Effcet Study On Enhanced Coagulation Of Low Turbidity And Micro Polluted Water By Sludge Reflux In Waterworks

Lake and reservoir water is typical low turbidity micro polluted drinking water source,because of low concentration of particulate matter, small particle size and the collision and aggregation of low efficiency, resulting in poor coagulation treatment effect. In recent years, sludge reflux process widely used in production practice, this process can not only reduce the waste water discharge, but also can reduce the chemical dosage, so as to reduce the amount of sludge, reduce sludge disposal costs. Therefore, the sludge reflux process becomes a research hotspot in recent years.This paper studied polymerization aluminum chloride, aluminum chloride, ferric chloride, ferric sulfate and low turbidity micro polluted water treatment effect, and the effect of powdered activated carbon(PAC) and polyacrylamide(PAM) on the polymerization aluminum chloride coagulant effect. The results showed that ferric chloride, ferric sulfate coagulation effect is obviously better than that of poly aluminum chloride, aluminum chloride. Powdered activated carbon can effectively improve the removal rate of organic matter, while the removal of polyacrylamide(PAM) is more effective for the removal of turbidity.Study on the hydrolysis of poly aluminum chloride form for the effect of sludge reflux effect, and The effect of ferric coagulant sludge reflux. And the effect of turbidity, organics, reflux ratio and reflux position on the effect of the sludge reflux was investigated, and the process of the sludge reflux was optimized. The results showed that the zeta potential of the conventional process and sludge recirculatio n process of flocs is almost equal, but different mixed depressant effect of backflow differences, with the conventional process compared, to charge neutralization is mainly mixed flocculation mechanism of the PAC20(high Alb), after the sludge reflux, effluent turbidity increase, and to bridging adsorption is the main mechanism of Fe Cl 3 and PFS, effluent turbidity reduce, polymerization aluminum in A lc is to improve the effect of sludge return, return sludge process can ’t improve the removal efficiency of dissolved organic matter. The total dissolved residual aluminum content has a direct correlation with the content of Ala in the scoagulation process, and the sludge return is not caused by the accumulation of residual aluminum. When the sludge reflux position in coagulant dosing, the coagulation effect is obviously superior to other return position, when the sludge reflux ratio is 0.5, the effluent turbidity is lowest, and the turbidity of the effluent is higher than that of the non reflux.Through online image collection system of flocs were observed in real time, and mainly studies the polymerization aluminum hydrolysis species and aluminum and ferric salt sludge reflux on floc formation, breakage and flocculation,floc particle size distribution effects. Studies have shown that: containing the content of Al b high polymerization aluminum(B=2) flocs slow growth and the formation of floc size small, is not conducive to the settlement of flocs, but the strength of the floc, dense structure, with a high content of Alc after hydrolysis agent, due to the molecular weight and strong ability to bridge, forming floc particle size is large, but the floc. The floc strength low. Return sludge flocs was broken, the flocs occur as a result of failure, decline and flocculation ability, floc breakage by bridging coagulant, can make it together again. Compared with the conventional process, the strength of the sludge is reduced, the recovery factor of the coagulation factors is related to the coagulant.