A hydrogen-based membrane biofilm reactor (MBfR) using H2 as electron donor was investigated to remove nitrate from groundwater. When nitrate was first introduced to the MBfR, denitrification took place on the shell...A hydrogen-based membrane biofilm reactor (MBfR) using H2 as electron donor was investigated to remove nitrate from groundwater. When nitrate was first introduced to the MBfR, denitrification took place on the shell side of the membranes immediately, and the effluent concentration of nitrate continuously decreased with 100% removal rate on day 45 under the influent nitrate concentration of 5 mg NO3^--N/L, which described the acclimating and enriching process of autohydrogenotrophic denitrification bacteria. A series of short-term experiments were applied to investigate the effects of hydrogen pressures and nitrate loadings on deniWification. The results showed that nitrate reduction rate improved as H2 pressure increasing, and over 97% of total nitrogen removal rate was achieved when the nitrate loading increased from 0.17 to 0.34 g NO3^--N/(m^2.day) without nitrite accumulation. The maximum deniwification rate was 384 g N/(m^3.day). Partial sulfate reduction, which occurred in parallel to nitrate reduction, was inhibited by denitrififcation due to the competition for H2. This research showed that MBfR is effective for removing nitrate from the contaminated groundwater.展开更多
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
A laboratory trial was conducted for evaluating the capability of a continuously stirred hydrogen-based membrane biofllm reactor to simultaneously reduce nitrate (NO3--N), sulfate (SO42-), bromate (BrO3-), hexav...A laboratory trial was conducted for evaluating the capability of a continuously stirred hydrogen-based membrane biofllm reactor to simultaneously reduce nitrate (NO3--N), sulfate (SO42-), bromate (BrO3-), hexavalent chromium (Cr(VI)) and para- chloronitrobenzene (p-CNB). The reactor contained two bundles of hollow fiber membranes functioning as an autotrophic biofiim carder and hydrogen pipe as well. On the condition that hydrogen was supplied as electron donor and diffused into water through membrane pores, autohydrogenotrophic bacteria were capable of reducing contaminants to forms with lower toxicity. Reduction occurred within 1 day and removal fluxes for NO3--N, SO42-, BrO3-, Cr(VI), and p-CNB reached 0.641, 2.396, 0.008, 0.016 and 0.031 g/(day.m2), respectively after 112 days of continuous operation. Except for the fact that sulfate was 37% removed under high surface loading, the other four contaminants were reduced by over 95 %. The removal flux comparison between phases varying in surface loading and 1-12 pressure showed that decreasing surface loading or increasing 1-12 pressure would promote removal flux. Competition for electrons occurred among the five contaminants. Electron-equivalent flux analysis showed that the amount of utilized hydrogen was mainly controlled by NO3--N and SO42- reduction, which accounted for over 99% of the electron flux altogether. It also indicated the electron acceptor order, showing that nitrate was the most prior electron acceptor while sulfate was the second of the five contaminants.展开更多
基金supported by the National Natural Science Foundation of China (No.50978190)the National High Technology Research and Development Program (863) of China (No.2009AA062902)
文摘A hydrogen-based membrane biofilm reactor (MBfR) using H2 as electron donor was investigated to remove nitrate from groundwater. When nitrate was first introduced to the MBfR, denitrification took place on the shell side of the membranes immediately, and the effluent concentration of nitrate continuously decreased with 100% removal rate on day 45 under the influent nitrate concentration of 5 mg NO3^--N/L, which described the acclimating and enriching process of autohydrogenotrophic denitrification bacteria. A series of short-term experiments were applied to investigate the effects of hydrogen pressures and nitrate loadings on deniWification. The results showed that nitrate reduction rate improved as H2 pressure increasing, and over 97% of total nitrogen removal rate was achieved when the nitrate loading increased from 0.17 to 0.34 g NO3^--N/(m^2.day) without nitrite accumulation. The maximum deniwification rate was 384 g N/(m^3.day). Partial sulfate reduction, which occurred in parallel to nitrate reduction, was inhibited by denitrififcation due to the competition for H2. This research showed that MBfR is effective for removing nitrate from the contaminated groundwater.
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.
文摘针对膜生物膜反应器(MBf R)研究中疏水性微孔膜供氧能力不足、耐污染性较差等问题,采用自聚合法对自制疏水性聚偏氟乙烯(PVDF)中空纤维膜进行表面改性,研究制备适用于MBf R技术的PVDF/p DOPA中空纤维复合膜。选取典型有机污染物牛血清白蛋白(BSA),考察原膜及表面改性膜的抗污染性能,并采用XDLVO理论定量解析BSA对PVDF原膜及PVDF/p DOPA改性膜的污染行为。研究结果表明,改性膜对BSA的吸附速率低于原膜,最终BSA吸附量为原膜的62.1%,进一步的氧传质实验表明BSA污染后,改性膜的氧总转移系数衰减率(14.0%)低于原膜(21.9%),显示出优于原膜的抗污染性能。XDLVO理论所涉及到的三种界面自由能中,粘附阶段和粘聚阶段的极性力界面自由能均起主导作用,决定总界面自由能的性质,范德华力界面自由能和静电力界面自由能绝对值相对较小,对膜污染影响较为微弱;PVDF/p DOPA改性膜与BSA之间的总表面自由能(10.53 m J/m2)远大于PVDF原膜(-12.52 m J/m2),较好的解释了原膜与改性膜耐污染性能的差异。
基金supported by the National Natural Science Foundation of China (No.50978190)
文摘A laboratory trial was conducted for evaluating the capability of a continuously stirred hydrogen-based membrane biofllm reactor to simultaneously reduce nitrate (NO3--N), sulfate (SO42-), bromate (BrO3-), hexavalent chromium (Cr(VI)) and para- chloronitrobenzene (p-CNB). The reactor contained two bundles of hollow fiber membranes functioning as an autotrophic biofiim carder and hydrogen pipe as well. On the condition that hydrogen was supplied as electron donor and diffused into water through membrane pores, autohydrogenotrophic bacteria were capable of reducing contaminants to forms with lower toxicity. Reduction occurred within 1 day and removal fluxes for NO3--N, SO42-, BrO3-, Cr(VI), and p-CNB reached 0.641, 2.396, 0.008, 0.016 and 0.031 g/(day.m2), respectively after 112 days of continuous operation. Except for the fact that sulfate was 37% removed under high surface loading, the other four contaminants were reduced by over 95 %. The removal flux comparison between phases varying in surface loading and 1-12 pressure showed that decreasing surface loading or increasing 1-12 pressure would promote removal flux. Competition for electrons occurred among the five contaminants. Electron-equivalent flux analysis showed that the amount of utilized hydrogen was mainly controlled by NO3--N and SO42- reduction, which accounted for over 99% of the electron flux altogether. It also indicated the electron acceptor order, showing that nitrate was the most prior electron acceptor while sulfate was the second of the five contaminants.