What is an Aerobic Septic System?

An aerobic septic system is one of the most common methods used for wastewater treatment. This article explains the aerobic septic system working, components, and applications.

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 very similar to a septic tank system, but the aerobic septic system uses an aerobic procedure instead of the anaerobic procedure.

These systems are most commonly used in areas where public drains aren’t common. So, these septic systems can be utilized 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.

The aerobic septic system or aerobic treatment system injects oxygen (O₂) inside the processing tank. The extra O₂increases 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. The aerobic treatment unit (ATU) will require regular maintenance for the rest of your life.

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, the 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.

Process:

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 helps 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.

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 is commonly used for a single-family homes and small businesses.

The stone/gravel drain field is a design that exists for 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:

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:

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:

Scum layer on top
Central liquid sewage layer
Lower mud layer

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

Read Also: Working of Trash Pump

2) Aerobic Treatment Unit (ATU)

ATU is 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 discharging it into the pumping tank.

4) Pump Tank

The pump tank usually contains a series of different sensors to regulate when the wastewater requires to drain. When the wastewater level reaches up to a specific level, the system triggers an alarm to notify you that the tank is full and you need to pump it.

There is a pipe or nozzle connected between the tank and the drainage area. The wastewater is generally distributed through the nozzle or pipe in the drainage areas.

Read Also: How to pump a Septic Tank?

Why do you need an Aerobic Septic System?

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

1) Small Installation Area

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 spaces because this system requires low installation 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 maintenance. In this way, you can save money.

How to Maintain an Aerobic septic system

Aerobic septic systems are one of the most advanced and complex systems for wastewater treatment. In the previous sections, you can see its working and comparison with traditional septic tank systems.

Follow the below-given steps to maintain your aerobic septic system.

1) Locate the Aerobic treatment system

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

To replace the lid, unscrew the lid and open it 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) Check Warning lights

Some aerobic treatment system has a warning light that starts illuminating if there is something wrong with your system. 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

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

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

4) Keep an eye on the spray fields

It is important to notice the small problem before it becomes a big one. When your system’s spray heads go bad or damaged, you should immediately replace them. Irrigation spray heads are not suitable for the optimum performance of the aerobic treatment system. Therefore, these sprinklers should not be used.

If your spray head is always on and you experience a foul smell or feel puddles of water in your septic tank system, it means that there is something wrong and you should contact a professional for the inspection.

An excellent method to keep track of the entire aerobic septic system (from the inlet to the spray head) 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 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:

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

6) Contact a specialist

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.

Advantages of an Aerobic Septic System

It consistently generates high-quality wastewater.
It reduces nitrogen emission
This system also significantly decreases the blockage of the drainage field
It is ideal for aquifers, open water sources, and contraction to property lines
It can be installed in soils and areas (areas with high water levels, etc.) where conventional septic systems could not reach.
This system can be used on poor soil types.
It can use to troubleshoot problems in the septic tank system
It requires minimum installation space and has a flexible design
The treated effluent by the aerobic system can be utilized for irrigation purposes
It is environmentally friendly
The aerobic septic system is generally faster than the anaerobic process
Aerobic systems can be designed for a variety of situations, including homes with high water usage or properties with poor soil conditions that may not be suitable for conventional septic systems

Disadvantages of an Aerobic Septic System

The aerobic treatment system has higher operating and maintenance costs
It requires higher maintenance.
Cold weather can have adverse effects on the system. Therefore, it should be isolated.
It needs more frequent pumping and maintenance.
Aerobic systems use electrically powered aerators and pumps, which can increase energy consumption and utility costs.
Improper system maintenance can lead to contamination.
Aerobic septic system has high installation, maintenance, and operating costs compared to conventional septic system.
If it is not properly discharged, there will be a slight smell.
It needs continuous monitoring and inspection compared to other systems.
Aerobic septic system has a high initial cost.
ATUs are more costly than regular systems.

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:

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

Aerobic Septic System Problems

Low Air Pressure: The aerobic septic system highly depends on the regular supply of oxygen to break down leftover products. It also needs a proper intake of oxygen to work efficiently. If the system isn’t receiving enough oxygen and the air pressure is low, you should immediately inspect the system. Contact the specialist to fix the problem.
Problem with the submersible pump: Sometimes, the submersible pump of the system starts creating problems and doesn’t work efficiently. In such conditions, inspect the pump and replace it. If your pump is damaged badly, you should replace it with the new one.
No Power: Sometimes, the power switch of the system work according to expectations. This happens frequently, and you can easily fix it yourself.
Sprinkler Not Working: The proper working of the sprinkler is very important for the efficient operation of the system. Sometimes, it starts creating problems due to that your system stops working or doesn’t work efficiently. Therefore, as the sprinkler goes bad, you should repair it immediately.
Timer or Photocell not operating efficiently: The timer and photocell are vital parts of an aerobic treatment unit. These parts hold the wastewater in the pump tank until it is ready to be drained. When one of these parts is failed, your system will not discharge wastewater efficiently and eventually allow excess water to accumulate in the system.
No proper maintenance: The proper maintenance of the aerobic treatment unit is very important for its efficient working. If you don’t maintain it properly, it goes bad and starts producing different problems.

Difference between an Anaerobic Septic System and an Aerobic Septic System

Features	Aerobic Septic System	Anaerobic Septic System
Basic process	The aerobic septic systems use aerobic bacteria to break down waste with O2	Anaerobic septic systems use anaerobic bacteria to break down waste without O2
Space requirement	It needs small installation space	It needs more installation space
Oxygen requirement	It needs oxygen for processing	It doesn’t need oxygen for operation
Maintenance	It requires a higher maintenance	It requires low maintenance
Efficiency	It is most efficient in waste treatment	It is less efficient in waste treatment
Treatment stages	This system completes a treatment process in primary, secondary (aeration), and tertiary (disinfection) stages.	This system completes a treatment process in the primary treatment (separation and breakdown of solid trash) stage.
Components	Drain field, settling chamber, and aeration chamber	Drain field and septic tank
Environmental impact	Aerobic septic system has a very low potential to contaminate the groundwater	Anaerobic septic system has a higher potential to contaminate the groundwater
Odor production	It is less likely to generate odor	It is more likely to generate odor
Cost	It has a higher initial cost	It has a lower initial cost
Nitrogen and phosphorus removal	Better removal capabilities due to multiple treatment stages	Limited removal capabilities
Suitability	It is ideal for sensitive environmental areas, urban areas, and smaller land	It is ideal for rural areas with larger land plots

FAQ Section

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 bacteria of your septic system.

What are the signs of a bad aerobic septic system?

Unpleasant odors and smells
Standing water
Pipe blockages
Slow drains
Sewage backup
Gurgling sounds
Alarm or warning lights
The unusually green or lush vegetation around the drain field
Poor water quality

Which is better conventional or aerobic septic system?

Conventional septic systems are typically more affordable than aerobic systems, although exceptions may exist. Additionally, conventional systems require considerably less maintenance compared to their aerobic counterparts.

What is the difference between aerobic and anaerobic septic system?

The aerobic septic systems use aerobic bacteria to break down waste with O2 while the anaerobic septic systems use anaerobic bacteria to break down waste without O2.

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