What Is Water Treatment Process?
Public water systems often use a series of water treatment steps that include coagulation, flocculation, sedimentation, filtration, and disinfection.
Water Treatment Process Steps
There are nine types of basic water treatment process steps that are described below-
Before treating water, firstly we have to collect the water from many sources like rivers, ponds, lakes, etc. But the collecting process of those waters is very difficult because they can be collected by complex pipelines and pumps, and that also can increase the total cost of the process.
When we are going to treat any type of water, we have to follow some steps, in those steps, screening is the first step that we have to follow.
In this screening process, we have to separate large particles or unusual materials from the water. This type of large material is removed by being captured with a large metal screen.
3. Chemical Addition
After that, this step will start, where chemicals are reacted with the smaller particles of the solution and create ‘floc.’ To initiate this process, some chemicals are used, which is known by coagulant. There are various types of coagulants are used in this process according to the situation and type of work.
In this step, we discuss about the working process of coagulants.
- Here, the coagulant is mixed with water, and after some time coagulant will start the coagulation process.
- The coagulation process is also known as flocculation.
After the completion of sedimentation, the water flows over the sedimentation basin. Some coagulated particles are stored at the bottom of the basin, and it will be removed after a certain period.
To filter the water more preciously, this step is done after the sedimentation process. Here, after sedimentation water is driven through different mediums like sand, activated granular carbons, gravel, etc to remove smaller particles.
After removing all the impurities from the water, there are also some amount of bacteria, microorganisms, viruses are present. To remove those particles, disinfection is necessary.
The most effective process to remove bacteria, microorganisms, and viruses is chlorination. It does not affect the taste of water, and there is no such higher chlorine odor.
After that, water is ready for service, but you need to store those water for future and emergency usage. Water is generally stored in underground tanks or over-ground tanks. Sometimes, drinking water are also stored for further usage.
Finally, water is ready for distribution, and it is distributed through pipelines, pumps, hydrants, tankers, hydro-meter, etc.
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Drinking Water Treatment
There are generally seven types of drinking water process is available, which are in following below-
- Screening is the process where it removes the major large floating and suspended particles.
- Generally, the water contains leaves, debris, paper, twigs, etc and those substances damage the equipment; that’s why the screening process is important.
- Two types of screen processes are available, those are coarse screen and fine screen.
- In coarse screen corrosion, resistive steel bars are placed at a distance of 5 to 15 cm. Here, screens are placed at 60 degrees.
- Fine screens are placed at just a lower level of the coarser screen. Here, steel bars are placed at a distance of 5 to 20 mm.
- This step is done after the completion of the screening process; here, the aerated operation is done by absorbing oxygen from the air.
- The aeration process helps to remove some soluble gases like carbon dioxide, hydrogen sulfide, etc.
- Sometimes, iron and manganese are present in soluble form in the water. Aeration helps to remove those materials from that.
- Sometimes, a higher amount of algae is present in the water, and it blocks the sand filter. To overcome this situation chlorination process is done to remove. The main steps of water treatment come after this step.
3. Coagulation and Flocculation
- To remove the small particles and suspended particles, the process is done.
- In the coagulation tank, a high-speed impeller is rotated to mix the coagulant properly.
- Flocculation takes place after coagulation is completed.
- In this step, water is gently stirred, and flocs are getting connected with another floc and create larger flocs.
- In flocculation, water flows through the basin at a very low speed. Here, different chamber is present to create flocs.
- After large flocs are obtained, then it settles at the bottom of the basin.
- Generally, for this operation, water is kept at the chamber for a long period.
- The materials which are stored at the bottom portion is called sludge, and there is a certain way to remove that material.
- This is the fifth step of water treatment process, where solids are separated from the water.
- In this step, the filter have a filtration rate of 4 to 5 cubic meter per square meter, and a rapid gravity technique also takes place.
- This process is done to remove bacteria, microorganisms, etc.
- It is the most effective process because it is simple & cheap.
6. Supplementary Treatment
Sometimes supplementary treatments are applied by adding fluoride and the name of the process is fluorination.
Drinking Water Quality Standards
Different types of parameters are discussed below:-
|Sl. No.||Parameters||Drinking Water IS 10500: 2012|
|Permissible limit||Maximum limit|
|3||pH||6.5 to 8.5||No Relaxation|
|5||Hardness (as CaCo3) (mg/l)||200||800|
|6||Alkalinity (as CaCO3) (mg/l)||200||600|
|7||Nitrate (mg/l)||45||No Relaxation|
|14||Cadmium (mg/l)||0.003||No Relaxation|