Cofiring biosolids in a spent sulfuric acid regeneration facility

In a process for regenerating spent sulfuric acid by dissociation of the spent acid in a furnace into its constituents--sulfur dioxide, water and oxygen, followed by recovery of sulfur dioxide, oxidation of sulfur dioxide to sulfur trioxide and hydration of sulfur trioxide to form sulfuric acid a process for improving the dissociation step comprising:

• conditioning dewatered biosolids from municipal or industrial wastewater treatment containing from about 70% to about 85% water by mixing together in a reaction zone the dewatered biosolids and at least a portion of the spent sulfuric acid for a period of time of from about 0.5 to about 5 hours thereby enhancing breakdown and combustion of said biosolids at the temperature of the furnace;
• introducing the spent sulfuric acid and conditioned dewatered biosolids mixture, air enriched to contain greater than 21% oxygen, and a fuel into said furnace maintained at a temperature of from about 1800.degree. to about 2000.degree. F;
• and
• controlling the quantity of spent sulfuric acid, the quantity of conditioned biosolids, the quantity of fuel and the degree of oxygen enrichment of said air to effect complete dissociation of said spent sulfuric acid and incineration of said biosolids.