Treatment of simulated dilute Ni2 +-containing wastewater by electrodeionisation with a bipolar membrane: Feasibility and current density distribution

• The EDI-BP allows the removal of Ni2 + completely from Ni2 +-containing wastewater.
• The feasibility of Ni2+-containing wastewater treatment by EDI-BP was validated.
• Ni2 +-free diluate and Ni2 +-containing concentrate can be acquired simultaneously.
• The current density distribution of the EDI-BP stack is uneven.
• The resins of different ionic form have different resistances.

A new configuration of electrodeionisation with a bipolar membrane (EDI-BP) with a segment electrode was proposed for the treatment of simulated dilute Ni2 +-containing wastewater. The feasibility of EDI-BP was analysed and experimentally validated, and its current density distribution was studied simultaneously. The results showed that the stack allows the removal of nickel and sulphate anions nearly completely from the 30 mg/L Ni2 +-containing wastewater. Under the experimental conditions, Ni2 +-free diluate and a 27-times concentrated solution (820 ± 50 mg/L) can be obtained. The current density distribution of the stack is uneven, which is reflected by the following order of the resistances of the resins, Dowex 650C and Dowex 550A, with different ionic forms: Ni2 + > Na+ > H+ and SO42 − > Cl− > OH−, respectively.