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Wastewater Treatment

Overpressure is a vital part of wastewater treatment. In fact, around half of the overall energy consumption of a wastewater treatment plant is used just for aeration.


Overpressure applications in wastewater treatment facilities

Wastewater treatment facilities are vital infrastructure in every municipality. As populations grow and the demand for clean water follows suit, only these can ensure that the resulting wastewater can be released safely into the natural environment.

Wastewater treatment takes place over a number of stages. Physical, biological and chemical processes work together to thoroughly remove impurities. The following applications in wastewater treatment use blowers or compressors for aeration or circulation.

Activated sludge process

The first step in treating wastewater is screening, a preliminary stage where the largest solids are removed. This consists of debris that has made its way into the sewage system, such as pieces of wood, rubbish, or plastic, which could clog pipes or damage equipment.

Diffused aeration

In a large-scale municipal treatment plant, the most common aeration method is diffused aeration. Diffused aeration introduces air to the wastewater via a network of diffusers. This aeration system comprises multiple devices in the shape of a tube, disk or plate and receive a constant supply of air by a blower or compressor. They use this to produce a stream of bubbles that rise through the tank. This provides the bacteria with the oxygen they need to thrive. The diffusers are spread out in a grid formation on the base of the tank to maximize their efficiency and ensure proper aeration.

Lagoon aeration

Lagoon aeration is an alternative to the activated sludge process used in smaller wastewater treatment plants, such as in rural areas where flow is low. It is also a biological process that relies on the natural microbes present in wastewater. However, instead of the large aeration tanks, wastewater is held in a series of shallow basins, also called lagoons. Air is continuously injected to provide the microbes with oxygen. Usually, this is provided through surface aeration, such as with a floating brush aerator. However, air flow can also be provided by a diffused aeration network connected to a blower or compressor.

Sequencing batch reactor (SBR)

Sequencing batch reactors (SBR) are a set of two or more basins or tanks with a common inlet in which a version of the activated sludge process takes place. Each basin goes through five distinct phases: filling, reacting (aerating), settling, decanting and idling. While one tank is settling or decanting, the other is aerating or filling, allowing continuous operation. Just like during a standard activated sludge process, air is introduced during the reaction stage to ensure the efficiency of the microbes. In larger treatment plants, this is usually done via a diffuser network connected to a blower or compressor, but may also be introduced mechanically.

Moving bed biofilm reactor

Treating wastewater in a moving bed biofilm reactor consists of an aeration tank, similar to an activated sludge tank, and free-floating carriers where biofilm can grow. These vary in size and shape to provide different surface areas and are typically made of a plastic with a similar density to water. A biofilm of bacteria forms on this surface. Just like in the activated sludge process, it is these bacteria that break down the dissolved contaminants. Aeration provided by a blower or compressor ensures that the carriers are in constant movement around the tank. This movement and the large surface area ensure maximum contact between the bacteria, the wastewater they are processing, and the oxygen they need to thrive.


Aeration of aeration tanks

Aeration plays an essential role in wastewater treatment. By continuously introducing oxygen into the wastewater, the naturally occurring microorganisms that break down the organic waste are stimulated and can work more efficiently. This results in cleaner water over a shorter period of time, which can then be released safely back into nature.

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Membrane bioreactor

The membrane bioreactor process is an alternative to the sedimentation stage that usually takes place after the activated sludge process. At the end of a standard aeration basin, where the treated wastewater is discharged, an ultra-fine membrane is installed. A vacuum pump creates a slight vacuum and pulls the effluent through the membrane. As the holes in the membrane are extremely small, the microbes present in the activated sludge cannot pass through and remain in the aeration tank.

Sand Trap Circulation

As well as organic matter, wastewater can contain sand, grit and small stones, particularly when it comes through road drainage systems after periods of heavy rainfall. These small pieces of debris are separated in a sand trap, also known as a grit chamber, where they sink to the bottom. The process can be accelerated by using a compressor or blower to circulate the wastewater. This mechanically separates the grit and causes it to drop to the bottom of the tank, where it can be removed.

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Filter backwash

Over time, the filters in the wastewater treatment process become coated and clogged. Filter backwashing is an effective type of preventive maintenance that can extend the life of a filter, allowing it to be reused for longer.

To do this, the flow of water is reversed and pumped backwards through the filter at a high velocity. This dislodges the build-up on the filter, allowing the filter to be reused. Additional air flow via a compressor or blower makes the process faster and more effective.

Anaerobic digestion

Wastewater treatment produces sludge as a by-product. This can either be disposed of or can continue for further processing. This additional step is called anaerobic digestion and takes place in a digestion tower. It can greatly reduce the amount of sludge and can also create useful by-products, such as biogas. Biogas can be used as a fuel to produce electrical power, for example, to run some of the treatment plant’s energy-intensive processes.

Compressors are used in the digestion tower to recirculate the biogas through the sludge, ensuring that heat is evenly distributed and avoid sediment settling at the bottom of the tank.

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Our solutions for wastewater treatment

Our extensive product range helps to always select the optimal overpressure generator for wastewater treatment applications. Both technically and economically. No matter your requirements. We have the best solution for you. Of course, always with the service tailored to your needs.

Activated sludge process
Diffused aeration
Lagoon aeration
batch reactor
Moving bed biofilm reactor
Other applications
Sand trap circulation
Filter backwash
Anaerobic digestion
Membrane bioreactor

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How do I choose the right technology for wastewater treatment?

A wastewater treatment plant is a complex set-up. As a result, there are a number of criteria to assess when considering which blower to purchase for your wastewater processing application. An engineering expert specialized in wastewater treatment plant should conduct the necessary calculations for your process requirements. The results of these will help you decide which technology to invest in. Among other things, the engineer will evaluate aspects such as the following:

  • Technology type
  • Ultimate pressure
  • Pumping speed
  • Flow
  • Seasonal fluctuations

If you need help choosing the right equipment, contact us. We are happy to advise you.

What is an aeration or wastewater blower?

In wastewater treatment, a blower provides a continuous flow of air to processes that require oxygen. This is essential for treatment stages that use naturally occurring microbes and bacteria to break down organic waste, as these need oxygen to work and multiply.

What are the different types of aeration blowers?

There are several types of compressors and blowers for wastewater treatment. The solutions from Busch comprise the following technology types:

1. Liquid ring compressors
2. Rotary lobe blowers
3. Claw compressors
4. Side channel blowers

Each technology has its own properties and strengths, and large wastewater treatment plants may benefit from combining different overpressure technologies for different applications. This can make the process more energy efficient, lowering overall operating costs.

How does wastewater aeration work?

Aeration is a vital part of wastewater treatment. The naturally occurring bacteria in the wastewater need oxygen to break down organic matter. This is injected into the aeration tanks by a compressor or blower, usually via a network of diffusers.

Overpressure equipment is also used in other applications within the wastewater industry, such as circulating the water to remove debris or cleaning filters.

How do you calculate the air blower capacity necessary for an aeration tank?

Determining the blower capacity you need for your aeration tank is a complex calculation. It depends on a number of variables, such as the amount of the organic matter the wastewater contains and the depths of the tank. These calculations should be conducted by an engineering expert specialized in wastewater treatment plant design. We can then help you make an informed choice on which technology is best based on this information.

What is an ETP blower?

An ETP blower is the name for any blower that is used in an industrial effluent treatment plant (ETP). It is used to treat industrial wastewater and ensure that it is safe to be re-released into the environment.