Richards Model Accurately Captures Methane Production Dynamics from Human Feces

In a 31-day biomethane potential assay conducted at 35 ± 2 °C, cumulative methane yield from a mixed community-derived human feces substrate reached 247.48 ± 5.83 NmL CH4 g−1 VS. Approximately 90% of the total methane production occurred within the initial 15 days, reflecting relatively rapid production dynamics under batch conditions.

The research, published in Frontiers in Bioengineering and Biotechnology by investigators at the Defence Research and Development Establishment in Gwalior, India, examined human feces as an abundant bioresource for decentralized energy recovery. The authors noted that the compositional heterogeneity of the material makes methane yield predictability challenging, which complicates anaerobic digester design, startup behavior, and process optimization.

To characterize the dynamics of methane generation, the researchers coupled their experimental batch measurements with nonlinear least squares regression across six kinetic models. The evaluated frameworks comprised the Modified Gompertz, First-order, Logistic, Richards, Cone, and Transfer Function models.

Among the six formulations, the Richards model demonstrated the highest accuracy in fitting the experimental observations, achieving a coefficient of determination of R² = 0.9973. The Logistic and Modified Gompertz models followed in performance, whereas the First-order model exhibited comparatively poorer results due to the inability of its simple exponential formulation to represent the distinct lag phase observed before methane generation began.

The investigators concluded that selecting an appropriate kinetic model substantially influences the characterization of methane dynamics and the estimation of kinetic parameters critical to anaerobic digestion. While this comparative approach offers a practical framework for evaluating heterogeneous substrates, the authors emphasized that further validation across broader feedstock varieties and operating conditions remains necessary before guiding reactor design and operational optimization.

Subject of Research: Kinetic modeling of methane production from human feces

Article Title: A comparative experimental and kinetic modeling study of methane production from human feces: insights into methane production dynamics and engineering considerations

Article References: Arya, R., Meghvansi, M. K., Pal, V., & Goel, A. K. (2026). A comparative experimental and kinetic modeling study of methane production from human feces: insights into methane production dynamics and engineering considerations. Frontiers in Bioengineering and Biotechnology, 14, Article 1965030. https://doi.org/10.3389/fbioe.2026.1965030

Image Credits: AI Generated

DOI: 10.3389/fbioe.2026.1965030

Keywords: anaerobic digestion, biomethane potential, human feces, kinetic modeling, Richards model, methane kinetics, bioprocess engineering, decentralized sanitation, comparative, experimental, kinetic, modeling