Abstract: A hydrothermal process (10) is integrated into a wastewater treatment facility (12) to fully oxidize an undigested wastewater sludge produced by the treatment facility. A thickened and conditioned feed mixture comprising sludge from the treatment facility is first pressurized to a critical pressure and then heated to a reaction initiating temperature below the critical temperature. An oxidant is injected into the feed mixture at the reaction initiating temperature to initiate an oxidation reaction in low light-off temperature constituents of the feed mixture to produce a partially reacted mixture and raise the temperature of the partially reacted mixture to at least the critical temperature for water in a supercritical water oxidation reactor (52). Heat from the supercritical water oxidation reaction is used to heat the feed mixture and also, to condition the sludge from the wastewater treatment plant preferably by thickening and heating the sludge.

Abstract: A hydrothermal process (10) is integrated into a wastewater treatment facility (12) to fully oxidize an undigested wastewater sludge produced by the treatment facility. A thickened and conditioned feed mixture comprising sludge from the treatment facility is first pressurized to a critical pressure and then heated to a reaction initiating temperature below the critical temperature. An oxidant is injected into the feed mixture at the reaction initiating temperature to initiate an oxidation reaction in low light-off temperature constituents of the feed mixture to produce a partially reacted mixture and raise the temperature of the partially reacted mixture to at least the critical temperature for water in a supercritical water oxidation reactor (52). Heat from the supercritical water oxidation reaction is used to heat the feed mixture and also, to condition the sludge from the wastewater treatment plant preferably by thickening and heating the sludge.