水处理变速絮凝工艺优化设计探讨

Discussion on Optimal Design of Variable-Speed Flocculation Process in Water Treatment

变速絮凝工艺采用由大到小的速度梯度G值,以适应絮体的形成规律。以高岭土和腐植酸配制试验水样、聚合氯化铝(PAC)为絮凝剂进行混凝搅拌试验,采用正交试验法,对三级变速絮凝工艺进行优化组合分析。结果表明,Ⅰ级慢搅速度和Ⅱ级慢搅时间为影响絮凝效果的显著因素;而III级慢搅时间为不显著因素,可以根据实际情况在一定范围内调整。在实际水厂设计中,应严格控制I级慢搅速度和Ⅱ级慢搅时间,从而有效提高颗粒之间的有效碰撞次数和改善絮体结构,获得更好的絮凝效果。

In order to produce better flocs,the velocity gradients are adopted from big to small during variable-speed flocculation process.Kaolin and humic acid suspension was selected as testing water samples,and polyaluminium chloride(PAC) as a coagulant.The coagulation stirring test and the orthogonal test method were used to analyze the optimal combination of three-level variable-speed flocculation condition.The results shows the slow stirring speed of Level I and the slow stirring time of Level II have a remarkable impact on flocculation efficiency,and,however,the slow stirring time of Level III has almost no impact.In the practical design of water plants the slow stirring speed of Level I and the slow stirring time of Level II should be strictly controlled to improve the rate of effective collisions and floc structure,to obtain better efficiency of flocculation.