Enhanced sludge dewatering via synergistic electrochemical and sulfate radical-based oxidation: Performance and mechanism

Sludge dewatering is significantly important for wastewater treatment plants due to the demand for sludge volume reduction. Cell disruption is the key to enhancing sludge dewatering. This study explored the potential of electrochemical oxidation (EO) coupled with advanced oxidation for cell disruption. An electrochemical combined with sodium sulfite sludge (EOSS) pretreatment process has been developed. The results showed that the sludge dewatering ability has been greatly improved after being treated by the combined system. The capillary suction time (CST) of sludge was 10.7, and 19.9 for EO and EOSS, respectively. The final sludge water content was reduced to 47.8% after being pretreated by EOSS, respectively. It was observed that EOSS pretreatment has led to the obvious reduction of sludge particle size and the increase of cell death ratio, chemical oxidation demand (COD), and lactate dehydrogenase (LDH) level. LDH, an inner material of cells, was detected in the leachate which indirectly indicates the cell lysis, as well as the COD increase. Hence, it suggests that EOSS is significantly efficient for cell disruption. The generation of •SO₄^- would have played a critical role in the cell disruption in the EOSS process. The proposed method in this study provides an alternative way of enhancing sludge dewatering.