Large-scale application of nutrient recovery from digested sludge as struvite

Struvite precipitation for nutrient recovery from wastewater and sewage sludge has been attracting interest, due to the remarkable fertiliser quality of the product. A method to recover struvite from digested sludge was developed at Stuttgart University, involving first an acidic dissolution of nutrients from digested sludge followed by a precipitation step. The application was first tested in a pilot scale plant and recently upscaled to a semi-industrial size by constructing a recovery plant at a municipal wastewater treatment plant. The study reports on the technical features and the operation of the large-scale plant with a short overview on the pathway leading to the construction, as well as quality of the product.