Partial oxidation of sewage sludge

An improved process for the low-cost disposal of noxious sewage sludge in a safe way without polluting the environment. In the process, sewage sludge having a solids content of about 0.5 to 20 wt.% is concentrated by pressing in a belt filter press, optionally followed by pressing in a high intensity press. It was unexpectedly found that the morphology of the resulting dewatered sewage sludge is changed by such mechanical treatment so that slurries with higher concentrations of solids are achieved. The dewatered sewage sludge is heated, flash evaporated and/or centrifuged, and mixed with a supplemental fuel e.g., liquid hydrocarbonaceous and/or solid carbonaceous fuel to produce a pumpable fuel slurry having a total solids content in the range of about 50 to 70 wt.% and comprising about 10 to 40 wt.% dewatered sewage sludge and having a higher heating value in the range of about 5,000 to 14,000 BTU/Lb. The fuel slurry may be reacted by partial oxidation in a conventional gasifier to produce synthesis gas and/or fuel gas. The thermal energy in hot byproduct steam and flue gas streams are used to heat the dewatered sewage sludge. In one embodiment, the pumpable slurry of dewatered sewage sludge and supplemental fuel is burned by complete combustion in a furnace or incinerator for the production of steam.