Wastewater Treatment

From providing oxygen to essential bacteria to keeping filters clean, blowers and compressors are present throughout the wastewater treatment process.

Wastewater treatment process

Wastewater treatment facilities are essential infrastructure in every municipality. The wastewater they process comes from buildings, whether house, office, shop or factory, as well as from road and highway drainage systems. It makes its way into drains, passes through the sewer system, and arrives at the treatment plant.

Blowers and compressors are present throughout the treatment process.

Before it can re-enter natural waterways, it is taken through a series of processes to clean it of solids, impurities, and pathogens.

Overpressure is a vital part of the wastewater treatment process. In fact, around half of the overall energy consumption of a wastewater treatment plant is used just for aeration. From providing oxygen to essential bacteria to keeping filters clean, blowers and compressors are present throughout the treatment process.

Applications

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Overpressure applications in wastewater treatment facilities

Wastewater treatment takes place over a number of stages. Physical, biological and chemical processes work together to thoroughly remove impurities and ensure clean water.

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.

Wastewater aeration process

Diffused aeration

In a large-scale municipal treatment plant, the most common aeration method is diffused aeration.

It introduces air to the wastewater via a network of diffusers in the shape of a tube, disk or plate. These diffusers receive a constant supply of air by a blower or compressor and produce a stream of bubbles that rise through the wastewater. The bubbles transport oxygen to all areas of the tank, allowing the bacteria to thrive.

The diffusers are spread out in a grid formation on the base of the aeration tank to maximize their efficiency and ensure proper aeration.

Lagoon aeration

Lagoon aeration is a variation of the activated sludge process used in wastewater treatment plants 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 typically used in the activated sludge process, 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 identical 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
Idling

While one tank is settling or decanting, the other is aerating or filling, allowing continuous operation.

In contrast to the multiple tanks that other wastewater treatment methods require, SBR allows the various processes to take place in a single multi-purpose tank, reducing the footprint of the plant.

SBR also permits greater control. Every batch can be individually monitored and the tank’s settings can be optimized accordingly.

Just like during a standard activated sludge process, air is introduced to ensure that the microbes can thrive. This happens during the reaction stage.

In larger treatment plants, a diffuser network is connected to a blower or compressor, but air may also be introduced mechanically.

Moving bed biofilm reactor

Treating wastewater in a moving bed biofilm reactor consists of an aeration tank and free-floating plastic chips.

These chips, known as carriers, provide a surface where a biofilm of bacteria can grow. Carriers vary in size and shape and are typically made of a plastic with a similar density to water so that they mix throughout the wastewater without sinking.

Just like in the activated sludge process, it is the bacteria that break down the dissolved contaminants. Aeration provided by a blower or compressor ensures that the carriers are in constant motion around the tank. This movement and the large surface area ensure maximum contact between oxygen, bacteria, and the wastewater being processed.

Membrane bioreactor

After the activated sludge process has taken place in the aeration basin, the wastewater is typically transferred to a sedimentation basin, where the remaining solids gradually sink to the bottom.

The membrane bioreactor process is an alternative that does not require an additional tank. At the end of the aeration basin, where the treated wastewater is discharged, an ultra-fine membrane is installed.

A vacuum pump draws the effluent through the membrane. As the pores 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

Filtration is a key part of wastewater treatment. But over time, the filters 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 build-up, allowing the filter to be reused.

Additional air flow via a compressor or blower makes the process faster and more effective.

Anaerobic digestion and biogas circulation

Wastewater treatment produces sludge as a by-product. This can either be disposed of or can continue for further processing in an additional step called anaerobic digestion.

This takes place in a digestion tower, where the biomass is heated and begins to ferment. It reduces in volume and gives off gases – predominantly methane and carbon dioxide. This is known as biogas, which can be used as a fuel to produce electrical power, for example, to run some of the treatment plant’s energy-intensive processes. Digestate, the nutrient-rich solids that remain, can be removed and used as a biofertilizer.

In the digestion tower, compressors recirculate the biogas through the sludge. This ensures that heat is evenly distributed and avoids 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.

Compare matching products

	DOLPHIN	MINK	SAMOS	SECO	TYR
Activated sludge process
Diffused aeration		✓	✓		✓
Lagoon aeration		✓	✓		✓
Sequencing batch reactor (SBR)		✓	✓		✓
Moving bed biofilm reactor		✓	✓		✓
Other applications
Sand trap circulation		✓	✓		✓
Membrane bioreactor		✓	✓		✓
Filter backwash		✓	✓		✓
Anaerobic digestion and biogas curculation	✓	✓	✓	✓

Wastewater treatment in practice

Increase in Sand Trap Effectiveness Thanks to Adjustable Claw Compressor

Municipal Sewage Treatment Plant in Kerteminde
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Energy-Saving Oxygenation of Aeration Tanks

Biological wastewater treatment
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Producing Energy with Less Energy

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Efficient Biogas Production in a Digestion Tower by Means of Reliable Claw Compressors

RWZI Amersfoort
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FAQ

What is an aeration or wastewater blower?

A blower is a machine that moves gas or air by increasing the pressure slightly. Air is trapped and compressed, then released again, now at a higher pressure. The exact operating principle depends on the type of blower.

There is no specific blower technology used for aeration: the name refers only to the blower application. 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 and compressors?

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

DOLPHIN – liquid ring compressors
MINK – claw compressors
SAMOS – side channel blowers
SECO – rotary vane compressors
TYR – rotary lobe 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 multiply and 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 flow rate you need for your aeration system is a complex calculation. It depends on a number of variables, such as the amount of the organic matter the wastewater contains and the depth of the tank.

These calculations should be conducted by an engineering expert specialized in wastewater treatment plant design. Based on this information, we can then help you make an informed choice on which technology is best.

Do I need a blower or compressor for my wastewater treatment process?

Which technology your process needs depends largely on your pressure requirements.

A compressor can provide air flow at a higher pressure than a blower. But for processes that do not require as much pressure as a compressor can offer, a blower is a better and more economical solution.

Contact us – we are happy to advise you on the best technology for your process.

How do I chose the right blower or compressor for my wastewater treatment process?

When considering which blower or compressor to use for your wastewater processing application, there are a number of criteria to assess. These include:

Technology type
Inlet flow
Overpressure requirements
Seasonal fluctuations

Because a wastewater treatment plant is a complex set-up, an engineering expert specialized in wastewater treatment plants should conduct the calculations that are necessary to make the final decision. The results of these will help you decide which technology to invest in.

We are happy to advise you on the best blowers or compressors for your wastewater treatment facility. Contact us!

What is the difference between a blower and a compressor?

While both a compressor and a blower create overpressure, they use different methods and give different results.

A blower uses a slight increase in pressure to push gas or air in a certain direction. A compressor raises the pressure of the gas or air by compressing it into a small space, making it denser before discharging it.