The wood-preserving process involves bath soaking and steam/vacuum drying of lumber and plywood. Preservatives used include creosote, chlorophenolic compounds, and inorganic arsenical and/or chromate salts. This industry generates approximately 719 Kg/yr of sludges (F032, F033, F034, F03S) containing chromium, copper, arsenic, and lead. It should be noted that these sludges are not currently listed as RCRA hazardous wastes, but are proposed for listing. The most prevalent current practice for managing these sludges is landfilling. Liquid wastes such as those from cooling towers are treated on-site by chromium reduction and precipitation with lime, hydrogen sulfide, or sodium sulfide. The wood-preserving industry uses 20 percent of all arsenic consumption, as approximately 90 percent of wood preservatives are in the form of chrome/copper arsenate.
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