Combined activated sludge-fixed film media treatment systems are an interesting innovation in treatment technology. By adding media into the aeration basin, increased biomass concentrations may be maintained with little or no increase in solids loading to the clarifier. The ideal combined system can treat higher organic and ammonia loadings than a conventional system, and is more resistant to temperature changes and shock loadings. Overloaded plants can be outfitted with media as an alternative to plant expansion, and initial designs of combined systems can result in smaller aeration basins and clarifiers in places of land scarcity. / Master of Science