A comparison study has demonstrated that Chemineer impeller mixers can save up to 85% energy in anoxic zones. Taking a typical water industry site with a total tank volume of 2861 m3, the annual energy cost of Chemineer’s SC3 impeller was £1,804 compared to the annual energy consumption of £ 12,781 when using a submersible mixer.

In a direct Computational Fluid Dynamics (CFD) comparison study to achieve the required velocity profile in a tank base, a Chemineer SC3 impeller mixer design has been found to use just 1.44 w/m3, (specific power consumption) compared to a submersible mixer’s 10.2 w/m3.

In a typical water industry site with a total tank volume of 2861 m3, the annual energy cost of Chemineer’s SC3 impeller was £ 1,804 ( 2861 m3 x 1.44 w/m3 @ 0.05 £/kW hr). The study demonstrates significant energy, carbon and cost savings compared to the annual energy consumption of £ 12,781 when using a submersible mixer (2861 m3 x 10.2 w/m3 @ 0.05 £/kW hr).

Chemineer also claim that for anoxic zone mixing, the slow speed impellers of top entry mixers are not only substantially more energy efficient, but also provide better flow patterns and increased flow velocities in the base of the tank.

A high efficiency axial flow hydrofoil impeller, Chemineer’s SC3 directs flow centrally downwards in the chamber and deflects radially outwards at the base of the tank. This scrubbing effect means that the base of the tank is kept clear and the solids are suspended. The flow pattern also shows that the surfaces velocities are reduced, and below a level where aeration could be a potential problem.