Combining electrocoagulation-flotation with anaerobic digestion for faecal sludge treatment: Micropollutant removal with simultaneous energy recovery.

Faecal sludge (FS) management in most developing countries remains inadequate. This study investigates the integration of electrocoagulation-flotation (ECF) with anaerobic digestion (AD) for sustainable FS treatment. A continuous-flow ECF reactor using iron electrodes was optimized across varying current densities (40-200 A/m2) and residence times (13-264 s) to assess the removal of heavy metals and organic micropollutants, including bisphenol A (BPA), 17α-ethynylestradiol (EE2) and carbamazepine (CBZ). The system achieved up to 99 % removal of Pb and Zn, 96 % of Cd, and notable reductions in micropollutants: 58 % EE2, 44 % BPA and 37 % CBZ. ECF treatment resulted in efficient dewatering within 26 s at 120 A/m2, concentrating nutrients and organics. Subsequent AD experiments showed enhanced methane yield from ECF-treated FS, reaching 292 mL CH4/g VS at a feedstock/inoculum VS ratio of 0.5. ECF-AD integration enables efficient pollutant removal, waste volume reduction and enhanced renewable energy recovery-supporting circular, sustainable FS management.