Aerobic digestion of municipal solid waste in Durham, UK

An in-vessel aerobic digestion plant has been in operation at the Thornley waste transfer station in County Durham, UK, since January 2002. Until recently the plant consisted of two aerobic digestion towers with a total capacity in excess of 30 000 t per annum; it processes unsegregated municipal solid waste (MSW) resulting in a diversion rate of over 70% of its input weight from landfill. This type of process is commonly referred to as mechanical and biological treatment (MBT) and is attracting significant interest from local authorities as an alternative to mass burn incineration and landfill disposal. In contrast to some other MBT systems, this system is configured to optimise conditions for maximum degradation of the biodegradable components of MSW commonly referred to as biodegradable municipal waste (BMW). While the current plant has been in operation for 4·5 years, assistance was sought from the UK Department for Environment, Food and Rural Affairs under the New Technologies Demonstrator Programme to support additional research and development with the aim of enhancing the process.