大蒜素包埋球对膜生物反应器混合液可滤性影响解析

将由大蒜素包埋在海藻酸钠中制成的大蒜素包埋球(AEBs)投加至膜生物反应器(MBR)中,以探讨大蒜素的群体猝灭(QQ)效应对MBR污泥混合液可滤性的影响。结果表明,QQ作用对污泥混合液性质影响显著,对MBR污染物去除影响较小;混合液中胞外聚合物(EPS)和溶解性微生物代谢产物(SMP)含量降低;通过对修正污染指数(MFI)检测表明,QQ可提高污泥混合液可滤性,该指标与胞外多糖浓度紧密相关。     

Fe3+对MBR减缓膜污染的研究进展

膜生物反应器(membrane bioreactor, MBR)作为一种高效的污水处理及回用工艺,比传统的活性污泥法具有更多优势。然而,膜污染问题是限制其广泛应用的关键性问题。众多研究者已证实Fe₃₊能有效的改善MBR中混合液的可滤性及减缓膜污染。本文简述了MBR污泥混合液中主要污染物—胞外聚合物(extracellular polymeric substances, EPSs),并总结Fe₃ 在去除混合液中污染物、减缓膜污染方面的效能及其对污泥混合液的影响。最后,对Fe₃ 在减缓MBR膜污染的未来研究方向进行展望。     

进水盐度对膜生物反应器运行效能的影响研究

进水盐度对膜生物反应器(MBR)的运行效能影响显著,尤其是进水含盐量为5 g/L时,明显恶化了污泥可滤性,膜污染速率加快;MBR混合液中溶解性微生物产物(SMP)和胞外聚合物(EPS)含量随钠离子浓度变化而变化,其中SMP中蛋白质含量与钠离子浓度密切相关;与紧密结合态EPS(TB)相比,钠离子含量对松散结合态EPS(LB)浓度的影响更大;不同盐度对COD及NH4+-N影响不明显,系统对COD及NH4+-N的去除效果稳定,分别保持在92%及94%以上,高盐度对MBR总磷去除率降低明显。     

铁系混凝剂的投加对膜生物反应器运行效能的影响

膜生物反应器(MBR)作为一种高效的污水处理及回用工艺,与传统活性污泥法相比具有众多优势。然而,膜污染问题限制了该工艺的进一步大规模应用。众多研究者已证实,投加铁系混凝剂能有效改善MBR中混合液的可滤性,从而减缓膜污染。本文首先介绍了胞外聚合物对膜污染的影响机制,然后总结了铁系混凝剂投加对MBR污染物去除、膜污染速率及Fe3+在污泥混合液中的分布的影响;最后,对铁系混凝剂在MBR中应用进行了展望。     

不同价态铁离子对膜生物反应器影响研究进展

膜生物反应器(Membrane bioreactor,MBR)作为一种新型的污水处理技术,近些年来备受关注。然而,膜污染问题成为了该工艺广泛应用的最大障碍。现已证明,向MBR中投加铁系混凝剂能够减缓膜污染。本文首先综述了不同价态铁离子对MBR污染物去除的影响,然后对铁离子在污泥混合液中分布及迁移转化进行了分析,接着阐明了铁离子对膜污染的影响,最后对该领域的研究进行了展望。     

NaClO原位清洗对膜生物反应器生物膜污染影响研究进展

膜生物反应器(MBR)的膜污染问题严重制约了该工艺进一步快速的商业化推广,全面认识NaClO原位氧化清洗对MBR生物膜污染的影响,对于开发新型膜清洗技术及MBR工程优化具有重要意义。本文针对目前NaClO原位氧化清洗的不足,从微生物胞外关键组分空间分布角度,综述了NaClO原位清洗对生物膜污染及生物絮凝的影响,并探讨了生物絮体重构机制及强化生物絮凝的相关措施。最后,本文从减缓膜污染的角度,对该领域未来的研究方向进行了论述。     

膜生物反应器中AHL分析技术研究进展

膜生物污染一直是膜生物反应器(membrane bioreactor,MBR)在废水处理工艺中需要解决的一大难题。最近研究表明：基于群体感应的淬灭技术可以作为MBR活性污泥体系中一种有效的膜生物污染防治策略。因而,识别和分析群体感应产生的信号分子是应用群体淬灭技术防治MBR中膜生物污染的关键。本文首先介绍了活性污泥体系中的群体感应机理和N-酰基高丝氨酸内脂(N-acyl homoserine lactone,AHL);其次,归纳近期研究中针对MBR中AHL定性和定量分析方法;最后,对MBR中AHL识别及分析技术应用进行了展望。     

基于XDLVO理论解析MBR膜污染研究进展

膜污染问题严重制约了膜生物反应器(MBR)的广泛应用,因此膜污染机制的研究对于有效控制膜污染十分重要。XDLVO理论合理地解析了范德华力、极性作用力、双电层作用力在膜污染过程中的贡献,有效地揭示了膜污染机理。本文首先阐述了XDLVO理论;然后运用XDLVO理论,解析界面微距离范围内膜表面凝胶层及泥饼层形成过程;最后总结了XDLVO理论在MBR膜污染方面的应用,并对该领域未来的研究方向进行了展望。     

MBR对污水中肠道模型病毒的去除效应

采用重力出流式膜生物反应器(MBR)对生活污水进行处理, 选择两种孔径的微滤膜考察其对污水中T4和f 2两种模型病毒的去除情况. 清水试验结果表明, 两种膜孔径组件对T4和 f 2病毒的实际截留率远大于理论截留率; 两种膜组件对T4病毒的截留均高于f 2病毒. 在MBR稳定运行状况下, 两种不同孔径的膜组件对同一病毒的截留效果无显著差别: 孔径为0.1 mm的聚丙烯(PP)和孔径为0.22 mm的聚偏氟乙烯(PVDF)对T4去除率均大于5.5 lg; 对f 2的去除率大于3.0 lg. 其原因是膜表面的滤饼层、凝胶层在病毒的截留中起了重要的作用. 膜生物反应器对病毒的去除由膜的截留、污泥絮体的吸附和生物灭活等作用共同完成. 进一步的研究发现: 活性污泥系统对病毒去除率稳定在97％以上, 主要依靠生物灭活作用完成对病毒的去除.     

污泥干燥预处理后与神府煤共成浆性的研究

以萘系阴离子表面活性剂为分散剂,考查了污泥干燥条件和粒径对神府煤成浆性的影响。结果表明,将污泥干燥后再制浆,明显提高了污泥煤浆的成浆浓度;升高干燥温度,有利于提高污泥煤浆的成浆浓度。干燥温度对污泥的可磨性影响较大。干燥温度越高,干燥污泥可磨性越好,球磨的污泥平均粒径越小,制得的污泥煤浆表观黏度越低;温度高于105℃,污泥的可磨性无明显差别,污泥煤浆的表观黏度亦无明显变化。污泥粒径越小,颗粒越细,一定程度上提高了煤粉的堆积效率,使污泥煤浆的表观黏度降低。     

The (in)significance of apparent viscosity in full-scale municipal membrane bioreactors

Ten pilot and full-scale municipal membrane bioreactor (MBR) plants throughout Europe were investigated during the period 2007–2008 using the Delft Filtration Characterisation method. Next to information on filterability the data also contain the necessary information to determine the apparent viscosity of activated sludge. The aim of this study was to quantify variations in the apparent viscosity of activated sludge in pilot and full-scale municipal MBR plants and correlate them with membrane performance. A statistical analysis was carried out in order to quantify the significance of the correlations between apparent viscosity and activated sludge characteristics. The main factor influencing activated sludge's apparent viscosity was found to be total suspended solids. Temperature was found not to have a direct impact on apparent viscosity within the range of temperatures of the pilot and full-scale municipal MBR plants studied (9.7–27.4°C). In terms of the reversible fouling potential and membrane performance, activated sludge filterability and MBR plant membrane permeability were not statistically affected by activated sludge's apparent viscosity variations. Therefore, even if apparent viscosity plays a major role in terms of oxygen transfer efficiency, it is not relevant when optimising membrane fouling control and membrane performance of current, full-scale municipal MBR applications.     

Visualisation and characterisation of biopolymer clusters in a submerged membrane bioreactor

A laboratory wastewater treatment membrane bioreactor (MBR) with a submerged hollow-fibre membrane was used to investigate the major foulants in sludge mixtures. Confocal laser scanning microscopy (CLSM) with a triple fluorescent staining protocol, i.e., SYTO9 for microbial cells, ConA-TRITC lectin for polysaccharides and NanoOrange for proteins, was utilised to visualise the fouling materials. A pool of biopolymer clusters (BPCs) ranging from 2.5 to 60 μm in size was identified in the liquid phase of the MBR sludge and in the cake sludge on the membrane surface. According to the CLSM examination, BPC are free and independent organic solutes that are different from biomass flocs and extracellular polymeric substances (EPS) and much larger than soluble microbial products (SMP). Compared to EPS, BPC contain more polysaccharides and proteins and less humic substances. It is believed that BPC are an important foulant that interacts with biomass flocs to form the sludge fouling layer on the membrane. A filtration test observed with the CLSM shows that BPC are apparently formed by the adsorption and affinity clustering of SMP within the sludge deposited on the membrane surface. The cake sludge on the fouled membrane has a much higher BPC content (16.8 mg TOC/g SS) than the MBR bulk sludge (0.4 mg TOC/g SS). It is argued that BPC behave as a glue to facilitate the growth of an impermeable sludge cake on the membrane surface, thus resulting in serious MBR fouling. These CLSM findings provide the first direct evidence of the presence of BPC in MBR and illustrate their essential role in membrane fouling.     

Mitigated membrane fouling in a vertical submerged membrane bioreactor (VSMBR)

In a laboratory-scale study, characteristics of membrane fouling in an A/O (anoxic/oxic) series membrane bioreactor (MBR) and in a vertical submerged membrane bioreactor (VSMBR) treating synthetic wastewater were compared under the same operating conditions. Accordingly, fouling characteristics of a pilot-scale VSMBR treating municipal wastewater were studied under various operating conditions. Various physical, chemical, and biological factors were used to describe membrane resistances. As a result, it was concluded that high concentrations of extracellular polymeric substances (EPS), high viscosity and a high sludge volume index (SVI) corresponded to high membrane resistance indicating severe membrane fouling in both the laboratory-scale MBRs and the pilot-scale VSMBR. In addition, high fouling potential was observed in the pilot-scale VSMBR at 60-day sludge retention time (SRT). In this case, as hydraulic retention time (HRT) decreased from 10 to 4 h, EPS concentrations increased and the average particle size increased, leading to reduced settling of the sludge and increased membrane fouling. To mitigate fouling, two different methods using air bubble jets were adopted in the pilot-scale VSMBR. As a result, it was found that air backwashing was more efficient for fouling mitigation than was air scouring.     

Lab-scale testing of a low-loaded activated sludge process with membrane filtration

Two membrane bioreactors (MBRs; volume = 300 L) equipped with different types of immersed membrane modules were operated simultaneously under the same laboratory conditions as a low-loaded activated sludge process without any membrane regeneration and excess sludge uptake (sludge retention time SRT up to 170 d; activated sludge concentration MLSS up to 11 g L⁻¹). The aim was to verify the quality of treated water and to study the properties of "very old" activated sludge. Another aim was to compare different selected membrane types and choose the best one for further pilot-scale testing. Presented at the 35th International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 26–30 May 2008.     

膜生物反应器在废水处理中的应用及研究

膜生物反应器是将生物反应器与膜分离技术相结合的一种高效废水处理新技术。介绍了膜生物反应器的类型、特点以及其在处理生活污水、工业废水、垃圾渗透液、粪便污水和中水回用中的研究和应用现状,提出了膜生物反应器所存在的问题及其研究进展。     

Improving the Performance of Membrane Bioreactors by Adding a Metabolic Uncoupler, 4-Nitrophenol

Effects of 4-nitrophenol (4NP) on the overall performance of membrane bioreactors (MBRs) were investigated in two bench-scale submerged MBRs. Positive impacts of 4NP on activated sludge production and membrane fouling were demonstrated over 45 days of stable operational period. After addition of 4-nitrophenol, the sludge production could be reduced effectively, but only a slight reduction in chemical oxygen demand removal was obtained. The effluent NH₄ ⁺-N concentrations were almost the same in two MBRs. The transmembrane pressures (TMPs) and resistance R increased with increasing mixed liquor suspended solid concentration at each MBR. The average daily TMP increase rates in the control MBR reactor remained at about 0.23 kPa day^?1 and dropped to about 0.12 kPa day^?1 in the 4NP-MBR. Compared with the control MBR, a wider dispersion and lower peak of floc size, a lower zeta potential, and a lower extracellular polymeric substance concentration were observed in the 4NP-MBR.     

Modification effects of amphiphilic comb-like polysiloxane containing polyether side chains on the PVDF membranes prepared via phase inversion process

Amphiphilic comb-like polysiloxane (ACPS) containing polyether side chains was used as the modification reagent in the preparation of hydrophilic porous poly (vinylidene fluoride) (PVDF) membranes via a phase inversion process. The effects of ACPS on morphology, crystallinity, mechanical properties, reservation of ACPS in the phase inversion process, chemical structure, hydrophilicity and filterability performance of porous PVDF membranes were discussed. It was found that the addition of ACPS would result in the delayed demixing which yields “sponge-like” sublayers and longer crystallization time during the membrane formation process. It was revealed that O/F ratios of the bulk membrane were almost the same as those of the corresponding casting solutions which obviously indicated the high reservation of ACPS in the membrane formation process. The fact that the O/F ratios in the membrane surface layers were much higher than those in the bulk membrane proved the enrichment of ACPS on the surface. The filterability experiments and water contact angle testing proved the hydrophilicity of the blend membranes. Through a schematic model, the mechanism relating the membrane structure and performance was interpreted. From the observed results, it can be concluded that ACPS acts as a potential candidate material for preparing PVDF membranes with extraordinary hydrophilicity and filterability. __________ Translated from Acta Polymerica Sinica, 2007, 12: 1168–1175