Direct thermochemical liquefaction of sewage sludge was studied as one economical solution to the sludge disposal problem. A continuous plant, which was capable of processing up to 500 kg/d as dewatered sludge, was operated at temperatures of 270-300°C, pressures of 6-12 MPa and holding times of 0-60 min for more than 700 hr without any trouble. Organic materials in sludge were converted into heavy oil with 40-53 %maf yields, and 11-16 %maf of the heavy oil were continuously separated from the reaction mixture by high pressure distillation. Heating value and viscosity of the heavy oil separated were 38 MJ/kg and 0.05 Pa·s, respectively. From the calculation of energy balance ona practical scale, sludge liquefaction process was evaluated as a net energy producer. The disposal of wastewater discharged from sludge liquefaction process was also discussed.
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Research Article| September 01 1992
Direct Thermochemical Liquefaction of Sewage Sludge by a Continuous Plant
Water Sci Technol (1992) 26 (5-6): 1175–1184.
S. Itoh, A. Suzuki, T. Nakamura, S. Yokoyama; Direct Thermochemical Liquefaction of Sewage Sludge by a Continuous Plant. Water Sci Technol 1 September 1992; 26 (5-6): 1175–1184. doi: https://doi.org/10.2166/wst.1992.0559
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