What is an Aerobic Septic System? | How does an Aerobic Treatment System Work?

An aerobic septic system also called an aerobic treatment system (ATS), is a small wastewater treatment technique that uses an aerobic method to digest sewages. The working of an aerobic septic system is like a septic tank system, but the aerobic septic system uses an aerobic procedure instead of the anaerobic procedure.

These systems are most common in that areas where public drains aren’t common. So, these septic systems can use for a single-family home or a small group of houses.

In contrast to conventional septic tank systems, aerobic treatment systems generate high-quality secondary sewage that may be purified and utilized for surface irrigation. This gives you more flexibility in the location of the leach site and halves the desired size of the leach site.

aerobic septic system

The aerobic septic system or aerobic treatment system injects oxygen (O2) inside the processing tank. The extra O2 increases the natural bacterial activity in the system and ensures further nutrient processing in the sewage. Some aerobic systems may also contain a pre-treatment tank and a final treatment tank that includes disinfection to additional lower pathogen levels.

This system has the advantage that it may use for houses with poor soil conditions and narrow portions, for areas with too high a water table, or houses near the surface water because these houses are sensitive to contamination from nutrients comprised in sewage. Aerobic treatment unit (ATU) will require regular maintenance for the rest of your life.

Read also: 2021 Latest Price for Septic tank repair and cleaning

How does an Aerobic Septic System work?

An aerobic treatment system is a system that uses mechanical components to treat the sewage and discharge the treated sewage into the absorption area. It uses aerobic bacteria that need to be pumped air to survive. These aerobic bacteria are named because they use O2 (the “aero” part of “aerobic”) to process organic matters that pass by the septic system. These bacteria can’t make alive and perform treatment without organic matter and oxygen. In contrast, anaerobic bacteria of the conventional septic tank system need an oxygen-consuming environment.

In the aerobic septic system, bacteria live in puddles or mud. During this, the surface or diffusion aerator simultaneously supplies additional oxygen and organic waste into the system. Bacteria eat the sewage products, breathe the air and release CO2 as waste products.

Aerobic treatment or aerobic septic system consists of the following processes that work together to deliver high-quality wastewater.

aerobic septic system working


  • Pre-Treatment: In this step, the septic tank is placed in front of the ATU (Aerobic Treatment Unit), or ATI-J can use a septic or trash tank as part of its equipment. This pre-treatment step separates the solids from the sewer water.
  • Aeration Chamber: In this step, a blower or an air compressor forces the air to mix with the wastewater. This step increases the growth of aerobic bacteria, which help to digest solids in the effluent.
  • Disinfection: This step has an extra treatment step for the wastewater leaving the aerobic treatment unit or ATI-J. In this step, you may use UV light or chlorine. UV light, bleach, chlorine, or other disinfection processes further treat the wastewater before it goes into the pump tank.
  • Final Treatment Disposal: ATI-J wastewater is discharged into the drainage area, whether it can be an evapotranspiration bed, an absorption area, or a sand filter.

For better understanding watch the below-given video:

What is a Conventional Septic Tank System?

A conventional septic tank system is a simple device for treating domestic wastewater. A conventional septic tank system has a septic tank and drainage ditches or an underground sewage infiltration system (drain field). This conventional system typically installs in a single-family home and small businesses.

The stone/gravel drain field is a design that is existing from a long time. The name of this design refers to the structure of the drainage area.

The conventional septic tank system works in the following way:

conventional septic system

  • With the drain field, the sewage from septic tanks is channeled into underground trenches made of flat gravel or stone.
  • After this, place a geo-fabric material on the trench top to keep dust, sand, or other debris away from the clean stone.
  • The wastewater is filtered through the stone and then treated by microorganisms when it grasps the soil below the stone or gravel trench.
  • The total area of ​​the stone or gravel system is relatively large and may not be appropriate for all areas and living conditions.

Components of an Aerobic Treatment System

The aerobic septic system generally consists of an absorption field, a disinfection chamber, an aerobic treatment unit, a pump tank, and a trash tank. The details of these components are given below:

components of Aerobic treatment System, Aerobic treatment System

1) Trash Tank

The mechanism of a trash tank is similar to a general septic tank of a conventional septic system. The trash tank collects the sewage and divides it into three different layers:

  1. Scum layer on top
  2. Central liquid sewage layer
  3. Lower mud layer

The wastewater moves through a T-shaped baffle into an aerobic treatment unit.

2) Aerobic Treatment Unit (ATU)

ATU is a part of an aerobic treatment system that utilizes aerobic bacteria to treat wastewater. The pumped air supplies an oxygen-rich atmosphere in which aerobic bacteria can grow and break down dangerous pathogens in the wastewater. The pumped air needs electricity and mechanical parts to function.

3) Disinfection Chamber

The wastewater from the aerobic treatment unit is fed into the disinfectant chamber. UV light, bleach, chlorine, or other disinfection processes further treat the wastewater before entering into the pump tank.

4) Pump Tank

The pump tank usually contains a series of floats to regulate that when the wastewater requires to drain. When the sewage level rises, an alarm will sound to notify you that maintenance is required. The wastewater is generally distributed through the nozzle in the drainage areas. Since the wastewater treats many times, it can be safely drained.

Why do you need an Aerobic Septic System?

There are the following reasons due to that you should use an aerobic septic system on your property:

1) It requires small space

The septic tank size depends on the number of people living in a house or building. Therefore, many septic tanks take up a lot of space for installation, which is a big problem for homes or properties with small spaces. But the aerobic septic system is a good option for houses having small space because this system requires low space.

2) Offer higher levels of treatment

aerobic treatment systems ensure cleaner wastewater and reduce the risk of groundwater pollution. If your home is in a zone with a high-water table, it is recommended to set up an aerobic treatment unit to stop water contamination.

3) Environmentally friendly

With an excellent aerobic septic unit, the wastewater used for cleaning or showering can be easily recycled and reused to supply water to the lawn. The water flows through the system, is treated, and then reprocessed.

If you want an environmentally friendly system, then an aerobic septic system is the best choice.

4) Reduces household waste faster

Compared to a similar conventional septic system, an excellent aerobic septic system can break down solid sewages faster. Due to this, sewage doesn’t gather to an alarming level. Therefore, this septic tank system doesn’t need to be pumped frequently.

5) Appropriate for all types of land

The main advantage of the aerobic septic unit is that it may use on all kinds of terrain. While conventional septic tank systems can’t use on lands with high groundwater. An aerobic treatment system has been carefully manufactured to work well and is friendly with all types of soils.

6) Save your money

This system treats the maximum part of the sewage in the water tank. Due to this, the drainage area doesn’t need numerous maintenances. In this way, you can save money.

Advantages and disadvantages of an Aerobic Septic System 

Consistently generates high-quality wastewater.Aerobic treatment system higher operating and maintenance costs.
It reduces nitrogen emissionCold weather can have adverse effects on the system. Therefore, it should be isolated.
This system also significantly decreases the blockage
of the drainage field
It needs more frequent pumping and maintenance.
Tested to extend the lifetime of the drain fieldIt needs higher electricity for working
It uses for aquifers, open water sources, and contraction to property lines.Improper system maintenance can lead to contamination
It can install in soils and areas (areas with high water levels, etc.) where conventional septic systems could not reach.Aerobic septic system has high installation, maintenance, and operating costs compared to a conventional septic system.
This system can be used on poor soil types.Blower noise
It can use to troubleshoot problems in the septic tank system.If it is not properly discharged, there will be a slight smell
It requires minimum installation space and has a flexible design.It needs more monitoring and inspection compared to other systems.
An aerobic septic system can install on different types of soil.There is no option for maintenance
The treated effluent can be utilized for irrigation so that the water can be reused.It needs more power
It also uses for challenging parcels and limited land.Aerobic septic system has high initial installation expenses
Requires less maintenance.
Environmental friendly.

How to Maintain an Aerobic septic system

The aerobic septic systems are one of the most advance and complex systems for wastewater treatment. In the previous sections, you can see its working and comparison with traditional septic tank systems. Following are the steps that are involved in the maintenance of an aerobic septic system.

1) How to access your Aerobic treatment system to make a proper check?

System access ports are typically 10 feet above the floor. It would be best if you tightened the lids to your access port. If they crack or discolor, you’ll need to replace them.

Unscrew and open the lids with attentiveness: Carefully loosen the lid to avoid hydrogen sulfide gas generated by the septic tank system. Hydrogen sulfide gas is dangerous if inhaled. Therefore, before inspecting the tank, ensure that the gas has been removed.

2) Most systems have warning lights to alert you to problems

You should have a system that produces an alarming light in a kind of problem. As the system produces alarming light, then you should immediately inspect your system and fix the problem. Remember, it is definitely better to find and solve a small problem than to ignore the system and make the problem worse, damaging the device.

3) Add chlorine to your tank

This is an easy step as long as you know the dosage and frequency mentioned in the instruction’s manual that comes with your aerobic septic system. Be careful that don’t use pool chlorine that doesn’t disinfect the sewage. But it kills your vegetation and grass.

Eliminate the lids from the aerobic treatment system, add the suggested quantity of septic-friendly chlorine and screw the lid back on its position.

4) Keep an eye on the spray fields

Here, too, it is important to notice the small problem before it becomes a big one. Damaged or poorly sprayed heads should immediately replace with suitable septic spray heads. Irrigation spray heads are not suitable for the working of an aerobic treatment system. Therefore, these sprinklers should not be used.

If the sprinkler is always on and you experience a foul smell or feel puddles of water in your septic tank system, then it is time to contact a maintenance specialist.

An excellent method to keep track of the entire aerobic septic system (from the inlet to the sprinklers) is to make a map of the spray field and the system. If you plan to renovate or expand your home, you can easily find missing or faulty spray heads and make safe decisions.

5) Keep a maintenance record

Knowing the model’s name, installation date, license status, and capacity of your aerobic treatment unit can help you to recognize the system type that you have and your system’s maintenance conditions.

Keeping all the tests and services running on your system up to date will help you keep tracking which part of your system you repaired and when. For example, when to add chlorine, clarity tests, and residual free chlorine results, the type and date of repair can specify exactly when to remove the trash tank, an aerobic treatment unit pumped.

Ensure that maintenance should perform after every six months. In this maintenance:

  1. Record and text the amount of free chlorine residue in the wastewater from the pump tank.
  2. Measure and record the depth of the slurry in the trash tank.
  3. Measure and record the sludge in ATU
  4. Conduct a clarity test and record its results (Pass or Fail).

6) When to conduct a maintenance specialist for Aerobic septic system

If you are checking your DIY (do-it-yourself) skills by maintaining your aerobic septic system, then it isn’t a suitable place to start. A well-operating aerobic septic system can keep your family healthy and keep your home’s working smoothly.

The most efficient method for maintaining an aerobic septic treatment system is to contact a maintenance specialist in emergency conditions. You should also have a specialist who performs regular system cleanings and inspections according to the maintenance recommendations.

What is the cost of an aerobic septic system?

The various aerobic septic systems have the following costs: 

  • Using conventional or gravity septic tank systems or using drainage technologies to achieve uniform distribution systems can cost anywhere from $ 20,000 to $ 30,000.
  • The cost of using an Aeration Treatment system to achieve type 2 is between $ 25,000 and $ 35,000.
  • Depending on the terrain, the cost of using an ATU in an underground drip irrigation line ranges from $ 25,000 to $ 36,000.
  • The cost of using an ATU in an Evo-transpiration bed varies from household to household but is between $ 25,000 and $ 41,000.

How to choose the right Aeration Septic System?

When you want to choose a good aeration septic system for your sewages, then the following are some factors that you should keep in mind:

aerobic system selection

  • Your maintenance lessening objectives
  • Tank size
  • Efficiency requirements
  • Plant location and environment
  • Your maintenance cost
  • O2 needs for the effluent
  • Total effluent volume
  • Capital cost and energy cost

FAQ Section

What is the difference between an Anaerobic Septic System and an Aerobic Septic System?

The anaerobic septic tank system consists of a seepage field and a treatment tank. The sewage is delivered into a treatment tank where the solid waste is deposited at the bottom, the slag on top, and the wastewater in the center. The wastewater is relatively clean. Therefore, it moves through a series of pipes hidden under the leach area. Some systems insert a divider box between the pipe and the tank to deliver the effluent more consistently. The final filtration step before the treated effluent is returned to the environment takes place at the leaching point.

While in the aerobic septic system, the aerator continuously supplies the bacteria in the tank with oxygen. The constant flow of O2 keeps the bacteria more active and accelerates the treatment activity. As mentioned above, there is also a movable pallet to avoid the effluent from splitting into three different layers. Even solid waste that could settle on the bottom of the anaerobic system is revealed to aerobic bacteria. This mechanism makes the wastewater from the leach site cleaner and easier to treat.

An aerobic system is more effective than an anaerobic septic system, but it has a complex installation process.  Anaerobic septic systems have less price than aerobic septic systems. Homeowners need to buy an aeration system in addition to the storage tank and leach site. The aerobic system is good for the atmosphere, but it is more expensive to own and run than a conventional septic system. It also needs more maintenance but anerobic bacteria are less active compared to aerobic bacteria.  

Can I put a aerobic septic tablet in my toilet tanks?

Yes, you can put an aerobic septic tablet into your toilet tank. For the cleaning of your tank, just put the aerobic septic tablet into your tank and leave it to do its work. This tablet will not damage your septic tank.

Can a root killer be used in an aerobic septic system?

Yes, a root killer can be used in an aerobic septic system according to need. It works without harming the natural bacterias of your septic system.

See More:

1) How does a Septic Tank System Work?

2) How does an Aquarium or Fish Pump Work?

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