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Electrocoagulation for printing ink wastewater treatment

Performance of electrocoagulation (EC) for minimizing the organic content of printing ink wastewater was investigated using either aluminum or iron electrodes. The process conditions varied included current density, conductivity, and pH of the treated wastewater. With both electrode materials, at an adjusted initial pH of 5.0 and conductivity of 1050 mS cm-1 and applied current of 1.0 A, it was possible to remove up to 90 % of the organic content in less than 5 minutes, thereby obtaining neutral water with turbidity less than 1 NTU. Furthermore, EC combined with chemical oxidation (i.e., in situ formed Fenton’ s reagent) gave improvements over a single EC process due to larger TOC reduction, up to 94 %, with complete color and turbidity removal at a pH of treated water between 6 and 7. It was shown that the crucial process parameter besides conductivity was the initial wastewater pH. The initial pH was optimized by taking into account electrode corrosion, i.e. the spontaneous dissolution of the sacrificial electrode materials. The initial pH of 5.0 was found to be superior to lower values. Through comparison of the results for coagulation and coagulation followed by adsorption or oxidation, the combined EC/oxidation process was found to be an effective alternative method for the treatment of such wastewater, and this system exhibited many advantages over traditional processes.

electrocoagulation (EC) ; chemical oxidation ; printing ink wastewater

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