Electrocatalytic membrane-driven ozonation to reconstruct the extracellular polymeric substance for enhanced sludge dewatering

Abstract

Modern wastewater treatment plants safeguard water environment but generate enormous waste activated sludge (WAS), posing significant environmental risks. Conventional WAS conditioning methods require intensive chemical dosages to alter EPS structures, leaving behind heavy metal ions and polymeric residues that complicate subsequent disposal processes. Herein, we proposed an electrocatalytic membrane (EM) system integrating O₃ aeration with catalytic ozonation, achieving a 47.2 % improvement in sludge dewatering properties. Reactive oxygen species (ROS) with redox potentials ranging from 0.33 to 2.70 V vs NHE were generated and ensured efficient sludge conditioning. Moderate oxidation was achieved by regulating the O₃ dosage (8.21 mg/g VSS), which reconstructed the extracellular polymeric substance (EPS) while avoiding excessive release of TB-EPS and intracellular organic matters arising from cell lysis. The increased protein/polysaccharide ratio and hydrophobicity of the sludge contributed to the enhanced dewatering performance. Moreover, Fe residuals from the catalyst were effectively reduced during the EM-facilitated electrocatalytic ozonation of the sludge, making it ideal for subsequent disposal and reuse. This approach provides a green solution for sludge conditioning, minimizing oxidant dosage and heavy metal residuals, representing a critical step in advancing wastewater treatment toward low-carbon, sustainable resource recovery.