Material and C/N flow analyses of alternative sludge pretreatment technologies for recovering carbon sources for denitrification

Abstract

Sewage sludge can serve as a carbon source for denitrification after pretreatment and hydrolysis. However, existing technologies have various technical routes and performances for carbon recovery and nitrogen release. To evaluate the abilities of different technologies to recover carbon sources, material and elemental flow analyses were performed by parameterising and balancing the sludge compositions and conversion coefficients based on 139 datasets. Technological routes with alkali/thermal and alkali/H2O2/microwave treatments statistically achieved the highest yields of volatile soluble solids, and those with thermal and mechanical treatments dissolved the most nitrogen during pretreatment. The technological route with alkali/thermal treatment achieved the highest effective carbon source of 191 g/kg of initial total solid on average when the potential carbon consumption by the yielded soluble total nitrogen and phosphorus was subtracted. This study provides important statistical evidence for the development and comparison of alternative technologies for recovering carbon sources from sludge for denitrification.