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Aeration in Wastewater Treatment

Aeration plays an essential role in municipal wastewater treatment. The aeration processes are supported by a compressor or blower from Busch.

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How does aeration in wastewater treatment work?

Wherever there are built-up areas, there is wastewater. This comes from all kinds of buildings – homes, offices, shops and industries – as well as from the streets after rain or snowfall. Municipal wastewater makes its way into drains, passes through the sewer system, and arrives at the treatment plant. There, a series of treatments await before it can re-enter natural waterways. The main stages involved are filtration and aeration. The aeration processes are supported by a compressor or blower from Busch.

Aeration plays an essential role in municipal 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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Screening

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.
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Sand trap water circulation

In the sand trap, also known as the grit removal tank, grit, sand and small stones sink to the bottom and are removed. This process largely works using gravity. However, some wastewater treatment plants additionally aerate their sand traps using a compressor or blower (1). The airflow the blower provides keeps the wastewater in constant circulation. This ensures that organic matter and any oils or grease remain suspended so that no sludge builds up in the sand trap. These float to the top (2), while the sand drops to the bottom (3). It is subsequently removed (4) and sent to landfill.

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Primary sedimentation

With the initial screening processes complete, the wastewater undergoes primary treatment. This sedimentation happens in a settling tank, where the remaining solids gradually sink to the bottom. From there, they can be drained off and removed as waste sludge. Although the wastewater now appears relatively clear and free from solids, it still contains a multitude of dissolved particles and organic matter. These are removed during secondary treatment.
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Activated sludge

The wastewater is transferred to the aeration tank, also known as the activated sludge tank (1). This is a biological wastewater treatment process that uses the high numbers of microbes and bacteria naturally found in wastewater. These digest dissolved organic compounds and other particles that were too small to be removed during primary sedimentation, creating water and carbon dioxide as byproducts. And as they eat, they multiply and form microcolonies that can be filtered out as solids.

For the bacteria to operate efficiently and multiply effectively, they need a continuous supply of oxygen. A blower or compressor (2) is connected to a network of diffusers (3) and provides air, which the diffusers use to create a steady flow of fine air bubbles (4) that rise through the tank. The airflow from the compressor or blower ensures a high oxygen concentration, stimulating microbial growth and allowing the bacteria to thrive.

This airflow also has a secondary effect of circulating the wastewater (5). A common problem in wastewater treatment is that the deeper and bigger the tank, the more challenging it is to ensure a consistent distribution of dissolved oxygen. The constant bubble movement keeps the wastewater in motion. The bubbles also help remove dissolved gases, such as hydrogen sulfide and ammonia, and other volatile organic compounds. As the bubbles rise through the water, they create a way out for the gases. The undesirable gases can escape with the bubbles into the air above the tank. This process is known as scrubbing.
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Secondary sedimentation

Once the wastewater contains a high number of solids, it is moved into the next tank (6) – the second settling tank of the treatment process. Here, there is no more aeration and no more water movement. As a result, the solids gradually fall to the bottom of the tank and form sludge (7). Some of this is removed as waste sludge, while some is returned to the activated sludge tank in order to increase the microbial population.
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Disinfection

With the organic matter removed, just one final step is necessary before the effluent can be released back into the environment. In most wastewater plants, the effluent is mixed with chlorine in the disinfection tanks and left to work for between 30 and 60 minutes before being dechlorinated again. In others, the effluent undergoes ultraviolet treatment. Both methods remove over 99% of any remaining harmful bacteria, leaving behind clean, safe, fresh water.
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Industrial wastewater treatment

The wastewater produced in certain industries can contain a number of by-products that should not enter the natural water supply. As a result, many of these industries have their own inhouse wastewater treatment plant so that the treatment can be specifically tailored to the contaminants that their process produces. This allows them to comply with any industry-specific regulations. These treatments may include removal of toxic materials, acids and alkalis, treating brine, and removal of various solids.

In some facilities, the wastewater may undergo the complete treatment process and be released back into the environment. In others, it may be partially treated, then sent to the municipal wastewater treatment plant.

Although the industry and the products to be removed vary and additional steps may be necessary, the general process remains largely the same: filtration followed by aeration. Just as in a municipal wastewater treatment plant, blowers or compressors are used to provide airflow to the aeration tank. However, as the wastewater can contain different and potentially harmful chemicals, there may be different requirements for the blower or compressor, such as corrosion resistance

Our solutions for wastewater treatment

Our specially designed overpressure solutions are operated in all sizes of wastewater treatment plants. Both municipal and industrial. The world over. When you choose an aeration blower or compressor from Busch, you are choosing technology that is both reliable and efficient, helping your process be the best it can be.

If you need help to select the appropriate blower for your aeration process, our project engineers will recommend the optimal solution. Precisely matched to your treatment plant capacity.If you need help to select the appropriate blower for your aeration process, our project engineers will recommend the optimal solution. Precisely matched to your treatment plant capacity.

 
Sand Trap Water Circulation
Aeration of aeration tanks
BLOWERS
 
 
TYR
SAMOS
COMPRESSORS
 
 
MINK

Learn more about wastewater aeration

What is the main purpose of aeration?

Aeration provides oxygen to the bacteria that naturally occur in wastewater. This allows them to multiply and efficiently digest dissolved contaminants. Wastewater is otherwise an anaerobic environment, so when all the oxygen has been used up, the bacteria would stop working. By reintroducing air using a blower or compressor, the bacteria can continue not just at their previous rate, but become increasingly more abundant and more efficient.

What are the different methods of aeration in wastewater treatment?

There are several different aeration systems available for wastewater treatment plants. The most common are floating brush aeration and diffusion.

Floating Brush Aerator

A floating brush aerator creates bubbles mechanically using metal brushes mounted on a horizontal rotor. As the brushes cut through the wastewater, they mix it with the ambient air. In doing so, air bubbles are introduced. These provide the microbes in the wastewater with oxygen. The movement that this process creates ensures that the oxygen is evenly distributed throughout the entire basin or tank.

Diffusers

Diffusers are the most common tool for wastewater aeration. They take the form of disks, tubes, or plates and are placed throughout the tank in a grid formation. A blower is connected to the diffuser network and provides air, with which the diffusers create a steady flow of fine air bubbles. These rise through the tank, both providing the oxygen the bacteria need to thrive and effectively circulating the wastewater.

Diffusers can aerate large tanks and are therefore suitable for treatment plants where large quantities of wastewater are treated.DiffuserDiffusers are the most common tool for wastewater aeration. They take the form of disks, tubes, or plates and are placed throughout the tank in a grid formation. A blower is connected to the diffuser network and provides air, with which the diffusers create a steady flow of fine air bubbles. These rise through the tank, both providing the oxygen the bacteria need to thrive and effectively circulating the wastewater. Diffusers can aerate large tanks and are therefore suitable for treatment plants where large quantities of wastewater are treated.

How does a wastewater treatment system work?

A wastewater treatment system is divided up into a number of different filtration and aeration processes. Firstly, the wastewater is screened and filtered to remove any large debris, such as plastic or plant debris, as well as sand and grit. A blower or compressor is used to circulate the wastewater during this process and improve the efficiency of the sand trap. Then the wastewater proceeds to the first settling tank, where primary treatment takes place. This separates the liquids and the solids – the suspended particles gradually sink to the bottom and are filtered out, while the liquids continue to secondary treatment. This biological process takes place in the activated sludge tank, where bacteria digest dissolved organic compounds and other small particles. As they do so, they form microcolonies that can be subsequently removed as solids. A blower or compressor injects air bubbles into the wastewater by means of a diffuser network. These air bubbles provide the bacteria with the oxygen they need to thrive. The wastewater is then transferred to the second settling tank, where the residual solids are filtered out. In order to ensure that all water-borne pathogens have been removed, the water is taken through one last disinfection process, then can be discharged.

Where is overpressure used in the aeration processes?

In the wastewater treatment process, blowers are used in two areas: in the sand trap and in the activated sludge tank. In the sand trap, they avoid sludge build-up by keeping organic matter suspended. They are also used in biological wastewater treatment systems, such as the activated sludge tank. There they provide the necessary oxygen for microorganisms to break down dissolved organic contaminants in the wastewater. The stream of bubbles also keeps the wastewater constantly in movement. This ensures an evenly distributed oxygen supply in all areas of the tank, which increases the efficiency of the process.

What are the advantages of aeration over alternative wastewater treatment processes?

Aeration in wastewater treatment has several benefits. Instead of introducing chemicals to the wastewater, which would subsequently need to be removed again before the water can be released, the activated sludge process makes use of the bacteria and microorganisms that naturally occur in wastewater. Aeration simply increases their efficiency and numbers to maximize the effectiveness and speed of the process without creating any harmful by-products.

What are the best blowers for aeration?

Busch has a variety of different blowers for aeration to choose from. Every blower has its own advantages and disadvantages, each of which can be decisive for your process. We are happy to advise you on which would be the best match for your exact application and to develop a solution for your entire plant.

What are the best blowers from Busch for the aeration process?

When it comes to aerating aeration tanks in wastewater treatment facilities, blowers and compressors from Busch have become the first choice among the technologies that can be used for overpressure generation.

The following overpressure equipment is especially suitable for wastewater treatment processes:

· Rotary lobe blowers
· Claw compressors
· Side channel blowers

Contact us to find the best solution for your process. We are happy to advise you.

What are some examples for the use of overpressure technology from Busch in aeration applications?

Blowers from Busch can be used for all aeration and air circulation processes in a wastewater treatment plant. Find out how customers in Denmark and Germany have used compressors from Busch to increase the efficiency of their sand traps. In the activated sludge tank, blowers provide oxygen to the naturally occurring microbes, which allows them to break down solid matter and multiply.

What are the key points to consider when buying overpressure equipment for aeration applications?

When considering which blower or compressor to purchase for your wastewater processing application, there are a number of criteria to assess. 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!

Wastewater Aeration in Practice

  • Increase in Sand Trap Effectiveness Thanks to Adjustable Claw Compressor

    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

    Energy-Saving Oxygenation of Aeration Tanks

    Biological wastewater treatment

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  • Perfect Water Treatment Thanks to Adjustable Rotary Lobe Blowers

    Perfect Water Treatment Thanks to Adjustable Rotary Lobe Blowers

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