Treatments of alkaline non-cyanide, alkaline cyanide and acidic zinc electroplating wastewaters by electrocoagulation

Treatments of alkaline non-cyanide, alkaline cyanide and acidic zinc electroplating rinse wastewaters were investigated in an electrocoagulation (EC) reactor using Fe plate electrodes. This is the first study involved with removals of zinc and cyanide together from three different wastewaters in the...

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Bibliographic Details
Published in:Process safety and environmental protection 2017-01, Vol.105, p.373-385
Main Authors: Kobya, M., Demirbas, E., Ozyonar, F., Sirtbas, G., Gengec, E.
Format: Article
Language:English
Subjects:
Acidic zinc
Alkaline cyanide
Alkaline non-cyanide
Alkalinity
Coagulation
Cyanides
Electrocoagulation
Electrodes
Electroplating
Industrial wastewater
Iron
Iron electrode
Operating cost
Operating costs
pH effects
Plating
Raw wastewater
Toxicity
Toxicity testing
Wastewater
Wastewater treatment
Water treatment
Zinc
Zinc plating wastewater
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Summary:Treatments of alkaline non-cyanide, alkaline cyanide and acidic zinc electroplating rinse wastewaters were investigated in an electrocoagulation (EC) reactor using Fe plate electrodes. This is the first study involved with removals of zinc and cyanide together from three different wastewaters in the literature. The effects of the operating parameters namely, initial pH (pHi), current density and operating time on the removal efficiencies were evaluated. The removal efficiencies and operating costs were determined as 99.8% for Zn and 0.74€/m3 at a pH of 7, 80A/m2 and 60min for alkaline non-cyanide, 99.9% for Zn, 99.9% for CN and 1.72€/m3 at a pH of 9.5, 60A/m2 and 60min for alkaline cyanide, and 99.9% for Zn and 2.26€/m3 at a pH of 8, 80A/m2 and 60min for acidic zinc electroplating wastewaters, respectively. Moreover, toxicity test was conducted to obtain information about the toxic effect of the raw and treated wastewaters. The toxicity results indicated that all the raw wastewaters contained hardly toxic effect (EC50 for acidic, alkaline cyanide and alkaline non-cyanide were 0.62, 5.25 and 3.38). On the other hand, the treated wastewater was non-toxic. This study revealed that the EC process with Fe electrode was very effective for removal of zinc and cyanide ions from different zinc electroplating rinse wastewaters.
ISSN:0957-5820
1744-3598
DOI:10.1016/j.psep.2016.11.020