Synergistic Enhancement of Biogas Production via Thermophilic Co-Digestion of Food Waste and Cheese Whey in a Continuous Stirred Tank Reactor

Abstract

The increasing demand for sustainable energy sources and the simultaneous generation of vast quantities of organic waste pose significant environmental and energy challenges worldwide. Anaerobic digestion (AD), a microbial-mediated process that converts biodegradable waste into biogas, offers an environmentally sound and cost-effective solution. This study investigates the thermophilic co-digestion of food waste (FW) and cheese whey (CW), two high-organic-load substrates, in a batch-fed Continuous Stirred Tank Reactor (CSTR). The co-digestion process aimed to evaluate synergistic improvements in methane yield, reactor stability, and process efficiency. Comprehensive physicochemical characterization of both substrates was performed to optimize substrate ratios. Experimental trials under controlled thermophilic conditions (52 ± 1 °C) revealed that co-digestion outperformed mono-digestion in terms of biogas production, methane concentration, pH stabilization, and COD reduction. Statistical analysis confirmed significant differences in performance among experimental setups. The findings highlight the potential of integrating food industry by-products into anaerobic digestion systems, promoting waste valorization, renewable energy generation, and a circular economy.