Evaluation of the Co-anaerobic Digestion of Food and Garden Wastes in a Two-Stage Pilot System

Purpose: The treatment and final disposal of municipal solid waste (MSW) can be an issue from environmental and social perspectives. In the search for MSW treatment technologies, anaerobic digestion (AD) emerges as a strategic technology to treat and convert solid organic waste into energy (biogas/methane). Thus, several advances have been proposed to reduce complexity and increase AD feasibility, such as Co-AD and two-phase AD. Accordingly, this work aimed to examine the efficiency of biogas production from Co-AD of food waste (FW) and garden waste (GW) in a two-phase pilot system. Methods: To test the two-phase Co-AD of FW and GW in a pilot system under mesophilic conditions at different hydraulic retention times (HRT: 2 and 3 days) and organic loading rates (OLR: 4, 6, 8, and 10 kg_VS/m³/d). Results: The highest biogas and CH4 production was achieved with an HRT and an OLR of 2 days and 6 kg_VS/m³/d, respectively. The removal of total solids, total organic carbon, total nitrogen, phosphorus, and chemical oxygen demand was 68%, 27%, 45%, 22%, and 69%, respectively. Conclusion: Co-AD of FW and GW through biogas/methane production in two phases represents a promising approach for the valorization of these wastes.