The South Shropshire biowaste digester, UK

Abstract

The South Shropshire biowaste digester is designed to recycle 5000 t per year of source-segregated household kitchen waste and green garden waste. This waste, collected at the kerbside, is transformed into renewable electricity and biofertiliser. It is one of nine full-scale projects funded by the UK Department for Environment, Food and Rural Affairs (Defra) to demonstrate technologies that enable biodegradable municipal waste to be diverted from landfill. Previous research, over a period of eight years leading to the biowaste digester, concentrated on the anaerobic digestion of food waste, which is able to contribute to the positive reduction in the emission of greenhouse gases in a number of different ways. As a renewable energy technology, anaerobic digestion is unusual in that the overall net reduction in the emission of carbon dioxide is greater than simply the carbon dioxide emissions from the fossil fuels that it displaces; however, apart from its application on sewage works and in landfill sites, the process is not yet widely applied in the UK. The project met the necessary permitting requirements and construction started in June 2005. The first biowaste was processed in March 2006 and the plant is operating at 50% of its design throughput. The first year of operation has shown that the quality of the biowaste is very different from that anticipated, in particular with a low capture of food waste. This issue is being addressed in order that the project can demonstrate the effective role that anaerobic digestion can play in the UK's future waste management strategy.