滤池反冲洗水回流强化混凝低浊微污染水特性

Strengthen of coagulation for light pollution water with low turbidity by recycling of backwash water from filter

以低浊微污染配水为研究对象,通过调整PACl投药量来控制絮体Zeta电位,考察不同混凝特性下滤池反冲洗水(FBWW)回流对混凝效能的影响。结果表明:Zeta电位接近-11mV时,FBWW回流对浊度具有良好的去除效果,沉后水浊度最大去除率为63.81%,高于其他电位下FBWW回流处理效果,沉后水中残余AlP含量最低(0.271mg.L-1)。但此阶段下过高的回流(12%)会导致水中PACl的额外消耗,使原水颗粒物难以获得足够的混凝剂而脱稳,致使浊度、CODMn、AlP、AlD等上升。Zeta电位接近0mV时,FBWW对浊度、CODMn、UV254、AlP均有良好的处理效果,AlD同时也能保持相对较低的值。当回流比在9%时,沉后水CODMn去除率达试验最高值34.21%。Zeta电位接近+4mV时,FBWW回流导致浊度、CODMn、AlP、AlD大幅上升,而UV254去除率得到提高。回流比为12%时,这种趋势最为明显,UV254去除率达试验最高值60.67%。通过对砂后水与沉后水有机物残余进行研究对比,沉后水与砂后水有机物的去除效果存在明显差异性,+4mV下UV254、CODMn去除率均高于其他电位。

This study focuses on distribution of light pollution water with low turbidity,by adjusting dosage of polyaluminum chloride（PACI）to control floc zeta potential.Influence of backwash water（FBWW）with different coagulation characteristics from filter on coagulation efficiency was also investigated.The results show that FBWW is of good efficiency on turbidity removal as zeta potential close to-11 mV.The maximum removal rate for settled water was 63.81%,and it was higher than that at other potentials by using this processing.And the lowest residual AlP content was found about 0.271 mg·L^-1 at this potential.However,excessive backflow（12%）can lead to additional consumption of PACl in this stage,which makes particle matter in raw water to obtain sufficient coagulant difficult and the system to lose stabilization,and so,turbidity,CODMn,AlP,AlD,etc.goes up.When zeta potential is close to 0 mV,the FBWW is also of good effect on CODMn,UV254 and AlP,and AlD can stay in a relative low value as well. If reflux ratio is 9%,the removal rate of CODMn can reach the highest test value,about 34.21%.When zeta potential is placed at close to ＋4 mV,the reflux of FBWW can cause substantial increase of turbidity,CODMn,AlP and AlD,while removal efficiency for UV245 is improved.This trend was most obvious for the backflow ratio about 12%,at which the highest test value of UV254（60.67%）is obtained.By comparing residual organic matters in filtered and settled water,a significant difference between these organic matters is found.The removal rates of UV254 and CODMn were higher for the filtered water at ＋4 mV.