Septic tanks are essential systems for wastewater treatment in many households, especially in rural areas without access to sewage networks. The proper functioning of a septic tank depends to a large extent on the bacteria that live inside it, which are responsible for decomposing and treating organic waste. In this article, we will explore in depth the role of these bacteria, how to maintain their balance and what to do when problems arise.
What is a septic tank and how does it work?
A septic tank is a self-contained wastewater treatment system designed to separate and treat solids from liquids in domestic wastewater. It consists of two main components: the septic tank and the drain field.
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The septic tank: This is an underground vessel where wastewater enters and is separated into three layers:
- Upper layer (scum): Composed of floating materials such as fats, oils, grease and foam.
- Middle layer (effluent): Partially treated water that flows into the drainage field.
- Bottom layer (sludge): Solid particles that settle to the bottom of the tank.
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The drain field: This is a series of perforated pipes set in a gravel bed that allows the treated water to percolate into the soil. Here, soil bacteria and other natural processes complete the treatment.
Types of bacteria in septic tanks
The success of the septic system depends largely on two types of bacteria:
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Anaerobic bacteria: These are the most common bacteria inside the septic tank, as they survive and thrive in oxygen-depleted environments. They break down solids and reduce the amount of sludge.
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Aerobic bacteria: These bacteria require oxygen and are extremely efficient in decomposing organic matter. They are mainly found in the drainfield, where the effluent interacts with the soil.
Both types of bacteria play a crucial role in the wastewater treatment process, and their correct function ensures effective and safe treatment.
How do bacteria affect the functioning of the septic tank?
Bacteria are the real ‘workers’ in a septic tank. They perform several essential functions:
- Decomposition of organic matter: Anaerobic bacteria break down solid waste at the bottom of the tank, converting it into more manageable gases and sludge.
- Prevention of sludge build-up: A healthy population of bacteria can keep sludge levels low, reducing the frequency of pumping required.
- Effluent purification: In the drainfield, aerobic bacteria treat the effluent, removing pathogens and other pollutants before the water seeps into the ground.
Factors that can harm bacteria in septic tanks
The bacterial balance is delicate and can be affected by several factors, compromising the performance of the septic system:
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Excessive use of chemicals: Many household cleaning products, such as bleach, disinfectants and antibacterial cleaners, can kill beneficial bacteria. Even the spillage of medicines, such as antibiotics, can disrupt the bacterial flora in the tank.
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Excess water: When the septic system is overloaded with excess water, it can dilute bacteria and cause the septic tank to not have enough time to process the waste properly. This can lead to premature displacement of solids into the drainfield, causing blockages.
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Improper use of the septic system: Disposal of non-degradable items such as sanitary napkins, nappies, plastics or fats can create blockages and decrease the efficiency of the system.
How to promote a healthy environment for bacteria
Maintaining a healthy bacterial population is essential for optimal septic tank performance. Here are some recommended strategies:
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Avoid harsh chemicals: Use biodegradable cleaning products and avoid pouring antibacterial products into the system.
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Minimise water use: Implement water-saving practices, such as fixing leaks, installing low-flow toilets and spacing out the use of water-intensive appliances.
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Adding supplemental bacteria: There are products on the market that allow you to increase the amount of bacteria in your septic tank. These products can be especially useful if you have had to use harsh chemicals or if you have noticed problems in your system.
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Keep a maintenance schedule: Pump your septic tank every 3 to 5 years, depending on its size and use. This helps remove excess sludge and allows bacteria to continue working efficiently.
Common problems and solutions
Maintaining a septic tank is not always easy. Here are some common problems and their solutions:
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Unpleasant odours: Unpleasant odours may indicate that the bacteria are not working properly or that there is a leak in the system. Check for blockages in the drain field and consider adding additional bacteria.
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Excessive sludge: If you notice that you need to pump the tank more frequently, it is possible that the bacteria are not breaking down the solids as they should. An analysis of the sludge may reveal the underlying cause, such as too high an organic load or excessive chemical use.
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Obstructions in the drain field: If the drains are slow, it may be a sign that the drain field is clogged. This could be due to an overload of solids or soil compaction. Installation of a distribution box or aeration of the soil can be effective solutions.
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