chemicals are used in water treatment

What are the chemicals used in water treatment

“No one lives without water!” The oxygen molecule saturated with hydrogen forms the basis of all living forms on Earth. Whether it’s cooking or basic sanitation needs. Water treatment remains a global challenge. Recent studies have found chemicals used in water treatment that will improve access to clean drinking water.

Why are the chemicals used for water treatment important?

Nowadays, the demand for potable water is constantly increasing, due to meeting human needs and supporting industrial activities. With increasing urbanization and economic development, the current water supply is unlikely to meet the ever-increasing demands. Hence, the chemical industry uses innovative water treatment methods in order to make the water acceptable for end-use. Such as drinking, cooking, irrigation, and industrial purpose to name a few. Water treatment methods use four basic processes, which include boiler water treatment, cooling water treatment, water purification, and sewage treatment. The substances that are removed during the water treatment process are suspended solids, viruses, fungi, bacteria, algae, and minerals. The process includes physical and chemical methods. The chemical used in this process is called a water treatment chemical.

The chemicals used in water treatment are:



chlorine dioxide

hydrochloric acid

soda ash or sodium bicarbonate

In addition to the chemicals mentioned above, there are many other chemicals used in water treatment. Coagulants, flocculants, softeners, and filter cleaners also form an important part of water treatment methods.

Aluminum sulfate

Aluminum sulfate is the main substance that helps condense pollutants in water. And adding slaked lime to adjust the pH of the water to get the best effect after thickening. Polyelectrolytes are used for condensation. It uses chlorine in addition to activated carbon. Ammonia is also used to treat free chlorine water to form stable chlorine deposits in the water to remove any unpleasant taste or odor. Water can also be fluoridated to prevent tooth decay, and gas used to purify drinking water is also included.

The importance of water treatment

The water treatment industry plays an important role in providing clean water and preventing various water-related diseases across the world. With the help of innovative boiler water treatment chemicals and other related chemicals. It is now possible to make polluted seawater, river waste, and sewage safe for human consumption.

CeraMic of Andijk II in the Netherlands has designed and developed a membrane that, unlike traditional membranes, provides advanced water filtration functions Meanwhile, water treatment giant PWN Technologies has been involved in the search for a unique water treatment solution that will use technologies including suspended ion exchange and membrane applications Ceramic and oxidation developed to help reduce the global water crisis.

Water treatment steps

Coagulation and flocculation

The two are usually the first steps in water treatment in which positively charged chemicals are added to the water. The positive charge of these chemicals neutralizes the negative charge of dirt and other dissolved particles in the water. When this happens, the particles combine with the chemicals and form larger particles called agglomerates. It is a simple mechanical process to remove large residues such as silt and rocks from the water. The water passes through the obstructions that block this waste (such as debris) and is treated in place to prevent clogging of the filter, which affects the subsequent treatment As the sorting process, you can remove a lot of large-volume waste, but you cannot remove soluble materials and small-volume waste.

Here, chemical methods can help us solve this problem because they can be added to remove dissolved and organic substances, chemicals called coagulants. Like aluminum carbonate and iron (II), chloride, it neutralizes the negative charge on small molecules of organic matter in the water, preventing them from repelling each other and binding them together.

Flocculation is the name of the mixing process that increases the amount of mixing, and the particles agglomerate to form the so-called lumps or impurities, and this is one of the most important steps of the water purification stages.


The conglomerates settle due to their weight at the bottom of the water source during sedimentation. This process is called sedimentation, where the sedimentation or sediment resulting from the coagulation and flocculation process takes place in the subsequent stages. It can be removed from the water, treated, and disposed of as this sludge is molecularly formed in the form of metal hydroxides. Which is formed during the process of coagulation and removal of organic matter, and some potential uses include adding it to fields where crops are grown. If this fails, it must be sent to a landfill or incinerated.


After removing the sludge, we enter the filtration stage. During this process, the sludge passes through the material layer, which helps to remove organic matter and particles that were not removed before by coagulation. The material used is usually a layer of sand over a layer of gravel. That being said, carbon in the form of charcoal can be used to help remove compounds that make water taste and smell foul. Once the clumps have settled to the bottom of the water supply system, the clear water at the top will pass through filters of different configurations (sand, gravel, charcoal) and pore sizes to remove dissolved particles. Chemicals such as dust, parasites, bacteria, and viruses.


After filtering the water. Its acidity can be adjusted because acidic water will corrode the pipes that pass through the water. It changes the color of the water, causes the ingress of toxic metals (such as lead). In order to reduce acidity. We pass the water through a limestone filter that contains calcium carbonate because it helps to increase the pH of the water and thus reduces the acidity. Conversely, when the acidity is low. Where acid is added, the water has high acidity, meaning the water is alkaline. This is rare and in some treatment plants, the water is softened at this stage. After the water has been filtered, disinfectants (such as chlorine and chloramines) can be added to kill any remaining parasites, bacteria, and viruses, and to protect the water from bacteria when it is brought into homes and businesses where water treatment methods and types vary.

Chemicals to be added in treatment plants

In some processing plants, it is necessary to add corrosion-resistant materials to prevent the metal in the pipeline from entering the water. to the inner surface of the tube.

After removing the dissolved solids from the water, we still have organisms that can cause diseases such as bacteria and viruses. Which must be disinfected before being transported to people’s homes through water pipes. This is achieved by adding a small amount of chlorine to the water. Chlorine is a powerful oxidant that can damage cell walls and destroy bacterial enzymes and proteins, but adding chlorine to water isn’t without its problems.

Chlorine can react with the remaining organic matter in the water to form Trimethane. THMS and chlorine in water have many benefits. To prevent the spread of waterborne diseases such as cholera and typhoid fever carefully monitor (typhoid fever) and (THM) content in the water to avoid exceeding the permissible level. In addition, the presence of organic matter in the water helps to form THM, and therefore chlorine must be added during the filtration process, and then the organic matter will be removed from the water, so as not to overdo THM and some water plants use ozone instead of chlorine, but for chlorine Benefits include the chlorine that remains in the water after it leaves the plants, helping to keep the water safe from pathogens before they enter the home.

Learn about the importance of laboratory tests for any treated water, here.

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