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ID/8/a2 MINNESOTA'S HAZARDOUS WASTES The amount of hazardous waste generated varies constantly, depending on production levels at manufacturing plants, and changes in product lines and manufacturing methods. Current estimates are based on two sources: disclosures submitted by waste generators to the Minnesota Pollution Control Agency and the Metropolitan Counties under the State hazardous waste rules, and an estimate based on industry -specific information gathered in other states. From these sources, we estimate that approximately 200,000 tons per year of hazardous wastes are generated in Minnesota --and as much as 3/4 of this comes from the seven -county Metro area. However, no one company is responsible for a significant portion of the waste stream, and over 2500 waste generators have been identified by the regulatory program. The wastes generated in Minnesota can be divided into a number of categories based on their physical and chemical characteristics. The principal categories of wastes we generate are: 1) HEAVY METALS AND INORGANIC RESIDUALS. This is the largest category, and reflects the predominance of the electronic, primary metal, and fabricated metal product industries in Minnesota. What are the wastes? They include spent electroplating and etching baths, rinse waters from electroplating, sludges from these operations, and other acid and alkaline solutions used in the manufacture of metal products. Why are theZ hazardous? Certain metals commonly used in these industries chromium, cadmium, nickel) are toxic. If they are placed in a sanitary landfill, they can contaminate groundwater. If they are sewered, as many wastes currently are, they can disrupt sewage treatment plant operations and contaminate the sludge from these plants, making this sludge harder to dispose of safely. Some plating operations use toxic "complexing agents" such as cyanide or sulfide. Acidic and alkaline solutions are corrosive. How should these materials be handled? Chemical treatment of these wastes is relatively easy and is a well -established procedure. Cyanides can be readily destroyed (many generators do this on -site). Toxic metals can be precipitated (converted to solid compounds) and separated from wastewater, which can then be sewered. The resulting precipitate may require disposal in a secure landfill. Acids and bases are easily neutralized. What facilities does Minnesota need? The need for treatment facilities is perhaps most acute in this category of wastes. Currently, many of these wastes are ser;ered, but pretreatment regulations which are taking effect will result in the need for facilities to treat the wastes. Anaqueous treatment plant which provides neutralization, cyanide destruction, chromium reduction, and metal precipitation is one of the most effective ways to handle these wastes. Residues from this facility could require secure landfill at another location. A metal recovery plant which recovers metals from wastewaters for reuse i aTso possible --the Twin Cities Metal Finishers Association is studying the feasibility of such a facility. (over)