THE FIRST COMMERCIAL SUPERCRITICAL WATER OXIDATION SLUDGE PROCESSING PLANT

Final disposal of sludge continues to be one of the more pressing problems for the wastewater treatment industry. The problems associated with land application, which is one of the preferred disposal methods, include health hazards, concentration of metals in soils, and competing uses for available land. Supercritical Water Oxidation (“SCWO”) provides an alternative method that addresses the health concerns associated with sludge disposal by completely converting all organic matter in the sludge to carbon dioxide, water, and other innocuous materials. A Supercritical Water Oxidation system using HydroProcessing, LLC's HydroSolids® process has been installed at Harlingen, Texas to process up to 9.8 dry tons per day of sludge. This system is the largest Supercritical Water Oxidation system in the world, and the only one built specifically to process sludge. Shakeout and startup of Unit 1 of two SCWO units has been accomplished over the last 5 months. The unit achieves greater than 99.9% destruction of COD in a sludge thickened to 6–8 wt.% solids. Harlingen Waterworks System estimates that the HydroSolids system will cost less than other alternatives such as Autothermal Thermophilic Aerobic Digestion and more traditional forms of digestion that still require dewatering and final disposal. The Waterworks plans to generate income from the sale of energy in the form of hot water and the use of carbon dioxide from the HydroSolids process for neutralization of high pH industrial effluent. The Waterworks also expects to generate income from the treatment of septage and grease trap wastes.