Treatment of Mid-Stage Pulping Effluent Using the Combined Process of Microelectrolysis and Fenton Oxidation-Coagulation

Abstract

Mid-stage Pulping Wastewater was pretreated in a combined system of microelectrolysis and Fenton oxidation-coagulation . When the aeration was 6L/min, the ratio of iron-carbon mass was 4/1, the addition of iron was 1500mg/L, pH was 4, and reaction time was 30min, the removal rates of COD and chrominance reached 65% and 60% respectively and the concentration of generated Fe2+ reached 157mg/L. Fe2+ generated by micro-electrolysis process was used for the following Fenton oxidation. When the conditions was without additional Fe2+, the addition of H2O2 (concentration is 30%) was 3mL/L, pH was 4, and the reaction time was 15min, the removal rates of COD and chrominance both reached over 80% and the concentration of generated Fe2+ reached 217mg/L. Fe3+ generated by Fenton oxidation was used for following studies of flocculation. The treatment efficiency of three kinds of flocculants PAM, PAC and silicate was compared. The results showed that the effect of PAM was best, the treatment efficiency reached the best when its additon was 0.15mL/L as pH was 7. the removal efficiency of COD reached 41% and the chrominance removal efficiency reached 75%, the final effluent chrominance was 4 and the COD concentration was 45mg/L which was lower than 60mg/L, that met with the first order of effluent standard.