Preparation of Composite Flocculant (Polyferric Silicate Sulfate and Chitosan) and Its Application in Wastewater Treatment

An inorganic polymeric composite flocculant polyferric silicate sulfate(PFSS) and assistant flocculant chitosan(CTS) have been prepared. Factors that influence the synthesis and applications of the flocculants have been investigated. The composition, dosage and pH value have been discussed in terms of treating the municipal wastewater. The optimal conditions of synthesis and application have been achieved by the flocculation test of simulated wastewater and municipal wastewater. The results show that the molar ratio of Fe/Si is 1, the basicity of PFSS is 1.5, pH of the polyferric sulfate(PFS) is 2, the activating time of the polysilicate(PS) is 1.5 h; the mass ratio of PFSS/CTS is 5∶1, the dosage is (20+4) mg/L, the range of pH is 6 to 9, the sedimental time is 15 min. The turbidity, chromaticity, and COD removing rate of composite flocculant PFSS-CTS reached 95.04%, 91.26%, and 83.45%, respectively, under optimized conditions.