絮凝剂缓解MBR膜污染研究

发布时间：2018-03-06 15:33

本文选题：膜生物反应器　切入点：絮凝剂　出处：《浙江工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：通过在膜生物反应器(MBR)持续运行过程中投加聚二甲基二烯丙基氯化铵(PDMDAAC)、聚合氯化铝(PAC)以及两者的复合絮凝剂,分别考察其缓解MBR膜污染的效果。试验测定MBR的运行周期、活性污泥毛细管吸水时间(CST)、Zeta电位、污泥体积指数(SVI)、污泥絮体粒径分布和胞外聚合物含量等参数的变化,并观察反应器运行过程中活性污泥变化情况,确定了三种絮凝剂量少最佳的补加剂量和投加方式。试验结果表明:通过投加絮凝剂能有效缓解膜污染。三种不同絮凝剂在相同剂量投加时缓解膜污染的效果PDMDAAC最好,复合絮凝剂次之,PAC效果最差。在补加剂量和投加时间间隔方式的试验中,PDMDAAC、复合絮凝剂、PAC都表现出补加剂量比投加方式对缓解膜污染更为有效。依据试验中跨膜压差(TMP)的变化趋势可确定首加400 mg/L PDMDAAC后,最佳补加剂量为90 mg/L。最佳补加剂量90 mg/L能明显延长MBR持续运行周期,是未补加絮凝剂反应器运行周期的3.4倍,而PAC的最佳补加剂量是120 mg/L。通过质量比6:4复合PDMDAAC和PAC的复合絮凝剂不仅能有效缓解膜污染,而且能够降低由单独使用PDMDAAC带来的运行费用。综合TMP增长趋势和SVI值变化可确定复合絮凝剂补加最佳剂量为60 mg/L。投加絮凝剂后,能减小污泥混合液的CST值,增大混合液Zeta电位,降低SVI值和EPS、SMP含量,絮凝剂的投加使活性污泥絮集更紧密,膜组件表面形成的滤饼层变薄,延长MBR恒流量下运行周期。絮凝剂对MBR出水水质无明显影响,投加PDMDAAC的MBR反应器对COD、TN的平均去除率分别为93.1%和89.1%,出水的浓度分别在45、5 mg/L以下,达到一级A排放标准。
[Abstract]:The effects of polydimethyldiallylammonium chloride (PDMDAAC), polyaluminum chloride (PAC) and their composite flocculants on MBR membrane fouling were investigated by adding polydimethyldiallylammonium chloride (PDMDAACN) and their composite flocculants during the continuous operation of the membrane bioreactor (MBR). The operating cycle of MBR was measured. The changes of activated sludge capillary water absorption time, such as Zeta potential, sludge volume index (SVI), particle size distribution of sludge floc and extracellular polymer content, etc., were observed during the operation of the reactor. Three kinds of flocculants with less dosage and optimum dosage were determined. The experimental results showed that the flocculant could effectively alleviate membrane fouling. The effect of three different flocculants on reducing membrane fouling was the best when the same dosage of flocculant was added. In the experiment of adding dosage and time interval, the compound flocculant PAC showed that the dosage of the compound flocculant was more effective than the adding way to mitigate the membrane fouling, according to the transmembrane pressure in the experiment. The variation trend of mg/L can be determined after the first addition of 400 mg/L PDMDAAC. The optimal dosage of 90 mg / L was 90 mg / L. The optimal dosage of 90 mg/L could prolong the continuous running period of MBR obviously, which was 3.4 times of that of the reactor without adding flocculant. The optimum dosage of PAC is 120mg / L. The composite flocculant with 6: 4 mass ratio of PDMDAAC and PAC can not only effectively alleviate the membrane fouling. The optimum dosage of compound flocculant is 60 mg 路L ~ (-1). After adding flocculant, the CST value of sludge mixture can be reduced, and the Zeta potential of mixed sludge can be increased. By reducing the SVI value and the content of SVI, adding flocculant makes the flocculation of activated sludge more compact, and the filter cake layer formed on the surface of membrane module becomes thinner, prolonging the running period under the constant flow rate of MBR. The flocculant has no obvious effect on the effluent quality of MBR. The average removal rate of COD ~ (2 +) TN in MBR reactor with PDMDAAC was 93.1% and 89.1, respectively, and the effluent concentration was below 45 ~ 5 mg/L, which reached the first class A discharge standard.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

【参考文献】