What is Biomat in a Septic System?

Septic systems are essential for managing household wastewater in areas without centralized sewage systems. One critical component of these systems is the biomat, a naturally occurring layer that plays a pivotal role in wastewater treatment. Understanding what biomat is and how it functions can help homeowners maintain their septic systems more effectively.

What is Biomat?

Biomat, short for biomaterial layer, is a gelatinous, blackish substance that forms in the soil beneath and around the drain field trenches of a septic system. This layer is primarily composed of anaerobic bacteria, which thrive in low-oxygen environments, along with other microorganisms and organic materials. The biomat forms as wastewater from the septic tank percolates through the soil, creating a biological and chemical barrier that regulates the flow of wastewater and the exchange of oxygen between the drain field and the surrounding soil.

Formation of Biomat

The formation of biomat begins when wastewater from the septic tank enters the soil absorption system. As the effluent trickles through the soil, bacteria and other microorganisms start to grow under the distribution lines where they meet the soil or gravel. Over time, these microorganisms form a black, jelly-like layer on the sides and bottom of the leach field trenches. This layer, known as biomat, is less permeable than the surrounding soil, which slows down the infiltration rate of wastewater, allowing more time for bacteria to treat the water before it is released into the environment.

Functions of Biomat

Biomat serves several crucial functions in a septic system:

Pathogen Reduction: The biomat layer helps to filter out viruses, bacteria, and other pathogens from the wastewater, reducing the risk of groundwater contamination.
Flow Regulation: By slowing down the flow of wastewater, the biomat ensures that the effluent has more time to undergo biological treatment before it reaches the surrounding soil.
Nutrient Processing: The microorganisms in the biomat break down organic matter in the wastewater, converting it into simpler compounds that can be absorbed by the soil.

Challenges Associated with Biomat

While biomat is essential for the proper functioning of a septic system, it can also pose challenges if not managed correctly:

Clogging: Over time, the biomat can become too thick, clogging the soil pores and preventing wastewater from infiltrating the surrounding soil. This can lead to slow drainage, backups, and wastewater overflows in the yard.
Groundwater Contamination: If the biomat becomes excessively thick and impermeable, it can prevent proper wastewater treatment, leading to the contamination of groundwater and nearby water sources.
System Overload: When the biomat restricts the drain field, excess sewage can return to the home or septic tank, causing damage to the system and potentially leading to system failure.

Maintaining a Healthy Biomat

To ensure the biomat functions effectively without causing problems, homeowners should follow these maintenance tips:

Regular Pumping: Regularly pump the septic tank to remove solids that can contribute to biomat formation and ensure efficient effluent distribution in the drain field.
Avoid Hydraulic Overloading: Limit excessive water usage and avoid disposing of non-septic-safe items, such as grease, chemicals, and solid waste, to prevent overloading the system.
Use Biological Additives: Consider using biological additives to boost the growth of healthy bacteria in the septic tank, which can help break down organic waste more effectively.

Conclusion

Biomat is a vital component of a septic system, playing a key role in wastewater treatment and pathogen reduction. However, it requires proper management to prevent issues such as clogging and groundwater contamination. By understanding the functions and challenges associated with biomat, homeowners can take proactive steps to maintain their septic systems and ensure their long-term functionality.