Selecting The Right Valve For Wastewater Treatment Applications

By Author: Rohan Rajput
Total Articles: 23
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Wastewater treatment is an important industrial process meant to improve the quality of wastewater. The quality of the treated water is dependent on the suitability and quality of the installed valves. The sedimentation, flow control, and the treatment of thick and industrial wastewater place high demands on the materials used for the valves.

Thus, it is vital that water treatment facilities use the correct valves in their systems. This will ensure that the piping systems operate consistently, safely, and effectively. This will also prevent unnecessary maintenance. This holds true for all types of water treatment from water desalination plants or producing high-purity water for pharmaceutical industries.

The following criteria must be taken into consideration while choosing a valve for wastewater treatment:

• Purpose of the valve: Whether it is for isolation or modulating/ throttling.

• Process parameters: The flow, pressure, and temperature of the wastewater.

• Chemical compatibility: The concentration, percentage of solids, media, and density of the chemicals. ...
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• Process requirements: The frequency of operation, the allowable leakage rate, available space, and cleanliness.

There are various types of valves used in water treatment applications. Industrial valves manufacturers design each of these to work in a specific manner and serve specific purposes. The following are some of the most common valve types used in wastewater treatment facilities.

1. Gate valves

Gate valves are considered to be full-stop valves. Gate valves have a disc or wedge that can be moved up and down to either block or allow the flow of water. They are mainly used to isolate or shut off the wastewater. Since gate valves are designed to either turn the current flow on or off, which means that they should not be used to adjust the water flow as this will cause them to wear down quickly.

Gate valves work well within high-temperature and pressure systems. Thus, they are ideal to use in manufacturing systems, pharmaceutical systems, gas and oil applications, and automotive and marine systems.

2. Butterfly valves

Butterfly valves are used to isolate or regulate the flow of the water. These have a circular disc mounted on a shaft in the center of the valve. The disc opens or closes the valve, functioning as a closing mechanism.

Butterfly valves are generally used in wastewater treatment for air supply systems. They are lighter and more compact than other valves and thus offer a cost-effective option for larger valve sizes.

Though they are economical, they do not handle sludge with solids/ stringy materials well and therefore tend to foul up with slurry applications. The cavities around the disc stem are especially vulnerable as they can potentially entrap fluids and slurries. This means that there is a risk of unwanted contamination in slurry services.

3. Check valves

Also known as non-return valves, check valves are designed to prevent backflow in piping systems. This helps in ensuring that the system operates properly and prevents damage from taking place. A check valve uses the pressure from the forward-flowing liquid to open the valve and any reversal of it will close it. So it allows the liquid to flow fully unobstructed in one direction and automatically shut off when the pressure is reversed or reduced.

They are used in many different applications, including wastewater treatment systems. They are ideal in a system where there is a continuous flow of liquid and where preventing backflow is important.

4. Globe valves

Globe valves are spherical in shape with two cavities separated by a circular opening. The opening forms the seat onto which a moveable plug, also called a disk and can be screwed in to shut off the flow. The plug is connected to a stem with a handwheel that is used for operation.
Globe valves are used for precise throttling and control services in wastewater treatment applications as they can be easily automated. However, like butterfly valves, they are also not able to handle slurries.

The wastewater treatment process is divided into three phases: primary, secondary, and tertiary. During the primary stage of the wastewater process, ball valves are used as it is necessary to use valves that are able to handle slurries. This is because the wastewater at this point still has sediment, solids, and sludge. During the secondary stage, butterfly and check valves are used as the remaining organic matter is removed using aeration systems and these types of valves are effective for it. In the tertiary stage, check valves, globe valves, and butterfly valves are used as there is no longer any sediment in the wastewater. Thus, while buying valves from valves and pumps manufacturers, the purpose of the valve must be kept in mind to ensure that one gets the valve that is fitted to their needs.

Using the right type of valves in the wastewater treatment system ensures a smooth overall operation. Valve failure will cause a process shutdown and also result in the destruction of the infrastructure. In addition to this, it can also result in dangerous conditions or environmental contamination. Industrial valves manufacturers in India provide a vast array of valve types to choose from, thus allowing the treatment systems to perform efficiently and effectively.

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