尼龙纺织布生物反应器处理生活污水的研究

采用尼龙纺织布代替膜生物反应器中的膜组件组成新型尼龙纺织布生物反应器(NWFBR),考察3种孔径的尼龙纺织布(0.031、0.019、0.015mm)生物反应器对模拟生活污水的处理效果,并对运行过程中尼龙纺织布的通量进行分析。结果表明,NWFBR工艺对浊度、SS、COD和NH3-N的去除效果很好。尼龙纺织布本身对COD有一定去除作用,对氨氮无去除作用。其清水通量和泥水混合物通量都明显比传统膜通量高。通过简单的物理清洗,布通量的恢复率达到90%左右。     

无纺布膜临界通量及其在洗浴废水处理中的应用研究

以无纺布平板膜生物反应器为试验装置,采用通量阶梯式递增法的临界通量进行了测定,研究了混合液污泥浓度(MLSS)对无纺布膜临界通量的影响,考察了膜通量对无纺布平板膜生物反应器长期运行的影响。试验结果表明,无纺布膜的临界通量与MLSS浓度成反比,当MLSS的质量浓度从3 g/L增长到9 g/L时,无纺布膜临界通量从17 L/(m2·h)下降到13 L/(m2·h)。在MLSS的质量浓度控制为5 g/L,膜通量低于临界通量15 L/(m2·h)的条件下,无纺布平板膜生物反应器可连续稳定运行130 d,且反应器出水各项指标均可满足GB/T 18920—2002《城市污水再生利用城市杂用水水质》标准的要求。     

膜生物反应器污泥混合液对膜污染影响研究进展

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,近年来备受关注,然而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.本文综述了污泥混合液各组分对MBR膜分离的影响,包括溶解性微生物代谢产物(soluble microbial product,SMP)、胞外聚合物(extracellular polymeric substances,EPS)、污泥浓度(mixed liquor suspended solids,MLSS)、颗粒粒径及无机物对膜污染影响,并对该领域未来的研究方向进行了论述.     

PAC投加对膜生物反应器的污泥特征和膜污染的影响

考察了投加粉末活性炭( PAC)对长期运行的膜生物反应器(MBR)中污泥混合液特性和膜污染的影响,并分析了其对膜污染的影响机理.结果表明,PAC的投加使污泥絮体平均粒径增加、污泥的粘度减小,而对污泥含量影响不大.投加PAC可降低混合液中溶解性EPS含量,质量浓度从MBR反应器混合液中的平均87.17 mg·L-1降至PAC-MBR反应器内65.54 mg·L-1;同时PAC对膜表面的EPS也有吸附作用,能将沉积在膜表面的EPS吸附到其表面,使得膜表面的EPS质量浓度从MBR反应器内的970.6 mg·L-1降至PAC-MBR反应器内的699.0 mg· L-1,同时改变了膜表面的EPS组成,使得蛋白质、多糖的质量比降低,减缓了膜的有机污染,延长了膜组件的清洗周期.     

无排泥条件下膜生物反应器污泥混合液可滤性分析

膜生物反应器（MBR）在无排泥条件下运行100 d,定期对溶解性微生物产物（SMP）、SMP分子量分布、胞外聚合物（EPS）中的蛋白质和多糖进行监测,应用修正的污染指数（MFI）考察污泥混合液可滤性的变化。实验表明：长时间无排泥运行模式下将导致污泥混合液可滤性的恶化;污泥混合液上清液中分子量（M_w）大于10 kDa 的SMP浓度对污泥混合液的可滤性产生强烈的负面影响;污泥浓度（MLSS）与混合液可滤性之间关系复杂,MLSS对污泥可滤性的影响存在一个临界值;EPS中的蛋白质60 d后发现可被微生物迅速降解,多糖类物质对污泥混合液可滤性有较强的负面影响。     

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。     

胞外聚合物对膜污染的影响及对策

膜生物反应器(MBR)中膜污染问题直接影响了工艺的稳定性和经济性。通过分析膜污染机理发现,胞外聚合物(EPS)在膜污染中起重要作用。从EPS的性质、组成及影响因素等方面进行了归纳总结,并对膜污染控制提出了相应的对策。     

浸没式双轴旋转厌氧膜生物反应器的污泥特性研究

研究了新型浸没式双轴旋转厌氧膜生物反应器(SDRAnMBR)处理模拟啤酒废水的污泥特性.结果表明,SDRAnMBR的污泥活性高,旋转剪切力没有对厌氧颗粒污泥的性质造成破坏并具有性能良好的絮体;而且能有效减轻污泥浓度、EPS、污泥粘度,污泥颗粒粒径的变化对膜污染的影响,使之能在较高的MLSS(18～19.5 g·L-1),较高的EPS浓度(50.9～63.9 mg·gMLSS-1)、较小的污泥颗粒粒径(4.00～36.54μm)和较大的污泥粘度(6.6～7.5mPa·s-1)时稳定运行.SDRAnMBR中由膜旋转形成的三相旋转流和厌氧颗粒污泥的协同作用,使SDRAnMBR具有性能良好的活性污泥,同时强化了膜组件的抗污染性能.     

填料对一体式膜生物反应器运行效能的影响

进行了组合式膜生物反应器(CMBR)和一体式膜生物反应器(SMBR)处理生活污水的试验研究,以考察填料对处理效果的影响及减缓膜污染方面的作用。在稳定期,CMBR对COD的平均去除率为96.7%,SMBR为95.9%,对NH3—N的去除率分别为95.6%和94.9%,试验结果表明,填料的添加对反应器COD和NH3—N的去除效果影响不大,但能有效增强反应器对总氮的去除,去除率从54.5%提高到67.5%;经102 d连续运行,CMBR膜组件清洗次数少于SMBR,说明添加填料不仅提高了膜生物反应器(MBR)的处理效果,而且相对有效地减缓了膜阻力升高的速度;单位膜面积上胞外聚合物(EPS)的面密度与2个膜生物反应器过膜压力随运行时间的变化规律基本一致,CMBR和SMBR中膜阻力与单位膜面积上EPS的面密度正相关,证明EPS对膜污染有着重要的影响。     

中空纤维膜生物反应器膜污染影响因素

该文研究了两种不同孔径的聚偏氟乙烯中空纤维膜生物反应器(MBR)在城市污水处理过程中不同外界因素对膜污染的影响.研究表明造成膜污染的主要因素有活性污泥特性、胞外聚合物(EPS)、膜孔径等.试验发现,膜的过滤性能下降并不完全由污泥浓度影响,真正造成膜过滤性能的下降可能是由于污泥自身性质的改变.随着污泥浓度的增加引起粘度的...     

基于MFC电场强化的MBR膜污染控制

将膜生物反应器(MBR)与微生物燃料电池(MFC)相结合,设计了一种MFC-MBR耦合工艺。对不同运行条件下MFC电场对MBR运行的影响与常规MBR(CMBR)工艺进行了对比。结果表明:以污水为基质的MFC产生的生物弱电场能有效控制膜污染速率,抑制不可逆污染。在不同污泥浓度下,MFC电场对于控制松散胞外聚合物(LB-EPS)中多糖类小分子污染物具有明显的优势,但对紧密胞外聚合物(TB-EPS)的控制并不明显。附加电场后,污泥zeta电位的绝对值分别降低2.7、7.1和4.1 mV,并促进了丝状菌的生长,使污泥絮凝性增强,污泥粒径变大。     

Influence of Dissolved Organic Carbon and Suspension Viscosity on Membrane Fouling in Submerged Membrane Bioreactor

Abstract

This paper deals with the membrane fouling in membrane bioreactor (MBR). Based on the experimental data obtained in the MBR pilot plant study, the influence of F/M ratio on the irreversible and reversible fouling was discussed in the wide range of MLSS concentration. In the case of lower MLSS concentration (2,000–3,000 mg/L), irreversible fouling rate of membrane increased with increasing F/M ratio because of the accumulation of DOC in the mixed liquor. It seems that soluble microbial products with the similar size of the membrane pore will be most responsible for the irreversible fouling. In the case of higher MLSS concentration (8,000–12,000 mg/L), reversible fouling rate of membrane increased with increasing F/M ratio because of the increased suspension viscosity caused by the increased activated sludge size or volume even in the same MLSS concentration.     

膜生物反应器处理小区污水条件的优化

由于膜污染是限制膜生物反应器(MBR)应用与推广的主要因素。为此,本研究以MBR处理某小区污水为例,选择粉末活性炭投加量、活性污泥浓度及曝气量进行L12(43)正交试验,确定最佳的操作条件分别为2 g/L、7 g/L、6 m3/h;并在此基础上进行平行对比试验,其膜阻的最大差值达21.05 kPa,导致膜污染形成和发展的主要物质蛋白质/多糖值与膜压差上升速率存在线性关系。     

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.     

Short-term fouling propensity and flux behavior in an osmotic membrane bioreactor for wastewater treatment

The short-term fouling behavior of forward osmosis (FO) membrane in an osmotic membrane bioreactor (OMBR) was investigated, using NaCl or MgCl₂ as the draw solutions. The effect of membrane orientation, mixed liquor suspended solids (MLSS) concentration and draw solution (DS) osmotic pressure on water flux and membrane fouling behaviors was examined, along with the effects of simulated elevated salinity on sludge properties and on membrane fouling. Water flux and membrane fouling were not significantly affected by both MLSS concentration (4.91–12.60 g/L) and osmotic pressure (3.0–15.0 MPa), but were severely affected by elevated salinity, due to changes in activated sludge properties, in particular the increase in extracellular polymeric substances (EPS) and sludge hydrophobicity. MgCl₂ as the DS showed more significant influence on activated sludge properties and membrane fouling than NaCl but gave rise to lower salt accumulation. Analyses of the membrane foulants showed that small sludge floc/particles and EPS (in particular, proteins) were enriched in the fouling layer. UPLC–MS/MS analyses of the proteins showed that hydrophobic proteins were the main cause of membrane fouling.     

膜生物反应器中微生物特征与膜污染的相关性

采用Anoxic/Oxic(A/O)工艺的浸没板式膜生物反应器处理城市生活污水。以PCR-DGGE和FISH等分子生物学方法对系统中的微生物学特性与膜污染的相关性进行了研究。结果发现:当MLSS为1.10×104mg/L时,占据最大体积分数的污泥颗粒的直径为47.75μm,小于2μm的微粒子体积分数为1.01%,同时,动胶菌比例达到最高值36.5%,膜组件操作压力达最低值4.5 kPa;而MLSS为2.05×104mg/L时,占有最大体积分数的污泥颗粒直径为24.54μm,小于2μm的微粒子体积分数为2.07%,动胶菌占全菌的比例为最低值15.5%,同时膜组件的操作压力大于17 kPa。结果表明,具有较佳的菌群多样性和较高比例动胶菌的活性污泥中,菌胶团的颗粒较大,且易造成膜孔堵塞的微小粒子相对较少,致使膜组件的操作压力降低。研究显示膜生物反应器中的微生物学特性也是膜污染的重要影响因素之一。     

Fouling control in activated sludge submerged hollow fiber membrane bioreactors

The goal of this study is to determine the impact of various operating factors on membrane fouling in activated sludge membrane bioreactor (MBR) process, typically used for water reclamation. In this process, ultrafiltration (UF) and microfiltration (MF) hollow fiber membranes, submerged in the bioreactor, provided a solid—liquid separation by replacing gravity settling. Activated sludge from a food wastewater treatment plant was inoculated to purify synthetic wastewater consisting of glucose and (NH₄)₂SO₄ as a source of carbon and nitrogen, respectively. The results clearly showed that membrane fouling, defined as permeate flux decline due to accumulation of substances within membrane pores and/or onto membrane surface, was greatly influenced by membrane type and module configuration. It was also found that the rate and extent of permeate flux decline increased with increasing suction pressure (or initial operating flux) and with decreasing air-scouring rate. The mixed liquor suspended solids (MLSS) concentrations, however, exhibited very little influence on permeate flux for the range of 3600-8400 mg/L. Another important finding of this investigation was that non-continuous membrane operation significantly improved membrane productivity. This observation can be explained by the enhanced back transport of foulants under pressure relaxation. During non-suction periods, the foulants not irreversibly attached to the membrane surface, diffused away from the membrane surface because of concentration gradient. Furthermore, the effectiveness of air scouring was greatly enhanced in the absence of transmembrane suction pressure, resulting in higher removal of foulants accumulated on the membrane surface. The use of intermittent suction operation may not be economically feasible at large-scale, but it may offer an effective fouling control means for small-scale MBR processes treating wastewaters with high fouling potential.     

膜生物反应器处理生活污水临界通量的研究

利用“通量阶式递增法”对临界通量进行了测定,得出MBR的3个水动力学操作区:超临界区、临界区和次临界区;在MLSS的质量浓度为6 000 mg/L、曝气量为0.5 m3/h的条件下,膜组件的临界通量区域为10.68～13.86 L/(m2.h),据此确定组件的次临界通量为12 L/(m2.h)。在此基础上研究了次临界通量下的运行特性,试验表明,次临界通量下的膜污染过程具有明显的两阶段特征:第一阶段的TMP呈平缓直线上升,第二阶段的TMP呈剧烈直线上升。     

重力出流式膜生物反应器污泥浓度的优化控制

采用重力出流式膜生物反应器(Membrane Bioreactor, MBR)工艺对生活污水进行了实验研究. 重力出流式MBR是利用液位水头重力驱动出水,整个系统结构紧凑,操作简便. 结果表明,随着污泥浓度增大(3.9~18.4 g/L),同样的曝气强度对膜表面滤饼层的剪切能力降低,膜通量下降;污泥粘度从5.4 mPa×s上升到680 mPa×s,相应的污泥中的传氧系数与清水中的传氧系数之比a从0.89降到0.10. 因此,从提高膜通量、氧传递速率和降低能耗的角度出发,将MBR的污泥浓度控制在适当范围是非常必要的. 此外,当污泥浓度大于4.8 g/L,污泥浓度的提高对有机物的去除、硝化以及反硝化速率的提高没有明显的贡献. 因此,从MBR的处理能力和运行能耗的双重影响确定MBR的最佳处理污泥浓度值为4~6 g/L,在该浓度区间,生物反应器系统对冲击负荷有较好的抵御能力,同时系统的运行能耗也较低.     

PAC投加量对MBR混合液性质及膜污染的影响

比较了1g／L及2g／L的PAC投加量对膜生物反应器中混合液性质及膜污染速率的差异。发现两系统上清液COD差距不明显,说明1g／L的PAC投加量忆足以吸附小分子的有机物。当PAC从1g／L增至2g／L时,从微生物絮体中提取的多糖平均值分别为：14．92mg／gMLSS、15．38mg／gMLSS;蛋白质平均值分别为18．82mg／gMLSS、17．58mg／gMLSS;且膜丝内部累积的多糖和蛋白质含量基本相同。当PAC投加量为2g／L时,部分破碎的PAC颗粒会进入膜孔内部,引起不可逆污染。