EFFECT OF OPERATING PARAMETERS ON THERMOCHEMICAL LIQUEFACTION OF SEWAGE-SLUDGE

To determine the optimum combination of operating parameters for direct thermochemical liquefaction of sewage sludge, dewatered materials (raw mixed sludges) were treated over a temperature range of 150-300°C, a holding time of 0-180min and a catalyst (sodium carbonate) loading of 0-5wt% using a batch reactor. By variance analysis, the lower limit of reaction temperature for the production of heavy oils was found to be 250°C. At that temperature, however, organic concentrations in the aqueous phase were still high. From the viewpoint of oil production and wastewater treatment, the optimum combination of operating parameters was a reaction temperature of 275-300°C, a holding time of 60 min and operation without catalyst. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.