Farley Groundworks & Building

Groundworks, Building & Sewage Treatment

Tel: 01189 454 223

Mob: 07939 601 737

How Does a Sewage Treatment Plant Work?

Farley Groundworks are experts in the installation, repair and upgrade of sewage treatment plants.  This article explains what a sewage treatment plant does, when it is needed and how it works.  Much of the material here has been prepared with the help of Tricel®, the UK leading manufacturer of wastewater treatment systems, septic tanks, pumping stations and rainwater harvesting tanks.  Farley Groundworks install Tricel® systems for our clients.

If you are not connected to mains drainage then you will need to install some form of sewage treatment system to process waste water into a form that can be safely drained into your local environment. The easiest and cheapest solution is a sepic tank which breaks down the waste and outputs purified liquid effluent which can drain into the ground.

However, in areas where soil drainage is poor or where the Environment Agency demands high standards of purity (for example near a water course) then a Sewage Treatment Plant must be used. This purifies the effluent to a much higher standard as described below.

The sewage treatment process takes place in three different stages, each of which happens in a different compartment of the sewage treatment plant…

Stage 1 – Primary Settlement

The wastewater is introduced into the the primary settlement chamber of the system.  Heavy sludge and solids separate from the liquid and these settle to the bottom of the tank.  A scum, mainly made of grease, is formed on the surface of this liquid.  Anaerobic breakdown begins to occur here and this improves the water quality.

Stage 2 – Aeration or Oxygenation

The liquid passes into the aeration chamber where masses of naturally forming bacteria inhabit a specially designed honeycomb bed and aerobic breakdown occurs.  These bacteria are sustained with air, which is continuously supplied from a purpose built air compressor in the top section of the system.  As the liquid flows slowly through the honeycomb bed, the bacteria consume the impurities and remove them from the liquid.

Stage 3 – Final Settlement & Clarification

The liquid then flows into the final settlement chamber and small quantities of bacteria (called residual sludge) are carried through with this liquid.  The residual sludge settles to the bottom of this chamber and a sludge return system returns the sludge to the primary settlement chamber.  The remaining treated liquid now meets the required environmental standard and can be passed out of the Tricel system.

It is possible to upgrade a septic tank to a full sewage treatment plant.  Tricel® have a range of products (known as Biocel) which can be used for this.  These systems take the effluent from a septic tank and pass it through an aeration chamber and a settlement chamber (as described above).

Our next blog post describes one of our projects to install a Tricel® sewage treatment plant.

If you want to discuss your sewage treatment needs and understand both practical considerations and environmental requirements then please contact us on 0118 945 4223, by email or via our contact form.  We will provide a free consultation and quotation without obligation.

There is more information about Tricel® on their website.

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