Submerged aerated filter (SAF) sewage treatment plants

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Utilising proven submerged aerated filter (SAF) technology, the Rewatec SAF range of sewage treatment plants provide the ideal solution for larger applications.

Rewatec submerged aerated filter (SAF)

What is a submerged aerated filter (SAF)?

The Rewatec submerged aerated filter (SAF) is a robust, GRP, wastewater treatment plant that combines energy efficiency with a low carbon footprint. 

The SAF process uses individual cells within the tank which are arranged in series and the wastewater flows through each chamber in sequence. Each cell contains a media on which biomass forms, and a fine bubble diffuser system feeds oxygen from blowers in the control kiosk to promote the growth of the biomass. 

A blower sends air to the bottom of the bed to provide oxygen for the biomass to support the oxidation process. The air stream promotes both efficient mixing of the effluent and disturbance of any excess solids from the filter medium. 

To optimise efficiency, all of our SAF products come with a steel painted kiosk as standard. This also includes a high/low pressure alarm and beacon. 

SAF Sewage Treatment Plant


Example applications 

  • hotels and inns
  • leisure facilities 
  • camping and caravan sites
  • schools
  • office buildings 
  • industrial sites

Adaptable to suit your needs

The Rewatec SAF sewage treatment plant is highly flexible. It can be installed in four variations, dependent upon population size and application parameters.  


SAF Sewage Treatment Plant Systems


  • single tank 
  • semi modular tank (two tank system)  
  • modular (three tank system)  
  • multi stream systems (bespoke application design)

How do our Rewatec SAF systems work?

The Rewatec SAF sewage treatment plants form three treatment stages; primary settlement, biological treatment (biological and aeration zone) and final settlement. Flow through all of the treatment stages from inlet to outlet occurs through gravity and an integral airlift. 

Submerged Aerated Filter Sewage Treatment Plant - Operation


Primary settlement tank

In typical installations, wastewater first flows into a primary settlement tank, allowing liquids to separate from suspended solids. The primary settlement tank is also designed to accomodate flows and load fluctuations.

Biological and aeration zone

Inside the Rewatec SAF, micro-organisms grow on floating biofilm media. They feed on organic wastewater pollutants, producing effluent composed of biomass particles and treated wastewater.

Our plastic biofilm media are specifically shaped to increase the surface area on which micro-organisms grow. This maximises their ability to treat wastewater and helps you minimise the size of the reactor.

Biomedia used in a Rewatec SAF

Bubbles from aeration continuously mix the contents of the Rewatec SAF to ensure optimal contact between wastewater and micro-organisms, improving their ability to remove wastewater pollutants (such as ammonia or organic matter).

Final settlement tank

After treatment, wastewater flows in the final settlement tank. Solids accumulate at the bottom of tank before being redirected to the primary settling area by a re-circulation pump (enabling partial nutrients removal). 

Rewatec SAF maintenance

We have a network of local service providers to maximise the life of your Rewatec SAF system and to provide years of reliable operation.

We stand by our products

For over 50 years, we have proudly developed sustainable and long-lasting products that make a real difference for our customers, our professional partners, and, above all, our planet.

Our experience in the industry allows us to give you a complete 25 year warranty for our Rewatec SAF sewage treatment plants and a 12 month warranty for our kiosks.

Rewatec 25 years warranty

Training programmes

​​​​​​At Premier Tech we provide a full range of training programmes to fully meet the requirements of our professional partners. If you require product functionality guidance or a more detailed training course for installations and bespoke set-ups, we can provide a solution to meet your needs. 

Contact us for more information

Available products

We offer a complete range of Rewatec SAF wastewater treatment plants to meet your needs. From 30PE to 600+PE, wherever your site, whatever the regulations, we have the right product to transform any challenge into a tailor-made solution. 

Free quote

We are here to help. Request a quote today and our team of experts will be in touch. 

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