Efficient degradation of m-cresol during catalytic wet peroxide oxidation with biochar derived from the pyrolysis of persulfate-ZVI treated sludge.

Sludge dewatering is crucial for cutting the cost of sludge post-disposal in wastewater treatment plants. Response surface methodology (RSM) was used in this study to sufficiently investigate the interaction among persulfate, zero-valent iron (ZVI) and reaction time on the sludge dewatering. Under the experimental condition at the central point in RSM, the sludge moisture content was reduced to 54%. The sludge-based biochar obtained from the pyrolysis of persulfate-ZVI treated sludge at the central point in RSM was marked as SC-M and tested for catalytic activity. With the catalyst SC-M, the removal rates of m-cresol and total organic carbon (TOC) were 98.1% and 84.2%, respectively. The persulfate-ZVI treatment for sludge dewatering facilitated increasing the proportion of iron species in SC-M, which contributed to its high catalytic activity. M-cresol degradation with SC-M was a two-period reaction including an induction period and a rapid reaction with the apparent activation energy at a low level. This study integrates the sludge dewatering by persulfate-ZVI treatment and m-cresol degradation by catalytic oxidation with the biochar SC-M prepared from the dewatered iron-rich sludge, providing an effective, economic and environment-friendly approach for sewage sludge utilization and management.