Rotary drum filter is an essential device in wastewater treatment, efficiently separating solids from liquids to enhance water quality, making it vital for various industrial and sewage treatment applications.

What is a drum filter?

A rotating drum filter is a device that separates solids from liquids using a spinning filter drum. Its primary components are a revolving drum with casing, a drive mechanism, a backwash system, and filter medium. Through mechanical filtration, the drum filter collects solid wastewater particles on its surface. The backwash process eliminates the trapped impurities, allowing for continuous filtration.

What are the components of a rotary drum filter?

The five primary components of a full drum filter system are typically the filter drum, housing, backwash system, drive device, and control system. Here are the specifics:

Filter drum

The central part of the rotating drum filter is the filter drum. It has strong mechanical strength and resistance to corrosion and is typically composed of synthetic fiber materials or stainless steel. Filter media covers the filter drum’s surface, and the pore size can be chosen based on requirements.

Drive device

The driving device is used to drive the filter drum to revolve, commonly using a transmission system made of an electric motor and a reducer. To maximize the filtration effect and operational efficiency, the drive unit’s rotation speed can be changed based on the filtration requirements.

Backwash system

High-pressure water pumps, backwash nozzles, and piping systems are all part of the backwash system. To eliminate accumulated solid suspended matter, the nozzle evenly sprays high-pressure water onto the filter drum’s surface while the high-pressure water pump supplies backwash water.

Control system

The backwash process is started automatically when necessary by the control system, which consists of sensors, controllers, and automation software to monitor a number of parameters during the filtering process, including inlet water flow, filter drum speed, filter cake thickness, etc.

Shell

Internal components are supported and fixed by the outer shell, which also serves to shield them from outside pollutants. In order to meet the needs of the wastewater treatment environment, the housing is often constructed from materials that are resistant to corrosion.

How do rotary drum filters work?

A slurry of suspended solids is fed into a revolving drum containing filter media to operate a rotary drum filter. One popular kind of discharge method for feeding the solid concentration slurry is belt discharge. Filtered solids can be reliably moved from the drum into the collection container using the endless belt conveyors. While the liquid travels through the filter media and is gathered in a vacuum receiver, the solids create a layer of cake on the drum’s surface as it turns. In order to improve the filtering effectiveness and remove moisture from the solids layer, a vacuum pump is employed to generate a vacuum pressure inside the drum.

Depending on the kind of rotary vacuum filter, the solids layer is then removed from the drum surface using either a roll discharge or a scraper blade. The filtrate is then pumped out for more treatment or release, while the solids are gathered and delivered for disposal or additional processing.

Types of rotary drum filters

There are several rotary drum type filters available, each with its own unique features and benefits. Some of the most common types include:

Rotating vacuum drum filters

A rotating vacuum filter is the ideal choice when low moisture content, efficient cake washing, and high filtration rates are required. They offer a high degree of adaptability and can handle a wide range of solids content and particle sizes.

String discharge filters

These filter drums use several parallel strings to support the filter media and allow for efficient cake discharge. They are ideal for applications requiring a clear filtrate and a high solids concentration.

Roll discharge filters

These filters use a roll discharge mechanism to remove the solids layer from the drum surface. They are ideal for applications requiring a high level of mechanical wear resistance, such as abrasive or gelatinous cakes.

Applications of drum filters in sewage treatment

Because of its automated operation features and effective solid-liquid separation capabilities, rotary drum filters are frequently used in sewage treatment facilities. Sludge dewatering, industrial wastewater treatment, primary treatment, and secondary treatment are its key application areas.

Primary processing

Drum filters are used in sewage treatment plants’ main treatment stage to eliminate silt and big suspended particles from wastewater, lessen the strain on later treatment equipment, and increase the system’s overall efficiency.

Secondary processing

In order to guarantee that the effluent water quality satisfies the discharge or reuse standards, the drum filter is utilized in the secondary treatment stage to further remove organic matter and fine suspended solids from the wastewater. To improve the solid-liquid separation effect, the drum filter can be employed in conjunction with biological treatment techniques (such as the biofilm method and activated sludge method).

Sludge dehydration

For sludge dehydration, rotary drum filters can also be used to remove water from the sludge, increase its solid content, decrease its volume, and lower the cost of further sludge treatment and disposal.

Industrial wastewater treatment

In order to remove suspended solids, grease, and other pollutants from wastewater, protect downstream treatment equipment, and enhance the overall treatment effect, drum filters are widely used in the printing and dyeing, papermaking, food processing, chemical, and other industries.

How to select a rotary drum filter

For water and wastewater treatment requirements, choosing the best rotary drum filter can be challenging. It’s crucial to take into account a few crucial elements when choosing a rotary drum filter to make sure the filter is ideal for your particular use case.

A) First and foremost, you should think about your application’s cleaning needs. The degree of cleaning needed for various applications varies, so it’s critical to choose a rotary drum filter that can efficiently remove the targeted impurities from the water.

B) Second, you should think about which filter cake is best for your application. The layer of solid particles that is eliminated from the water during the filtration process is known as the filter cake, and it is essential to the filter’s overall performance. Choosing a rotary drum filter that can reliably create the perfect filter cake that is simple to remove and discard is crucial.

C) Mechanical pressure is another crucial element to take into account. Depending on the particular requirements of the application, the rotating filters can function under either positive or negative pressure. To guarantee optimum performance, it’s critical to choose a filter that can function at the necessary mechanical pressure.

D) It’s crucial to think about how the filter integrates with other parts of the filtration system in addition to the filter itself. The solid concentration slurry created during the filtration process is stored and transported using the slurry tank and slurry pumps. For the entire filtration system to function smoothly, it is crucial to confirm that the rotary drum filter is compatible with the slurry tank and pumps.

E) Finally, you should think about any special needs or limitations that apply to your application. A few examples of this are space constraints and certain environmental circumstances. By taking these things into account, you can choose a rotary drum filter that will filter effectively and efficiently and is tailored for your particular application.

Conclusion

Rotary drum filter is an effective solution in water treatment, significantly improving water quality by efficiently separating solids from liquids. With its advanced design and diverse applications, this device plays a vital role in treating wastewater and industrial processes, making it an ideal choice for organizations aiming for environmental sustainability.

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