The Actiflo process manufactured by I. Krueger, Inc. (Cary, NC) is a sand ballasted flocculation/clarification system. This system has a flocculation stage, analogous to the solids contact stage of other solids contact processes (e.g., CONTRAFAST and DensaDeg), followed by a clarification step. The microsand added prior to the flocculation stage provides additional surfaces for collisions with particulate material in untreated water and the resulting particulate and microsand floc create large, heavy particles that settle rapidly, allowing the clarification step to be operated at a high surface overflow rate. A cyclone separates the higher density microsand particles from other solids so the sand can be recycled.
The manufacturer typically expresses rates relative to clarification area, which do not take into account total footprint due to flocculation, chemical addition, sand handling, etc. Data from three previous pilot studies were presented and discussed in this report (see Chapter 2 of the project report). Characteristics of the Actiflo system demonstrated during these previous pilot studies include the following:
- Hydraulic loading rate of 20 gpm/ft2 or higher (rates expressed relative to clarification area)
- Median turbidity <1 ntu and 95th percentile turbidity <2 ntu (when polymer used)
- Data on residual solids produced by this process are limited, but indications are that the residuals are typically <0.5 percent solids
Process Schematic (Provided by I. Kruger, June 2006)
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