循环水排污水中杀菌剂、缓蚀阻垢剂对混凝效果的影响

Effects of Bactericides,Corrosion and Scale Inhibitors on Coagulation in Blow-down Water From Circulating Water System

混凝沉淀法处理循环水排污水时,由于排污水中残余药剂的影响,混凝往往达不到理想效果。为了寻求药剂对混凝过程及机理的影响,首先对混凝剂（PAC）、助凝剂（PAM）的投加量以及混凝条件进行优化,然后在优化的混凝条件下,考察单体药剂以及复配药剂对排污水混凝效果的影响,还考察了药剂对PAC最佳投加量的影响,并采用扫描电镜观测不同条件下絮凝体的微观结构。结果表明,PAC和PAM的最佳投加量分别为40 mg/L、0.8mg/L,最佳混凝条件为快速搅拌时间3min、慢速搅拌速率90r/min、快速搅拌速率300r/min、慢速搅拌时间10min;在此条件下,排污水浊度去除率可达93.49%。PASP对排污水混凝效果影响最大,且剩余浊度波动性大,波动范围0.85～1.78NTU（Nephelometric Turbidity Unit）;1227对PAC最佳投加量影响最大,波动范围20~70mg/L。排污水存在复配药剂时,其混凝后得剩余浊度都大于无药剂时的0.98NTU。不同条件下的排污水混凝所得絮凝体结构存在明显的差异,从而导致了混凝效果的不同。

When the blow-down water from circulating water system is treated by coagulantsedimentation method,the water treatment agents in it would have a certain effect on coagulation effect.For seeking influence of the agents on the coagulation process and its mechanism,the dosages of coagulant,coagulant aid and operating conditions were optimized firstly,and then the effects of single and compound water treatment agents on coagulation were investigated.In addition,the effects of agents on optimum dosing amount of coagulant were investigated and flocculation obtained under different conditions was analyzed by SEM.The results showed that the optimized dosages of PAC and PAM were 40 mg/L and 0.8 mg/L,respectively,and the optimal operating conditions were fast stirring for 3 min at 300r/min and slow stirring for 10 min at90r/min,under which the coagulation effect of blow-down water was best and turbidity removal rate reached 93.49%.Polyaspartic acid（PASP）had a greatest influence on coagulation of blowdown water and residual turbidity raged from 0.85 to 1.78 nephelometric turbidity unit（NTU）,while dodecyl dimethyl benzyl ammonium chloride（1227）had a greatest influence on the optimum amount of PAC,which ranged from 20 to 70mg/L.Residual turbidity was greater than 0.98 NTU at the existence of compound agents.According to SEM photos,the difference in microstructures of flocculation from blow-down water at different coagulation conditions led to different coagulation effect.