Nickel removal from wastewater by electroflocculation-filtration hybridization

Electroflocculation (EF) has been used for decades in heavy metals removal. Understanding its mechanisms in order to improve process efficiency is still demanded. This work was aimed at obtaining high removal efficiency of Nickel from wastewater. Electroflocculation with iron electrodes hybrid with filter paper, micro- and ultra- filtration bench scale tests were performed with and without the introduction of external oxygen. A dissolved oxygen exhaustion point (DOEP) during EF process could be regarded as the deflection point of ferrous accumulation. Research results indicated that (a) with the hybridization of EF without aeration followed by microfiltration, and (b) aeration-enhanced EF followed by settling and mechanical filtration, the residual nickel and iron could meet the discharge standard of metal finishing industry. Aeration-enhanced EF process hybrid with microfiltration exhibited the potential to provide better removal results of nickel to meet the stringent standards of unrestricted irrigation and directly river discharging.