改性凹凸棒土及粉末活性炭助凝聚硅硫酸铝消除微污染水中有机氯

以硅酸钠和硫酸铝为原料制备了聚硅硫酸铝絮凝剂(PASS),采用强化混凝的处理方法,对微污染水中有机氯(OCPs)的消除进行了研究.同时,考察了混凝剂投加量、pH值、原水浊度、粉末活性炭和改性凹凸棒土助凝剂等因素对OCPs消除效果的影响.结果表明:PASS投加量为5 mg·L-1时,OCPs的去除率可以达到57%~87%,浊度去除率可以达到99.1%,其效果好于聚合氯化铝(PAC);PASS混凝处理OCPs的最佳pH值范围是6~7;OCPs的去除与浊度的去除具有显著相关性,原水浊度的大小会影响OCPs的去除,低浊条件下OCPs和浊度的去除率明显低于中浊和高浊条件;粉末活性炭和改性凹凸棒土作为助凝剂与PASS复配均可显著提高OCPs的去除率,分别达到78%~100%和72%~95%.相较而言,凹凸棒土储量丰富,廉价易得,因此,以改性凹凸棒土替代粉末活性炭更有优势.

Elimination of OCPs from micro-polluted water by coagulation with polysilicate aluminium sulphate with assistance of modified attapulgite and powder activated carbon

Polysilicate aluminium sulphate (PASS) flocculant was prepared by sodium silicate and aluminum sulphate. The elimination of organochlorine pesticides (OCPs) from micro-polluted water by coagulation with PASS was studied. The effects of the dosage of coagulant, pH values, initial turbidity as well as the addition of assistant coagulant on the elimination efficiency of OCPs were determined respectively. The result showed that under the dosage of 5 mg·L^-1 PASS, the removal rates of OCPs and turbidity reached 57%~87% and 99.1%, respectively, much higher compared with polyaluminium chloride (PAC). The best range of pH values was 6~7 for OCPs elimination. The removal rates of OCPs were relevant to the turbidity, and increased with the increasing in initial turbidity. Modified attapulgite and powder activated carbon used as assistant coagulants significantly enhanced the coagulation, with the removal rates of OCPs of 78%~100% by powder activated carbon and 72%~95% by modified attapulgite, respectively. As attapulgite is abundant, cheap and easy to acquire, it is more suitable to be used as the assistant coagulant compared to powder activated carbon.