Characterization of the archaeal community fouling a membrane bioreactor

Biofilmformation, one of the primary causes of biofouling, results in reducedmembrane flux or increased transmembrane pressure and thus represents a major impediment to the wider implementation of membrane bioreactor (MBR) technologies for water purification. Most studies have focused on the role of bacteria in membrane fouling as they are the most dominant and best studied organisms present in the MBR. In contrast, there is limited information on the role of the archaeal community in biofilm formation in MBRs. This study investigated the composition of the archaeal community during the process of biofouling in an MBR. The archaeal community was observed to have lower richness and diversity in the biofilmthan the sludge during the establishment of biofilms at low transmembrane pressure (TMP). Clustering of the communities based on the Bray-Curtis similarity matrix indicated that a subset of the sludge archaeal community formed the initial biofilms. The archaeal community in the biofilm was mainly composed of Thermoprotei, Thermoplasmata, Thermococci, Methanopyri, Methanomicrobia and Halobacteria. Among them, the Thermoprotei and Thermoplasmata were present at higher relative proportions in the biofilms than they were in the sludge. Additionally, the Thermoprotei, Thermoplasmata and Thermococci were the dominant organisms detected in the initial biofilms at low TMP, while as the TMP increased, the Methanopyri, Methanomicrobia, Aciduliprofundum and Halobacteria were present at higher abundances in the biofilms at high TMP.     

重力出流式膜生物反应器的膜通量及膜污染控制研究

采用新型的重力出流式膜生物反应器(MBR)处理生活污水和垃圾渗滤液,考察了其在长期运行过程中膜通量的变化规律及其影响因素.结果表明,该MBR能够在较低液位水头(8.5～15.0 kPa)的作用下连续出水,并获得较高的膜通量.处理生活污水时,平均膜通量为11.2 L·(m²·h)^-1;处理垃圾渗滤液时,平均膜通量为6.4 L·(m²·h)^-1.研究发现,污泥浓度对膜通量影响大小与曝气强度有关.当曝气强度小于400 m³·(m²·h)^-1时,膜通量随着污泥浓度的升高显著下降;当曝气强度大于400 m³·(m²·h)^-1时,膜通量几乎不受污泥浓度和曝气强度的影响.对膜的化学清洗试验表明,NaOH+NaClO溶液清洗效果最佳,膜通量可恢复至初始通量的85%以上.进一步研究表明,混合液中高浓度的溶解性胞外聚合物是MBR处理垃圾渗滤液时膜通量较低的主要原因.     

Investigation of adsorption/desorption behavior of Cr(VI) at the presence of inorganic and organic substance in membrane capacitive deionization (MCDI)

The adsorption and desorption behavior of Cr(VI) in membrane capacitive deionization (MCDI) was investigated systematically in the presence of bovine serum albumin (BSA) and KCl with different concentrations, respectively. Results revealed that Cr(VI) absorption was enhanced and the adsorption amount for Cr(VI) increased from 155.7 to 190.8?mg/g when KCl concentration increased from 100 to 200?mg/L in the adsorption process, which was attributed to the stronger driving force. However, the adsorption amount sharply decreased to 90.2?mg/g when KCl concentration reached up to 1000?mg/L suggesting the negative effect for Cr(VI) removal that high KCl concentration had. As for the effect of BSA on ion adsorption, the amount for Cr (VI) significantly declined to 78.3?mg/g and pH was found to be an important factor contributing to this significant reduction. Then, the desorption performance was also conducted and it was obtained that the presence of KCl had negligible effect on Cr(VI) desorption, while promoted by the addition of BSA. The incomplete desorption was obtained and the residual chromium ions onto the electrode after desorption was detected via energy-dispersive X-ray spectroscopy (EDS). Based on above analysis, the enhanced removal mechanism for Cr(VI) in MCDI was found to be consisted of ion adsorption onto electrode surface, the redox reaction of Cr(VI) into Cr(III) and precipitation, which was demonstrated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM).     

固定化微生物技术在大气恶臭污染物处理中应用研究进展

恶臭污染物（Odor pollutants）是指一切刺激嗅觉器官引起人们不愉快感觉以及损害生活环境的恶臭气味物质的统称。文章首先简要地介绍了大气中恶臭污染物的来源、分类以及危害等,指出大气恶臭污染物的主要来源主要包括农牧业来源、工业生产过程来源和城市垃圾处理恶臭污染来源等;其次,文章对能够处理大气恶臭污染物的反应器类型及其应用现状进行了系统的总结,提出能够应用于大气恶臭污染物处理的固定化微生物技术主要包括生物过滤池、生物滴滤塔和生物膜反应器等;同时着重综述了处理大气中恶臭污染物的影响因素,如底物、微生物、填料、微生物固定化方法、pH值和温度等因素对大气中恶臭污染物净化效率的影响,并且对固定化微生物技术生物转化与生物降解恶臭污染物的微观机理进行了一定的归纳与总结;最后还对固定化微生物技术在处理恶臭污染物方面的应用和未来发展趋势进行了展望,指出如果要真正实现固定化微生物技术在大气恶臭污染物处理中的工业化应用,今后还需要加强以下几个方面的研究工作：优势微生物菌剂的培育、固定化载体的开发与改良、固定微生物反应器的构建与优化和固定化微生物技术与其它单元技术的联用等。     

在线超声作用下流化床膜生物反应器的膜污染机制

在流化床膜生物反应器中引用在线超声技术来控制膜污染,考察了在线超声对污泥混合液特性的影响,探讨了在线超声作用下的膜污染机制。结果表明：在线超声流化床膜生物反应器的跨膜压差（TMP）增长速度明显慢于普通流化床膜生物反应器,可延长膜清洗周期约51％。在线超声作用下,污泥平均粒径降低约70μm,污泥胞外聚合物（EPS）含量增加（14±5）mg／g,混合液溶解性微生物产物（SMP）有所降低;同时,在线超声使得污泥浓度和混合液粘度降低,从而改善了混合液的过滤性,有助于膜污染的控制。分析表明,在线超声能够减少膜表面不可逆污染的发生,膜的主要污染机制为泥饼层污染。     

膜-生物反应器中溶解性微生物产物的研究进展

本文就膜 -生物反应器中溶解性微生物产物的生成特性及其影响的研究进展进行了总结。在膜 -生物反应器中 ,膜的高效固液分离作用在提高系统容积负荷和出水水质的同时 ,也使生物反应器成为一个相对封闭的系统。以腐殖质、多糖、蛋白质等物质为主要成分的溶解性微生物产物是生物处理出水中溶解性TOC或COD的主要组成部分 ,主要产生于微生物的基质分解过程和内源呼吸过程 ,其高分子物质的含量较多且可生物降解性较差 ,因此 ,在膜 -生物反应器中会出现积累。溶解性微生物产物的过高积累不仅有可能降低膜过滤出水的水质稳定性 ,而且有可能影响污泥活性 ,并引起膜污染。进水浓度和污泥浓度是影响溶解性微生物产物产生量的重要因素。目前有关膜 -生物反应器中溶解性微生物产物的研究还很不完善 ,有很多问题需进一步研究     

曝气对管式MBR膜污染及临界通量影响

采用管式膜微滤高岭土悬浊液,考察了恒通量下曝气对膜污染的影响,并对不同膜面气体流速下跨膜压力和膜污染周期变化进行了研究,此外,采用阶梯通量法对临界通量进行了测定。结果表明,曝气可显著减缓膜污染,延长膜污染周期,同时提高膜的临界通量;随着膜面气体流速由0.067 m·s-1提升至0.251 m·s-1时,膜污染平均速率由0.366 kPa·h-1降低至0.104 kPa·h-1,膜污染周期由8 d延长至31 d,临界通量由8~10 L·（m2·h）-1提高至22~26 L·（m2·h）-1。此外,通过惯性模型分析发现,膜的临界通量与膜面混合流速呈良好的线性关系,R2=0.98;但随着膜面气体流速的增加,悬浊液中高岭土粒径逐渐变小,并且通过膜表面污染阻力构成分析发现,膜表面不可逆污染阻力由13.9%提高至31.6%,这不利于膜污染控制。     

焦化废水的一体化膜—序批式生物反应器处理

采用一体化膜-序批式生物反应器(SMSBR)处理焦化废水，初步研究表明在水力停留时间(HRT)为32.7h，泥龄(SRT)为600d，平均COD容积负荷为0.45kg/(m3·d)的条件下，生物反应器上清液的COD难以降至100mg/L以下(平均为111.4mg/L)，而通过膜的出水，COD可以稳定在100mg/L以下(平均为86.4mg/L)，膜所截留的COD在后续的反应中得到进一步降解而未产生显著积累；在保证温度和碱度的情况下，出水NH3-N浓度低于1mg/L；硝酸盐细菌比亚硝酸盐细菌对温度的冲击更敏感，从而引起出水NO2-N的积累；系统在好氧反应阶段同时存在硝化和反硝化作用；膜分离对污泥的浓缩过程并未使剩余难降解有机物的去除得到强化，而膜污染速率在这一过程中表现较快。     

处理垃圾渗滤液的反渗透膜污染研究

膜污染及其防治是影响膜系统运行效果的重要因素。本研究选取工程中运行一年多的处理垃圾渗滤液的碟管式反渗透膜,经研究判断,污染絮体的主要成分是有机物,并含有Al、Si等的胶体物质以及Fe和Ca的化合物。通过化学清洗来验证对污染层结构的判断,先碱洗后酸洗的清洗效果远远好于先酸洗后碱洗,有机物在污染层形成过程中起主要作用,减少渗滤液中的有机物质,将会大大减轻膜污染的发生。     

两室阳膜电解再生脱硫吸收液的影响因素研究

利用二室阳离子膜电解装置,以亚硫酸钠和亚硫酸氢钠溶液模拟钠碱烟气脱硫吸收富液,进行吸收液再生规律的研究。实验考察了流体流速和槽压对膜电解过程的影响,明确了其相关规律,确定了较佳操作参数。研究结果证明:增大槽压和流体流速有利于脱硫富液的电解再生,而且钠离子浓度越低电解再生越容易。同时,实验中注意到电解过程中溶液伴渗对电流效率和钠离子迁移率有较大的影响。