强化混凝去除尖针杆藻

嘉陵江水系藻类暴发,水源水中的藻类在水厂前处理工艺中难以去除,造成该流域附近10余个水厂发生滤池堵塞现象,其中个别水厂滤池反冲洗周期由正常情况的24 h缩短至2~3 h,严重影响净水厂的正常运行,使得制水能力大幅降低。针对藻类(优势藻为硅藻中的针杆藻)暴发问题,通过对比PAFS、PAC和PFC3种混凝剂的除藻除浊效果,选取PAFS为最佳混凝剂;通过添加预氧化剂和助凝剂强化混凝除藻效果,其结果表明,使用助凝剂PDMDAAC的对PAFS的助凝效果最好,其余药剂结合PAFS的除藻效果为PPC>ClO2>PAM>H2O2>HCA-1,并将其应用到现有水厂,结果表明,0.6mg/L PDMDAAC+25 mg/L PAFS在水厂混凝沉淀,尖针杆藻含量降至49×104~55×104cells/L,其除藻率可达70%~75%,大大减轻了滤池的运行负荷,使得水厂运行恢复到正常水平。

Removal of synedra acus by enhanced coagulation

Because of the algae outbreak in Jialing River water system, the algae in source water was hard to be removed in pretreatment process, which caused more than 10 water factorties' blockage in filter and shorten the backwashing cycle from normal 24 h to 2 h. It seriously affected normal operation and dramatically decreased the producing ability of waterworks. Due to the algae outbreak (the dominant species was synedra acus belonging to Diatoms), the effect of PAFS, PAC, and PFC coagulants on algae removal and turbidity removal was compared, with PAFS presenting the best effects, which was chosen as the optimal coagulant. In addition, different pro-oxidations and coagulant aids were added to enhance flocculation removal effects of algae, the result showed that PDMDAAC combined with PAFC gave the best effect, and other promoting coagulation effect was PPC>ClO₂>PAM>H₂O₂>HCA-1. Using 0.6 mg/L PDMDAAC+25 mg/L PAFS applied to exising plants, the residual algae decreased to 49×10⁴~55×10⁴ cells/L, the algae removal rate could reach up to 70%~75%, which greatly reduced the operation load of the filter and recoved the normal operating mode of the waterworks.