Low-cost Enhancement of Biogas Production from Cow Dung using Ash and Inorganic Additive Mixtures

Increasing fossil fuel costs and environmental impacts have intensified the need for renewable energy solutions such as biogas and hydrogen. Biogas, produced through anaerobic digestion of organic waste, is a promising option but is constrained by limited methane yield. This study addresses the limitations of low biogas yield in biogas production by optimizing anaerobic digestion with supplemental additives. Batch experiments under ambient and controlled mesophilic (37 ± 1 °C) conditions were conducted with cow dung as the primary substrate, and supplementary additives were evaluated. To enhance biogas yields, chemical additives (FeCl₃, NiCl₂, CaCO₃, and urea) and cow dung ash were used, along with higher mesophilic temperature. The novelty of this work lies in examining the combined effect of inorganic additives as a mixture on the rate of biogas production, as well as comparing the influence of a higher operating temperature, inorganic additive mixtures, and cow dung ash on total cumulative biogas production. Results showed that a chemical mixture (FeCl₃, NiCl₂, urea, CaCO₃) boosted biogas output by 40%, while cow dung ash (5 g/L) supplementation increased production by nearly 50%. These findings suggest that tailored additive blends or ash can significantly enhance biogas generation through trace mineral supplementation, pH stabilization, and improved microbial activity. By leveraging locally available ash and low-cost additives, this approach provides a scalable, economically viable strategy for rural biogas systems. Overall, this research delivers practical and cost-effective methods to augment biogas yields from biomass, offering a model for sustainable and circular energy solutions.