Man drinking water from bottle

How to Produce Solar Distilled Water?

Solar powered distillation is the process of vaporizing and turning seawater into safe drinking water with the use of the sun’s rays. Solar stills come in different sizes and designs. The first solar distillation plant was built in the 19th century in Chile to provide safe drinking water for its inhabitants.

Solar Distilled Water and Its Purpose

Solar distilled water

Solar distilled water

It is recommended that drinking water should have 100 to 1000 mg/l of salt. Often, this amount of salt is added afterwards to the solar distilled water to keep the electrolyte levels balanced and to avoid any health complications.

In addition to the solar water distillation process providing safe drinking water, solar distilled water is also used for leading acid batteries, hospitals, laboratories, and producing commercial products.

Solar Distillation Process

Similarly to the earth's natural water cycle, the solar water distillation works by storing unpurified H2O in a container in a place where it would be the most exposed to the sun's rays. Heat from the sun causes the water to vaporize once it reaches an appropriate temperature, leaving all the heavy metals, salts and microbes behind. The clean vapor is caught in the still. When the temperature and pressure are right, the water molecules turn into liquid form which is pure water safe enough to drink.

Types of Solar Stills

Single-Basin Solar Still

The Single-Basin Solar Still is one of the most common types of solar distillation stills. The basin of the still is covered by either plastic or glass. The evaporated water is condensed at this spot which leads into a rainwater channel. The more heat produced by sunlight, the darker is the basin of the still. More pure water will be produced in the evening, because of the temperature contrasts between the inside of the device and the outside of the device. Other facts that affect the efficiency of the still are basin water depth, location, solar radiation intensity, wind velocity, glass cover material and the heat capacity of the still. To explain this further see the diagram below.

Multi-Stage Flash Distillation Still (MSF)

Solar Still

Solar Still

MSF is used on a larger scale, where the distillation plants provide safe drinking water to hundreds and thousands of people. The incoming seawater goes through the heating stages within the still. After it passes through the last heating stage and before entering the first flash-boiling (flashing stage), the water is further heated in the brine heater by using externally supplied steam. This procedure raises the water to its highest temperature which then passes through the various stages of flashing. The vapor procedure at every stage is controlled and monitored so that the heater brine enters each chamber at the proper pressure and temperature. Each stage has a lower temperature than the preceding one to cause proper evaporation.

Emergency Solar Still

The Emergency Solar Still is similar to the Single-Basin Solar still. It is used for emergencies when clean water is needed immediately for survival. A simple mixing bowl can be used as a basin. Plastic foil goes on top of the basin, both the foil and the basin can be held together by rubber. A small stone or a similar small weight is placed in the middle of the foil covering the bowl, creating a cone shape form. Then the water that needs to be vaporized is put into the bowl.

The Primary Purpose of Solar Distillation

Solar distillation is used by developing countries all over the world. 844 million of people in the world currently do not have access to clean water. This system uses natural sources to vaporize water and supply those who are in need. In coastal areas, there is more access to seawater, therefore creating a greater chance of providing safe drinking water to humans.

Solar distillation allows people to obtain clean, safe to drink water by vaporizing seawater using the sun's rays and natural heat. This process is important for developing countries, where there is no secure access to clean water. The Single-Basin Solar still is used for the distillation of a relatively small amounts of water, Multi-Stage Flash Distillation is used to provide drinking water for thousands of people at one time. The Emergency Stolar Still is significant for situations when pure water is needed urgently, as humans can only survive a couple of days without water. Drinking clean water will prevent any chemicals, metals, and microbes entering the body. However, by utilizing natural resources, solar distillation can continue to save many lives. If you are interested in getting a at home unit click here.

   

References And Recommended Reading

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    http://www.sersc.org/journals/IJAST/vol29/7.pdf
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    https://pdfs.semanticscholar.org/3adc/8605ab7e1c6869a9951e3eca615d53dbbe02.pdf
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    https://academic.oup.com/ijlct/article/11/2/211/2198322/Energy-and-exergy-analysis-of-passive-solar
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    https://link.springer.com/article/10.1007%2Fs12046-015-0445-8
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    https://www.ctc-n.org/sites/www.ctc-n.org/files/UNFCCC_docs/ref22x62_7.pdf

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