Behaviour of nitrogen during liquefaction of dewatered sewage sludge

The behaviour of nitrogen compounds during the liquefaction of dewatered sewage sludge was examined. After liquefaction (at 150–350°C), the product mixture was separated into oil A (water-soluble), oil B (water-insoluble), aqueous phase and solid residue. Partition of nitrogen to oil occurred at > 150°C. Above 150°C, 60% of the nitrogen in the sewage sludge was transferred to the aqueous phase. Solubilization and decomposition of the nitrogen compounds were promoted at 150°C. The distribution of nitrogen to oil B obtained by liquefaction at 300°C was 9%, whereas that to oil A was 11%.