A review of flammable gases from human waste sludge as a potential source of energy

For well over five decades, the world has experienced a significant population and urbanization growth rates and therefore resulting to an exponential surge in the demands of the natural resources like energy, water, land, and food, all of which not subjected to infinite growth. Increasing urbanisation has increased environmental challenges, that are associated with managing waste and emissions as part of global sustainable development objectives. This has become more important to contemplate different sustainable strategies to produce and utilise energy as well as manage waste. Based on a number of studies, one of the potential renewable sources of energy is the use of flammable gases generated from waste in human sewage system but this potential source of energy, which correlates with the human population, has not been effectively exploited as a renewable source due to the technological gap, economical obstacles, and regulations barriers. This paper analyzes and establishes the sewage system critical elements with effective potential of breaking down the organic matters in human waste to efficiently produce and extract flammable gases such as methane that can be used as an effective energy source. It also reviews the mathematical modelling of fermentation process to quantify of methane production in sewage system. This paper contributes to analysis the critical parameters that can directly effect on methane production and presents obstacles in implementing biogas from sewage systems. This technology can be improved to move towards the worldwide carbon footprint reduction.