复合式膜生物反应器去除城市污水中TN的研究

采用复合式膜生物反应器（HMBR）中试装置处理城市污水,考察了对TN的去除效果并探讨了脱氮机理。试验结果表明,HMBR能够显著提高脱氮效果,对TN的平均去除率为50．9％,比常规膜生物反应器（CMBR）提高了13．8％。由于生物膜对松散附着型胞外聚合物（LB-EPS）的吸附作用,HMBR中的LB—EPS与CMBR的相比明显降低。LB-EPS的降低使HMBR中絮体的粒径增加了近1倍,絮体密度明显增大,提高了同步硝化反硝化的效果。另外,一定厚度的生物膜同样可以进行同步硝化反硝化。与CMBR相比,HMBR中的活性污泥絮体和生物膜在提高脱氮效果上分别贡献了8％、5．8％。     

抽停比和膜组件放置方式对MBR膜污染的影响

采用PVC新型材料MBR反应器处理模拟生活污水,控制其MLSS在4 500~6 500mg/L之间,探讨了出水抽停比和膜组件的放置方式对膜污染的影响。结果表明,当以12 min为一周期时,其最佳抽停比为9 min/3 min,这一模式是该新型材料MBR反应器的经济出水模式;当进行在线清洗时,膜组件水平放置的MBR反应器的膜污染速率为2.26 kPa/d,膜组件竖直放置的MBR反应器的膜污染速率为1.28 kPa/d;进行在线水洗和0.02%的次氯酸钠清洗,可有效降低膜污染速率,延缓膜污染,降低运行成本。     

海绵填料对AAO—MBR处理效能及膜污染的影响

在相同的运行条件下,分别采用AAO—MBR与AAO—HMBR(投加海绵填料的复合式膜生物反应器)处理生活污水,考察投加海绵填料对AAO—MBR处理效能及膜污染的影响。结果表明,两种反应器对生活污水中的COD、氨氮、TN均有较好的去除效果,出水中除TP之外的其他指标浓度均能满足《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准。投加填料后,反应器对COD、氨氮、TN和TP的去除率分别由92.71%、95.08%、41.87%、64.13%提高至96.06%、98.34%、59.10%、72.20%;另外,膜污染状况也有所改善,当跨膜压差(TMP)达到26kPa时,HMBR运行了20 d,而MBR仅运行了13 d;在60 d的运行过程中,MBR中的膜组件进行了4次清洗,而HMBR中的膜组件仅清洗了2次。运行相同时间后,MBR的膜表面有清晰可见的污染物附着,而HMBR的膜表面仅有少量污染物附着;红外光谱分析表明,膜表面滤饼层污染物主要为蛋白质与多糖。     

CEPT-MBR处理污水效能与膜污染控制效果

对化学强化一级处理-膜生物反应器(CEPT-MBR)工艺处理污水的效能与膜污染情况进行了研究,并与单独MBR工艺进行比较。结果表明,CEPT-MBR工艺对污水中总磷、UV254、COD的去除效果优于MBR;两者对浊度、氨氮的去除效果相近且去除率均较高。考察两个系统的跨膜压差(TMP)变化后得出,CEPT-MBR工艺有效地减缓了膜污染,降低了TMP的上升速率,比MBR的膜清洗周期延长了21.7%。     

添加剂对减缓膜生物反应器中膜污染的作用研究

膜生物反应器(MBR)具有高效、出水水质好的特点,在生活污水和工业废水处理中得到应用,但膜污染是MBR广泛应用的主要障碍。通过向膜生物反应器中投加添加剂,人为改善反应器中活性污泥混合液的性质,从而减缓膜污染进程成为一种新兴的膜污染控制技术。总结近年来对添加剂减缓膜生物反应器中膜污染的效果和机制的研究,以期找到更有效、廉价的减缓膜污染添加剂。     

MBR处理印染废水的膜污染及清洗研究

膜生物反应器（MBR）是一种新型反应器，处理印染废水时除污效果很显著，但长时间的运行会造成膜的严重污染，为此对A／OMBR（厌氧—膜生物反应器）处理印染废水时的膜污染情况和清洗效果做了研究。结果表明，膜污染主要是由膜表面凝胶层造成的；化学清洗的效果优于物理清洗（化学清洗能恢复膜通量约90％以上，而物理清洗仅能恢复膜通量约70％）；NaOH的清洗效果优于NaOCl。     

不同填料对减缓A/O-HMBR系统膜污染的试验研究

为了考察投加悬浮填料与组合填料的2组缺氧/好氧-复合式膜生物反应器(A/O-HMBR)系统减缓膜污染情况,对2组反应器的跨膜压差(TMP)、膜面胞外聚合物(EPS)平均含量、填料表面EPS平均值以及各种膜阻力进行比较,结果表明投加组合填料相对投加悬浮填料更有利于降低A/O-HMBR系统膜污染速率。     

电絮凝强化膜生物反应器除磷研究

采用电絮凝/膜生物反应器(EC-MBR)工艺对模拟生活污水进行了强化除磷研究.结果表明,通过控制电流强度及通电时间,可使除磷率维持在95%以上,出水总磷<0.5 mg/L;同时,对COD和氨氮的去除率也分别在90%和95%左右.电絮凝的加入可以增加污泥活性,降低污泥粘度、平均粒径以及上清液中的有机物浓度,这在一定程度上延缓了膜污染,使反应器能够在较长时间内稳定运行.     

膜生物反应器膜污染及其防治技术

讨论了膜污染对膜生物反应器运行的影响,对膜污染现象、膜污染过程及其种类对膜生物反应器的冲击进行了综述。通过分析认为：膜污染的影响因素主要有膜的性质、活性污泥混合液和膜组件的运行条件等,其中后两者为主要因素。     

好氧MBR与序批式MBR处理生活污水的比较

比较了中试规模的好氧式膜生物反应器及序批式膜生物反应器处理生活污水的效果。结果表明，两者对COD及氨氮的去除效果相当，且都具有良好的抗冲击负荷能力；在总氮去除上，序批式膜生物反应器优于好氧式膜生物反应器；在稳定运行阶段，当好氧式膜生物反应器及序批式膜生物反应器处理同等水量时，过膜阻力增加率分别为1．68和1．03kPa／m。通过测定膜丝上多糖的含量分析了两者在膜污染速率上存在差异的原因，发现序批式膜生物反应器膜丝上的多糖含量要少于好氧式膜生物反应器。     

Reduced membrane fouling in a novel bio-entrapped membrane reactor for treatment of food and beverage processing wastewater

A novel Bio-Entrapped Membrane Reactor (BEMR) packed with bio-ball carriers was constructed and investigated for organics removal and membrane fouling by soluble microbial products (SMP). An objective was to evaluate the stability of the filtration process in membrane bioreactors through backwashing and chemical cleaning. The novel BEMR was compared to a conventional membrane bioreactor (CMBR) on performance, with both treating identical wastewater from a food and beverage processing plant. The new reactor has a longer sludge retention time (SRT) and lower mixed liquor suspended solids (MLSS) content than does the conventional. Three different hydraulic retention times (HRTs) of 6, 9, and 12 h were studied. The results show faster rise of the transmembrane pressure (TMP) with decreasing hydraulic retention time (HRT) in both reactors, where most significant membrane fouling was associated with high SMP (consisting of carbohydrate and protein) contents that were prevalent at the shortest HRT of 6 h. Membrane fouling was improved in the new reactor, which led to a longer membrane service period with the new reactor. Rapid membrane fouling was attributed to increased production of biomass and SMP, as in the conventional reactor. SMP of 10-100 kDa from both MBRs were predominant with more than 70% of the SMP <100 kDa. Protein was the major component of SMP rather than carbohydrate in both reactors. The new reactor sustained operation at constant permeate flux that required seven times less frequent chemical cleaning than did the conventional reactor. The new BEMR offers effective organics removal while reducing membrane fouling.     

A/HMBR组合工艺处理生活垃圾中转站废水

采用厌氧-复合式膜生物反应器（A／HMBR）组合工艺处理模拟生活垃圾中转站废水,考察了水力停留时间和回流比对COD、NH3-N、TN去除效果的影响。结果表明,在水力停留时间为42h、回流比为3时,系统对COD、NH3-N、TN的去除率最高,分别为95％、89％、78％。复合式膜生物反应器中膜污染的主要原因为溶解性有机物对膜孔的堵塞。     

Critical flux and chemical cleaning-in-place during the long-term operation of a pilot-scale submerged membrane bioreactor for municipal wastewater treatment

The critical flux and chemical cleaning-in-place (CIP) in a long-term operation of a pilot-scale submerged membrane bioreactor for municipal wastewater treatment were investigated. Steady filtration under high flux (30 L/(m² h)) was successfully achieved due to effective membrane fouling control by sub-critical flux operation and chemical CIP with sodium hypochlorite (NaClO) in both trans-membrane pressure (TMP) controlling mode (cleaning with high concentration NaClO of 2000-3000 mg/L in terms of effective chorine was performed when TMP rose to 15 kPa) and time controlling mode (cleanings were performed weekly and monthly respectively with low concentration NaClO (500-1000 mg/L) and high concentration NaClO (3000 mg/L)). Microscopic analysis on membrane fibers before and after high concentration NaClO was also conducted. Images of scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that NaClO CIP could effectively remove gel layer, the dominant fouling under sub-critical flux operation. Porosity measurements indicated that NaClO CIP could partially remove pore blockage fouling. The analyses from fourier transform infrared spectrometry (FTIR) with attenuated total reflectance accessory (ATR) and energy dispersive spectrometer (EDS) demonstrated that protein-like macromolecular organics and inorganics were the important components of the fouling layer. The analysis of effluent quality before and after NaClO CIP showed no obvious effect on effluent quality.     

Novel electrokinetic approach reduces membrane fouling

An innovative submerged membrane electro-bioreactor (SMEBR) was built to reduce membrane fouling through a combination of various electrokinetic processes. The objective of this research was to assess the capability of SMEBR to reduce fouling under different process conditions. At the bench scale level, using synthetic wastewater, membrane fouling of the SMEBR was compared to the fouling of a membrane bioreactor (MBR) in five runs. Different protein concentrations in the influent synthetic wastewater were selected to develop different membrane fouling potentials: high (240 mg/l), low (80 mg/l) and zero protein addition. The MBR and SMEBR were operated at a flux equal to the membrane critical flux in order to create high fouling rate conditions. Membrane fouling rate, expressed as the change in the trans-membrane pressure per day (kPa/d), decreased in the SMEBR 5.8 times (standard deviation (SD) = 2.4) for high protein wastewater, 5.1 times (SD = 2.4) for low protein content, and 1.3 times (SD = 0.7) for zero protein, when compared to the MBR. The supernatant concentrations of the soluble microbial products (SMP) were 195–210, 65–135 and less than 65 mg/l in respective experimental series. Following the bench scale study, membrane fouling was assessed in a pilot scale SMEBR, fed with raw un-clarified municipal wastewater, and operated under real-sewage variable quality conditions. The pilot SMEBR exhibited three times smaller membrane fouling rate than the MBR. It was concluded that electrokinetic processes generated by SMEBR led to a reduction of membrane fouling through: i) removal of soluble microbial products (mainly protein and polysaccharides) and colloidal organic materials; ii) change of the structure and morphology of the suspended solids due their conditioning by DC field.     

淹没式复合型MBR处理城市生活污水的效能研究

为了缓解缺水压力，在传统膜生物反应器（CMBR）的基础上开发出了一种新型城市污水处理回用工艺——淹没式复合型膜生物反应器（SHMBR），并考察了对城市生活污水的处理效果。试验结果表明，SHMBR可以在CMBR的基础上进一步提高生物量，并明显改善了对有机物和NH4^＋-N的去除效果。试验中对TN、TP的去除效果没有提高，原因可能是生物膜的厚度不够，没有在生物膜内部形成厌氧微环境。另外，SHMBR的除磷效果没有增强还可能与生物膜的SRT较长以及聚磷菌主要生活在活性污泥中有关。     

三种一体式MBR的膜污染趋势比较

对活性污泥—膜生物反应器、生物膜—膜生物反应器、复合式膜生物反应器的除污效果和膜污染趋势进行了研究。结果表明:活性污泥—膜生物反应器的膜污染程度最轻,膜通量下降速度最慢,膜污染也最容易消除;生物膜—膜生物反应器的膜污染程度最重,膜通量的下降速度最快;较大的曝气量可减轻膜的污染程度并减缓膜通量的下降速度。     

SMBR在次临界通量下的运行特性

利用“通量阶式递增法”测定了两种膜组件的临界通量,在此基础上考察了次临界通量下的运行特性。试验发现,次临界通量操作下的膜污染过程具有明显的两阶段特征,与第一阶段跨膜压差(TMP)平缓直线上升相对应的膜污染机制主要是膜孔堵塞和凝胶层污染,与第二阶段TMP剧烈直线上升相对应的膜污染机制则是颗粒沉积层污染;先清水冲洗再化学清洗的方式能有效恢复膜的过滤能力,其中清水冲洗能有效去除颗粒沉积层污染,而化学清洗则能有效去除膜孔堵塞和凝胶层污染。     

Membrane coagulation bioreactor (MCBR) for drinking water treatment

In this paper, a novel submerged ultrafiltration (UF) membrane coagulation bioreactor (MCBR) process was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5h. The MCBR performed well not only in the elimination of particulates and microorganisms, but also in almost complete nitrification and phosphate removal. As compared to membrane bioreactor (MBR), MCBR achieved much higher removal efficiencies of organic matter in terms of total organic carbon (TOC), permanganate index (COD(Mn)), dissolved organic carbon (DOC) and UV absorbance at 254nm (UV(254)), as well as corresponding trihalomethanes formation potential (THMFP) and haloacetic acids formation potential (HAAFP), due to polyaluminium chloride (PACl) coagulation in the bioreactor. However, the reduction of biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) by MCBR was only 8.2% and 10.1% higher than that by MBR, indicating that biodegradable organic matter (BOM) was mainly removed through biodegradation. On the other hand, the trans-membrane pressure (TMP) of MCBR developed much lower than that of MBR, which implies that coagulation in the bioreactor could mitigate membrane fouling. It was also identified that the removal of organic matter was accomplished through the combination of three unit effects: rejection by UF, biodegradation by microorganism and coagulation by PACl. During filtration operation, a fouling layer was formed on the membranes surface of both MCBR and MBR, which functioned as a second membrane for further separating organic matter.     

Tracing biofouling to the structure of the microbial community and its metabolic products: A study of the three-stage MBR process

The biofouling characteristics of a sequential anoxic/aerobic-membrane bioreactor (A/O MBR) were analyzed during the three-stage process (fast-slow-fast transmembrane pressure (TMP) increasing). The results indicated: during the stage 1 (before day 1), the microbial communities in the activated sludge (AS), cake sludge (CS) and biofilm (BF) were similar to each other, and the adsorption of microbes and the metabolic products was the main factor that led to TMP increase; during the stage 2 (between day 1 and day 7), the cake layer begun to form and the TMP continued to rise gradually at a reduced rate compared to stage 1, at this point a characteristic microbial community colonized the CS with microorganisms such as Saprospiraceae and Comamonadaceae thriving on the membrane surface (BF) probably due to greater nutrient availability, and the predominance of these species in the microbial population led to the accumulation of biofouling metabolic products in the CS, which resulted in membrane fouling and the associated rise in TMP; during the final stage (after day 7), the biofilm had matured, and the activity of anaerobes stimulated cake compaction. The statistical analysis showed a correlation between the TMP changing rate and the carbonhydrates of soluble microbial products (SMPc) content in the CS. When the SMPc concentration rose slowly there was a low level of biofouling. However, when the SMPc accumulating rate was greater, it resulted in the more severe biofouling associated with the TMP jump. Furthermore, the correlation coefficient for the TMP increase and protein concentrations of extracellular polymeric substances (EPSp) in the CS was highly significant. The cluster analysis suggested that the AS microbial community remained stable during the three TMP change stages, while the CS and BF community were changed accompanied with the TMP change. The interaction between the microbial communities and the metabolic products lead to the significant correlation between them. The EPSp in conjunction with the SMPc were the main factors that accelerate the membrane fouling. The rapid rise of SMPc triggered a sudden increase in the TMP, while the accumulation of EPSp caused the sustained rise in TMP.