Assessment of bio methanation from cattle manure through continuous stirred tank reactor (CSTR)

Abstract

This study explores biogas production through anaerobic digestion of cattle manure (CM) in a Continuous Stirred Tank Reactor (CSTR), employing a Response Surface Methodology (RSM) to optimize conditions for enhanced methane yield. Cattle manure, a primary substrate in biogas generation, holds untapped methane potential due to its high fibre content, which remains only partially degraded in typical single-phase CSTR systems. Experiments were conducted under controlled mesophilic conditions to compare biogas outputs with and without stirring mechanisms. Key variables, including volatile solids (VS), volatile fatty acids (VFA), total alkalinity (TA), and pH, were monitored and optimized using a Box-Behnken design. Results demonstrated that stirring increased methane yield significantly up to 0.4713 m³/kg VS, attributed to uniform microbial activity and enhanced degradation of organic matter. Statistical analysis via ANOVA confirmed the regression model's reliability, showing significant factors influencing biogas production. This study’s findings underline the efficiency of serial CSTR configurations and optimized operating conditions for sustainable biogas production.