Freeze Desalination as Point of Use Water Treatment Technology: A Case of Chromium (VI) Removal from Water

Abstract

Options to develop tanning industries could be hindered even in the presence of huge leather industry raw materials due to the requirements of high-tech contaminant removal technologies, especially in developing countries. This study was initiated to investigate the efficiency of freeze desalination for Cr(VI) removal using refrigerators to generate fresh water. Synthetic solutions that represent major ion compositions of drinking water as well as deionized water to which known concentrations of Cr(VI) spiked into it, were added and frozen in a closed freezer unit. The effects of different parameters such as initial concentration, freeze duration, ice nucleation, fraction of ice volume, and influence of co-occurring ions were evaluated in relation to the quality of produced ice. The physicochemical characteristics of the produced meltwater were also evaluated. A high total water recovery of up to 85% was achieved in the experimental evaluation. Cr(VI) removal efficiency of up to 80% from simulated tap and 93 to 97% for deionized water spiked with Cr(VI) were found in this batch partial freezing. Freeze desalination was found to be relatively viable desalination technology in terms of quality of water produced, options on the use of cost effective refrigerants and technologies which could have a pertinent importance to save energy consumption of freezers.