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.     

预涂PAC动态膜生物反应器长期运行特性研究

利用普通工业滤布和粉末活性炭（PAC）形成预涂动态膜（PDM）,然后置入活性污泥池中形成预涂动态膜生物反应器（PDMBR）。通过两个周期共计153d的试验表明,PDMBR长期运行稳定性良好。试验过程中膜通量为13.7 L·m^2·h^1,HRT为10h,平均COD去除率为90.70％,平均NI4^＋ -N去除率为96.15％。SEM分析知,造成膜污染的最主要的因素是PDM膜面的生物凝胶层,其次是压实的PDM膜层,而膜基质（滤布）由于受到外层PDM和生物凝胶层的双重保护而几乎没有受到污染,阻力变化不大,因而膜清洗容易。     

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。     

投加粉末活性炭对膜生物反应器性能的影响

采用两组膜生物反应器(反应器1未投加粉末活性炭,反应器2投加粉末活性炭量为500mg/L)研究了在相同的进水和运行条件下其混合液特性和膜过滤阻力的变化.研究发现:加入活性炭可有效延缓混合液的黏度,胞外聚合物(EPS)含量、微细颗粒的含量和膜过滤阻力的增加,而且黏度和EPS含量有较好的线性相关性.分析认为膜孔堵塞仅在很短的时间内(≤1 min)起作用,因此膜孔堵塞模型可并入膜本身阻力模型;大于膜孔径而小于1 μm的颗粒物是形成沉积层的主要物质,而沉积层阻力是膜过滤的主要阻力.     

粉末活性炭膜生物反应器深度处理印染废水的中试

开展了粉末活性炭膜生物反应器深度处理印染废水的中试研究,探讨了其对出水COD_(Cr)、色度、悬浮物的去除效果。结果表明,在粉末活性炭投加量为400～500 mg·L~(-1)的条件下,COD_(Cr)、色度、悬浮物的去除率分别达到了55%～68%、80%～92%、74%～92%,出水水质可满足GB 4287-2012《纺织染整工业水污染物排放标准》中表3规定的特别排放限值。中试工程直接运行成本为1.35元·m~(-3),对于有迫切提标需要的印染工业园区,粉末活性炭膜生物反应器深度处理印染废水在经济上是可行的。     

膜生物反应器与粉末活性炭-膜生物反应器除污染特性对比研究

采用膜生物反应器(MBR)和粉末活性炭-膜生物反应器(PAC-MBR)两种工艺处理微污染原水,考察了两阶段进水情况下的除污染效能及初始有机物和氨氮质量浓度对各工艺除污染特性的影响。结果表明,进水有机物含量对MBR和PAC-MBR除污染的效果有较大的影响,当CODMn由(3.67±0.11)mg/L增加至(4.11±0.23)mg/L时,两种工艺对CODMn的去除率分别由(23.1±9.8)%和(37.6±5.5)%增加至(35.4±12.6)%和(43.1±17.0)%。两个阶段各工艺出水的NH3-N质量浓度均小于0.4 mg/L,且系统连续运行过程中出水的NO2--N质量浓度分别低至(7.5±5.8)μg/L和(6.1±3.6)μg/L,显著低于原水中的平均值(76.9±7.6)μg/L。同时发现PAC-MBR工艺中PAC延长了微生物与有机物的接触时间,并为微生物生长提供了载体,可有效提高细菌的总耗氧速率(SOUR),并使生物处理系统中的有机物浓度的临界值降低,从而有效提高整个生物处理系统中有机物和氨氮的去除率。     

活性炭提高膜生物反应器运行性能的研究进展

通过投加粉末活性炭(PAC)/颗粒活性炭(GAC)改善污泥混合液性质从而减缓膜污染是膜生物反应器(MBR)领域的研究热点,重点介绍了最近五年有关活性炭与MBR结合处理不同类型废水的研究进展,投加PAC/GAC对MBR处理能力的影响,对减缓膜污染的作用,尤其是结合动态膜(DM)论述对污泥性质的改善.重点讨论了活性炭在好氧...     

膜生物反应器中污泥特性对膜污染的影响研究

膜生物反应器(MBR)是膜技术与污水生物技术的组合工艺，与传统污水处理工艺相比具有许多优点，但膜污染目前仍是限制MBR广泛应用的突出问题。有效的膜污染防治技术，可以增加膜通量，增强系统稳定性，减少系统维护和运行费用。在膜过滤过程中，污泥混合液的特性对于膜污染具有重要作用。近年来围绕污泥特性对膜污染的防治问题取得了许多研究成果，膜污染的数学模型研究也得到了很大发展。     

动态膜生物反应器的过滤性能及运行特性研究

采用滤布为基材形成动态膜生物反应器在低温条件下(9～13℃)处理校园生活污水.结果表明动态膜能在滤布表面很快形成且稳定存在.出水浊度小于9.5 NTU,TSS多数运行时间为零,最大不超过5.0 mg/L,COD和氨氮去除率分别为72%～89%和66%～94%.动态膜的过滤阻力比微滤/超滤膜要低2～3个数量级,泥饼层阻力是主要的污染阻力.     

膜生物反应器中铁含量对活性污泥性能的影响

通过分析膜生物反应器中铁含量对活性污泥性能的影响,得知在一定条件下,随着污泥中铁含量的升高,污泥的脱氢酶活性随之上升,上清液含铁量对污泥脱氢酶活性的影响跟污泥中含铁量影响相反;污泥含铁量对污泥比耗氧速率的影响与对脱氢酶活性的影响相反,其原因在于污泥浓度增加及污泥絮体变大影响了溶解氧和基质从反应器混合液向絮体内部的扩散,导致污泥内部氧气不足,从而使微生物的耗氧活性随之降低;随着上清液中铁含量的增加,污泥比耗氧速率随之升高,上清液中铁离子浓度的增高会使生物铁污泥性能劣化,导致生物铁污泥絮体的解絮,污泥颗粒变小,污泥内部溶解氧上升,从而使污泥耗氧活性增高,因此合理投加一定量的生物铁才能使污泥性能达到最佳。     

Comparison of the filtration characteristics between biological powdered activated carbon sludge and activated sludge in submerged membrane bioreactors

The filtration performances of submerged membrane bioreactors (SMBR) with and without the addition of powdered activated carbon (PAC) were investigated respectively under the same feed and operation conditions. A series of experiments were conducted to analyze near-critical flux, effect of air-scouring rate and time of stable filtration operation of both systems. The experimental results demonstrated that pronounced flux enhancement was achieved by adding 1.2 g/L PAC. The near-critical flux for the biological powdered activated carbon (BPAC) system was about 32% higher than that for the activated sludge (AS) system. Increasing the air-scouring rate led to a more significant flux improvement for the BPAC system compared to the AS system. Long-term operation indicated that, at constant flux, the TMP increasing rate of the BPAC system could be lagged and thus cause the extension of operating intervals about 1.8 times compared to the AS system. Quantitative calculations showed the total hydraulic resistance of the BPAC system was about 44% lower than that of the AS system, and this decrease was mainly caused by the reduction in cake resistance. Analyses were then made from various aspects such as floc size distribution and apparent viscosity of the mixed liquor to elucidate the major factors giving rise to different filtration characteristics.     

Effect of powdered activated carbon type on the performance of an adsorption-microfiltration submerged hollow fiber membrane hybrid system

This study highlights the importance of the type of powdered activated carbon (PAC) on the performance of an adsorption-MF hollow fiber membrane hybrid system. Submerged UF hollow fiber membrane with pore size of 0.4 Μm was used along with the PAC in a single reaction tank to treat the wastewater. This procedure is different from the commonly adopted practice of having adsorption with PAC as a pretreatment step to membrane operation. This system is helpful in containing the PAC within one system, allows certain variation in feed characteristics and improves the efficiency of the hybrid system. The overall performance of the membrane hybrid system was evaluated based on TOC removal, UV₂₅₄ absorbance, turbidity removal and flux development. It is important to select a right PAC type to be used in the hybrid system in order to minimize the PAC dose and to enhance the performance. The adsorption capacity of the activated carbon had a greater influence on the overall performance of the hybrid system than other physical properties of the PACs and must be given greater consideration when selecting the PAC for the membrane hybrid system. Scanning electron micrograph (SEM) analysis of the cake deposit over the membrane helps to support the reason for moderate retention of organics.     

粉末活性炭性质对PACT工艺的影响研究

采用A/O生物活性炭(PACT)工艺处理工业园区综合废水水解酸化出水,考察了粉末活性炭性质对PACT工艺的影响,确定了PACT工艺的强化效率和影响因素.结果表明:采用PACT的A/O工艺可提高10％以上的COD和色度去除率,但对氨氮、TN和TP的去除促进作用并不明显.粉末活性炭的中孔容积和比表面积是影响PACT工艺强化作用效率的重要参数.     

Removal of perfluorinated compounds by membrane bioreactor with powdered activated carbon (PAC): Adsorption onto sludge and PAC

The comparative study was conducted to investigate the performance and removal efficiencies of PFOS and PFOA in MBR and PAC-MBR. Solid phase extraction (SPE) followed by HPLC coupled with tandem MS (HPLC/MS/MS) was applied to quantitatively identify PFOS and PFOA in aqueous and sludge samples. Removal efficiencies of these two compounds were less than 7% in MBR, which suggest that MBR could not effectively remove PFCs due to their persistent in the activated sludge process. In contrast, removal efficiencies of 77.4% for PFOS and 67.7% for PFOA were observed in PAC-MBR with PAC dosage of 30 mg/L, indicating that adsorption of PFCs onto PAC plays an important role in their removal. Moreover, with the increase of PAC dosage from 30 mg/L to 100 mg/L in PAC-MBR, removal efficiency for PFOS or PFOA both increased to more than 90%. Mass balance of PFOS and PFOA was established to explore their removal mechanisms in MBR and PAC-MBR. Results show that PAC-MBR can effectively remove these two compounds in the wastewater by PAC adsorption, which was identified as the major removal mechanism. In MBR, adsorption onto activated sludge was the only mechanism for removal of PFCs.     

正渗透膜生物反应器膜过滤特性研究

以氯化钠为驱动溶质,采用正渗透膜生物反应器处理模拟生活污水,系统地考察了各因素对正渗透膜过滤性能的影响。结果表明,随着驱动液浓度增加,水通量和反向盐通量也随之增加;正渗透膜活性层朝向驱动液时(AL-DS)的水通量和反向盐通量较活性层朝向原料液(AL-FS)时大;水通量和反向盐通量与错流速率正相关,在错流速率较低时增加不明显;随着活性污泥浓度增加,水通量呈下降趋势,而反向盐通量呈上升趋势。     

投加粉末活性炭对超滤膜去除海水中有机物的影响

超滤膜的有机污染问题是膜法海水预处理技术在海水淡化工程应用面临的重要挑战,粉末活性炭吸附是目前常用的膜前预处理手段之一。本文对比分析了直接超滤和投加粉末活性炭后对海水中有机物的截留能力,利用三维荧光光谱分析了投加粉末活性炭对超滤膜截留有机物的影响机制,并考察了海水超滤过程中通量变化及膜污染情况。研究结果表明,投加粉末活性炭能够强化超滤膜对海水浊度和有机物的去除,当粉末活性炭投量为200mg/L时,整个系统对海水中DOC去除率从直接超滤时的55.1%提高到77.6%。利用粉末活性炭的吸附作用及其在超滤膜表面形成的疏松滤饼层能够显著提高超滤系统对海水中腐植酸类有机物的去除能力。与直接超滤相比,粉末活性炭-超滤系统对改善膜通量的作用有限,但粉末活性炭形成的滤饼层能够避免超滤膜与有机物直接接触,可显著减缓超滤膜的不可逆污染。     

典型金属离子冲击对膜生物反应器运行的影响

对进水中Na+,Ca2+和Fe3+冲击对膜生物反应器(MBR)运行的影响进行了探讨。实验结果表明:进水中3种金属离子冲击对MBR去除COD影响较小,适量质量浓度的Fe3+有利于NH3-N的去除,然而Na+与Ca2+对NH3-N去除影响不明显;进一步研究发现进水中Na+将引起反应器内上清液(SMP)质量分数上升,从而增加膜过滤阻力;进水中Fe3+质量浓度为50 mg/L时显著降低本体溶液中SMP质量分数,有利于减缓膜污染,而当Fe3+质量浓度为150 mg/L时SMP质量分数升高,使膜污染率升高;研究中也发现进水中Ca2+在50或150 mg/L时都可有效地减缓膜污染,进水中金属离子质量浓度与EPS中TB质量分数关系密切。     

Adsorption of disperse dye by powdered activated carbon

The purpose of this laboratory study is to investigate the effectiveness of powered activated carbon (PAC) on the removal of chemical oxygen demand (COD) and color of disperse dye and the effect of PAC particle size on the treatment efficiency. The adsorption isotherm parameters for the Langmuir, Freundlich and BET model are determined using the adsorption data. It has been found that the multilayer BET isotherm yields significantly better fit to the observed data than the monolayer ones. A simplified mass transfer model is proposed in the present work also for estimating the external mass transfer coefficient using the initial adsorption data at low PAC dosage.