| A great quantity of literature about the recent achievement on coagulatien-flocculation mechanism and the research progress on inorganic polymer flocculants were reviewed. Based on the comparison of coagulation-flocculation performance between inorganic polymer and organic polymer flocculants, a new type of composite flocculants was given.Three kinds of cationic organic polymer flocculants (COPFs) with different electric density and molecular weight were compared, demonstrating the influence of electric density and molecular weight. Meanwhile this thesis studied on the characteristics of OPFs working as assistant flocculants in kaolin simulated suspending liquid.The thesis also researched the application of composite flocculants. Firstly, utilize composite flocculants to decontaminate papermaking wastewater, as a result , the composite flocculants obtained lower turbidity, color and total organic carbon with higher coagulation-flocculation effectiveness. Secondly, contrasted the efficacy between composite flocculant PACS with PAC on pilot-scale experiment with coagulation-precipitation-filtration process in the Ninth water supply plant Beijing. The outlet water treated by composite flocculant PACS had more efficiency and advantages, lower and steady turbidity, lower dissolved organic carbon, fewer number of particles.A newly developed optical monitoring technique coupling with the conventionaljar test was applied to investigate the behavior of polyaluminum chloride (PAC) and three kinds of cationic organic polymer flocculants (COPFs). Discuss the characteristics of floe structure breakage and regrowth, while, utilize the strength factor and recovery factor to illustrate the character of floe.
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