Over the past few years I have become an academic expert in "sewage sludge" – the residual, semi-solid mix of excrement packed with microorganisms that is left behind within wastewater treatment plants. Every year the UK alone produces approximately 1.4m tonnes of the stuff. About 80% of it is spread on fields as manure, but this still leaves us with a headache – what do we do with the rest?
* This article was originally published here
