Combined polyferric sulfate coagulation with fenton pretreatment for antibiotic fermentation wastewater

The combined, polyferric sulfate (PFS) coagulation with Fenton was investigated for the pretreatment of non-degradable antibiotic fermentation wastewater. The experimental results indicated that 62.21% of COD was removed and the ratio of BOD5/COD (B/C) increased from 0.25 to 0.53, under the optimum conditions of pH 4, coagulant dosage 200mg/l, stirring time 12min and settling time 1h. In addition, optimal conditions of Fenton process were determined to be Fe2+ concentration of 1.2g/L, H2O2 dosage of 0.5g/L, pH of 3 and reaction time of 3h. Up to 87.57% of the final COD removal efficiency and 0.86 of B/C were achieved. Owing to the residual Fe 31 ions of PFS coagulation effluent, the subsequent Fenton process actually was consist of Fe2+/Fe3-/H2O2 system. From the circle OH characterization by means of Electron paramagnetic resonance (EPR), it was believed that Fe2+/Fe3+/H2O2 system could produce more circle OH than Fe2+/H2O2 system.