Résumé : |
A total of 82 samples typical of leather industry solid waste materials was evaluated for chromium leachability by EPA Extraction Procedure Toxicity (EPT) and Toxicity Characteristic Leaching Procedure(TCLP) methods. These samples consisted promarily of wet blue leather trimmings and shavings, dry leather trim scrap, buffing dust and sludge. For acidic materials(pH<5) such as wet blue and dry leather wastes, TCLP extraction was 4-5 times more aggressive than EPT due to the complexing effect of acetate ion. The majority of such materials would exceed a regulatory threshold of 5.0mg/l if based on total Cr rather than CrVI. For alkaline sludge wastes, the difference in EPT and TCLP extraction was quite small, if indeed significant, and a majority of samples was below 5.0mg/l. Chromium leachability from dry leather waste was substantially lower than wet blue, despite higher solids content. Thus, leather drying appears to have a major beneficial effect. Efforts to analyze the effects of moisture level, chromium content and pH were inconclusive, and more work is planned to further clarify their role in chromium leachability. |