Sludge drying leads to organic nitrogen mineralization

Abstract

Sludge drying leads to volatisation and removal of part of nitrogen contained in sludge. Removed nitrogen is usually condensed and recirculated to activated sludge process. It is assumed that mass of volatised nitrogen is equal to mass of soluble nitrogen in sludge. However results obtained from full-scale drying facility shows that mass of volatised nitrogen is 100% higher than mass of soluble nitrogen. It is suspected that nitrogen mineralization occurs due to high temperature maintained in dryers (> 220°C). These results are important as higher mass of nitrogen in condensate makes its removal economically reasonable. This paper shows results of nitrogen mass balance of full-scale drying facility.