Heavy metals, Metal trade, Metal work
A study was performed involving the leaching characteristics of three synthetically-generated metal finishing sludges. Three precipitates (one hydroxide, two sulfide-based) containing varying concentrations of cadmium, copper, lead, nickel and zinc were dewatered and subjected to an EPA-regulated limits. The sludge generated from an insoluble sulfide process exhibited the fewest parameters in violation (two), while the soluble sulfide sludge had one metal in compliance and the hydroxide sludge had none. On a metal-by-metal basis, the lead and copper exhibited the greatest capacity to withstand resolubilization in a low pH (5) environment. Nickel and zinc were present at the highest leachate concentrations in all three sludges. Cadmium extraction concentrations varied. In conjunction with this study, a montmorillonite clay was combined with each sludge on a mass ration basis to discern metal attenuating effects under a low pH environment. The presence of the clay served to reduce metal leachate rates for two of the three sludge-types tested. However, neither sludge-type exhibited leachate concentrations below federally regulated limits. On a metal by metal basis, lead and copper were attenuated to the highest degree, nickel and zinc the lowest. The presence of clay in copper and lead-dominant sludges may serve to lower extract concentrations for both metals and possibly provide an opportunity to have the sludge(s) declared non-hazardous. Conversely, sludges consisting predominantly of nickel and/or zinc would require disposal in a secure landfill.
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Dietz, John D.
Master of Science (M.S.)
College of Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Cherniak, Christopher M., "Metal Leaching Characteristics of Three Synthetically Generated Metal Finishing Sludges" (1985). Retrospective Theses and Dissertations. 4845.