Treatment FAQ

how each process works in water treatment

by Dr. Ines Cassin Published 2 years ago Updated 2 years ago
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Water Treatment Process: Follow Water Through a Surface Water Treatment Plant

  • Coagulation. Coagulation is defined as the water treatment process of increasing the tendency of small particles to...
  • Flocculation. Following the coagulant chemical addition and the rapid mix processes, the raw water will continue on to a...
  • Sedimentation (or Clarification). The water...

Full Answer

What are the 5 stages of water treatment?

Water Treatment Process: Follow Water Through a Surface Water Treatment Plant

  • Coagulation. ...
  • Flocculation. ...
  • Sedimentation (or Clarification) The water continues on to the sedimentation basin, or clarifier, after the flocs have been formed. ...
  • Filtration. ...
  • Disinfection. ...
  • Chlorination Operations. ...
  • Conclusion. ...

What are the steps in the water treatment process?

What are the main treatment steps in a water treatment plant to treat river water?

  • Coagulation.
  • Coagulation-Flocculation.
  • Flocculation.

What are the methods of water treatment?

Methods of the water treatment process The water treatment process includes many operations like screening, aeration and sedimentation, sedimentation with coagulation, softening, filtration, disinfection, etc. The water treatment process generally adopted depends upon the quality of raw water and the quality of water derived. Methods of the water treatment process are explained below. 1.

What is the process of water treatment?

What are the 6 methodologies used in water treatment?

  • Coagulation / Flocculation. Coagulation is adding liquid aluminum sulfate or alum and/or polymer to raw or untreated water. …
  • Sedimentation. …
  • Filtration. …
  • Disinfection. …
  • Sludge Drying. …
  • Fluoridation. …
  • pH Correction.

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How does the process of water treatment work?

Water flows through a filter designed to remove particles from within it. The filters are made of layers of sand and gravel, and in some cases, crushed anthracite. Filtration collects the suspended impurities in water, enhancing the effectiveness of disinfection. These filters are routinely cleaned by backwashing.

What are the 4 steps of water treatment?

4 Steps of Community Water TreatmentCoagulation and Flocculation. ... Sedimentation. ... Filtration. ... Disinfection.

What are the 3 parts of the water treatment process?

There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment.

What are the 7 methods of water treatment?

Top 7 Methods of Water TreatmentCoagulation / Flocculation. Coagulation is adding liquid aluminum sulfate or alum and/or polymer to raw or untreated water. ... Sedimentation. When water and flocs undergo the treatment process, they go into sedimentation basins. ... Filtration. ... Disinfection. ... Sludge Drying. ... Fluoridation. ... pH Correction.

What are the 5 stages of water treatment?

Public water systems often use a series of water treatment steps that include coagulation, flocculation, sedimentation, filtration, and disinfection.

What are the stages of water treatment plant?

What Are the Different Stages of Water Treatment?Collection. Before the water can be treated, it must first be collected from lakes, rivers and reservoirs. ... Screening. ... Chemical addition. ... Coagulation. ... Sedimentation and clarification. ... Filtration. ... Disinfection. ... Storage.More items...

What are the 3 stages of wastewater treatment PDF?

Wastewater is treated in 3 phases: primary (solid removal), secondary (bacterial decomposition), and tertiary (extra filtration).

What is flocculation and coagulation?

Coagulation and flocculation are two separate processes, used in succession, to overcome the forces stabilising the suspended particles. While coagulation neutralises the charges on the particles, flocculation enables them to bind together, making them bigger, so that they can be more easily separated from the liquid.

What are the different types of water treatment?

Four Common Water Treatment Methods:Reverse Osmosis Water Filtration. Reverse Osmosis is a process where water pressure is employed to force water through a semi-permeable membrane. ... Ultraviolet Water Sterilization and Filtration. ... Filtration. ... Distillation.

What are stages of water?

There are four main stages in the water cycle. They are evaporation, condensation, precipitation and collection. Let's look at each of these stages.

What are the steps of water treatment?

Today, the most common steps in water treatment used by community water systems (mainly surface water treatment) include: Coagulation and flocculation are often the first steps in water treatment. Chemicals with a positive charge are added to the water.

How does a water treatment unit work?

Even though EPA regulates and sets standards for public drinking water, many Americans use a home water treatment unit to: 1 Remove specific contaminants 2 Take extra precautions because a household member has a compromised immune system 3 Improve the taste of drinking water

What is the process of boiled water?

Distillation is a process in which impure water is boiled and the steam is collected and condensed in a separate container, leaving many of the solid contaminants behind. Disinfection. Disinfection is a physical or chemical process in which pathogenic microorganisms are deactivated or killed.

Why is surface water more contaminated than ground water?

Typically, surface water requires more treatment and filtration than ground water because lakes, rivers, and streams contain more sediment and pollutants and are more likely to be contaminated than ground water. Some water supplies may also contain disinfections by-products, inorganic chemicals, organic chemicals, and radionuclides.

What is a water softener?

Water Softeners. A water softener is a device that reduces the hardness of the water. A water softener typically uses sodium or potassium ions to replace calcium and magnesium ions, the ions that create “hardness.”. Distillation Systems.

What is the most common type of water treatment system?

The most common types of household water treatment systems consist of: Filtration Systems. A water filter is a device which removes impurities from water by means of a physical barrier, chemical, and/or biological process. Water Softeners. A water softener is a device that reduces the hardness of the water.

Why is chlorine added to water?

After the water has been filtered, a disinfectant (for example, chlorine, chloramine) may be added in order to kill any remaining parasites, bacteria, and viruses, and to protect the water from germs when it is piped to homes and businesses.

Why is drinking water not used in drinking water treatment plants?

The only drawback in this process is, once the water leaves the treatment plant to the households, bacteria in contact with the water will get ingested and cause diseases. There is no protection past the treatment plant. Maybe, that is why it is not commonly used in drinking water treatment plants.

What happens when you add chlorine to water?

Once chlorine is added to water, the remaining chlorine present in water is less concentrated. Chlorine acts as a barrier between germs and water. It also reacts to any organic agent available in the water.

What is the process at a water treatment plant?

You can find praises of water treatment plants anywhere. You may have read long passages of how useful these plants are and wondered, but what is the process at a water treatment plant? How do they purify the water?

Types of water treatment plants

Two types of water treatment plants are commonly seen in Bangladesh. Effluent treatment plants are used to deal with wastewater filled with toxic and chemical waste in industries that produce it in bulk.

What kind of water treatment plant should you get?

What kind of water treatment plant you should get mainly depends on what do you want it for. ETP has a more complex mechanism than STP. It is more expensive to build an effluent treatment plant.

What are the stages of water treatment?

Several processes are at your disposal for implementing the various preparation stages of water treatment: Physical processes for mechanical preparation such as aeration, sedimentation or thermal influence. This also includes the use of screens, filters and sieves. Biological processes such as anaerobic wastewater ...

What are the two types of wastewater treatment?

Firstly, problematic substances are removed from the water. This is done with cleaning, iron removal, manganese removal, sterilisation, desalination or softening .

What is the purpose of return sludge?

The other part of the sludge, also known as "return sludge" is returned to the aeration tank to ensure that there are enough microorganisms in the aeration tank to break down the dirt. After biological treatment, approximately 90% of the wastewater is cleaned of biodegradable substances.

What is the name of the tank that cleans wastewater?

In most wastewater treatment plants, the water pre-purified in the mechanical treatment stage now reaches what are known as aeration tanks, which are often designed as circulation tanks. This is where the biological cleaning takes place.

What is the process of converting methane gas into electricity?

A pump transports the fresh sludge to what is known as a digestion tower. In the digestion tower, methane gas is produced in four phases (hydrolysis, acidification, acetone gene and methanogene phase); it is converted into electricity in a block heating plant and can be used to supply the plant with energy.

How much of the wastewater is removed in the first stage?

In the first stage, the still completely untreated wastewater is mechanically treated; this removes about 20 - 30% of the contained solids. To achieve this, the wastewater is guided into a screening plant, where a screen or sieve drum filters out coarse impurities such as leaves, paper or textiles.

Why is water a precious commodity?

Water is a precious commodity. To protect our natural waters and to support drinking water production, all wastewater is therefore first cleansed of containments and pollutants before it is returned to the water cycle. To treat the water and to achieve the best possible, natural water quality, different processes are used.

What is water treatment?

Water treatment is the process of removing all those substances, whether biological, chemical, or physical, that are potentially harmful to the water supply for human and domestic use. This treatment helps to produce water that is safe, palatable, clear, colorless, and odorless. Water also needs to be non-corrosive, meaning it will not cause damage to pipework.

How does aerated water work?

After screening, the water is aerated (supplied with air) by passing it over a series of steps to take in oxygen from the air. This process helps in expelling soluble gases such as carbon dioxide and hydrogen sulfide (both of which are acidic, so this process makes the water less corrosive) and expels any gas eous organic compounds an undesirable taste to the water. Aeration also removes iron or manganese by oxidation of these substances to their insoluble form. Iron and manganese can cause peculiar tastes and can stain clothing. Once in their insoluble forms, these substances can be removed by filtration.

What is the process of separating solids from liquids?

Filtration is the process where solids are separated from a liquid. In water treatment, the solids that are not separated in the sedimentation tank are removed by passing the water through sand and gravel beds. With a flow rate of 4–8 cubic meters per square meter of filter surface per hour, rapid gravity filters are often used.

What happens after aeration?

After aeration, coagulation occurs to remove the fine particles (less than 1 µm in size) suspended in the water . In this process, a chemical called a coagulant (with a positive electrical charge) is added to the water, which neutralizes the fine particles' negative electrical charge. The coagulant's addition takes place in a rapid mix tank where a high-speed impeller rapidly disperses the coagulant.

What is the process of wastewater treatment?

Wastewater treatment is a complex topic that involves numerous processes, components and equipment that all have the singular goal to turn any liquid into water that can either be reused or returned to the water cycle.

How does wastewater get into a plant?

It is usually done by pouring the wastewater into big sedimentation tanks (can either be square, circular or rectangular) for the macrobiotic solid matter to settle at the bottom or at the surface of tanks. Once the solid matter settles, it turns into sludge that is removed using large scrappers and is moved to the center of the cylindrical tanks. After that, the sludge is pumped out of the tanks for further treatment (it can be used as a fertilizer), with the remaining water also being pumped out for secondary treatment.

Why is chlorine used in wastewater treatment?

In some cases, chlorine is used to disinfect the effluent in order to complete the secondary treatment process .

What is the secondary process of treatment?

The secondary process of treatment is where the removal of fine and dissolved colloidal organic matter occurs, with the help of microorganisms (algae, fungi, and bacteria) that help decompose the organic matter to stable organic forms . When the effluent leaves the sedimentation tank in the primary stage, it is typically transferred to a facility that uses this treatment, and different processes (activated sludge process, aerobic digestion, anaerobic ponds, etc.) are used by different plants when removing organic matter. By the end of this treatment process, the remaining organic matter turns into large particles that settle down at the bottom of huge tanks, which makes them easy to separate from the remaining wastewater. In some cases, chlorine is used to disinfect the effluent in order to complete the secondary treatment process.

Why is wastewater treated in a tertiary stage?

After the primary and secondary treatment stages, wastewater needs to undergo the tertiary treatment process to ensure that it is free of suspended and dissolved substances. Even though the effluent from the secondary stage is somewhat safe for release into the environment, undergoing the tertiary stage is necessary for the following reasons: (1) it has the ability to remove up to 99% of the wastewater’s impurities; (2) it produces effluent water that is close to drinking water quality; (3) to meet standard requirements in developed countries; (4) for the removal of hazardous nitrogen and phosphorus compounds.

What happens when sedimentation leaves the sedimentation tank?

When the effluent leaves the sedimentation tank in the primary stage, it is typically transferred to a facility that uses this treatment, and different processes (activated sludge process, aerobic digestion, anaerobic ponds, etc.) are used by different plants when removing organic matter.

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Coagulation

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Coagulation is defined as the water treatment process of increasing the tendency of small particles to attach to one another and to attach to surfaces such as the grains of a filter bed. Many surface water supplies contain particles that are too small to settle out of solution on their own. These small particles often carry a sm…
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Flocculation

  • Following the coagulant chemical addition and the rapid mix processes, the raw water will continue on to a flocculation basin. The goal of the flocculation treatment process is to increase the size of the flocs in order to increase their ability to settle out.
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Sedimentation

  • The water continues on to the sedimentationbasin, or clarifier, after the flocs have been formed. The goal of this stage of the treatment process is to reduce the amount of solids in the water before the water is filtered in the next treatment step. The large flocs will settle out of suspension via gravity. Clarifiers can remove a very large percentage of the suspended materials in water. I…
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Disinfection

  • As discussed previously, the surface water treatment rule requires both the filtration and disinfection of surface water sources. The water must be disinfected now that it has been filtered.
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Chlorination Operations

  • Chlorination was one of the first drinking water disinfection methods. It is still the most commonly used disinfection method used today. The filtered water is injected with either liquid sodium hypochlorite, gaseous chlorine, or solid calcium hypochlorite. Chlorine is a strong oxidant. It is used to both disinfect and also to remove color, taste and odor compounds, iron and manganes…
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Conclusion

  • In order to meet the requirements of the Surface Water Treatment Rule, a water system must both remove and inactivate the pathogens in the water. This process begins with coagulation, which destabilizes the particles in the water. Then, during flocculation, the destabilized particles bump into each other and form larger and larger flocs. These large flocs are given adequate time to se…
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