The predominant source of lead and cadmium in baghouse dust or scrubber sludge is the scrap metal used for casting. To reduce the level of these contaminants, one must identify the incoming source and arrange to acquire charge material which contains lower concentrations. A charge modification program at a large foundry was successful in reducing the lead and cadmium levels in their waste to below EP-Toxicity values (Stephens 1988). Due to the higher cost of high grade scrap and the difficulty of obtaining a reliable and continuous source, most foundries are not able to economically employ this method.
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