Performance evaluation of a bipolar electrolysis/electrocoagulation (EL/EC) reactor to enhance the sludge dewaterability

► This study explores the efficiency of the EL/EC reactor for sludge dewaterability. ► Maximum reductions in CST and SRF were observed at 20min and 30V. ► A maximum sludge disintegration of 2.5% was achieved by the reactor. ► Electrocoagulation helped to achieve a higher degree of sludge disintegration. ► Electrocoagulation also maintained a desired degree of sludge dewaterability. The present study aimed to evaluate the performance of a bipolar electrolysis/electrocoagulation reactor designed to enhance the sludge dewaterability. The reactor was 15L in volume, with two series of plates used in it; Ti/RuO2 plates for the electrolysis of the sludge, and also aluminum and iron plates for electrocoagulation process. The dewaterability of the sludge was determined in terms of its capillary suction time (CST) and specific resistance to filtration (SRF), while the degree of sludge disintegration was determined based on the value of degree of sludge disintegration (DDSCOD). The maximum reduction in CST and SRF was observed at a detention time of 20min and a voltage of 30V. However, increasing of both detention time and voltage significantly increased the values of CST and SRF even to an extent that they both exceeded those of the untreated sludge. The optimal degree of sludge disintegration achieved by the present study was 2.5%, which was also achieved at a detention time of 20min and a voltage of 30V. As reported previously, increased DDSCOD values led to increasing CST and SRF values, due primarily to the disruption of the sludge flocs. According to the results from the present study, it can be concluded that simultaneous application of electrocoagulation and electrolysis is effective in enhancing the sludge dewaterability, because electrocoagulation helps to achieve a higher degree of sludge disintegration while maintaining the desired sludge dewaterability.