Extraction and analysis of extracellular polymeric substances in membrane fouling in submerged MBR

The extraction and analysis of EPS in active biomass and membrane fouling were performed to investigate the influence of extracellular polymeric substances (EPS) on membrane fouling of MBR. The new membrane and fouling membrane surface morphology was characterized by EDX analysis. The results show that membrane contaminant is mainly composed of organic compounds. EPS in active biomass and membrane pollutant were extracted by method of alkaline regular centrifugation. Most of EPS were found to have high molecular weight over 12,000 D, which is very difficult to degrade. The total EPS contents in the extracted solution and the contents of polysaccharide protein and DNA in EPS were respectively analysed with TOC analysis and by phenol-sulfuric acid method, modification of the Bradford method and the fluorometric method. The analytical results indicate that the content of EPS in membrane fouling is about four times as much as that in active biomass, and polysaccharide is the most important pollutant on membrane, as well as protein’s role in membrane fouling is not negligible, whereas the DNA is not important in membrane fouling because of its content (non-dialysis) in membrane contaminant being less than that in the active biomass. In addition, the results in electrophoresis experiment provide the information about the concentrated distribution of molecular weight of large fragment DNA in both membrane contaminant and the biomass.     

Application of MBR for hospital wastewater treatment in China

In China, the number of hospitals has increased to 19,712 in 2008, with the production of hospital wastewater reaching 1.29 × 10⁶ m³/d. Membrane bioreactor (MBR) technology presents a more efficient system at removing pathological microorganism compared with existing wastewater treatment systems. In the past 8 yr, over 50 MBR plants have been successfully built for hospital wastewater treatments, with the capacity ranging from 20 to 2000 m³/d. MBR can effectively save disinfectant consumption (chlorine addition can decrease to 1.0 mg/L), shorten the reaction time (approximately 1.5 min, 2.5-5% of conventional wastewater treatment process), and attain a good effect of inactivation of microorganism. Higher disinfection efficacy is achieved in MBR effluents at lower dose of disinfectant with less disinfection by-products (DBPs). Moreover, when capacity of MBR plants increases from 20 to 1000 m³/d, their operating cost decreases sharply.     

New configuration of a membrane bioreactor for effective control of membrane fouling and nutrients removal in wastewater treatment

Excess aeration to membrane surface is common for controlling membrane fouling in a submerged membrane bioreactor (MBR) system, but significant energy is consumed for excess air production. Therefore, an alternative strategy for membrane fouling control is currently needed. A new configuration of MBR was proposed in this study to control membrane fouling effectively. To reduce biosolids concentration near the membrane surface, the position of the membrane module in MBR was elevated from the bottom to the top in the reactor. This could divide the reactor to two different zones: upper and lower zone. Air was not supplied at the lower zone whereas aeration was given to the upper zone where the membrane filtration was carried out. Biosolids concentration was reduced in the upper zone because the mixed liquor was settled down to the lower zone. Membrane fouling could be lessened in the upper zone due to the reduced biosolids concentration. Therefore, to verify if this new configuration of MBR could mitigate membrane fouling, the effect of changing vertical position of the membrane module in MBR on membrane fouling was investigated. Prior to verification the effect of elevation of membrane module on membrane fouling, influence of MLSS concentration on membrane fouling was investigated first. Transmembrane pressure (TMP) increase became steep as MLSS concentration increased. And the immersed membrane module was elevated from the bottom to the top of the MBR. When the upper membrane was located in the bioreactor, less membrane fouling was observed. This could demonstrate a possibility of new MBR design to control membrane fouling. In addition, reduced dissolved oxygen level in the returned sludge to anoxic tank could increase denitrification efficiency if this configuration is directly applied to biological nutrient removal processes.     

MBR工艺处理餐饮废水中DOM组分的特性

通过组分划分试验,对平板膜生物反应器中的溶解性有机物进行分离得到四种组分,并借助于分子量技术、荧光技术深入研究各组分对膜污染的影响。结果表明强疏水性（HPO）组分表现出最强的膜污染趋势,而弱疏水性（TPI）组分呈现出最高的可生物降解性,生物降解去除率可达91．8％。     

软硬性填料对MBR处理效率和膜污染的影响

膜生物反应器（MBR）在污水处理领域的应用日益广泛,填料的投加对MBR污水处理效率和膜污染进程有一定的影响。本文分别向MBR中投加不同量的软性和硬性悬浮填料,研究了悬浮填料对MBR运行效率及膜污染的影响。结果表明,投加填料后MBR对COD、氨氮和总磷等污染物的处理效率有所提高,明显减缓了膜污染的进程。软性填料对MBR的改善效果优于硬性填料,投加20%的软性填料时,系统对COD、氨氮和总磷的去除率分别可达96.53%、98.21%和52.75%,系统运行30天时的膜污染情况比未投加填料的系统减缓了41.43%。通过对比发现软性填料能够为微生物提供更大的生存空间,提高反应器内的微生物量,从而提高MBR对污水的处理效率同时改善膜污染,是一种加强MBR系统的适宜填料,最佳投加量为反应器有效体积的20%。     

同质增强型PMIA中空纤维膜污染及其MBR工艺处理城市生活污水

以碳酸钙悬浮液、活性污泥混合液及蛋白溶液作为过滤介质,采用标准堵塞过滤和沉积过滤数学模型预测3 h内膜污染类型,结合膜孔径分布、过滤介质粒径分布和污染阻力分布,研究同质增强型聚间苯二甲酰间苯二胺（PMIA）中空纤维超滤膜污染机理。将同质增强型PMIA中空纤维膜应用于MBR系统处理城市生活污水,监测其长期运行的出水水质;借助场发射扫描电镜和特征X射线能谱仪对比分析水洗和化学清洗效果。研究结果表明,当过滤介质为蛋白时,t-t/V线性相关系数为0.9940,膜污染符合标准堵塞模型;当过滤介质为碳酸钙悬浮液和污泥混合液时,V-t/V线性相关系数分别为0.9733、0.9994,二者较为符合沉积模型。应用于MBR中的同质增强型PMIA中空纤维膜对COD、NH₄⁺-N、TP的平均去除率分别为97.78%、96.71%、49.81%,出水水质较好。经化学清洗后膜表面元素接近于原膜,清洗效果较佳。     

MBR工艺在合成氨工业废水处理中的应用

膜生物反应器(MBR)是将污水的生物处理技术与膜分离技术相结合的高效废水生物处理工艺,可有效处理合成氨工业产生的高NH3-N含量的废水。MBR投运后,出水COD含量70 mg/L,NH3-N含量可稳定在25 mg/L,2套MBR系统的产水量均为150 m3/h,达到了设计要求。1年多的实际运行情况表明,该污水处理系统为企业的节能减排提供了可靠保障,但运行中也出现了一些问题,这些问题的有效解决对废水处理站的长期稳定运行至关重要。     

微生物代谢产物对膜生物反应器膜污染的影响

针对膜生物反应器（MBR）在运行过程中溶解性微生物代谢产物（SMP）及胞外聚合物（EPS）对膜污染进行研究。实验过程中对MBR内的污泥混合液进行了定期膜阻力监测。结果表明,SMP和EPS对膜过滤阻力有负面的影响。SMP中相对分子质量分布（Mw）在3～10 kDa对膜内部阻力影响显著,SMP中Mw＞10 kDa的大分子有机物及EPS浓度对膜外部阻力影响明显。通过傅里叶转换红外光谱（FTIR）检测膜表面污染物表明,EPS主要由多聚糖、蛋白质和腐殖酸组成,而污染层中的SMP主要是多聚糖和腐殖酸。     

膜生物反应器中的膜污染及其再生

作为21世纪最具潜力的水处理技术之一,膜生物反应器受到越来越多的重视,在污水处理与回用中有着良好的应用前景,但膜污染和膜再生技术已成为制约其发展的瓶颈.介绍了膜污染的分类和机理,并从膜的性质、混合液的性质以及操作条件等方面对形成膜污染的影响因素及膜污染的防治进行了综述,同时阐述了几种常用的膜污染再生方法.     

A novel approach to an advanced tertiary wastewater treatment: Combination of a membrane bioreactor and an oyster-zeolite column

A combination of a microfiltration-membrane bioreactor (MBR) and oyster-zeolite (OZ) packed-bed adsorption column was studied for the first time to evaluate the advanced tertiary treatment of nitrogen and phosphorous. The membrane module was submerged in the bioreactor and aeration was operated intermittently for an optimal wastewater treatment performance. Artificial wastewater with COD_cr of 220 mg/L, total nitrogen (T-N) of 45 mg/L, and total phosphorous (T-P) of 6 mg/L was used in submerged MBR with MLSS of 4,000–5,000 mg/L. The experiments were performed during a 100-day period with periodic membrane washing. The results showed that COD_cr could be effectively removed in the MBR alone with over 96% removal efficiency. However, T-N and T-P removal efficiency was slightly lower than expected with only the MBR. The permeate from MBR was then passed through the OZ column for tertiary nutrient removal. The final effluent analysis confirmed that nutrients can be additionally removed resulting in over 90% and 53% removal efficiencies for T-N and T-P, respectively. The results of this study suggest that the waste oyster shell can be effectively reclaimed as an adsorbent in advanced tertiary wastewater treatment processes in combination with a MBR.     

MBR和BAF用于城市污水深度处理的工艺特性比较

采用膜生物反应器(MBR)和曝气生物滤池(BAF)2种工艺分别对以生活污水为主的城市污水进行深度处理,以达到污水回用的目的.中试结果表明,在平均水温仅为5℃的情况下,MBR工艺的处理效果明显优于BAF,MBR_4~+工艺对COD、BOD＿5、NH_4~+-N和TP的去除率分别可以达到75%、92%、95%和90%,,而BAF对COD、BOD_5、NH_4~+_N和TP的去除率仅为70%、78%、29%和82%.经核算,MBR和BAF的污水处理运行费用分别为0.82元·m~(-3)和0.55元·m~(-3).与BAF相比,MBR具有处理效果优良、出水稳定、占地面积少,且维护管理方便等特点,因此,在以污水回用为目的的实际工程中推荐采用MBR工艺.     

超市废水的膜生物反应器中污泥特性之变化

在以处理超市废水实际工程的基础上,通过对污泥性质中的胞外聚合物（EPS）、溶解性微生物产物（SMP）、污泥粒径分布（PSD）变化的分析,得出污泥性质在接种膜生物反应器（MBR）后发生了明显的变化。对SMP的荧光分析发现,芳香族蛋白质类物质的量随着运行时间的增加有减小的趋势,而色氨酸类蛋白质类物质的量则相反。同时,发现EPS中荧光峰发生了显著的位移,说明了EPS性质发生了变化;通过对污泥的红外分析,发现污泥主要以糖类、蛋白质和脂肪族类物质为主,而随着时间的变化,污泥中的代表羟基基团的峰强度发生了明显的变化,说明污泥性质发生了变化;此外,通过PSD分析发现,污泥粒径中大粒径颗粒（大于100μm）是逐渐减小的,而小粒径颗粒（10μm）逐渐增多。     

膜生物反应器处理生活污水的实验研究和工程设计

通过浸没式膜生物反应器处理生活污水的实验研究,在给定气水比、停留时间、污泥负荷、污泥浓度、膜出水工作压力等设计参数的条件下得出膜生物反应器对有机物、氨氮的去除效果以及洗膜的方法。并以工程实例介绍膜生物反应器（MBR）处理生活污水的设计与计算方法。     

Physicochemical and Advanced Oxidation Processes – A Comparison of Elimination Results of Antibiotic Compounds Following an MBR Treatment

The occurrence of pharmaceuticals in the environment has become a subject of concern in recent years. A vast number of these compounds have been detected in sewage treatment plants (STP) effluents, surface waters and, less frequently, in ground and drinking water all over the world. Adverse effects caused by pharmaceuticals include aquatic toxicity, resistance development in pathogenic bacteria, genotoxicity and endocrine disruption. Nowadays, it is widely accepted that the main source of pharmaceutical pollution in the aquatic environment are STPs effluents. Therefore, the discharge of pharmaceutical residues with the effluents of STPs should be minimized as far as possible. Degradation of persistent organic pollutants such as pharmaceuticals in water and wastewater can be achieved using advanced treatment technologies such as membrane bioreactors (MBRs) in combination with advanced oxidation processes (AOPS). This paper evaluates the treatment of three antibiotics of large consumption rates worldwide (roxithromycin, sulfamethoxazole and trimethoprim) by MBR followed by different AOP-steps. The identification and quantification of the precursor compounds and degradation products observable during the different treatment steps applied were performed with liquid chromatography coupled with high resolution mass spectrometry (LC-MS)     

臭氧-活性炭技术对膜生物反应器膜污染减缓研究

本研究目的是探讨臭氧-活性炭技术对膜生物反应器（membrane bioreactor,MBR）膜污染减缓的影响。通过短期批式实验表明,粉末活性炭（power activated carbon,PAC）可强化臭氧的氧化效果,臭氧投加量超过0.25mg/(gSS)将恶化污泥混合液可滤性;对滤出液残余臭氧浓度检测表明,PAC的加入有利于维持本体溶液臭氧浓度。臭氧-活性炭技术引入MBR系统有助于膜污染的减缓,反应器内微生物活性受到一定的抑制作用,但对MBR出水水质影响较小;臭氧-活性炭减小了反应器内溶解性微生物产物（soluble microbial products,SMP）中的蛋白质及多聚糖含量,显著降低了污泥絮体中松散的胞外聚合物（loosely bound EPS,LB）及胞外聚合物（extracellular polymeric substances,EPS）中蛋白质浓度,以上结果表明应用臭氧-活性炭技术来延缓MBR膜污染是可行的。     

Dyeing and printing wastewater treatment using a membrane bioreactor with a gravity drain

A laboratory-scale membrane bioreactor (MBR) with a gravity drain was tested for dyeing and printing wastewater treatment from a wool mill. The MBR was operated with continuous permeate by gravity and without chemical cleaning for 135 days. Results showed that excellent effluent quality could meet the reuse water standard in China. The average concentrations of COD, BOD₅, turbidity and color in the effluent were 36.9 mg l⁻¹, 3.7 mg l⁻¹, 0.2 NTU and 21 dilution times (DT), respectively. The average removal rates of COD, BOD₅, turbidity and color were 80.3%, 95.0%, 99.3% and 58.7%, respectively. The membrane flux increased with increasing of aeration intensity, and its increasing rate was related to pressure-heads. The higher the pressure-head, the greater the impact of aeration intensity on membrane flux. Statistical analysis also showed that both the pressure-head and aeration intensity significantly affected membrane flux. Due to its compact design, simple operation and easy maintenance, MBR with a gravitational filtration system hs low energy consumption and is cost-effective to build and operate. If the life expectancy of the membrane is set for 3–4 years and the membrane flux is set at 15 l/m²·h, such a MBR would be very competitive.     

Application of A/O‐MBR for treatment of digestate from anaerobic digestion of cow manure

BACKGROUND: Anaerobic digestion (AD) is widely used as an animal manure bioconversion technology. However, the effluent obtained from the digester during the wet‐AD process requires to be treated carefully before discharge if AD technology is to be developed as an effective and environmentally advantageous animal manure treatment. RESULTS: An anoxic/aerobic‐membrane bioreactor(A/O‐MBR) system has been developed for digestate treatment in an AD system treating cow manure. The performance of the A/O‐MBR system in terms of removal of nitrogen, COD and phosphorus were investigated. Results indicated that the average removal efficiencies of NH₄‐N⁺, COD and PO₄^3?‐P were 98.1%, 96.3% and 76.6%, respectively. The fouled membrane from the A/O‐MBR system was cleaned effectively using NaOH and a 30h soak time. CONCLUSION: This study suggests that it is technically feasible to use the A/O‐MBR for the treatment of digestate from a cow manure AD system, and can provide an environmentally acceptable way for the application of wet‐AD in animal manure treatment. Copyright © 2010 Society of Chemical Industry     

MBR与CAS法处理市政污水的比较

比较了采用浸没式平片膜组件的膜生物反应器(MBR)与传统活性污泥工艺(CAS)处理市政污水时平均容积负荷率、平均污泥负荷率及各自出水BOD5/COD值;考察了MBR中水温及水力停留时间(HRT)对NH3-N去除效果的影响。MBR对有机物去除效果好于CAS,当MBR的HRT为3.2h,处理后出水COD去除率为93.07%,BOD5为99.08%,都好于CAS处理后的出水。水温由(8±4)℃升至(25±5)℃,MBR对NH3-N去除率由7.55%升至71.9%;提高MBR的HRT至6h,NH3-N去除率可达97.3%。     

MBR强化脱氮除磷工艺处理城市污水的中试

针对城市污水处理,提出了膜-生物反应器(MBR)强化脱氮除磷工艺,并开展了近3个月的中试。试验结果表明,COD、总氮、氨氮及总磷去除率分别达到86.5%、69.3%、98.0%及81.0%,平均出水COD、总氮、氨氮及总磷质量浓度分别为26、9.3、0.44、0.44 mg.L-1,达到国家一级A排放标准;内源反硝化、反硝化除磷及同步硝化反硝化现象的共同存在使工艺的脱氮除磷性能得到整体强化;蛋白质和多糖是膜污染的主要有机成分,采用次氯酸钠溶液定期清洗可维持MBR强化脱氮除磷工艺的稳定运行。     

Flat-plate submerged membrane bioreactor for the treatment of higher-load graywater

Graywater treatment has been the focus when topics of decentralized treatment systems are discussed. In this paper, the treatment of higher-load graywater, a mixture of washing machine and kitchen sink wastewater, was investigated. A 10 L lab-scale submerged membrane bioreactor (subMBR) was operated with a flat-plate membrane for 87 days. Permeate was intermittently withdrawn at constant transmembrane pressure (TMP) induced by water level difference and without pump requirement. The pollutants' removal and membrane behavior were monitored. The COD removal was around 96% and a permeate COD of about 26 mg L^− 1 was obtained. The total linear alkylbenzene sulfonate (LAS) removal achieved was > 99%, indicative of its non-inhibited degradation even at influent concentration of 30.8 mg L^− 1. The subMBR was operated at almost stable and constant flux of 0.22 m³ m^− 2 d^− 1 at a mean HRT of 13.6 h.