Recovery of nickel, phosphorus and nitrogen from electroless nickel-plating wastewater using bipolar membrane electrodialysis.

Electroless nickel-plating (ENP) wastewater is challenging to treat because of its complex composition. This study used bipolar membrane electrodialysis (BMED) to remove and recover Ni2+, NH 4 +, total phosphorus (TP) and NO 3 − from ENP wastewater. The results show that current density significantly affects ion removal and recovery, current efficiency, specific energy consumption and ion migration velocity. When the current density was 20 mA/cm2, the removal ratios of Ni2+, NH 4 +, TP and NO 3 − were 100%, 98.6%, 99.3% and 100% after 14 h, respectively, and their recovery ratios were 92.6%, 75.5%, 94.5% and 90.6%, respectively. The removal kinetics analysis showed that the removal of Ni2+, NH 4 +, TP and NO 3 − was consistent with the zero-order kinetics process. The current efficiency variated from 42.5% to 39.0% and 37.7%, and the specific energy consumption decreased from 1.67 to 1.38 and 1.32 kW h/mol with the equipped wastewater compartments increased from one to two and three in a BMED system. Post treatment, Ni2+ was recovered as Ni(OH) 2 , with a purity of 82.6% (commercial Ni(OH) 2 purity = 90%). TP was recovered as struvite with a purity of 95.3%, and the physicochemical properties of the obtained struvite were similar to commercial struvite. NH 4 + was recovered as (NH 4) 2 SO 4 and NH 3 •H 2 O. Therefore, BMED is an effective method to recover Ni2+, TP and NH 4 + from ENP wastewater. [Display omitted] • Electroless nickel-plating wastewater was treated using a BMED system. • Ni2+ was recovered in the form of Ni(OH) 2 with a purity of 82.6%. • Total phosphorus was recovered in the form of struvite with a purity of 95.3%. • NH 4 + was recovered in the form of (NH 4) 2 SO 4 and NH 3.•H 2 O. [ABSTRACT FROM AUTHOR]