Study On The Preparation And Performance Of High-silica Polysilicate Aluminum Sulphate Flocculant

Flocculation is one of the most important steps in water processing, because it affects the performance of following flows, the treated water quality and the cost. So it has becoming the most important field of application in environmental engineering. The urgent task is to research and develop a new-type inorganic macromolecular flocculants of high-efficient, nonpoisonous and low-price, and this is an important subject being paid most attention in the worldwide water treatment at present.Cationic metal-polysilicate complexes being studied in this article is a new category of inorganic polymer flocculants. This flocculants have been focused to this coagulants study because of its high flocculent effect, low price and widely application in various water processes. And it is expected to replace the expensive organic polymer coagulants which were often suspected of being dangerous to human.The preparation technique of HSPSAS was introduced in this paper. The parameters of the process were discussed by the method of orthogonal design, such as molar ratio of Al/Si, the pH of polysilicate, the aging time of polysilicate, the pH of PSAS, the aging time of PSAS, intake of PSAS, and so on, and then an optical technology was obtained. Based on these conditions, the paper fixes the key experiment on the preparation of high-silica polyaluminum silicate flocculants and its flocculent effect in water treatment.Liquid high-silica polysilicate aluminum cannot become a commercial production because of its low stability, although it has high flocculent effect. The experiment analysed the factors that impact the stability of this flocculants, and found that this problem can be solved by lowering the storage temperature, decreasing the concentration and adding proper stabilizer. The test provided a significative and effective explore in improving the stability of this flocculants.The HSPSAS was found to be more effective than PAC in the removal of COD and TP by comparison treating 4 sorts of surface water, dyeing wastewater, and tap water using these two flocculants respectively.According to the national standard, the quantity of Al³⁺ and SiO₂ in the wastewater were tested. The result show that the quantity of Al³⁺ and SiO₂ remained in treated water is lower than 0.2mg/L, which meets the World Health Organization'sstandard.At the end of the experiment, flocculent mechanism of HSPSAS and function model of aluminum salt & polysilicate was analyzed initially.