Introduction

The U.S. Environmental Protection Agency IEPA) Is interested in evaluating technologies for their capability to recover metals from sludges and wastewaters. Section 3004 of the Resource Conservation and Recovery Act (RCRA), as amended by the Hazardous and Solid Haste Amendments (HSWAJ of 1984, restricts the disposal of RCRA-regulated hazardous wastes in or on the land. The land disposal prohibitions are waived if the hazardous wastes intended for disposal are treated such that they do not exceed a maximum concentration of hazardous constituents set by EPA or if the wastes are treated using a treatment method set by EPA. Also, HSWA authorizes waiving the disposal of untreated hazardous wastes if facilities seeking disposal of untreated wastes can demonstrate to the Administrator that the hazardous constituents of wastes intended for disposal will not migrate from the disposal site as long as the waste remains hazardous. The EPA publishes these land disposal restrictions in the 40 Code of Federal Regulations (CFR) Part Z68,

The amendments to RCRA specify dates by which land disposal restrictions are to take effect for specific hazardous wastes. The Land Disposal Restrictions for the first third, the second third, and the last third of scheduled RCRA Wastes identify treatment methods and standards that must be met before these listed wastes can be land-disposed. The first third rules were finalized In August 1938, the second third rules were finalized in June 1989, and the rules for the last third were proposed in late 19B9 and finalized in May 1990. This report presents information on the state of the art of metals recovery technologies to support EPA's Office of Solid Waste in identifying waste-management options for the recovery of metal-bearing sludges and wastewaters that «ay Pe regulated under RCRA. Waste treatment technologies (e.g., chemical precipitation) that could eventually result in recovery of specific metals are also included in this report. The focus of this report is on established rather than emerging technologies in order to provide useful information on Innediately available technologies to industry.

This report covers nine major metal-waste-producing industries: 1) metal coatings; 2) smelting and refining of nonferrous metals; 3) paint, ink, and associated products; 4) petroleum refining; 5) Iron and steel manufacturing; 6) photographic industry; J) leather tanning; 8) wood preserving; and 9) battery manufacturing. These industries were selected because of the high metal concentrations associated with the sludges and wastewaters generated by plants within each of these Industry segments. Section 2 of this report characterizes the wastes generated by these industries and addresses current waste-management practices.

Metals recovery technologies addressed in this report include the following: chemical precipitation, electrolytic recovery, high-temperature metals recovery (HTMR), membrane separation, leaching, adsorption, and evaporation. For each of these technologies, Section 3 presents a discussion of the following parameters: 1) design specifications of applicable processes, 2) waste characteristics affecting performance, 3) pretreatment/post-treat-ment requirements, 4) available performance data, 5) availability of the technology and feasibility for treating wastes addressed in Section 2, 6} environmental impact/residue management, and 7) cost-effectiveness. Ongoing research projects In the area of metals recovery, such as those being conducted by the U.S. Bureau of Mines, are also highlighted.

Section 4 summarizes the conclusions of this study with respect to the applicability of different technologies for potential treatment of various sludges and wastewaters. A glossary of technical terms is provided at the end of this report.

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