How to purify seawater into fresh water, and can seawater be purified into freshwater?

Seawater desalination is the process of removing salt from seawater into fresh water, and there are four main methods: thermal energy method (distillation method and freezing method), mechanical energy method (pressure dialysis method and reverse osmosis method), electrical energy method (electrodialysis method) and chemical energy method (solvent extraction method and ion exchange method). Commonly used desalination methods include distillation, reverse osmosis, and electrodialysis.

1: Freeze seawater by cooling method to achieve the purpose of desalination.

The basic process flow of marine seawater desalination machine is as follows: seawater is pumped into the pretreatment system by the water supply pump, and then filtered into the quartz sand and activated carbon filtration system after the chemical dosing system is added with fungicide and flocculant. After the seawater enters the high-pressure pump after the pretreatment system, under the action of the high-pressure pump, it enters the high-desalination rate spiral membrane, and the pressure is increased by controlling the pressure regulating valve, so that part of the pure water in the seawater enters the porous collection pipe through the membrane, and flows out of the equipment through the hose, while the salt is blocked on the surface of the membrane and discharges most of the seawater out of the equipment.

After water quality reduction, pH adjustment and antiscalant addition, the filtered low-pressure seawater enters the high-pressure pump for pressurization, and the other enters the pressure exchange energy device, and the boosted seawater is pressurized by the booster pump and mixed with the high-pressure pump effluent into....

One of the easiest ways to turn seawater into fresh water is distillation, heat the seawater so that the water in it turns into steam, and then let the steam condense. Since the salts dissolved in seawater do not come out with steam, the resulting water is distilled water that is almost pure water. However, both heating and condensation require energy.

Kilojoules of energy are required for every 1 gram of water evaporated. Therefore, this method can save the emergency, but it is not a long-term solution.

Another method of desalination is the freezing methodThe seawater is frozen and frozen, and the salt is separated while the liquid freshwater becomes solid ice.

Both methods have drawbacks that are difficult to overcome. Distillation consumes a lot of energy and produces a lot of scale in the instrument, but not much fresh water is obtained. This is a very uneconomical way.

The freezing method also consumes a lot of energy, but the resulting fresh water is not tasteful and difficult to use.

The consequence of the sea water turning into fresh water

If all the seawater on the earth turns into fresh water, it will cause the earth's environmental pollution to become more serious. Without seawater, there is no ability of seawater to inhibit pollutants or small bacteria.

Then, with the increase of the volume of freshwater, many bacteria and microorganisms in freshwater will have a broader stage to grow and multiply. They will breed in large numbers, and the fresh water will become less clean, causing a lot of pollution.

The seawater desalination methods to be used include seawater freezing method, distillation method, ammonium carbonate ion exchange method, reverse osmosis method, etc.

At present, the mainstream methods used are distillation and reverse osmosis. These two methods require more energy and need to add a lot of chemicals for purification, resulting in many countries currently have no way to have their own desalination plants, which is why seawater desalination has been carried out for more than 400 years, and there is still no way to meet the needs of all mankind.

Main uses of seawater desalination:

Desalination is the use of seawater desalination to produce fresh water. It is an open source incremental technology to realize the utilization of water resources, which can increase the total amount of fresh water, and is not affected by time, space and climate, with good water quality and gradually reasonable, which can ensure a stable water supply for coastal residents such as drinking water and industrial boiler water supply. The process of obtaining fresh water from seawater is called desalination.

Desalination is mainly used to provide drinking water and agricultural water, and sometimes edible salt is also produced as a by-product. Desalination is popular in the Middle East and is also used on some islands and boats.

The method of desalination of seawater into fresh water is as follows:

1. Distillation desalination.

Our planet is actually a large desalination still. What is this big still used to heat it? It is the sun, and the energy of the sun shines on the surface of the sea to evaporate the water.

What does this large still use to condense the water vapor? It is the cold air flow in the upper altitude and the polar regions. The condensed water vapor falls to the ground in the form of rain or snow, which is free of desalinated seawater.

The fresh water produced with this large natural still is free because the energy used comes from the sun and is free; The equipment used is also off-the-shelf, and we didn't spend any money on the equipment.

However, it is different in artificial stills. We all know that in order for one kilogram of water to evaporate into vapor, 539 kcal of thermal energy must be supplied, which is the so-called latent heat of evaporation of water.

2. Multi-effect evaporation and desalination.

Multi-effect evaporation, heating to vaporize seawater.

It takes 539 kcal to produce every kilogram of water vapor produced, and when these water vapors are condensed into one kilogram of fresh water with cold seawater, the 539 kcal of heat is lost to the cold seawater, which is a very wasteful thing.

Multi-effect evaporation is a method of reusing this heat to produce many times as much fresh water.

We can use the boiler to produce steam as a heat source for distillation, and the seawater enters the first evaporator, also known as the first evaporator; The vapor generated in the boiler enters the underside of the first effect evaporator, separated by a metal wall.

If the pressure of the vapor produced in the boiler is one atmosphere or 1013 millibars, the temperature of the vapor under the first effect evaporator must be 100 degrees Celsius.

Desalination is the use of seawater desalination to produce fresh water. It is an open-source incremental technology that enables water use and can increase the total amount of freshwater without being affected by time, space and climate. So how do you desalinate seawater?

1. Freezing method, that is, freezing seawater to freeze it, and the salt is separated when the liquid seawater becomes solid ice.

2. Reverse osmosis method, also known as ultrafiltration method, uses a semi-permeable membrane that only allows solvents to pass through and solutes to separate seawater from fresh water. Under normal circumstances, fresh water diffuses to the seawater side through a semi-permeable membrane, so that the liquid level on the seawater side gradually rises until a certain height does not stop, this process is called osmosis. If an external pressure greater than the osmotic pressure of the seawater is applied to one side of the seawater, then the pure water in the seawater will reverse osmosis into the fresh water.

The biggest advantage of the reverse osmosis method is energy saving.

3. Solar energy method, solar distillation method is the use of simple solar distillation. The still consists of a tank with a black porous felt core floating cavity covered by a transparent, closed glass covering the top. Sunlight is projected through the transparent overlay onto the bottom of the black, adiabatic trough and converted into heat.

That's all there is to know about desalination.