Aerobic Septic Systems

Cost, Maintenance and How They Work

Aerobic Septic Systems Let's Talk About Them: How does an aerobic septic system work? How do you maintain an aerobic septic system? And how much does an aerobic septic system cost?

What is an Aerobic Septic System?

An aerobic septic system is a type of wastewater treatment system that uses aerobic microbes to break down waste more efficiently than conventional septic systems.

It consists of a trash tank for initial waste separation, followed by an aerobic treatment unit where an aerator circulates oxygen to support the microbes.

After treatment, the wastewater flows into a pump tank, where it may undergo further treatment like chlorination before being dispersed, typically via drip irrigation or spray heads. Finally, the treated water is absorbed into the soil, making it environmentally friendly.

How Does an Aerobic Septic System Work?

There are conventional septic systems and then there are the more complex aerobic septic systems. The difference is, in a word, oxygen. While a conventional septic system uses only the septic tank to separate solids, fats and grease, an aerobic treatment unit (ATU) uses Oxygen infusion for digestion rather than the anaerobic process.

Just as in the case of conventional (or standard) systems, an aerobic septic system uses natural processes to treat wastewater.

An oxygen-rich bacterial environment works to digest and break down sewage inside the ATU (Aerobic Treatment Unit).

“So… what type of septic system do you have, or what would you need if you were building a new home or renovating?

No, it’s not exactly the sort of question that would get conversation bubbling around the water-cooler. But it is an important question to ask because not all septic system types are created equal and, in certain locations and situations, some work better than others.

Table of Contents

Aerobic Septic Systems - Summary Video

Please note these costs will vary, depending on the region of British Columbia and the accessibility of supplies. For a quote specific to your location and situation, call 250-768-0056 to speak with one of our maintenance experts. Or leave your details here and one of our experts will be in touch with you soon.

Conventional Systems vs Aerobic Systems

Conventional Systems

In this kind of system, solid waste enters your septic tank and settles at the bottom. This, over time, turns into sludge. Meanwhile, the liquid waste that ends up inside your septic tank rises to the top.

Enter your little buddies, the anaerobic microbes that live inside your tank. These tiny fellas get to work and help break down the liquid and solid waste in a process that produces wastewater. (In some cases, this wastewater passes through a final treatment tank).

But overall, that’s it – the work of your conventional septic tank is just about done. All that needs to happen now is for the wastewater to be directed to a drain field that you’ve prepared earlier and with much caution. You will have to ensure the soil is permeable, that the wastewater will not saturate nearby water tables and that the absorption of the wastewater into the soil will not be blocked or deviated by restrictions such as bedrock.

Aerobic Systems

Solid waste and liquid waste enter the trash tank where, like in a standard septic tank, the waste separates into solids at the bottom and liquids at the top. And it is here, inside the trash tank, where the similarities between your new aerobic septic system and your old conventional system end.

What is now wastewater flows from the trash tank and into the aerobic treatment unit. It is here that most of the treatment occurs (or, reworded for the informal aerobic septic system owner: here is where the cool stuff happens). While aerobic treatment units come in many different designs, their job is simple: to house an aerator that circulates oxygen bubbles through the wastewater in a similar fashion to a fish tank pump. This additional oxygen provides a stable environment for aerobic microbes.

Now, if anaerobic microbes were your buddies, aerobic microbes are your comrades – the kind that would come to your aid in battle if there was indeed a battle going on and they were slight… larger. You are very fond of your comrades, these aerobic microbes because they break down the effluent a lot faster and more effectively than even the strongest anaerobic microbe could.

Once your comrades have done their work, the liquids flow into the pump tank. If you are using drip irrigation, the pump tank can start emitting the water straight away. If you are dispensing the water as a spray, a final treatment is performed before the water enters the pump tank(commonly with a tablet or liquid chlorinators) or an individual tank just prior to the pump tank for the water chlorination, to eliminate any remaining pathogens. The now environmentally-safe water passes into the pump tank, where the pump gets to work and directs the water to spray heads around your lawn or vegetation.

As a final step, the water is absorbed into the soil.

Aerobic Septic Tank Treatment Process

1. Pre-Treatment

This can mean having a septic tank staged in front of the ATU or an ATU can have a settling or trash tank as part of the unit.  This pre-treatment stage will separate the solids from the wastewater.

2. Aeration Chamber

Forced air mixes with the wastewater either by an air compressor or a blower.  This step supports the aerobic bacterial growth that will aid in the digestion of solids in the wastewater.

3. Disinfection

This step involves an additional treatment step for the effluent leaving the ATU. This can mean the use of chlorine or ultraviolet light.

4. Final Treatment Disposal

The effluent leaving the ATU is discharged into a drain field, whether it be a sand filter, absorption field or an evapotranspiration bed.

How Much Does an Aerobic Septic System Cost?

An aerobic septic system will cost anywhere between $20,000 – $40,000, depending on the type of system you choose.

Aerobic septic systems are more complex than standard systems, and because of this, they are also more costly. The value lies in the speed and advanced level of treatment that you can expect from an aerobic septic system.  

Here in British Columbia, Canada we can estimate costs based on a few systems:

Type 2 Septic System Costs Using an ATU with Aeration and Drain Field

  • Gravity or conventional septic systems or using a uniform distribution along with drain field technology used to achieve a type 2 system can cost between $20,000 – $30,000.
  • Using an ATU (Aeration Treatment Unit) septic system installation to achieve a type 2 can range from $25,000 – $35,000
  • Using an ATU with a subsurface drip line can range from $25,000 – $35,000 depending on the topography
  • Using an ATU with an Evotranspiration bed can cost between $25,000 –  $40,000 depending on the home

When using an engineer to design a Type 3 septic system, which requires an added disinfection to the aeration unit we can approximate an added cost from $10,000 – $15,000 more than the above-evaluated cost points.

Here is more information on how the cost of a septic system is evaluated: Costing a Septic System

Design Services are typically $2000 for Type 1 Gravity systems and $2500 for Type 2 Gravity systems and Pressure systems.

Aerobic Septic System Maintenance: What’s Involved?

Aerobic Septic systems are one of the most complex and advanced systems for treating waste – and now we know how it works and how it compares to a conventional septic system. But what’s involved in maintaining an aerobic septic system?

First, it’s important to know how to access your system to make the proper checks.

The access ports to your system will usually be within 10 feet of your home, at ground level. The lids to your access ports should be screwed shut. If they are cracked or discoloured, it’s a good sign that it’s time to have them replaced

Unscrew and open the lids with caution – septic systems produce hydrogen sulfide gas, which can be harmful if inhaled. So make sure you let the gas clear before checking the tank.

Most systems are equipped with an alarm light that signals an issue.

Keep an eye on this, because finding and fixing a problem while it is still minor is definitely more ideal than neglecting your system and letting a problem fester for long enough to damage the equipment.

Add chlorine to your tank.

This is something you can easily do yourself, so long as you have checked the frequency and dosages specified in the owner’s manual accompanying your particular system. Do not use pool chlorine as this will not disinfect the wastewater. It will, however, kill your grass or vegetation.

Remove the lid to your aerobic septic system, add the recommended amount of septic-friendly chlorine, then screw the lid back into place.

Keep an eye on the spray fields.

Again, it’s about noticing the minor problems before they become major. Spray heads that are broken or not spraying correctly should be replaced with proper septic spray heads. Do not use irrigation sprinkler heads as these are not compatible with the operation of a septic system.

If the spray heads are constantly on, if you notice puddles of water or if there is a foul odour coming from your septic system, it might be time to call a maintenance expert.

A great way to keep track of your entire aerobic septic system, from the access ports all the way to the spray heads, is to have a map of the system and the spray field. This will help you locate faulty or missing spray heads and make safe decisions if you’re planning home renovations or extensions.

Keep a maintenance record.

Having on hand the model name, capacity, state license and the date that your system was installed will help you identify which system you have and the maintenance requirements specific to your system. And documenting the dates of all services and tests performed on your system will help you keep track of what happened when. For instance, you will know precisely the type and date of any repairs, when to add chlorine, the results of the free chlorine residual and clarity tests and when to have the trash tank and the aerobic treatment unit pumped.

Make sure that at least every six months: the free chlorine residual of the effluent in the pump tank is tested and recorded; the depth of the sludge in the trash tank is measured and recorded; the volume of the sludge in the aerobic treatment unit is measured and recorded, and; a clarity test is conducted and the results of this test (pass or fail) are recorded.

Advantages & Disadvantages Of An Aerobic Septic System

The Benefits

The Negatives

A higher level of effluent treatmentBlower noise
Useable on poor soil typesSlight smell if not vented properly
Used for challenging lot spaces and restrictive topographyDraws more power
Used in setback constrictions to property lines, open water sources, aquifersMaintenance is not an option
More green - utilizes smaller drain field footprintsHigher initial installation costs
Proven to extend drain field life spanPoorly maintained systems can cause contamination
Greatly reduces drain field cloggingToo much water can overburden the system
Great for water conservation, many states allow for irrigationCold weather can have adverse effects, must be insulated.
Reduces nitrogen
Offsets initial costs by extending overall system performance and longevity

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As certified designers and installers we’re happy to discuss your future plans, or if your existing system is causing functional concerns we also do repairs to septic systems.

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Key Takeaways

  • Aerobic systems use oxygen, unlike conventional systems that rely on anaerobic processes. This oxygen infusion allows for more efficient digestion of sewage.
  • Aerobic systems are especially useful in areas near water bodies where conventional systems may fail. The treated effluent from aerobic systems is better for these sensitive environments.
  • Benefits of aerobic systems include better treatment quality, suitability for remote areas, and better water conservation.
  • Disadvantages include that they have higher initial costs, require more power, and require regular maintenance.
  • Aerobic septic systems are generally more expensive than conventional ones. Costs will vary depending on the system type and location. 
  • Regular maintenance is crucial. This includes checking system access ports, monitoring alarms, adding chlorine, inspecting spray fields, and keeping maintenance records. Professional servicing is recommended at least every six months.

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