Separation Performance of Ion-exchange Membranes for Electrolytes in Drainage Nutrient Solutions subjected to Electrodialysis

The possibilities of applying electrodialysis separation of electrolytes (NO3−, H2PO4−, SO42−, NH4+, Na+, K+, Ca2+ and Mg2+) in drainage nutrient solutions prior to their recycling in a greenhouse was investigated using two types of ion-exchange membranes. The effects of the characteristics of the ion-exchange membranes as well as the pH of the drainage nutrient solution on the separation performance of the electrolytes were also investigated. The results indicated that ion-exchange membranes for deacidification (AC-220 membranes) separated both monovalent and divalent ions from the drainage nutrient solution, while, ion-exchange membranes for desalination (AC-110 membranes) separated monovalent ion selectivity. Regarding the relative energy consumptions and current efficiencies, the ion-exchange membranes for deacidification performed better than those for desalination. The separation performance of both types of ion-exchange membranes was not significantly influenced by the pH of the drainage nutrient solution.