Removal and recovery of nickel ion from wastewater of electroless plating by reduction crystallization

Wastewater treatment after electroless nickel plating runs has been known to be difficult and this has been a subject of worldwide concern. Discarding wastewater of electroless nickel plating into sea was prohibited under the London Dumping Treaty since 1996. We have studied on recovering nickel from wastewater by reduction crystallization. In this study, the characteristics of nickel ion removal and recovery were investigated in the process of reduction crystallization using a laboratory scale batch crystallizer (500 ml), in order to propose a new process for wastewater treatment from nickel plating. In the reduction crystallization, which can use hypophosphite ion as a reducing agent for nickel ion in the wastewater, nickel ion could be recovered as a form of nickel metal by seeding nickel powder having large specific surface area.