Ontzilten

Ontzilten is the process of removing salt and other dissolved minerals from saline water to produce freshwater or water suitable for drinking, irrigation, or industrial use. It encompasses several technologies and is widely deployed in regions facing water scarcity or limited freshwater resources. The term is commonly used in Dutch language contexts, with desalination as the equivalent English term.

Desalination typically relies on physical separation technologies. The most common method is reverse osmosis, which uses high pressure to drive water through semi-permeable membranes while leaving salts behind. Thermal methods, such as multi-stage flash distillation and multi-effect distillation, are used in some plants, particularly where heat is readily available. Electrodialysis and related processes are used for brackish waters, and research into forward osmosis and capacitive deionization is ongoing.

Preparing seawater for treatment involves pretreatment steps to remove particulates and biofouling agents. The main by-product of ontzilten is concentrated brine, which requires careful disposal or beneficial use to minimize environmental impact. Energy consumption is a primary consideration influencing cost and feasibility; energy recovery devices and variable energy pricing can improve efficiency.

Desalination capacities are concentrated in arid and coastal regions, where freshwater scarcity or drought resilience is a priority. Large-scale plants supply municipal drinking water and industrial process water; smaller facilities serve agricultural irrigation in some contexts. Ongoing challenges include reducing energy use, minimizing environmental effects from brine discharge and intake, and addressing siting and regulatory issues.