HyperClassic Mixers

Mixing re-defined

The HyperClassic Mixer was developed in 1985 in the Fluid Mechanics Department at the Friedrich-Alexander University, Erlangen-Nuremburg, to support a thesis on the most energy-efficient mixing system design.

Rather than just upgrading traditional mixer designs, the team started from scratch – drawing on a wealth of new technology and advances in Computational Fluid Dynamics (CFD Modelling). With no bias towards old designs holding them back, they added a whole new dimension to the world of mixing.

Results were so spectacular that they knew it would have immediate appeal to the wastewater market, and so in 1989 they released it to the industry.


The iconic HyperClassic Mixer has a vertical shaft with a patented, hyperboloid-shaped impeller. Minimal maintenance is required: submerged parts are not subject to wear and the drive unit is easily accessible, being installed above water level.

Rag resistant

The impeller is suspended just above the tank floor, and due to its unique shape and the large diameter shaft, ragging is virtually eliminated. This is unheard of in other conventional designs.

Mixing where you need it most

The impeller fins create a very strong flow across the bottom of the tank, preventing sedimentation where it is most likely to occur.

No air entrainment

Upon reaching the walls, the flow rises towards the water surface. By the time it reaches the surface, the flow velocity has reduced sufficiently to minimise turbulence and prevent air entrainment.

The secret of torroidal flow

The water flow is then directed towards the centre of the tank, from where it is directed downwards again to the shaft and impeller. A torroidal flow pattern is created throughout the tank, ensuring complete homogenisation, i.e. all particles are distributed evenly throughout the tank. Torroidal flow patterns are common in nature: hurricanes, whirlpools and magnetic fields – further evidence of their efficiency.

Virtual walls

When used in wastewater treatment, especially in anoxic or anaerobic tanks, the unique flow pattern generated by HyperClassic Mixers can be used to create ‘virtual separating walls’.  This creates multiple zones which ensures complete mixing and provides significant process benefits.

Independent mixing and aeration

When combined with aeration diffusers, HyperClassic Mixers can be used for swing zones and SBRs where intermittent aeration and mixing is required.  They can also be used to maintain mixing in aeration zones with low BOD load where the energy from aeration is insufficient to maintain solids  in suspension.

The truth about other designs

Compared with other mixers, it is easy to see why the HyperClassic Mixer is the most efficient: most other vertical shaft mixers have only an axial flow, meaning that the water flow is directed either upwards or downwards. With either of these, there is significant energy loss on the tank floor at the surface. The latter also causes surface turbulence and results in little velocity at the sides and bottom. With horizontal mixers, a huge amount of energy input is needed at the start of the flow pattern to ensure that there is sufficient residual energy at the end of the flow pattern and in the tank extremities.


The HyperClassic Mixer however, has both an axial (vertical) and radial (radiating horizontal) flow, meaning that the entire contents of the tank are kept in motion with minimal energy input. For example, complete mixing with adequate bottom flow velocities to maintain activated sludge in suspension can be achieved at a power density of down to 1.2 W/m³. This means that a single 1.5kW HyperClassic Mixer can mix a tank of up to 1250m².

A common trap

Mixer performance should never be assessed on power density (W/m. Unfortunately, this is still a common, if flawed, practice. One of the best measures is minimum bottom flow velocity, and mixing and retention tests in dynamic system using tracer dyes.  These measures quickly level the playing field and protect you form unsubstantiated performance claims.

Global success

With installations around the globe, the HyperClassic Mixer is a proven success internationally.

Recent advances

The revolutionary Evolution 7 design was launched in 2014 at the IFAT Exhibition and represents a further advance in ground-breaking energy efficiences.

Features & Benefits



Hyperboloid mixer body

By directing the water flow from axial (down the mixer shaft) to radial (along the tank floor), frictional lossestd are minimized and the highest efficiencies are achieved

Energy dissipated along the tank floor and upwards

No sedimentation or dead zones

Anti-rag design

Superior to all other mixer designs in regard of ragging

All drives and bearings above the water line

All maintenance items are easy to access and not prone to water damage

No bottom bearing (except in exceptional circumstances)

No need for draindown during installation or removal

Self-centering impeller

Minimises forces and vibration

Low rotational speed

Prevents floc shear

Internationally proven performance

Peace of mind



Where are HyperClassic Mixers used?

Why are they selected?


Anoxic and anaerobic zones

Energy efficiency

Mixing and equalization tanks

Ease of maintenance

Sludge tanks

No ragging or clogging

Sequencing Batch Reactors (SBRs)

Complete suspension and homogenisation

Swing zones where independent aeration and mixing is required

Maintaining ‘virtual separating walls’

Aeration zones with low BOD demand


Flocculation tanks