Abstract:A novel inorganic polymer flocculant, poly-ferric sulfate (BPFS) was prepared by oxidation of ferrous sulfate using domestic Thiobacillus ferrooxidans (T∙f) under acid condition. The optimal conditions for the preparation were pH value of 1.5, (NH₄)₂SO₄ dosage of 0.5 g/L, initial Fe²⁺ concentration of 45g/L, inoculum 10%, rotating speed of 120 r/min, reaction time of 5−6 d and reaction temperature of 30 °C. Under the optimal conditions, the BPFS product with pH value of 1.5−2.2, basicity of 17.5%−22.7% and total iron content of 43.87−45.24 g/L was obtained. The application of the BPFS to three wastewaters was carried out, and the removal efficiencies of COD, decolorization and Zn²⁺ by BPFS can be reached 70%, 90% and 99%, respectively. The result suggests that the BPFS is an excellent flocculant for water treatment.

Key words: ferrite; poly-ferric sulfate; flocculant