Sewage Treatment Plants Explained

Sewage Treatment Plants
(Wastewater Treatment Plants)

Domestic sewage treatment plants have been in the UK for around 25 years, One of the first being the Klargester BioDisc which was first introduced back in 1974.


Sewage treatment plants are used in areas where there is no mains drainage and are used to convert raw sewage effluent into a purer state. This means that the sewage effluent from your sewage treatment plant can legally be discharged into lakes, rivers, soil and streams with permission from the Environmental Agency.

How the sewage treatment plant works.

All household waste from sinks, baths, showers and toilets leave the property and enter into the sewage treatment plant.

1) The first compartment is where all the sewage waste enters.  It is called the primary holding tank.
From this first compartment all the liquid slowly drains off into the second compartment.
The majority of the solid waste remains in this first compartment.
Because of this, the sewage treatment will need desludging at frequent intervals, usually sewage treatment plants are designed to give one year’s storage in domestic applications.
2) The second compartment of the sewage treatment plant is where the treatment process begins.
It is here that all the micro biological organisms live.  Over time they break down the sewage effluent.  From here the sewage effluent is discharged into the third compartment.
3) The third compartment is where the treated effluent is discharged from the sewage treatment plant into your desired location.

Sewage treatment plants are much preferred and more likely to be accepted by the Environmental Agency to the common septic tank due to the treatment of the waste water leaving the system. The treated effluent from sewage treatment plants are up to 98% cleaner than raw sewage and therefore environmentally friendly.

Septic tanks act only as a holding tank for the solid waste and no treatment is achieved in the system itself, thus the Environmental Agency prefer the installation of a sewage treatment plant.

Sewage treatment plants work by one of two ways;

The most common would generally have an air compressor above ground which pumps air into the sewage treatment plant. The biomass (bacteria) which breaks down the sewage needs oxygen to live and aids in the digestion process.

The second way is feeding the oxygen into the sewage treatment plant without the need of an external air compressor. This is done by using rotating discs inside the tank to act as a medium for supporting the bacteria which carries out the aerobic treatment process. As the internal discs rotate it draws air into the system.

For more advice on sewage treatment plants or Environmental Agency Discharge consent please contact us on 01923 261660 or via email