Green Biodigester Septic Tank

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A biodigester septic tank is a waste and sewerage management and treatment system. It is a new technology that replaces the normal septic tank (soak away). It can be of great use in both residential and commercial buildings. Unlike the normal septic tanks, the solid and liquid wastes are treated so that they can be used in other ways. A biodigester septic tank is a one-time waste control and management solution.

How it Works

The biodigester septic tank is based on biodegrading processes. This is the breaking down of organic waste matter into carbon dioxide, methane and water. The bacteria in the tank feed on the organic wastewater and the dark water as they come in. As a result, they become water and gas. The effluent takes about 2 weeks to decompose.

The methane gas is what most people call Biogas. It can also be harnessed and used for cooking and powering generator. However, the gas production is in small quantity except for large biodigesters. As a result, it is released to the atmosphere as the collection is impossible. We design separate systems for Biogas production. After the water treatment is complete, it leaves through the outlet for recycling or left to soak into the soil. The water is very rich in nitrogen therefore great for irrigation purposes. In addition, the water can be used for other things like flushing the toilets.

The septic tank uses the displacement principle. The amount of wastewater flushed into the system displaces the equivalent volume from the biodigester tank to the soak drain.

Advantages of Biodigester Septic Tank


Installing a biodigester septic tank is cheaper than constructing the old septic tank. You only have to excavate a hole and drainage trenches if water will not be recycled. In addition, it saves money on emptying which is now not necessary.


A biodigester septic tank changes the environment in so many ways. It produces no foul smell. The water soaks into the surrounding soil, thereby increasing the amount of underground water. As a result, soil fertility increases and crop production improves. In addition, there is no wastewater discharge in the streets making it cleaner and most importantly safe.

Structure and Design

The biodigester septic tank is built from reinforced concrete. For this reason, it is much stronger compared to other septic tanks built with blocks. Secondly, the tank already has enzymes. As a result, it can hold pressure and stress without cracking therefore very reliable and durable.

In addition to this, the biodigester septic tank takes up relatively small space and produces no foul smell. It is eco-friendly.

A biodigester septic tank has full approval and recommendation from the National Environment Management Authority and the Ministry of Water and Irrigation. We also give 5 years post installation warranty which covers faults from construction.

Types of Biodigester Septic Tank

The difference in the biodigester septic tanks is based on the size. The 3 types are:

Standard Biodigester

A standard biodigester tank is the smallest tank available. It has the capacity to manage waste for 20 users. As a result, it is most preferable for use at a residential home.

Jumbo Biodigester

It is of moderate size and has the capacity to hold the waste from at least 100 people. For this reason, it is ideal for hotels, mid-size properties, apartments and small gated communities.

Jumbo Deluxe Biodigester

This is the biggest tank in the market. It can hold up to 400 users. It is suitable for big establishments, shopping malls, big hotels, hospitals, schools and estates.

Despite the above, we can build custom biodigester tanks can based on the client’s needs and requirements.

Biodigester Septic Tank Structure

Our Biodigester Septic Tank structural design is well thought out so as to ensure effectiveness and durability. Our biodigester septic system design has three parts:

  • Grease interceptor
  • Biodigester tank
  • Soakage drain.

Grease Interceptor

On getting into the system, the wastewater is divided into grey water and black water. Blackwater is sewage that has come into contact with faecal matter. On the other hand, grey water is sewage from kitchen sink and bathrooms.

Greywater has a lot of oils, fats, grease and detergents. As a result, it is chemically unstable. For this reason, it passes over the biodigester tank and goes through the grease interceptor to remove the oils. This is because the oils can be harmful to the environment. After this, the oil-free water goes to the soak pit.

Biodigester Tank

On the other hand, black water is directed into the biodigester tank. The already present anaerobic bacteria feed on the faecal waste in order to rid it of the pathogens and treat the black water. The solid waste matter settles at the bottom of the biodigester tank through sedimentation. They decompose to water and gas as a result of biological activities.

Soakage Drain

This is a tank where treated water collects and percolates into the ground.

Biodigester septic tanks provide the best sanitation system solutions. They are easy to manage and maintain with no extra cost or evacuation. It doesn’t get filled and pollutes the environment like the normal soak away tank.

It is important to note that disposing non-degradable waste materials into the system is not a good practice. Some of these materials include cigarette butts, sanitary pads, and condoms among others. If they enter the system, the system will be blocked or fill up.

In addition, some cleaning detergents like phenyl are not appropriate for use. This is because they can harm the bacteria in the tank making it less effective. Replace them with our recommended cleaning detergents. Other liquids like paint and solvents can also harm the bacteria. Do not flush them down.

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