PDMDAAC助凝PAC处理高浊度丙烯酸乳液废水

Treatment of high turbidity acrylic emulsion wastewater by coagulation of poly aluminum chloride with poly dimethyl diallyl ammonium chloride

聚二甲基二烯丙基氯化铵(PDMDAAC)助凝剂主要用于低浊度天然水体的除浊,而很少用于高浓度的生产废水处理,为此,采用PDMDAAC助凝聚合氯化铝(PAC)处理高浓度丙烯酸乳液废水,考察了PAC投加量、m(PDMDAAC)∶m(PAC)、初始pH、沉淀时间对PAC混凝效果的影响,并分析了PDMDAAC的助凝机理。结果表明,PDMDAAC助凝剂对高浓度丙烯酸乳液废水混凝的处理效果明显,可以高效地去除COD和浊度。其最优混凝条件:PAC投加量为350 mg/L,m(PDMDAAC)∶m(PAC)为2%、初始pH=7.0,沉降时间为20 min。在最优混凝条件下进行中试混凝实验,废水COD由11 396 mg/L降为417 mg/L,COD去除率达到96.3%,浊度由11 220 NTU降为39 NTU,浊度去除率达到99.6%。由激光粒度和SEM分析可知,PDMDAAC助凝PAC的絮体粒径为12.4μm,PDMDAAC助凝PAC的絮凝机理更趋向于吸附电中和作用,而吸附架桥作用较弱。

Poly dimethyl diallyl ammonium chloride coagulant is mainly used for turbidity removal of low-turbidity natural water bodies,and is rarely used for the treatment of high-concentration production wastewater. Treatment of high turbidity acrylic emulsion wastewater by coagulation of poly aluminum chloride(PAC) with poly dimethyl diallyl ammonium chloride(PDMDAAC) was investigated. The effects of coagulant dosage,proportion,initial pH value and precipitation time on the coagulation effect were explored,and the flocculation mechanism of the composite coagulant was analyzed. The experiment results indicated that PDMDAAC coagulant worked for the removal of COD and turbidity from the high concentration acrylic emulsion wastewater. The optimal operating parameters were obtained such as the dosage of PAC(350 mg/L),proportion of m(PDMDAAC)∶m(PAC)(2%),pH value(7.0) and settling time(20 min). Under the above conditions in pilot coagulation experiments,COD decreased from 11 396 to 417 mg/L with the removal rate of 96.3% and the turbidity drop from 11 220 to 39 NTU with the removal rate of 99.6%. The laser particle size and SEM analysis showed that PDMDAAC/PAC coagulation floc particle size was 12.4 μm,and the flocculation mechanism of PDMDAAC/PAC was mainly charge neutralization in treatment of acrylic emulsion wastewater,not adsorption bridging.