The simplest ways to purify, sterilize and filter water

Weather of Arabia - Seawater desalination is the process of converting salty seawater into fresh water that is drinkable or for use in agriculture and industry. This process is considered an important solution for places that suffer from a shortage of drinking water, or that rely mainly on salty water. In this article, I will explain in detail some Simple methods for desalinating sea water.

Distribution of water on the surface of the Earth... salty seas and an urgent need for fresh water

Most of the water on the surface of the Earth is present in the seas and oceans in the form of salt water, and the percentage of salt water is about 97.5% of the total water on the surface of the Earth or in its interior, while the percentage of fresh drinkable water does not exceed only 2.5% .

The consumption of fresh water for drinking varies from one country to another; Whereas in industrialized countries, a person can consume about 500 liters of water per day, while in developing countries, a person can only consume about 50 liters per day.

This estimate includes all human activities of various types, and this clearly confirms the urgent need for fresh water in the future to meet the needs of the expected increase in population and the rise in the standard of living in many countries. Seawater contains a variety of dissolved salts such as sodium, calcium and magnesium salts, which come in The form of chlorides, sulfates, or carbonates. This water is not suitable for direct human use for drinking, bathing, or cooking food. Dissolved salts in marine water are usually in the form of negatively charged ions, which are temporarily separated. For example, table salt (sodium chloride). In water, it is in the form of positive sodium ions and negative chloride ions.

In areas that lack fresh drinking water, such as desert areas and areas prone to drought, their residents resort to desalinating seawater to get rid of dissolved salts and benefit from them. Among the methods used to desalinate water are:

Desalination using semi-permeable membranes

The Arab Muslim scientist Al-Biruni was one of the first scientists to innovate the use of semi-permeable membranes to desalinate water. In his historic experiment, he placed a clay flask in seawater and allowed it to fill itself with fresh water. Over time, this technology developed into more advanced forms.

Semi-permeable membranes are usually used today in water desalination, where a device consisting of three chambers and two semi-permeable membranes is used that separates the middle chamber from the two side chambers. Using an electric current between the electrodes in the two side chambers, ions from the salts present in seawater pass through the two membranes and the positive ions move toward The negative electrode (cathode), while the negative ions move towards the positive electrode (anode). Thanks to this process, the water is purified and extracted from the middle chamber in the form of fresh, drinkable water.

This technology has been used for water desalination since 1960 in many regions of the world, including some regions in the Middle East such as the Arab Republic of Egypt and the Kingdom of Saudi Arabia, as well as in the south of the former Soviet Union and some regions of the United States. It is estimated that there are about 8,000 units using this type of technology around the world.

Semi-permeable membranes are also used in a method known as the “reverse osmosis method” . This method is based on the phenomenon of osmotic pressure, where water can move from a dilute solution to a concentrated solution of salt. However, this process usually requires high pressure, which can reach 50 times the pressure of the normal atmosphere, and advanced membranes have been invented for use in this method in Jeddah desalination plant in Saudi Arabia.

Water storage

It is preferable to store water in open containers for a period ranging between 5 and 24 hours. This storage contributes to the precipitation of many impurities and eliminates about 50% of the bacteria present in the water. With regard to schistosomiasis, storing water for 48 hours can lead to the elimination of the stage. This parasite lives in river water.

Water filtration and filtration

You can easily purify the water by filtering it using a cotton cloth, making sure to exclude the bottom of the pot if there is a lot of sediment. In addition, you can use a water filter made of clean sand, gravel, and cloth to effectively purify and filter the water, and you can easily make a natural filter. Simple: Cut a bottle in half, then close its mouth with a piece of cloth or mesh. After that, a layer of clean sand can be placed, then a layer of fine gravel, and finally a layer of coarse gravel. These layers can be repeated alternately to obtain a simple natural filter system. And effective.

Water aeration

Aerating the water means allowing air loaded with oxygen to permeate the water. This process increases the percentage of dissolved oxygen in the water, which improves its taste and quality. Aeration can be achieved by placing the water in a bottle or container half full (jerry can), then closing it and shaking it as much as possible. This procedure contributes to getting rid of impurities such as iron and manganese salts in the water.

Boiling water kills germs

Boiling water is considered an effective way to get rid of many germs and kill bacteria. However, after boiling, it is preferable to leave the water exposed to the air in an open container, and this is better if it is placed in the refrigerator. This procedure helps the water regain some of the percentage of oxygen that it loses during the boiling process. It also helps make the water taste better again. According to EPA recommendations, water should be boiled for at least one minute for most people, but it can be three minutes if a person is above one mile in altitude above sea level.

Use ultraviolet rays to sterilize water from germs

If you raise your head to the sky on a sunny day, you will find the sun offering you a valuable free gift. It is the way in which the world gets rid of most of the accumulated germs. If these germs are left unchecked, they may be a threat to the health of all of us, and all you need to do is put water. In PET bottles that are usually used in filling drinks, then leave them for 6 hours under the sun, and the ultraviolet rays will do the work, removing bacteria, viruses, germs and amoeba from the water. This method is known as the “ SODIS Method” for purifying water, and it is a method Recognized and accredited by WHO and UNICEF; It is an effective method that has received awards from the International Red Cross due to its efficiency.

The reason for sterilizing water is using sunlight

Ultraviolet rays have the ability to eliminate bacteria by direct action, and are widely used in sterilization processes. These rays are able to convert oxygen dissolved in water into active oxygen, which can kill pathogens; As it is noted that the temperature of the water rises under the influence of sunlight (it reaches about 50 degrees Celsius), it can speed up the water sterilization process up to three times faster than what happens if the process is carried out at room temperature.

Steps to sterilize water using sunlight

After removing the labels from the transparent plastic bottles, they can be filled with water until it reaches 3/4 level, then the lid is closed, and it is disturbed for 20 seconds to increase the dissolved oxygen content in the water. After that, the bottle should be filled with water, and it should also be placed in an inclined place facing the sunlight. Direct.

It is also preferable to use a black surface under the bottles to improve the level of sterilization. The duration of the sterilization process depends on the brightness of the sun, and should not be less than 6 hours , and extend to up to two days on cloudy days. It is advised not to use transparent glass or PVC containers in this process, as they may obstruct some Harmful wavelengths and experiments conducted in Swiss research laboratories, specifically in the Swiss Federal Laboratories for Materials Testing and Research, proved that polyethylene is completely safe to use as bottles for drinking water, and this method of sterilization has greatly contributed to reducing the spread of diseases.

Sterilize water using chlorine or Clorox

This method is approved by the World Health Organization, and to apply it, you must first verify that the chlorine used is free of any chemicals or odors. After that, three drops of chlorine can be added to every liter of water (equivalent to one teaspoon per 20 liters of water) in Clear water condition, or 6 drops of chlorine per liter of water (equivalent to 2 teaspoons per 20 liters of water) if the water is cloudy and afterwards, the water should be left to air for at least half an hour, after which time it is safe to drink. All of the previous methods can be combined together to improve the process of purifying and sterilizing water, or one of them can be used depending on the availability of materials and the type of pollution present in the water.

Although these methods may be relatively simple, desalination is a technological process that requires regular care and maintenance, and there are advanced and complex technologies used in large desalination plants to meet the needs of cities and dry areas.

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