A novel application of membrane distillation to facilitate nickel recovery from electroplating wastewater
In many years, the nickel electroplating technique has been applied to coat nickel on other materials for their increased properties. Nickel electroplating has played a vital role in our modern society but also caused considerable environmental concerns due to the mass discharge of its wastewater (i.e. containing nickel and other heavy metals) to the environment. Thus, there is a growing need for treating nickel electroplating wastewater to protect the environment and, in tandem, recover nickel for beneficial use. This study explores a novel application of membrane distillation (MD) for the treatment of nickel electroplating wastewater for a dual purpose: facilitating the nickel recovery and obtaining fresh water. The experimental results demonstrate the technical capability of MD to pre-concentrate nickel in the wastewater (i.e. hence pave the way for subsequent nickel recovery via chemical precipitation or electrodeposition) and extract fresh water. At a low operating feed temperature of 60 °C, the MD process increased the nickel content in the wastewater by more than 100-fold from 0.31 to 33 g/L with only a 20% reduction in the process water flux and obtained pure fresh water. At such high concentration factors, the membrane surface was slightly fouled by inorganic precipitates; however, membrane pore wetting was not evident, confirmed by the purity of the obtained fresh water. The fouled membrane was effectively cleaned using a 3% HCl solution to restore its surface morphology. Finally, the preliminary thermal energy analysis of the combined MD-chemical precipitation/electrodeposition process reveals a considerable reduction in energy consumption of the nickel recovery process.