Study On Coagulating Property Of Inorganic Polymer Flocculants

Coagulant was one of the key factors affecting the efficiency of coagulation process. Alum was the most frequently applied traditional coagulant in the world. During the past decades, inorganic polymer flocculants (IPFs) have been developed rapidly and applied widely. Among them, polymer aluminum chloride (PAC) was one of the typical products and its efficiency was proved to be superior to the traditional coagulations. Alum in PAC was divided into three forms including Ala(monomer), Alb(oligomer and polymer), and Alc(sol-gel or colloidal hydroxides) with Al-Ferron reaction kinetics. Simulative and practical water were managed with Ala, Alb, and Alc by using jar test, the removal efficiency by coagulation was researched , the floc structure (particle diameter,particle size distribution,and fractal dimension) was investigated with the Malvern Mastersizer 2000, moreover, the mechanisms of coagulation was employed. The results demonstrated that Ala, Alb, and Alc performed differently owing to their contributions to the particle destabilization and aggregation. The high efficiency of PAC was also indicated by the floc size and structure results, with great size increase and rather compact flocs were observed for hydroxyl polymer aluminum flocculants. When the dosage of total Al was identical, Alb was as much as Alc on the removal efficiency, Ala was inferior to the others.Researches on the speciation, structure of different Al flocculants, and flocculation mechanism of various components, in order to develop new coagulation process and IPFs with higher efficiency. PACS originating from reaction between PAC and anionic polymer silica acid in given condition was a novel flocculant. However, PACS instead of PAC applying in the ninth water treatment plant was not confirmed, still be short of practical research. PACS was utilized in the jar and medium-sized test,the flocculent efficiency in practical water was researched, the results indicated that PACS in the process of adsorption and bridging was better than PAC, not only consolidate the capability of Alb making colloid granule destabilization and improving floc sedimentation performance, but also enhance turbidity and colloid granule removal, save dosage of the flocculants about 50 percents. Besides, PACS was similar to PAC on filtration pond of head loss and filtration period.