Heavy metals separation from geothermal waters for agricultural irrigation

Reverse osmosis (RO) is one of the most widely used technologies for achieving safe water reuse and can be effectively applied in wastewater recovery for crop irrigation. This paper presents the results of research involving the use of a two-stage RO system connected in series to produce water for agricultural use. A critical factor in applying this technology was achieving the target boron concentration. The effectiveness of the technology is also discussed with respect to the heavy metal content of the permeate. Pre-treatment steps, such as pre-filtration, deironing, and ultrafiltration (UF), are employed to remove colloidal particles and reduce membrane fouling, thereby enhancing longevity. Previous studies have shown that a two-stage reverse osmosis (RO-RO) system for geothermal water desalination (with initial mineralization of 2.5 g/L) produces permeate with a mineralization of 0.094 g/L and permissible heavy metal concentrations that do not adversely affect the quality or safety of irrigation water. Furthermore, due to the permeate’s physicochemical composition, treated geothermal water can be used for drip irrigation without the risk of clogging installations. Future innovations should focus on energy-efficient membrane materials and real-time monitoring to further optimize the desalination process, ensuring sustainable agricultural reuse without soil or crop contamination.