Feasibility assessment of humidification–dehumidification and adsorption water treatment processes for real-time treatment of plating industry wastewater

Abstract

A plating solution is typically diluted because Zn-Ni-plated iron substrates with hydrophobic characteristics result in a larger amount of water drag-in from the preceding rinse than the plating solution drag-out. The diluted plating solution is discarded because of its reduced plating efficiency. However, its disposal can have substantial economic and environmental impacts. The aim of this study was to concentrate a diluted plating solution through the humidification–dehumidification (HDH) and adsorption water treatment (AWT) processes to assess its reusability in the electroplating process and establish the feasibility of these processes. The HDH product contained many contaminants (total dissolved solids > 521 ppm) such as heavy metals, chemical compounds, and ions. Moreover, the concentrated plating solution obtained using HDH did not satisfy the required standards in terms of plating efficiency and corrosion resistance. This was demonstrated by the hull cell test. In contrast, the AWT product showed a remarkable absence of contaminants, making it a suitable alternative to degreasing as a pre-treatment before electroplating. The hull cell test results obtained employing the concentrated plating solution derived from the AWT process indicated a 12 % increase in the plating efficiency and demonstrated effective corrosion resistance. Furthermore, the AWT process exhibited a low specific energy consumption (1.87 kWh/m3) compared with the HDH process (5.16 kWh/m3). To conclude, the AWT process has distinct advantages in terms of water quality, plating efficiency, and specific energy consumption. This establishes its effectiveness for treating plating solutions.