PRODUCTION OF HEAVY OIL FROM SEWAGE-SLUDGE BY DIRECT THERMOCHEMICAL LIQUEFACTION

As one economical solution to the sludge disposal problem, direct thermochemical liquefaction was studied. A demonstration plant with a capacity for processing up to 5 t/d as dewatered sludge was operated at a condition of high temperature and high pressure (300 degrees C, 10 MPa). As a result, about a half or the organic materials in the sludge (48 % maf) were converted into heavy oil and a quarter of the heavy oil synthesized (11 % maf) were separated from the reaction mixture by high pressure distillation. Heating values of the heavy oils distilled were 37-39 MJ/kg. From the calculation of energy balance on a practical scale, it was estimated that 1.5 t/d of separated heavy oil could be produced as surplus energy through the treatment of 60 t/d of dewatered sewage sludge.