Application of Structured Sheet Media IFAS for Ammonia Polishing From a Trickling Filter Solids Contact Process

Trickling filter solids contact (TF/SC) processes offer the energy efficiency and resistance to shock loads of a trickling filter, along with the improved settling characteristics and higher quality effluent of an activated sludge system. When operated at low trickling filter organic loading rates, the systems are also capable of high degrees of nitrification, though nitrification performance can be sporadic at times. As an alternative to installing intermediate clarifiers or solids reaeration basins, which may be costly or difficult to integrate in some applications, IFAS media could be installed within existing solids contact basins to increase the system MCRT and improve nitrification results. This paper discusses the design, installation, and operation of a full scale TF/SC–IFAS system in Coldwater, Michigan, USA. The purpose of this plant upgrade was to polish effluent ammonia concentrations to ensure compliance with new effluent ammonia discharge limits.