Sludge-to-energy systems can make the circular economy a reality by turning waste into a resource, and here is how: wastewater treatment plants separate sewage into solid “sludge” and liquid water. This methane – rich sludge then undergoes two processes – thermal hydrolysis and anaerobic digestion – to quickly and efficiently remove pathogens and harness biogas. The resulting biogas can then be used as on – site energy to power the wastewater treatment plant, or can be purified further and sold as natural gas. In addition, the solid digestate left over after anaerobic digestion can be used to enhance soil.

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