Physicochemical Characteristics and Potentials of Kitchen Food Waste, Untreated Food Effluent, and Cow Rumen Content as Substrates for Biogas Production via Anaerobic Digestion

Anaerobic digestion (AD) stands as a promising solution for organic waste management and renewable energy production. However, its effectiveness relies on substrate selection and an understanding of biogas production dynamics. Hence, the objective of this paper was to evaluate the physicochemical characteristics and potential of kitchen food waste (KFW), untreated food effluent (UFE), and cow rumen content (RC) as substrates for biogas production via anaerobic digestion (AD) using appropriate standard methods. Substrates were physicochemical characterized and monitored over 35 days for biogas yield, pH variation, and nutrient dynamics. The co-digestion biodigester yielded the highest cumulative biogas volume (13000.97 ml/kg VS), followed by RC (11708.97 ml/kg VS), KFW (8360.29 ml/kg VS), and UFE (4522.26 ml/kg VS). The highest total organic carbon (TOC) removal (97.47%) was recorded in the RC biodigester. Microbial analysis revealed viable anaerobic bacteria ranging from 1.26–2.44 × 10⁴ CFU/g in KFW, 1.5–6.4 × 10³ CFU/mL in UFE, and 2.93–5.71 × 10⁴ CFU/mL in RC. Biogas production was significantly influenced by substrate composition and digestion time (p < 0.05). Changes in nitrate, phosphate, and TOC concentrations confirmed active microbial metabolism and nutrient utilization. These findings highlight the efficiency of co-digestion in enhancing biogas yield and promoting sustainable organic waste management.