Ballasted flocculation is a high-rate, physical-chemical clarification process, using rapid mixing flocculation and sedimentation for enhanced reduction of suspended solids and biochemical oxygen demand (BOD). It is a four-step process consisting of coagulation, flocculation, clarification, and separation.
The difference with the conventional treatment system is the addition of micro-sand as seed for developing high-density floc, which makes the clarification 10 times faster. Hence, there is a higher treatment rate of flows. The resulting high settling rates allow the system to fit into a fraction of the space required for conventional treatment systems, making them more attractive for retrofit and high rate applications.