Author: Barry G. OliverPublisher:
ISBN:
Category : Heavy metals
Languages : en
Pages : 76
Book Description
The electrochemical plating of Cu, ln, Ni and Cd from aqueous solutions has been studied using standard plate type electrodes and improved efficiencies were attained with fluidized bed electrodes. Because direct electroplating from sludge was found to be inefficient, acid and base additions were made to solubilize the metals prior to plating. Little economic advantage wou1d be gained by recovering sludge constituents, since processing costs for the large volumes of dilute leachate would be high. Therefore, the removal of heavy metals from wet sludge to reduce their toxicity does not appear to be economically feasib1e. The meta1s and phosphorus in sludge incinerator ash can be solubilized with H2S04 in a countercurrent stepwise process which uses most of the acid. Further processing of the H2S04 leachate for recovery of va1uable constituents is complicated by the presence of large quantities of iron in the leachate. Neutra1ization of the leachate with NaOH precipitates all the metals and phosphorus. Electroplating can remove Cu, ln, Ni and Cd from the ammonia, leach and ammonium phosphate can be recovered from the solution after electrolysis. While processing costs for incinerator ash are much less that those for wet sludge, the procedure does not appear to be economically viable except for very large treatment plants.
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