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Brackish water or seawater

In wastewater treatment, brine waste is the super concentrated by-product that results from treating brackish water or seawater. This treatment is accomplished by using a method of desalination to convert saline water into potable water. Desalination (also termed desalinization) occurs in desalination plants or water treatment plants. Each of these plants produce brine waste, which is considered an industrial waste.

Treatments resulting in brine waste

Brine waste may result from many separate methods of distillation. The traditional process used for industrial distillation is vacuum distillation. Basically, this concept uses a vacuum to separate the salt from water at a reduced pressure. One of the newest processes, [[multi-stage flash distillation] is the leading method for desalination thus far. This method differs greatly from vacuum distillation because it requires a lot of heat energy to work. Cogeneration includes the use of heat from another source such as nuclear power plants. This is controversial process for producing potable water because nuclear power plants are thought to be radioactive and unsafe. Brackish water reverse osmosis (BWRO) is a process that uses a thin layer of material to filter only water through the system. BWRO is another more recently implemented desalination method .

Treatment facilities

With the amount of attainable freshwater rapidly depleting from sources worldwide, desalination plants and wastewater treatment plants are becoming more necessary and more abundant. Most of the desalination plants worldwide are located in the Middle East . Listed below are a few examples of desalination plants around the world:

• In Oman most of the saltwater desalination plants are in close proximity to the shore. These plants include, Al Gubrah and Barka.

• In the United Arab Emirates a few of the coastal desalination plants include Fujairah, and Jebel Ali, which is the largest plant in the world.

• Desalination plants occur across the United States, on both coasts and near the Gulf. The most notable ones are in Tampa Bay, which has the largest plant in United States, the Carlsbad desalination plant, and the El Paso (Texas) desalination plant, which recycles wastewater and is also the world’s furthest inland desalination plant .

Methods of brine disposal

The most common recycled use for brine waste is saltcrete, which is put into an asphalt mixture for making roads. If brine waste is not recycled into salcrete, then it is disposed by desalination plants by releasing it into streams and rivers to end up in the ocean as a plume (hydrodynamics). The rationalization behind this alternative, is that natural ocean currents will mix the brine plume into the already salty seawater and the resulting salinity increase will be so slight that it will have insignificant effect on the ecosystem.
When the desalination plant is far from the coast of an ocean, waste disposal can be a longer process. Although somewhat energy and time intensive, a more recent method of brine disposal is to treat brine by reverse osmosis which produces very salt concentrated waste. Then, the super concentrated brine is dried out, the water is evaporated, and the salt product can be distributed for commercial use .

Brine waste in the ecosystem

The brine waste by-product released into rivers, streams, and oceans is an environmental concern for desalination plants that are not located near the ocean .

“The coastal water that is close to the outfall receives an extremely high concentration of salt” .

High salt concentration has an altering effect on the flora and fauna of the directly contaminated area. Increased salinity pushes living biota to the extremes of their tolerance limits. This change affects all of the organisms of that ecosystem in a negative way, either directly or indirectly. The loss of a keystone species through alteration of community structure is an especially significant event. The loss of a keystone species displays how salinity acts as a stressor on the environment . The approach to the extreme end of an organism’s tolerance limits from saline water can be toxic for that organism. According to the broad definition of an environmental risk assessment (ERA), an unnaturally high amount of salinity can be considered a toxin .

An environmental stressor such as the increased presence of salt in estuaries has been linked to an increase in the consumption of plants . In this sense, the plant consumers are the herbivores of that area. According to a general rule of ecology, an increase in herbivores means fewer plants in that area. Total community collapse in that ecosystem is more likely to occur if one of the voraciously consumed plant species in that area is a keystone species. The loss of total mass of natural plants in the newly saline area leaves that ecosystem vulnerable to invasion of halophytic plants. According to another general rule of ecology, the invasion of a non-native species is also detrimental to the community structure of an ecosystem. Non-native species do not have a natural predator in the area they have invaded. Population control of the invasive species becomes difficult or non-existent due to lack of predation.

When the invasion of a halophytic plant species leads to total takeover of the area, it usually means a loss of all native species of that area. Increasing the salinity of an ecosystem (that is not naturally high in salt), results in the loss of sustainable living for native species to that area. A loss of species diversity occurs due to the environment becoming more saline.