Reuse of sludge waste in Electro-Fenton:Performance and life cycle assessment

Abstract

To address aggravating environmental and energy problems, the harmless treatment and resource utilization of waste has become an inevitable choice. In this study, we report a highly efficient and low-carbon reuse approach of coagulation sludge waste based catalysts for electro-Fenton(EF) process to treat wastewater. The results showed that the relative amount of iron element in flocs increase gradually along with the growth in coagulant dosage, the main composition of floc is iron-HA complex and the interaction force acting between them was weak complexation. According to evaluation by electrochemical characterization, the selectivity of sludge electrodes for hydrogen peroxide in Oxygen Reduction Reaction (ORR) process was more than 40%. Without add additional Fe2+, the as-prepared cathode material is able to achieves 98.7% bisphenol A (BPA) pollutant removal from wastewater within 130 min treatment due to its highly active two-electron reduction of oxygen (O2). Based on life cycle assessment (LCA) results, compared to traditional sludge disposal, the raw sludge used for EF could reduce fossil resource consumption by 73.7% and carbon emissions by more than 97.1%. The coagulation sludge applied in the field of EF in this paper proposes a novel and reliable way of collaborative treatment of sludge and sewage pollutants, and has certain guiding significance in environmental treatment and sludge recycling.