强化预处理-超滤-纳滤组合工艺处理污水处理厂二级出水试验研究

Study on the treatment of secondary effluent from wastewater treatment plants by the enhanced pretreatment-ultrafiltration-nanofiltration hybrid process

针对二级出水中有机物和金属离子含量高等问题,以哈尔滨市文昌污水处理厂二级出水为研究对象,以强化混凝/吸附-超滤-纳滤组工艺进行处理。结果表明:空白组对COD_(Mn)和TOC的平均去除率分别为78.2%和72.3%,混凝强化组对COD_(Mn)和TOC的平均去除率分别为86.3%和83.4%,吸附强化组对COD_(Mn)和TOC的平均去除率分别为95.4%和94.6%。三组纳滤试验对TP的去除率均达到73%以上,对TN与NH-N的去除率仅为30%左右。从对金属离子的去除效果可以看出,组合工艺对二价和三价离子的去除效果优于一价离子。膜污染实验中混凝强化组纳滤膜的膜阻力最大,对纳滤膜污染控制效果最差,吸附强化组对纳滤膜污染的控制最优。EEM分析结果证实纳滤膜截留的有机物主要为腐殖酸、富里酸、小分子蛋白质和氨基酸等。从污染后纳滤膜SEM可知,三组试验中纳滤膜均受到不同程度的污染,但污染后纳滤膜表面区别不大。

To reject high concentration of organic pollutants and heavy metal ions of secondary effluent,a coagulation/adsorption enhanced pretreatment-ultrafiltration-nanofiltration hybrid system was applied to treat the secondary effluent taken from Harbin Wenchang Sewage Treatment Plant.The average removal efficiencies of COD_(Mn)and TOC in the control group were 78.2%and 72.3%,respectively.The average removal rates of COD_(Mn)and TOC in the coagulation enhanced group were 86.3%and 83.4%,respectively.The average removal efficiencies of COD_(Mn)and TOC in the adsorption enhanced group were 95.4%and 94.6%,respectively.The removal rate of TP in the three nanofiltration tests was above 73%,and the corresponding value for TN and NH-N was only about 30%.The hybrid process showed a higher rejection for the divalent and trivalent ions than the monovalent ions.Membrane fouling tests demonstrated that the membrane resistance of the enhanced coagulation group was the largest,and the controlling effect of membrane fouling was the worst,whereas the best membrane fouling controlling effect was observed for the adsorption-enhanced group.The EEM analysis confirmed that the main organic compounds retained by the nanofiltration membrane were humic acid,fulvic acid,small molecular protein and amino acid.According to the SEM images of the fouled nanofiltration membrane,all membranes were polluted to different degrees,and there was little difference on the surface of the fouled membranes.