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DTIC ADA1020666: Treatment of Plating Wastewaters by Ferrous Reduct... |
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by Defense Technical Information Center |
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Current practice in treatment of mixed metal wastewaters |
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containing hexavalent chromium consists of acidic (pH |
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approx. 3) chromium reduction followed by alkaline, metal- |
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hydroxide precipitation; a two-stage process. A single- |
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stage process could reduce capital and operation costs. |
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Synthetic chromium, cadmium, and nickel wastewaters were |
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successfully treated by ferrous sulfate and sodium |
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sulfide in a single cell reactor at alkaline pH (7-10), |
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thus clarifying conflicting reports in the literature. |
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Batch tests were performed to study this process. Solids |
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were removed by membrane filtration. Metal residuals were |
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analyzed by atomic absorption spectrophotometry. Chromium |
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was rapidly and stoichiometrically reduced by ferrous |
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sulfate. Sodium sulfide by itself negligibly reduced |
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chromium, and was no better than hydroxide in |
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precipitating cadmium and nickel. However, in combination |
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with ferrous sulfate, sulfide improved chromium reduction |
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and metal removal. Alkalinity, EDTA and cyanide |
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interfered with chromium reduction and metal removal; |
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calcium hardness counteracted these interferences. |
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(Author) |
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Date Published: 2019-12-15 07:01:51 |
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Identifier: DTIC_ADA1020666 |
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Item Size: 35599425 |
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Language: english |
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Media Type: texts |
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# Topics |
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DTIC Archive; Higgins,Thomas E ; ARIZ... |
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