The BIOSTYR DUO system from Kruger USA integrates biological aerated filter and moving bed biofilm reactor (MBBR) technologies. Biological treatment and filtration occur simultaneously within the system, and two separate media types are contained within the same treatment cell. Wastewater first flows through an MBBR media layer, which provides a large surface area for biofilm growth and treatment. Flow then passes through the BIOSTYRENE media layer, which provides additional fixed-film treatment and filtration as the water flows up through the fixed bed. The buoyant BIOSTYRENE media is retained by a concrete deck with multiple strainers, and the system uses a gravity-driven backwash for excess solids removal with no pumping. It offers significantly increased BOD and ammonia loading rate capabilities, while maintaining low effluent BOD, TSS and ammonia values. 919/677-8310; www.krugerusa.com.