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The rapid mix system is designed to accomplish this. The rapid mix design consists of piping leading from the entrance tank to the flocculator entrance. The piping contains two orifices. One orifice is for macro-mixing and the other orifice is for micro-mixing. The orifices decrease the cross sectional area of the flow allowing for a higher velocity and thus turbulence. Turbulence, measured in energy dissipation rate, is associated with the formation of eddies which mix the alum to the length scale at which viscosity overrides the formation of eddies with a larger energy dissipation rate being associated with a smaller eddies. The length scale at which the eddies can mix the alum to is known as the Kolmogorov length scale.
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EPS: Energy Dissipation Rate
There are two main forms of mixingThe two different orifices in the rapid mixer are for the two types of mixing that occur. One is for macro-mixing and the other is for micro-mixing. Macro-mixing mixes the alum to the length scale at which micro-mixing can start. Micro-mixing distributes the eddies to the length scale that molecular diffusion can finish the task.
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