Evaluation of Various Biomass Feedstocks for Biogas Generation at Psychrophilic and Mesophilic Temperatures at Higher Altitudes of Nepal

Abstract

This study aimed at testing the feasibility of different animal manures as a substrate for biogas production at psychrophilic and mesophilic temperatures. Anaerobic digestion of animal manure at psychrophilic and mesophilic temperatures has not yet been explored in the higher altitudes in Nepal (> 3,000 meters above sea level), probably due to less effective biogas yield as cold temperature retards the growth rate of the microbes responsible for anaerobic digestion. A lab-scale anaerobic digester was constructed to run on a continuous mode process. Methane production from five different substrates, i.e., cow dung, horse dung, sheep dung, human feces, and co-digestion (combination of those substrates) was conducted at four different temperatures, i.e., 10°C, 17°C, 30°C, and 40°C, for three months. The study assessed the type of feed used in anaerobic digesters for biogas production at different temperature ranges. The results obtained reflected that the highest biogas yield potential lied in sheep dung followed by cow dung and then a combination of substrates in all the four temperatures. This study provided scientific evidence for establishing a waste based technology at higher altitudes for the production of biogas to address challenges in the energy sector and promote sustainable development.