sediment increase as temperature decreases,and the transfer and transformation rate coefficients increase as temperature increases.The varia-tions of transfer and transformation parameter D values depend on fugacity capacities,and transfer and transformation coefficients simultaneously.The performance of the model is evaluated by comparing the predicted and observed concentrations in the water and sediment of the Liao River.The predicted values agree well with the observed value in the order of magnitude,in most cases within the factor of 3.It is believed that the model is appropriate for simulating the long term fate of POPs in the Liao River.
基金This work was supported by the Foundation for Young Teachers of Dalian University of Technology(Grant No.2002120113)the Specialized Research Foundation for the Doctoral Program of Higher Education of the Ministry of Education of China(Grant No.20030141022).
文摘The purpose of this study was to investigate nitrifying bacteria and denitrifying bacteria isolated from aerobic granules.Aerobic granules were formed in an internal-circulate sequencing batch airlift reactor(SBAR)and biodegradation of NH_(3)^(−)-N was analyzed in the reactor.Bacteria were isolated and determined from aerobic granules using selected media.The growth properties and morphology of bacteria colonies were observed by controlling aerobic or anaerobic conditions in the culture medium.It was found that bacteria in aerobic granules were diverse and some of them were facultative aerobes.The diversity of bacteria in aerobic granules was a premise of simultaneous nitrification and denitrification.
文摘The paper discusses how to reach the equilibrium and optimization GI during the period of economic transformation. The market economy might not work because of its mechanism flaws, based on the assumption that the government is the supplier and the market economy is the demander Of GI, there is an equilibrium and optimization issue. The theory suggests that GI could reach equilibrium through adjusting the government revenue, thus leads to the result of functional complement between the market economy and the GI, and the optimum economic efficiency.
