NaClO重复清洗膜污染效能及卤代副产物生成研究

Study on Membrane Fouling Efficiency of Repeated Cleaning with NaClO and Generation of Halogenated By-products

以过滤二沉池出水后受污染的超滤膜为研究对象,考察NaClO溶液对污染膜重复清洗后超滤膜的截留效果、NaClO的清洗效能及清洗过程中毒性副产物的累积情况。结果表明,NaClO溶液重复清洗会导致膜损伤,进而导致超滤膜对TOC和TP的截留率在NaClO溶液重复清洗6次后分别降低了65%和23%;同时膜通量恢复率随清洗次数增加整体呈现上升趋势。NaClO清洗液经多次使用后,剩余清洗液中大部分毒性氯代副产物会逐渐积累,如二氯乙酸(DCAA)、三氯乙酸(TCAA)、水合三氯乙醛(CH)、1,1-二氯丙酮(1,1-DCP)、二氯乙腈(DCAN)和三氯乙腈(TCAN);剩余清洗液中三氯甲烷(TCM)随着清洗次数增加呈现出先增高后逐渐稳定的趋势,而三氯乙烯(TCE)浓度则随清洗次数增加先增高后降低。

The fouled ultrafiltration membrane after filtering the effluent of the secondary sedimentation tank as the research target,the interception efficiency of the ultrafiltration membrane after repeated cleaning by NaClO solution,the cleaning efficiency of NaClO and the accumulation of toxic by-products during the repeated cleaning were investigated.The results showed that the repeated cleaning of the fouled membrane by NaClO solution damaged the ultrafiltration membrane,which caused the removal of TOC and TP gradually reduced by 65%and 23%,respectively after the repeated cleaning of six times.Meanwhile,the recovery rate of membrane flux showed an overall upward trend with increasing the cleaning times.After repeated use of NaClO solution for chemical cleaning,the most toxic chlorinated by-products in the remained NaClO solution would gradually accumulated,such as dichloroacetic acid(DCAA),trichloroacetic acid(TCAA),chloral hydrate(CH),1,1-dichloroacetone(1,1-DCP),dichloroacetonitrile(DCAN)and trichloroacetonitrile(TCAN).The Trichloromethane(TCM)concentration increased first and kept nearly stable with the increase of cleaning times.However,the concentration of trichloroethylene(TCE)in the solution performed a trend of firstly increasing and then decreasing with extending the cleaning times.