Enhancing Methane Generation in Sewage Systems Through Sewer Pipe Design Optimisation

Municipal solid waste management presents significant environmental challenges, with the organic fraction of municipal solid waste (OFMSW) contributing notably to greenhouse gas (GHG) emissions. Sewage systems offer a unique opportunity to harness methane as a renewable energy source.
This paper investigates methane generation in sewer systems through numerical modelling of anaerobic digestion processes using MATLAB, with a focus on two-phase flow in gravity-enhanced sewer systems.
A sewer pipe model, with radius ranging from 0.4 m to 1.8 m and a length of 1 meter, was analysed under different conditions. Methane production averaged 1.37 m³ per day when the pipe was 50% full (as illustrated in Figure 3) corresponding to approximately 13.4 kWh of energy. Elevated sewage temperatures further enhanced methane recovery. The model also examined factors influencing methane production, including sewage temperature, velocity, pressure gradient, pipe length, slope, and diameter.
The findings demonstrate the substantial energy potential within sewage systems, with methane generation capable of supplementing household energy needs.
This paper contributes to the development of waste-to-energy technologies by optimising sewer pipe design and operation, which can help mitigate methane emissions and support global efforts to reduce GHG emissions. The results underline the potential of integrating methane recovery into renewable energy strategies, offering a sustainable solution for urban energy needs.