STARTUP AND INITIAL OPERATIONS OF THE NEW COKE PLANT WASTEWATER TREATMENT SYSTEM AT USS GARY WORKS

U. S. Steel (USS) designed, constructed, and started up a new wastewater system for contaminated flushing liquor treatment at its Gary Coke Operations in Gary, Indiana. The plant was placed into operation in late 1998. It treats a wastewater flow of 250 gpm from the second largest coke plant in North America. The treatment facilities consist 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 about 3,000 mg/L are treated in the biological system. Each of the two activated sludge tanks has in Integral Clarifier and anoxic and aerobic zones to accomplish nitrification, denitrification, and secondary clarification in a single tank. Excess sludge is dewatered on a belt filter press and recycled by application to the coal used for cokemaking. This paper will review the design basis for the plant, present startup and operating experience, and summarize “lessons learned” as a result of implementing this treatment approach, which is believed to be one of the more unique and novel found in the coke by-products industry today.