Mixers and flow inducers have a wide variety of uses across many different industries:
In wastewater treatment the most common uses include the suspension of micro-organisms, the dispersion of oxygen, the mixing of different streams (eg. influent and RAS) and the blending of chemicals (eg. flocculation).
Many types of mixers are available and they should be selected, sized and positioned according to the required task, the tank geometry including any flow impediments, the tank retention time, the characteristics of the wastewater and accessibility constraints. Intelligent selection is an important part of optimising the treatment process and reducing investment and operating costs.
Mixer performance is still all too commonly compared on the basis of Power Density (W/m3) and Thrust (N). Both of these are poor measures of mixing performance and as such have limited use. Where no settlement is required a comparison of Minimum Bottom Flow Velocity (m/s) is imperative, and where no dead zones or short-circuiting (ie. optimum retention) is required then CFD modelling backed up by dye testing after commissioning is recommended. Another useful and low cost test for homogeneity in activated sludge processes is where Mixed Liquor Suspended Solids (MLSS) are sampled at different locations and depths and concentrations compared.
We highly recommend in-situ testing after commissioning. This protects you from spurious performance claims and ensures optimum treatment performance.
Once you’re clear on your selection criteria, you may find our selection guide below useful. Click on the links for full details of each product: