Thermal hydrolysis sludge pretreatment

Abstract Conventionally, anaerobic digestion (AD) of sewage sludge proceeds in large tanks with long hydraulic retention times and limited volatile solids reduction. To improve volatile solids reduction (and methane production) and reduce digester volumes, thermal hydrolysis is increasingly implemented as a pretreatment with installations in more than 22 countries on 5 continents with over 120 plants. The technology combined with AD has been commercially operational at full scale since 1995 and has demonstrated increased digestion loading rate, improved biodegradation (especially for activated sludge), and enhanced dewaterability.