3rd-century desalination course and desalination methods

Detonation, desalination or desalination is a series of industrial processes used to remove all or part of salts and excess minerals from water. The term was used to remove salts and dissolved minerals from water. Seawater can be desalinated so that it can be used in real life such as agriculture, drinking and industry.

This applied science now includes a large number of countries suffering from water scarcity and is expected to grow significantly in the next decade due to the expected water crisis in many countries of the world, Some statistics indicate that due to the lack of clean water, Hundreds of thousands have died humanely. The Arab Gulf states are also desalinating water at the industrial level. For now, California has suffered from severe rainfall and drought shortages over the past few years, That is why they have begun to build 17 desalination plants on an industrial scale.

Desalination requires technologies that consume a lot of energy and money and have a detrimental effect on the environment. Energy consumption in the desalination process is an important problem and difficult obstacles to overcome, It is also one of the objectives that the Science Centre is working on to find less energy-efficient and more efficient alternatives. And environmentally friendly.

Current global trends vary between desalination or waste, rainwater treatment and reuse. We found that most desalination plants are located in the Arabian Gulf and Libya, While most treatment plants are located in different parts of the world, such as the United States, Singapore and European countries.

Desalination takes place in three basic stages before distribution and pumping into the grid as follows:

• Primary water treatment
• Salt removal process
• Final water treatment

Desalination methods

Current desalination methods revolve around two approaches:

1. Longer the use of the membrane, which is sometimes called reverse osmosis, Electric method.
2. Using thermal fumigation, This method is called distillation.

Use of membrane: In the desalination process, A semi-port membrane called reverse osmosis membrane is used because it allows fresh water to pass in the direction of low pressure without allowing salts and bacteria to pass through it. This requires increased pressure on the side of the seawater-filled membrane, It is about 70 bars (70 air pressures). This pressure is usually created by an electric pump. Other membranes are also used for this process, Like electric nomads. There are other types under study, Like anterior osmosis, and nano-nomination, and desalination membranes, Most of the current research focuses on finding better and more efficient membranes, Desalination is therefore expected to be deployed in many places. Twenty-five years to come.

Distillation: This process involves raising the temperature of the saline solution to boiling point and forming water vapor, which then condenses into distilled water, This makes distilled water salt-free. This distilled water has no taste and is then treated with additives to make it suitable for drinking or irrigation. This technique is usually used when treatment is needed for semi-free saline solution for industrial, chemical and biological applications, Etc.

The thermal energy used can come from natural gas, coal, nuclear reactors or from steaming water.

Four types of distillation are used in the sweetener process:

• Normal distillation: Boil the saline solution in a tank without pressure. Water vapor rises to the top of the reservoir and exits through a path connected to an condenser, Which condenses water vapor into water droplets that are collected in the distilled water tank. This method is used in desalination plants with smaller production capacity.
• Multi-stage flash: Based on the fact that the degree of boiling of the liquid is proportional to the pressure on it, The lower the pressure on the liquid, the lower the pressure on the liquid, dropped his boiling point. In this way, Salt water is heated and passed through successive low pressure chambers, The water turns into water vapor that condenses on a cold surface. Collected and processed in appropriate quantities for drinking. This method is used in desalination plants with a large production capacity (30,000 cubic meters, or about 8 million gallons of water per day).
• Multi-stage distillation (multi-effect): The multiple effect still uses steam rising from the first evaporator to condense into the second evaporator. therefore Condensation heat is used to boil the saline solution in the second evaporator, Thus, the second evaporator acts as a steam condenser from the first evaporator, The task in the second evaporator becomes similar to heating the steam in the first evaporator. Similarly, The third evaporator acts as an condenser for the second, and so on, Each evaporator in the chain is called an effect.
• Solar distillation: This method depends on the use of solar energy to heat the saline solution to evaporation, It is condensed on a cool surface and assembled in pipes.

Desalination stages

1. Primary water treatment: Removes suspended solids such as dirt and bacteria from most water. It is performed by traditional primary water treatment or by modern primary water treatment. During this process, Some chemicals are added to facilitate processing.
2. Sweetener: Removes all dissolved salts, viruses and other substances from water such as chemicals and organics that are transported and dissolved in water. They are made using membrane or distillation. See dessert methods
3. Final water treatment: Where some salt and other materials are added to make water fit for human use, Only if the purpose of the process is to serve facilities related to direct human consumption (e.g. drinking, domestic use or agriculture). Salt is not added if salt is used in industrial applications and pharmaceuticals, It can negatively affect product quality.

Environmental problems and factors to look at

Environmental issues should be taken into account when studying desalination. The entire desalination process consumes a lot of energy obtained by burning fuel, oil, electricity or nuclear power, Or raise co2 or worry about complications of radiation leakage. In addition Environmental concerns are the remnants of the desalination process, called saline solution, When thrown into the sea increases the amount of salts dissolved in them, this negatively affects marine life. It is necessary to choose where to draw water and how to pump water to the desalination plant, This may increase the energy used, As well as choosing where to treat water. Focus with salt to avoid harmful effects on aquatic life. Chemicals used in the desalination process have other problems, And if its limits are exceeded, They can cause long-term disease.

Areas of research and development

In research centers around the world, Do research on one of the following topics:

• Find alternatives to the current desalination process methods: By creating new membranes better than those that exist and selecting the appropriate chemical and operational factors in the salt separation process.
• Finding alternatives to added chemicals: Use of genetic engineering to accelerate water purification and microbial treatment
• Look for alternatives to the energy used in the desalination process: Use renewable energy sources such as solar, wind or wave energy.

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