Start-up and Initial Operations of the New Coke Plant Wastewater Treatment System at U.S. Steel Gary Works

摘要

U.S. Steel designed, constructed and started a new wastewater system for contaminated flushing liquor treatment at its Coke Operations in Gary, Ind. The plant commenced operation in late 1998 and treats a wastewater flow of 250 gallons per minute from the second largest coke plant in North America. The treatment facility consists of oil/tar separation, equalization, steam distillation for removal of free ammonia and acid gases, and activated sludge nitrification and denitrification. After steam stripping, total nitrogen concentrations of approximately 3000 mg/l are treated in the biological system. Two activated sludge tanks, each with an integral clarifier and anoxic and aerobic zones, accomplish nitrification, denitrification and secondary clarification in a single tank. Excess sludge is dewatered on a belt filter press and recycled (applied on coal for cokemaking).Start-up and operational experience on this unique coke plant wastewater treatment system at Gary proved the design to be capable of rapid start-up, good performance and easy operation.