• Anaerobic biodegradability;
  • Biological sludge;
  • Box–Wilson experimental design;
  • Fenton pre-treatment;
  • Floc disintegration


Fenton process was investigated for the purpose of biological sludge disintegration. The Box–Wilson experimental design was employed to evaluate the effects of major process variables (Fe(II) and H2O2 concentrations) on both disintegration and dewatering performance of sludge. Results showed that 4 g Fe(II)/kg total solids (TSs) and 60 g H2O2/kg TS are efficient for floc disintegration. Fenton pre-treatment enhanced the biodegradability of sludge. For 4 g Fe(II)/kg TS and 60 g H2O2/kg TS, 19.4% higher methane production was achieved compared to raw sludge in biochemical methane potential assay. Fenton pre-treatment resulted in the release of organic sludge components into the liquid phase. For 4 g Fe(II)/kg TS and 60 g H2O2/kg TS, dissolved organic carbon and total nitrogen in sludge's supernatant increased by 75.74 and 60.60%, respectively. Fenton pre-treatment enhanced the filterability of sludge and it can be applied for conditioning purpose before mechanical dewatering units.