As a result of recent developments in the area of hazardous waste management, the U.S. Environmental Protection Agency is evaluating the performance of various technologies for the treatment and/or the destruction of certain wastes that are presently being disposed of in landfills and surface impoundments. As a part of this program, the University of Cincinnati is testing currently available treatment technologies that are applicable to metal- and cyanide-bearing hazardous wastes at the U.S. EPA Test and Evaluation Facility in Cincinnati, Ohio. The following unit processes have been evaluated: alkaline chlorination, lime precipitation/flocculation/setting, multi-media filtration, anion exchange, and cation exchange. Examination of several process configurations, utilizing the above-mentioned unit processes, did not produce any treatment train that could prevent codeposition of cyanides and metals in the sludges when the feed stream contained mixed metals and complexed cyanides. It was also determined that special anion exchange resins are capable of removing the complexed cyanides that are not destroyed by alkaline chlorination. Concentration of each of the metals in the final effluent from the cation exchange unit was less than 0.4 mg/L.
