Study on anaerobic co-digestion of cow dung and fruit waste for biogas production

Abstract

Aim/Background: The declining availability of fossil fuels cannot meet the increasing global energy demands and contributes significantly to greenhouse gas emissions, worsening global warming. Additionally, poor management of organic waste, including livestock and food scraps, poses environmental pollution risks. Anaerobic co-digestion (AnCoD) of livestock waste and food scraps offers a sustainable solution, producing renewable biogas while minimizing ecological impact. This study aims to evaluate whether co-digesting cow manure (CM) with fruit waste (FW) in varying ratios can enhance biogas production and methane quality. 

Methods: This experimental study was conducted using five batch anaerobic digesters (each with a 5 kg capacity) under mesophilic conditions (37°C) over a 14-day retention period. The digesters, labeled Case-1 through Case-5, contained different CM-to-FW ratios: 1:1, 4:1, 1:4, 3:2, and 2:3. Pretreatment of substrates was performed prior to digestion, and critical process parameters such as temperature, pH, and biogas volume were monitored throughout the study. 

Results: Among all tested ratios, Case-2 (4:1 CM to FW) demonstrated the highest biogas yield, achieving a methane concentration of 49%. The results indicated that proper substrate proportioning significantly influences the efficiency of anaerobic digestion. Additionally, the process remained stable under mesophilic conditions, with favorable pH levels throughout the experiment. 

Conclusion: This study confirms that the AnCoD of CM and FW under mesophilic conditions is a promising strategy for enhancing biogas production. The findings highlight that substrate composition plays a critical role in determining biogas yield and methane quality.

Keywords: Anaerobic digestion, anaerobic co-digestion, bioenergy, biogas, renewable energy, Synergistic effect