2) Mr. Ofer Guy

As water scarcity impinges agriculture, non-potable sources are being considered, including brackish groundwater and saline drainage water. However, high salt levels in brackish water prevent its use for high value crops which usually are quite sensitive to the sodium and chloride content. Reverse osmosis (RO) removes the salt but also removes divalent ions that are beneficial for plant growth. Replenishing divalent ions in the RO permeate by blending in brackish groundwater (BW) can add back undesirable levels of chloride and sodium ions. This dilemma can be addressed with monovalent selective electrodialysis (MSED) which reduces chloride and sodium content while preserving divalent ions, and it has been explored for preparing irrigation water from brackish water. However, MSED is presently significantly more expensive than RO. To overcome this economic challenge, we have adopted a blending approach. We blend MSED diluate with RO permeate to reduce the need to operate MSED to a high level of monovalent ion removal. The improved performance (based on plant mass and yield) of RO/MSED blends over RO/BW blends and over RO alone were demonstrated in irrigation experiments with lettuce and strawberries which are typical high-value greenhouse crops.