The BIOACTIFLO system from Kruger USA combines contact stabilization and microsand ballasted clarification to treat wet-weather flows. Return activated sludge from existing clarifiers is combined with excess flows into a solids contact tank. A targeted mixed liquor suspended solids concentration is maintained in the contact tank to facilitate rapid uptake of soluble biological oxygen demand via contact stabilization, which is followed by clarification. The combination results in total BOD removals in excess of 85 percent, more than 95 percent TSS removal and total phosphorus levels less than 0.15 mg/L. Existing ACTIFLO installations can be easily converted to BIOACTIFLO, and the ACTIFLO train can also be used for tertiary treatment during dry weather flows. 919/677-8310; www.krugerusa.com.