An innovative method for fractionally removing high concentrations of Ni2+, PO43−, TP, COD, and NH4+-N from printed-circuit-board nickel plating wastewater

Abstract

In this study, we employed an innovative method to fractionally reduce high concentrations of nickel (Ni2+), PO43−, total phosphorus (TP), chemical oxygen demand (COD), and ammonia nitrogen (NH4+-N) from printed-circuit-board nickel plating (PCBNP) wastewater, a hazardous waste. The removal efficiencies of Ni2+, PO43−, TP, COD, and NH4+-N from PCBNP wastewater using electrochemical deposition, CaO-enabled complex dissociation, and Fenton oxidation as well as the removal mechanism were studied. The results revealed that Ni2+ was removed in the process of electrochemical precipitation; NH4+-N and fractions of TP and COD were removed in the complex dissociation process using CaO; and COD and TP were removed in the Fenton process. The removal efficiencies of Ni2+, PO43−, TP, COD, and NH4+-N were respectively 99.99%, 99.97%, 99.70%, 98.16%, respectively, and 99.43%, when the current density was 25 mA/cm2, CaO dosage was 12.5 wt%, and m(FeSO4·7H2O):m(H2O2) was 1:8. Ni2+ was mainly recovered as Ni-P during the electrochemical deposition process, whereas NH4+-N was removed during the dissociation process using CaO. COD was oxidized to CO2 and H2O, and PO43−, phosphite (HPO32−), and hypophosphite (H2PO2−) were mainly removed as FePO4 via the Fenton oxidation process. Adjust the pH to 6.0 by NaOH after Fenton treated effluent. An economic evaluation determined that the cost of treatment of PCBNP wastewater was 136.604 $·m−3. Moreover, the treated wastewater could be discharged directly to an industrial park. This method provides a novel approach for the treatment of PCBNP wastewater.