Iron Based Bioflocculant, Preparation And Applied Research

Flocculation is an important technology in water treatment, and the effect of floculation is directly affected by its performance. Therefore, it is significant to synthetize a novel floculant with high efficiency, low-cost and low-toxicity.The iron-bioflocculant possesses a superior performance than traditional pharmaceuticalm, has been highly valued by academic and enterprises circles.In order to solve the problems of the previous preparation of flocculants, a new appoarch is employed to prepare iron-bioflocculant (BPFS), by using polmyer iron sulfate (FeSO4·7H2O) as raw material, through the catalytic oxidation action of Thiobacillus ferrooxidans. The method has vast application prospect because of low-cost, low-consumption and high stability.Thiobacillus ferrooxidans was naturally isolated from extremely acidic condition. The influence of pH, temperature, inoculation amount on its activity was studied.Results showed that the bacteria owns excellent oxidation activity when conditions were pH 2.0, temperature 30℃and 10% of inoculum.Based on the best cultivating domestication conditions (pH 2.0, (NH4)2SO4 dosage 3g/L, initial concentration of Fe2+ 9g/L), we acquired the high-efficiency bacteria which was cultivated through the optimal conditions:pH 1.5, (NH4)2SO4 dosage 0.5g/L, initial concentration of Fe2+ 45g/L. Under the optimal conditions, the BPFS product, with pH 1.5-2.2, basicity of 17.5%-22.7% and total iron content of 43.87-45.24 g, was obtained.By investigating the flocculation performance of BPFS, we found that pH had little effect on the flocculation efficiency. When dosage of BPFS was 1.25mL/100mL, pH of wastewater was 8, stirring velocity was 50-100r/min and sedimentation time was 20min, the removal of turbidity is superior to PFS and crassitude and close-grained floe was observed. The test of practice performance for sewage treatment shown that> 70% of COD in landscape water,>90% of decolorization for dyeing wastewater and> 99% in zinc containing wastewater can be accomplished, respectively. The flocculation efficiency of BPFS was better than that of PFS and PAC.The Infrared transmittance spectrum (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and GC-MS were employed to analysize the structure of BPFS. Results showed that this new flocculant was polyol.The volatile metabolin of BPFS contain ester, amides classes, alkane hydrocarbons and a small amount of alkaloids, benzene class, etc. By studying flocculating mechanism, it is found that the outstanding flocculation performance was owing to the cooperative effect of charge neutralization, absorbing and bridging network.