전기펜톤공정을 이용한 석유화학공장 폐활성슬러지의 감량화 가능성 평가

Abstract

The reduction of excess activated sludge from petrochemical plant was investigated by the electro fenton (E-Fenton) process using electrogenerated hydroxyl radicals which lead to mineralization of activated sludge to CO2, water and inorganic ions. Factors affecting the disintegration efficiency of excess activated sludge in E-Fenton process were examined in terms of five criteria: pH, H2O2/Fe2+ molar ratio, current density, initial MLSS (mixed liquid suspended solids) concentration, H2O2 feeding mode. TSS and TCODcr reduction rate increased with the increasing H2O2/Fe2+ molar ratio and current density until 42 and 6.7 mA/cm2, respectively but further increase of H2O2/Fe2+ molar ratio and current density would reduce the reduction rate. On the other hand, as expected, increasing pH and initial MLSS concentration of activated sludge decreases TSS and TCODcr reduction rate. The E-Fenton process was gradually increased during first 30 minutes and then linearly proceed till 120 minutes. The optimal E-Fenton condition showed TSS (total suspended solids) reduction rate of 62∼63% and TCODcr (total chemical oxygen demand) reduction rate of 55∼56%. Molar ratio H2O2/Fe2+ = 42 was determined as optimal E-Fenton condition with initial Fe2+ dose of 5.4 mM; and current density of 6.7∼13.3 mA/cm2, initial MLSS of 7,600 mg/L and pH 2 were chosen as the most efficient E-Fenton condition.