Vaughan’s Rotamix system sets itself apart from the competition with no moving parts in the tank, removing the need to empty a tank for service and maintenance of the mixing system by keeping serviceable components out the tank or digester, and ensuring reliability and efficiency for wastewater treatment plants across Australia.

Vaughan’s Rotamix system is second to none when it comes to mixing large volumes! Municipal wastewater treatment plants across Australia now insist on Vaughan Rotamix, with plant operators commonly saying “the Rotamix system is not the squeaky wheel on site, it just works”.

The Rotamix System is a series of fixed-floor and wall-mounted nozzles inside a tank or digester that induce mixing energy to the tank volume.

The heart of the system is a Vaughan chopper pump. This extreme duty pump supplies flow to the nozzles, condition media, and prevents blockages.

Figure 1: The Rotamix concept.

So how does reliability ensure efficiency? By establishing and maintaining active volume mixing. A great deal of energy is expended to achieve active volume mixing from a stand-still, and it is more efficient to continuously maintain mixing than to re-start following a failure.

Further efficiencies are achieved in two ways:

1. Rotamix is paired with a Variable Frequency Drive. For a typical system, mixing energy can be reduced periodically throughout the day, resulting in energy savings

2. Biogas generation rates increase when solids are continuously conditioned and fully suspended within the tank volume, allowing organisms easy access to the volatile solids they feed on. This gas can be used to generate electricity and thus subsidise plant energy requirements

Designed and configured for each individual application

Each Rotamix system is unique, designed and configured for the sludge rheology, tank geometry, and local process considerations of each individual site.

Figure 2: CFD Analysis.

Vaughan uses state-of-the-art Computational Fluid Dynamics (CFD) modelling to design each system that can accurately model not just the tank geometry, but also piping and other obstructions to ensure proper mixing.

The Rotamix system incorporates several basic principles of physics and hydraulics including uniform field of flow, vertical field of flow, induced flow, surface contact, and Dual-Zone Mixing which ensures even mixing velocity across the entire cross-section of the tank. The result is a homogenous volume, an even distribution of solids, and a constant temperature.

In digester applications, foaming can be a major operational challenge. To complement the Rotamix system, Vaughan has developed the Foambuster mixing assembly, which can be added to any Rotamix system or provided as a standalone system.

The Foambuster uses a splash-plate to produce a field of droplets which suppress foaming at the surface before it can interfere with process operation. To date, there are 65 Rotamix systems at wastewater treatment plants across Australia and New Zealand, with more in the planning stages.

Vaughan Chopper Pumps and Rotamix Systems for Australasia are supplied by Pump Systems Pty Ltd in Australia, and Pump Systems Ltd in New Zealand. Further details are available from their website, or freephone 1 800 121 452.

This sponsored editorial is brought to you by Pump Systems. For more information, visit

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