Rotex Brush Aerators


The brush rotor was the brainchild of the same man who designed the oxidation ditch: Dr I A Pasveer.

Modern Rotex Brush Aerators are more efficient descendants of the original Pasveer brush rotor design. Their traditional use is for oxidation ditches but they can also be used in other configurations.

Directional Flow

Brush rotors are horizontal shaft surface aerators used for oxygen transfer and directional mixing in wastewater treatment. The rotating brush introduces oxygen into the water and induces a strong horizontal flow. Baffles are often installed downstream of the brush rotor to ensure uniform aeration and mixing down to the tank floor.

Market Leading Efficiency

Rotex brush aerators are widely recognised as being the most efficient aerators in their class, typically having a guaranteed oxygen transfer efficiency of 2.0kgO2/kWh in standard conditions. Oxygen transfer and mixing power are controlled by varying the water level (and therefore immersion depth of the aerator) and/or by adjusting the speed of rotation. Variable Frequency Drives (VFDs) are a common method of adjusting the speed of rotation in order to optimise energy efficiency.

The Rotex aerator is made of a seamless, hollow shaft to which the rotor blades are clamped in a star pattern. The blades are offset to form a spiral pattern around the shaft to reduce ‘tramping’ and bearing load as the aerator rotates in water. Rotex aerators can be supplied with access platforms and/or inspection covers for ease of inspection and maintenance.

Integrated Bridge

Rotex Brush Aerators are commonly integrated with an access bridge complete with inspection covers. This allows for offsite pre-fabrication, quick and safe installation, and easy maintenance access.

Superior Build Quality

Rotex also leads the way in build quality, manifested by superior reliability and longevity. Gearboxes are typically designed with a service factor of ≥2.0, which well exceeds most alternative designs.


Rotex Brush Aerators have been installed in wastewater treatment processes throughout the UK, from rural wastewater plants in the Scottish Highlands to dairy effluent treatment plants in South West England. They are commonly custom-designed for installation in existing oxidation ditches, and are frequently installed without draindown.

Our Rotex Brush Aerator is a modern alternative to, and suitable replacement for, existing brush aerators such as Whitehead & Poole, Biwater, Maxi, Midi, Mammoth and O2 Rotors.

Features & Benefits



High oxygen transfer rates (SAE of 2.0kgO₂/kWh)

Improved energy efficiency and reduced costs

Strong directional mixing

Maintain solids in suspension

Rotor blades arranged around shaft in a spiral pattern

Reduced impact on bearings

Robust, reliable design - proven worldwide

Safe investment and reduced risk

Long-life bearings

Cost savings from reduced maintenance frequency

Vertical splash plates

Protect bearings and drive units

Optional horizontal splash cover

Improved QHSE compliance by the reducing splashing and bio-aerosol release

Clamp-on (rather than welded) galvanised or stainless steel blades

Extended blade life through reduced fatigue and corrosion

Shaft designed for up to 10m single span

Eliminates the complexity of cost of supporting civil structures when spanning wide lanes

Baffles provided where specified

For uniform transfer of oxygen and flow velocity in deeper tanks

Low vibration

Energy efficiency and extended asset life

Optional access bridges

Improved accessibility for inspection and maintenance


Where are Rotex Brush Aerators used?

Why are they selected?


Oxidation ditches

Where live installation is required (i.e. no draindown)


To replace aging or failing equipment

Annulus tanks

To improve oxygen transfer and mixing efficiency


To improve longevity and reliability