How can Carrousel® systems treat to such low nutrient limits?

Carrousel® systems have been around since the advent of nutrient removal in the United States, the late 1970s. A combination of dedicated volumes (aerobic, anoxic, and anaerobic) with unlimited and free (no pumps required) internal recycle allows for a TN of less than 3 mg/L and a TP of less than 0.3 mg/L, or even lower. Recent research has suggested that the combination of repeated floc shear in the aeration zones and the reflocculation in the long channel zones significantly enhances simultaneous nitrification/denitrification as well.