Achieving Extremely Low Effluent Total Nitrogen and Total Phosphorous Concentration at Very Low Solids Retention Times Using IFAS Technology

The paper presents results from eighteen-month long testing at the Cocoa Beach Water Reclamation Facility in Florida which was conducted to investigate the ability of Integrated Fixed Film (IFAS) processes with extremely short SR Ts to remove total nitrogen (TN), the effect of process designs and operations on meeting extremely low effluent TN concentrations, and reliability of performance. The paper also reports the ability of development of a large population of phosphorous-accumulating organisms (PAOs) within the sludge blanket when the sludge blanket depth is carefully controlled in the secondary clarifiers. Last but not least, the paper summarizes the evolving understanding of the possible biological phosphorous removal mechanism within the sludge blanket, the effect of process operation conditions on meeting low total phosphorous (TP) concentration, and reliability of performance.