Preparation And Study Of A New Composite Flocculant

In the various methods of wastewater treatment, flocculation is one of method is in common use. So flocculants are the important materials in wastewater treatment. The study of safety, high efficiency, low consumption and non-second pollution flocculants is the main research direction of flocculants. The composite flocculants are one of important development trends in future. In the study, AlCl3·6H2O、ZnCl2and PAM have been used as the materials to make a new inorganic-organic composite flocculants zinc-based composite flocculant.In the preparation of the zinc-based composite flocculant, the paper discusses various factors that influence the flocculent performance of zinc-based composite flocculant.Besides, the paper also discusses the methods to improve stability of zinc-based composite flocculant. Meanwhile, the paper discusses the technical conditions which influence the flocculent effect of zinc-based composite flocculant, and compared with poly ferric sulfate (PAC) and polyaluminum chloride(PFS) in the flocculation performance.In the zinc-based composite flocculant preparation research foundation, a response surface analysis was applied to optimize the best operating condition of zinc-based composite flocculant, its result as follows(weight%):zinc chloride optimal dosage is11.4%, aluminum chloride optimal dosage is11.2%, polyacrylamide optimal dosage is0.0157%and hydrochloric acid optimal dosage is3.1%. The factors of zinc chloride dosage and aluminum chloride dosage have more effect than polyacrylamide dosage on flocculation of the zinc-based composite flocculant, and hydrochloric acid dosage has no effect on flocculation. The paper studies on the amount of stabilizer. The results show that the best amount of stabilizer (weight%) is0.005%.With zinc-based composite flocculant to processing the coking wastewater and dying wastewater, we determined zinc-based composite flocculant in the pH value was10has the good flocculation performance. And wastewater temperature has little effect on flocculent perfonnance of zinc-based composite flocculant. The best amount of zinc-based composite flocculant to processing the coking wastewater is1.2ml/L Turbidity removed rate and COD removed rate may respectively achieve98.1%and76.02%. when zinc-based composite flocculant processing the dying wastewater, The best using amount is1.6ml/L. Turbidity removed rate and COD removed rate may respectively achieve95.0%and85.69%. When processing the dying wastewater and the coking wastewater, it has the bettertflocculation performance than polyferric sulfate (PAC) and polyaluminum chloride(PFS).The paper analyzes initially the flocullent mechanism of zinc-based composite flocculant with electron microscopy, zinc-based composite flocculant achieves flocculation mainly by compressing the electric double layer, charging neutralization action and absorption bridging action, accompanied by volume sweep precipitation simultaneously.The research result show:zinc-based composite flocculant has the good processing effect to the industrial wastewaters, it presents the very good application value.