In any septic system that is based on wastewater treatment and infiltration into the native soil, a biomass develops at the soil interface.


Although this could be a sign of future problems for some systems, it isn’t the case for all technologies, and it is generally essential to the proper functioning of the system.

In the case of a System O)) solution, there are different components that treat the water: microorganisms inside and around the Advanced Enviro))Septic (AES) pipes, the system sand, and the biomass under the pipes, specifically those inside the system sand, called “biomat”.

DBO))Clic - The passively-controlled biomass of a System O)) septic system 1
The biomass under a system from 2003, inspected in 2020, is well-balanced.

the biomass inside and around the pipes

The microorganisms inside and around the AES pipes are the first to treat the effluent leaving the septic tank. The importance of the treatment depends on the water’s retention time, which in turn depends on the sieve analysis of the system sand and the permeability of the biomat.

system sand

System sand limits the flow of water to allow the biomass enough time inside the pipes to properly digest pollutants. Since we are now deep underground, the oxygen is generally less so that we are mainly in an anaerobic environment.


Anaerobic bacteria can develop and thrive, allowing for a second type of treatment. This mass of anaerobic bacteria in the sand is known as biomat.


The more the biomat develops, the more the sand’s porosity goes down, increasing the water’s retention time inside the pipes which improves the first aerobic treatment and the filtration of pollutants. This improvement of treatment in the pipes by increased retention time is important as it reduces the quantity of pollutants that reach the biomat.


For most conventional systems, it is this uncontrolled growth of the biomat that clogs the native soil, caused by the absence of treatment before the wastewater infiltrates into the soil as well as the absence of aerobic conditions.

how is the biomat controlled?

Many processus – including alternating between aerobic and anaerobic conditions, constant aeration and rest periods – ensure the size of the biomat becomes balanced under the AES pipes. This allows for optimal treatment without degradation over time.

You can read more about these in the DBO))Clic – Sludge.


Different components of a System O)) solution are responsible for the treatment of wastewater, including microorganisms inside and around the Advanced Enviro))Septic pipes, the system sand, and the biomat.


Each component has a specific role and together form a combination that is ideal for wastewater treatment. It is important to note that the biomass can be controlled and that it is required for the proper functioning of System O)) solutions and – by the same token – preserving nature’s balance.


For a more detailed explanation, you can access a more technical document by clicking below.


Our local representatives are available to advise you and present you all our available System O)) wastewater treatment solutions.


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