Efficiency and Cost of the “Fenton+Recapter” Combined Process for Treating the Electroplating Nickel Wastewater

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Abstract The aim of this work was to investigate the “Fenton+Recapter” combined process for treating electroplating nickel wastewater. Firstly, five commonly used dithiocarbamate heavy recapters (DTC types) were compared and selected through trial tests. Then, the optimization of the sole Fenton process was carried out, including the dosing molar ratio of Fe2+/H2O2, the dosage of H2O2 and the reaction time. At last, the optimization and cost analysis of the combination process was carried out to meet the nickel wastewater treatment standards and to determine the optimal fit point. The experimental results showed that DTC-2 was a more suitable heavy recapter, with advantages of wide pH adaptation range (3.0-11.0), strong anti-interference, fast Ni removal rate, and low cost (1.20 ¥/t). The optimal molar ratio of Fe2+/H2O2 in the sole Fenton process was determined to be 0.8, which resulted in the optimum breaking effect and a 98.5% removal rate of Ni. The optimization of the combined process parameters showed that when the dosage of heavy recapter DTC-2 (1%) was 0.08 mg/L, 0.19 mg/L, 0.5 mg/L, 1.25 mg/L, 7.5 mg/L, and 25 mL/L respectively, the residual concentration of Ni in Fenton effluent was 0.2 mg/L, 0.3 mg/L, 0.5 mg/L, 0.7 mg/L, 1.0 mg/L, and 1.5 mg/L, which all could meet the discharge standards (concentration of Ni ≤0.1 mg/L). The best fit for the “Fenton+Recapter” combined process was to first treat nickel wastewater with Fenton until the Ni concentration was about 1.0 mg/L, and then use heavy recapter DTC-2 to capture and treat the wastewater until it meets the standard discharge. Under this condition, the treatment cost of the combined process was the lowest (7.79 ¥/t).

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