Minimization of freshwater usage in hydroponic cultivation by mixing it with desalinated geothermal water using membrane processes

Freshwater resources are becoming increasingly scarce due to climate change, population growth, and intensified agricultural demands, making searching for alternative water sources a pressing global issue. Research conducted using a geothermal water treatment system (a two-stage main treatment RO-RO system) identified the possibility of using treated geothermal water as a supplementary source of water resources for hydroponic cultivation. To achieve water parameters that meet the requirements for drinking water, and indicators determining the suitability of water for crop irrigation, the treatment process parameters were adjusted. It was shown that the use of the proposed system and mixing the permeate (treated geothermal water) with tap water in a 70/30 ratio enables the production of water with suitable parameters for hydroponic lettuce cultivation. The results of post-harvest analyses of lettuce leaves confirmed it. These findings demonstrate the potential for reducing freshwater consumption in hydroponic cultivation by using properly treated geothermal water. • A two-stage reverse osmosis (RO-RO) system enabled effective treatment of geothermal water for agricultural irrigation. • Treated geothermal water mixed with tap water at a 70/30 ratio met standards for drinking and irrigation water. • Post-harvest analysis confirmed that the produced irrigation water is suitable for hydroponic lettuce cultivation. • The study demonstrates the possibility of geothermal wastewater reuse to reduce freshwater usage in the agricultural sector.