Assessment of Biomethanation from Cattle Manure Through Continuous Stirred Tank Reactor (CSTR)

This study explores biogas production through anaerobic digestion of cattle manure (CM) in a Continuous Stirred Tank Reactor (CSTR), using 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 fiber content, which is only partially degraded in typical single-phase CSTR systems. Experiments were conducted under controlled mesophilic conditions to compare biogas outputs with and without stirring. 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 showed that stirring significantly increased methane yield to 0.4713 m3 .kg-1 VS, attributed to uniform microbial activity and enhanced degradation of organic matter. The findings also show that intermittent stirring improves methane yield by 34.36%, achieving a peak value, and offer practical insights into energy-efficient alternatives to continuous mixing, with direct implications for scaling up industrial biogas systems. Statistical analysis via ANOVA confirmed the regression model’s reliability, identifying significant factors influencing biogas production. This study’s findings underscore the efficiency of serial CSTR configurations and optimized operating conditions for sustainable biogas production.