Especially on ships, islands and in coastal regions with limited natural freshwater resources, seawater can be used for drinking and service water and expands our water sources globally. The most common methods for seawater desalination are traditional evaporation and reverse osmosis.
In seawater desalination using reverse osmosis, the high salt content in particular is removed and particles, organic substances, bacteria, heavy metals, toxins, viruses and germs are almost completely separated. To overcome the osmotic pressure, the seawater is forced through a semi-permeable membrane by a high-pressure pump which only allows small molecules to pass through and thus separates the salt from the water. The high pressure to be generated is determined via the salt content of the raw water and is approximately 2-3 kWh per m³ of permeate. Due to the simple and space-saving design, reverse osmosis is still an economical process that offers far more advantages than the high energy consumption. In order to operate reliable and stable seawater desalination, contamination such as oil or chemicals must be eliminated. Shipping routes, ports and polluted waters must be taken into account in the planning stage.
Almost half of the global desalination capacity is concentrated in the Middle East and North Africa. Depending on the method and the salinity of the seawater, highly concentrated brine remains after desalination. If the brine is simply fed back into the sea or the river, this can severely disturb the sensitive ecology of the water. Since the brine increases the salt content, can contain toxic chemicals and heavy metals from the desalination process and contributes to the lack of oxygen in the water, it is important to use the brine reasonably instead of simply releasing it into the environment. According to the latest studies, the brine can be used for breeding special forms of aquaculture. The recovery of valuable metals such as lithium, boron, bromine, uranium and salts is also becoming increasingly important as the demand for raw materials increases and technologies continue to develop.