Advanced treatment of bio-treated effluents of printing and dyeing wastewater using sub-micron CaO2/Fe2+ oxidation

The sub-micron CaO2/Fe2+ oxidation system was successfully applied in the advanced treatment of bio-treated effluents of printing and dyeing wastewater, and effectively removed the main disinfection byproduct (DBP) precursors. Operating at FeSO4·7H2O dosage 1.0 g L-1, n(CaO2/Fe2+) 8:1, pH 4.0 and reaction time 1.5 h, about 84.2% of chemical oxygen demand (COD), 82.1% of colority were removed and an increase of the survival rate of Daphnia magna from 20% to 45% was achieved. The degradation of bio-treated effluents of printing and dyeing wastewater by sub-micron CaO2/Fe2+ oxidation system was described by a pseudo second-order kinetic. Compared with the protein-like extracellular organic matter and soluble microbial products (SMPs), fulvic acid-like substances and humic acid-like substances were more easily removed using the oxidation system. The effluent quality meets the reuse of urban recycling water-water quality standard for industrial uses (GB/T 19923-2005, in Chinese).