A United Nations-supported study highlights a significant environmental dilemma: desalination plants worldwide are producing highly salty wastewater and toxic chemicals detrimental to the environment. The study forms part of a broader research endeavor aimed at securing fresh water supplies for our increasing population without causing environmental harm.
Desalination plants globally are discharging more salt-laden brine than previously estimated, with over half the brine originating from four Middle Eastern countries: Saudi Arabia, the United Arab Emirates, Kuwait, and Qatar. Saudi Arabia alone accounts for 22% of the output. The hypersaline brine, consisting of about 5% salt, often contains toxins such as chlorine and copper used in the desalination process. This percentage is significantly higher than global seawater, which contains about 3.5% salt.
Understanding Desalination
Desalination refers to the process of removing salts from water to produce water quality (salinity) that meets different human use requirements. Seawater desalination can supplement water supplies beyond what is available from the natural hydrological cycle, thus providing an “unlimited,” climate-independent, and consistent supply of high-quality water.
The Growing Demand for Water
The “conventional” water sources, including rainfall, snow-melt, and river runoff captured in lakes, rivers, and aquifers, are no longer sufficient to meet human demands in water-scarce areas. This growing scarcity conflicts with Sustainable Development Goal (SDG) 6, which focuses on ensuring the availability of clean water for current and future generations.
Desalination of seawater and highly brackish water is increasingly viewed as a feasible solution for primarily domestic and municipal needs. However, it is crucial to couple these supply enhancement strategies with water demand mitigation approaches, such as water conservation and improved efficiencies.
The Environmental Consequences of Desalination
Desalination’s environmental footprint is considerable. The discharged brine raises the salinity level, posing a significant risk to marine life and ecosystems. The higher temperature of this area decreases the dissolved oxygen level, leading to hypoxia. These hypoxic conditions have been linked to the formation of dead zones in the ocean. Additionally, desalination requires large amounts of energy, mostly derived from burning fossil fuels, thus contributing to global warming.
Potential Opportunities from Desalination Byproducts
Despite these challenges, desalination also presents significant opportunities. The brine discharge can contain valuable elements like uranium, strontium, sodium, and magnesium, which have the potential to be mined. Furthermore, brine has shown potential for use in aquaculture, with increases in fish biomass of up to 300%. It has also been used successfully to cultivate dietary supplements like Spirulina and irrigate forage shrubs and crops.
There is a pressing need to transform this environmental issue into an economic opportunity, especially in countries that produce large volumes of brine with relatively low efficiencies. Making desalination technologies more affordable and accessible will improve desalination’s viability for addressing SDG 6 in areas where high economic costs have previously limited developments. Technological advancements for lower environmental impacts and economic costs, along with innovative financial mechanisms to support the sustainability of desalination schemes, are likely required.