Bio-reduction of nitrate from groundwater using a hydrogen-based membrane biofilm reactor

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.

Simultaneous removal of COD and nitrogen using a novel carbon-membrane aerated biofilm reactor

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.

Fe(Ⅱ)EDTA络合吸收耦合H_(2)-MBfR处理NO效能

构建Fe(Ⅱ)EDTA络合吸收耦合H_(2)-MBfR一体化系统,驯化具有同步反硝化及铁还原能力的混合菌种,在维持反应体系稳定反硝化性能的基础上,探究进水Fe(Ⅱ)EDTA浓度、pH值对NO去除效率的影响,分析微生物群落结构.结果表明,Fe(Ⅱ)EDTA络合吸收耦合H_(2)-MBfR还原一体化系统对NO具有稳定去除效能,最大去除效率为99.50%.提高初始Fe(Ⅱ)EDTA浓度有助于Fe(Ⅱ)EDTA-NO的生成,且体系内的NO平均去除速率随着Fe(Ⅱ)EDTA浓度的提升而提升.在Fe(Ⅱ)EDTA浓度为10mmol/L时,NO最大去除速率达到44.68mg/(m3·h).pH值升高则不利于Fe(Ⅱ)EDTA-NO的生成,控制pH值为6更适合一体化系统运行.微生物群落结构分析发现一体化阶段优势菌门Proteobacteria、Bacteroidetes和Firmicutes,在该反应器中承担着重要的功能和作用,其丰度占比分别为50.35%,16.43%,14.98%.

膜曝气生物膜反应器处理航天生活废水效能研究

针对未来星球基地与长期地外飞行产生废水的处理需求,构建了膜曝气生物膜反应器(MABR),以探究该工艺对含尿液与卫生废水的模拟航天废水的处理效能。通过为期376 d的连续试验,开展了反应器启动和驯化,对含不同体积分数尿液的生活废水、飞行阶段废水的处理效能进行研究。结果表明,对尿液体积分数10%的生活废水,MABR稳定运行时可实现97%的总有机碳(TOC)去除率,以及83%的总氮(TN)去除率;对尿液体积分数40%的生活废水,可实现99%的TOC去除率,以及92%的总氮去除率;对飞行阶段废水,可实现98%的TOC去除率,以及65%的总氮去除率。从反应器的活性污泥中检测到丰富的反硝化细菌以及少量厌氧氨氧化菌。经历驯化后,MABR在286 d内对航天生活废水中碳、氮保持了较高的去除率,从而初步验证了该工艺应用于载人航天生活废水处理的可行性。

膜曝气生物膜厚度控制研究进展

生物膜厚度控制是膜曝气生物膜反应器(MABR)工艺运行管理的关键,存在获得最佳碳氮磷同步去除效能的最优生物膜厚度.本文回顾了近20年来有关MABR生物膜厚度控制技术(包括定期冲刷、连续水力剪切、真核生物捕食、群体感应淬灭)的研究发展历程,探讨展望未来的研发方向,以期为MABR工艺向水质提升与节能降碳高质量发展提供参考.

膜曝气生物膜反应器脱氮性能研究

膜曝气生物膜反应器(MABR)有效地将生物膜法技术和膜分离技术结合在一起,在污水脱氮方面潜力巨大。以MABR处理模拟生活污水和豆制品加工废水,着重考察了MABR的稳定性及脱氮性能。结果表明,在HRT=12 h、曝气压力=10 kPa和C/N=5时,MABR对模拟生活污水处理效果最佳,COD、氨氮、TN的平均去除率分别为92.0%、86.5%、83.3%。而在HRT=8 h和曝气压力=10 kPa时,MABR对豆制品加工废水处理效果最佳,COD、氨氮、TN的容积负荷分别为1320、125.5、184 g(/m^(3)·d),平均去除率分别可达到84.2%、81.5%、79.7%,优于传统生物膜法脱氮。

金属膜过滤工艺保障不同管材供水管网水质生物稳定性的研究

供水管网末梢水水质生物安全问题受到了广泛关注。采用生物膜环状反应器(BAR)模拟实际供水管网,探究了自来水和金属膜滤后水(膜滤水)对5种管材管壁生物膜影响的异同性。结果表明,金属膜过滤工艺对水中浑浊度、溶解性有机碳的平均去除率分别为93.4%、19.0%;5种管材管壁生物膜在生长稳定期的生物量排序为铜<不锈钢≈聚氯乙烯(PVC)≈高密度聚乙烯(HDPE)<球墨铸铁;自来水体系中反应器进出水平均浑浊度分别为1.52、3.44 NTU,而膜滤水体系反应器进出水平均浑浊度分别为0.10、0.42 NTU,且各管材管壁生物膜生长缓慢。这是因为膜滤水体系微生物群落物种丰富度较低,管壁生物膜样品的OTU数减少了39.7%~56.5%,耐氯致病菌(分枝杆菌、甲基杆菌等)相对丰度明显减少。因此,金属膜过滤工艺可有效保障供水管网饮用水水质生物稳定性。

膜曝气生物膜反应器处理合流制溢流污水的实验研究

以聚丙烯复合材料经熔融拉伸制成的帘式超薄微孔中空纤维膜为载体,构建膜曝气生物膜反应器装置处理合流制溢流污水,研究在不同水力停留时间、曝气压力、水流流速条件下,膜曝气生物膜反应器对水体中污染物COD、NH_(4)^(+)-N、TN的去除率。结果表明:膜曝气生物膜反应器对水体中各项污染物均有较好去除效果。水力停留时间为12 h时,COD、NH_(4)^(+)-N、TN去除效果较好,去除率分别为80.8%、82.4%、65.4%;水力停留时间为8 h时,TP去除效果达到34.2%,后期逐渐趋于平缓。溶解氧浓度随曝气压力增加而增加,曝气压力达到25 kPa之后COD、NH_(4)^(+)-N达到较佳的去除率,平均去除率分别为82.2%、84.1%;而TN去除的最佳曝气压力为15 kPa,去除率为70.0%。水流流速为0.03 m/s和0.05 m/s时,反应器整体运行效果较好,对COD、NH_(4)^(+)-N、TN的平均去除率分别为81.8%、83.5%、67.8%。

Simultaneous removal of selected oxidized contaminants in groundwater using a continuously stirred hydrogen-based membrane biofilm reactor

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.

Bioreduction of nitrate in groundwater using a pilot-scale hydrogen-based membrane biofilm reactor

A long-term pilot-scale H_(2)-based membrane biofilm reactor(MBfR)was tested for removal of nitrate from actual groundwater.A key feature of this secondgeneration pilot MBfR is that it employed lower cost polyester hollow fibers and still achieved high loading rate.The steady-state maximum nitrate surface loading at which the effluent nitrate and nitrite concentrations were below the Maximum Contaminant Level(MCL)was at least 5.9 g·N·(m^(2)·d)^(–1),which corresponds to a maximum volumetric loading of at least 7.7 kg·N·(m^(3)·d)^(–1).The steady-state maximum nitrate surface area loading was higher than the highest nitrate surface loading reported in the firstgeneration MBfRs using composite fibers(2.6 g·N·(m^(2)·d)^(–1)).This work also evaluated the H_(2)-utilization efficiency in MBfR.The measured H_(2)supply rate was only slightly higher than the stoichiometric H_(2)-utilization rate.Thus,H_(2)utilization was controlled by diffusion and was close to 100%efficiency,as long as biofilm accumulated on the polyester-fiber surface and the fibers had no leaks.

Nitrifying population dynamics in a redox stratified membrane biofilm reactor(RSMBR)for treating ammonium-rich wastewater

Nitrogen removal performance and nitrifyingpopulation dynamics were investigated in a redox stratifiedmembrane biofilm reactor(RSMBR)under oxygen limitedcondition to treat ammonium-rich wastewater.When theNH_(4)^(+)-N loading rate increased from 11.1±1.0 to 37:2±3:2 gNH_(4)^(+)-N·m^(-2)·d^(-1),the nitrogen removal inthe RSMBR system increased from 18.0±9.6 mgN·d^(-1)to 128.9±61.7 mgN·d^(-1).Shortcut nitrogen removal wasachieved with nitrite accumulation of about22:3±5:3 mgNO_(2)^(-)-N·L-1.Confocal micrographsshowed the stratified distributions of nitrifiers anddenitrifiers in the membrane aerated biofilms(MABs)atday 120,i.e.,ammonia and nitrite oxidizing bacteria(AOBand NOB)were dominant in the region adjacent to themembrane,while heterotrophic bacteria propagated at thetop of the biofilm.Real-time qPCR results showed that theabundance of amoA gene was two orders of magnitudehigher than the abundance of nxrA gene in the MABs.However,the nxrA gene was always detected during theoperation time,which indicates the difficulty of completewashout of NOB in MABs.The growth of heterotrophicbacteria compromised the dominance of nitrifiers inbiofilm communities,but it enhanced the denitrificationperformance of the RSMBR system.Applying a highammonia loading together with oxygen limitation wasfound to be an effective way to start nitrite accumulation inMABs,but other approaches were needed to sustain orimprove the extent of nitritation in nitrogen conversion inMABs.

Anaerobic-aerobic processes for the treatment of textile dyeing wastewater containing three commercial reactive azo dyes:Effect of number of stages and bioreactor type

In this study,the effect of number of stages and bioreactor type on the removal performance of a sequential anaerobic-aerobic process employing activated sludge for the treatment of a simulated textile dyeing wastewater containing three commercial reactive azo dyes was considered.Two stage processes performed better than one stage ones,both in terms of overall organic and color removal,as well as the higher contribution of anaerobic stage to the overall removal performance,thereby making them a more energy efficient option.The employment of a moving bed sequencing batch biofilm reactor,which uses both suspended and attached biomass,for the implementation of the anaerobic stage of the process,was compared with a sequencing batch reactor that only employs suspended biomass.The results showed that,although there was no meaningful difference in biomass concentration between the two bioreactors,the latter reactor had better performance in terms of chemical oxygen demand(COD)removal efficiency and rate and color removal rate.Further exploratory tests revealed a difference between the roles of suspended and attached bacterial populations,with the former yielding better color removal whilst the latter had better COD removal performance.The sequential anaerobic–aerobic process,employing an aerobic membrane bioreactor in the aerobic stage resulted in COD and color removal of 77.1±7.9%and 79.9±1.5%,respectively.The incomplete COD and color removal was attributed to the presence of soluble microbial products in the effluent and the autoxidation of dye reduction metabolites,respectively.Also,aerobic partial mineralization of the dye reduction metabolites,was experimentally observed.

膜曝气生物膜反应器膜传氧速率的影响因素研究

膜曝气生物膜反应器(MABR)膜的传氧性能对MABR工艺的设计具有重要意义,本文通过小试对MABR膜传氧速率的影响因素进行了研究.结果表明,在相同运行条件下MABR膜元件采用并联方式较串联方式更有利于提升MABR膜的传氧性能,平均膜传氧速率随着供气流量的提高先增大后趋于稳定,随着供气压力的升高略有增加,随着反应液温度升高变化不明显,随着测试液中溶解氧浓度的升高而降低;停止供气后,MABR仍具有一定的传氧能力.本研究采用膜组件并联方式连接,在供气压力2 kPa,供气气量100 mL/min条件下,平均膜传氧速率达到12.7 g O_(2)/(m^(2)·d).

膜曝气生物膜反应器处理生活污水的脱氮性能研究进展

膜曝气生物膜反应器(MABR)作为一项将膜技术与生物处理技术相结合的新型污水处理技术,与传统生物处理技术相比,凭借其极高的氧传输效率而大大降低电耗以及提高水处理效果,成为污水处理领域新的研究热点之一。由于MABR特殊的生物膜结构,使其传质性能优于传统生物膜,并且能够凭借同步硝化反硝化实现高效脱氮除碳的目的。膜组件作为MABR的核心单元,是气体依附膜孔向液相扩散的媒介,同时也是微生物生长的载体。具有特殊结构的膜材料能形成利于脱氮除碳的特殊生物膜结构,从而使MABR实现高效运行。分析了异向传质生物膜结构,论述了MABR运行的基本原理,总结了不同膜材料和运行参数对生活污水MABR脱氮运行性能的影响,并对MABR的研究趋势进行了展望。

高回流比对序批式生物膜反应器脱氮性能的影响

硝化液回流是污水生物脱氮工艺实现前置反硝化脱氮的重要手段,通常回流比为200%~400%。本文研究了高回流比对序批式生物膜反应器(SBBR)脱氮性能的影响,结果表明,在回流比为300%、1000%、3000%三种条件下回流比为3000%的总氮去除率最高,稳定运行期间TIN平均去除率为98.69%±0.81%,同时也使NH_(4)^(+)-N得以完全氧化。推测在高回流比引起的强对流环境下,生物膜内传质效率得以加强,从而提高了同步硝化反硝化(SND)效果。本研究结果对集成分散式污水处理装置的研发及改善市政污水处理生物脱氮效率具有重要意义。

膜曝气生物膜技术在污水处理中的研究及应用现状

膜曝气生物膜反应器(MABR)技术是一项热门的新型污水处理技术,由传统的生物膜水处理技术与气体分离膜技术结合而成。作者介绍了MABR技术的工作原理、影响因素、主要特点及应用现状,并进行了概括总结,列出了该技术的优势,同时也提出可改进的地方,希望能为今后MABR技术的研究提供参考。

基于MABR的压裂返排液处理及微生物群落研究

压裂返排液含有多种复杂有机物,毒性高、盐度高以及可生化性差。设计了1个三级MABR系统用于压裂返排液的处理,该系统在最适宜运行参数下表现出优异的除碳脱氮性能,出水经过芬顿试剂处理后满足污水综合排放二级标准。MABR系统对COD、NH^(+)_(4)-N和TN的去除率分别达到79.30%、96.06%和75.61%。微生物分析表明MABR生物膜富集了丰富的功能菌群,Proteobacteria(变形菌门)、Bacteroidetes(拟杆菌门)是生物膜中的优势菌群。阐明了MABR处理压裂返排液的技术可行性,为MABR在处理相关废水中的应用奠定了基础。

平板膜生物膜反应器降解DMS实验研究

挥发性有机硫化物(VOSCs)有着非常低的嗅阈值,且有较强的毒性及腐蚀性。分析了平板膜生物膜反应器(MBfR)降解二甲基硫(DMS),并考虑了甲醇对于反应器性能的影响。结果表明:在循环营养液没有添加甲醇的情况下,反应器的最大去除能力(EC_(v,max))仅为65 g/(m^(3)·h)(DE为25%),但依旧好于其他传统生物过滤器和生物滴滤器。此外,在循环营养液中适量地添加甲醇,可以有效地提升反应器的性能:当甲醇的浓度达到1000 mg/L时,反应器的EC_(v,max)提升至119 g/(m^(3)·h)(DE为43%);但进一步提升甲醇的浓度,反而抑制了反应器的性能。结果还表明:DMS/甲醇的最佳配比为1500 mg/Nm^(3)/1000 mg/L。因此,MBfR有着很好前景的技术,且在优化比率下可以用于处理复合污染物。

气态烷烃基质膜生物膜反应器去除地下水中氧化态污染物研究进展

随着社会不断发展,民众对饮用水质量的要求日益提高。地下水作为重要的饮用水来源,正面临严峻的氧化态污染物污染问题。近年来,一种以气态烷烃作为电子供体的膜生物膜反应器(Membrane Biofilm Reactor,MBfR)技术在处理地下水中氧化态污染物方面展现出良好的效果与优势。本文首先阐述了气态烷烃基质MBfR去除氧化态污染物的工作原理及其技术特点。其次,论述了气态烷烃基质MBfR还原硝酸盐、高氯酸盐等不同种类氧化态污染物的可行性与有效性。随后,列举了气态烷烃驱动氧化态污染物还原过程中烷烃氧化菌、污染物还原菌等核心功能菌及相关功能酶,并阐明了其中的微生物作用机制。最后,提出了该技术在应用推广方面所面临的挑战,并阐述了相应的解决思路。本文为地下水中氧化态污染物的绿色、低碳控制提供了新的思路,对天然气利用及地下水修复的新技术研发具有重要的理论指导意义。

应用于MBfR技术的DOPA/DETA共沉积表面改性复合膜性能研究

由于疏水性聚偏氟乙烯(PVDF)中空纤维膜应用于膜生物膜反应器(Membrane Biofilm Reactor,MBfR)存在泡点压力低、氧传质性能差、耐污染性差等问题以及单独多巴胺(DOPA)对膜表面改性存在反应时间长、稳定性差等问题,本研究采用多巴胺/二乙烯三胺(DOPA/DETA)共沉积体系对本实验室自制的疏水性PVDF中空纤维膜进行表面改性,获得PDA/DETA-coated PVDF复合膜。研究表明,PDA/DETA-coated PVDF复合膜水接触角由原膜的86.1°降至45.9°,复合膜表面亲水性大幅提升;泡点压力由8 kPa提升至70 kPa,传质推动力大幅提升;氧传质性能为原膜的1.61倍(KLa由0.89×10^(-2)min^(-1)提升至1.43×10^(-2)min^(-1))。通过FTIR,XPS,FESEM与AFM分析,表明PDA/DETA成功沉积到膜表面,改性层较为致密均匀。之后对复合膜物理/化学稳定性进行测试,复合膜具有良好的物理/化学稳定性。