混凝剂对化学强化MBR深度处理印染废水的影响

Impacts of coagulant on a chemically enhanced MBR applied for advanced treatment of dyeing wastewater

在自主开发的化学强化MBR(膜生物反应器)技术的基础上,考察30mg/LFeCl3,30mg/LFeCl3和30mg/LCaCl2的组合以及30mg/LCaCl2三种混凝剂投加方式对其深度处理模拟印染废水二级出水的效果以及对膜污染的影响.结果表明,单独投加FeCl3及FeCl3和CaCl2的组合提高了化学强化MBR装置对色度、COD、氨氮和总磷的去除效果.单独投加FeCl3及FeCl3和CaCl2的组合都可以有效地缓解膜污染,其中投加FeCl3和CaCl2组合的效果更好,而单独投加CaCl2将会加重膜污染.FeCl3的絮凝作用可以降低胞外聚合物(EPS)的含量并增加污泥颗粒粒径.此外,CaCl2可以强化FeCl3的絮凝作用,提高膜污染的延缓效果.然而,单独投加CaCl2由于刺激EPS的产生并造成污泥颗粒粒径的减少,从而加重了膜污染.FeCl3和CaCl2都有利于溶解性有机物(DOM)中的小分子量片段向大分子量片段的转化,其中CaCl2的影响更大.

The impacts of coagul2nt on the effluent water quality and membrane fouling of a chemical enhanced membrane bioreactor （CEMBR） applied for advanced treatment of dyeing wastewater were investigated. In this study, three adding modes of 30 mg/L FeCl3, the combination of 30 mg/L FeCl3 and 30 mg/LCaCl2 and 30 mg/LCaCl2 were applied, and synthetic secondary effluent of dyeing wastewater composed of disperse red was used as influent of the CEMBR. The results showed that adding FeCl3 and the combination of FeCl3 and CaCl2 could enhance the removal of color, chemical oxygen demand （COD）, ammonia nitrogen and total phosphorus, and alleviate the membrane fouling of CEMBR. Compared with the addition of FeCl3, adding the combination of FeCl3 and CaCl2 had better effect on reducing membrane fouling. It could be attributed to the facts that FeCl3 could reduce the extraeellul2r polymeric substances （EPS） and increase the particle size in sludge by floccul2tion, and CaCl2 could enhance the floccul2tion of FeCl2. However, only adding CaCl2 deteriorated membrane fouling due to the increase of EPS and reduction of particle size in sludge. Furthermore, both FeCl2 and CaCl2 could increase the ratios of matters with bigger molecul2r weight （MW） in dissolved organic matters （DOM）, and the impact of CaCl2 on MW distribution was more remarkable than that of FeCl3.