Synergistic optimization of electrochemical and garbage enzyme pretreatments enhances anaerobic co-digestion kinetics and energy recovery from landfill leachate and sludge

The present study focus on synergistic effects of electrochemical oxidation (EO) and garbage enzyme (GE) pre-treatment on enhancing the biodegradability index of landfill leachate (LL) and improving methane production, with particular emphasis on energy recovery. The research was conducted in three sequential phases. First, EO was applied to increase the biodegradability of LL, while evaluating key operational parameters including current density, electrode spacing, and reaction time. Second, a biological fermentation reactor was used to generate extracellular enzymes—namely amylase, protease, and lipase—from organic waste. Third, an anaerobic digestion reactor was operated under mesophilic conditions (37 °C) with a 24-day incubation period to promote methane generation. In addition to methane production, anaerobic reactor performance, methane yield, and overall energy balance were systematically assessed. The results demonstrated that the highest methane yield (0.35 L/ g sCOD removed ) was achieved in reactor R2, which was fed with 35% (v/v) LL pre-treated using EO and supplemented with 10% (v/v) GE. Correspondingly, R2 exhibited the greatest energy output, reaching 27.95 kJ/g VS removed . Compared to control reactors pre-treated with EO alone, anaerobic reactors receiving combined EO and GE pre-treatment showed an increase in energy efficiency ranging from 0.5 to 2.57 kJ/g VS removed . Overall, findings indicate that the integration of EO and GE as pre-treatment strategies, followed by anaerobic co-digestion, represents a promising strategy for enhancing biogas and energy yields from LL in anaerobic co-digestion reactors and maximizing energy recovery.