How can methane from sewage sludge be used at a wastewater treatment plant?

At a wastewater treatment plant, methane is produced as a beneficial by-product of anaerobic digestion, a biological process where microorganisms decompose organic sludge solids in the absence of oxygen.12

Once captured, this methane—a primary component of biogas—is typically utilized on-site to improve the facility's energy efficiency and reduce operating costs. Common applications include:12

• Heat Generation: The methane is burned to provide heat for the digestion tanks themselves, which helps maintain the specific temperature ranges required for the bacteria to function efficiently.12
• Electricity Production: The gas is used as fuel in combustion engines or turbines to generate electricity for the plant’s operations.123

By capturing and using this methane, treatment plants prevent it from being flared or vented directly into the atmosphere, where it would otherwise contribute to global warming. In some advanced systems, such as those utilizing thermal hydrolysis prior to digestion, the increased production of biogas can even make a wastewater treatment plant energy self-sufficient.132