Comparison of Captor System with Other Fixed-Film Media Nitrification Systems

Abstract

Abstract Laboratory experiments were conducted at 20–25°C to compare the performance of three different types of Captor media with a rock-gravel media and a plastic trickling filter-packing media. The open-cell Captor media performed better than the gravel media and plastic trickling filter media at all loading rates up to 0.592 kg NH3-N/m3/d. Even at the highest NH3-N loading rate, the effluent NH3-N concentration was less than 1.0 mg/L in the open-cell Captor media effluent. The closed-cell, carbon-impregnated Captor media did not perform as well as the open-cell media. The reduction of temperature to 10–12°C reduced the performance of the Captor system to some extent, but NH3-N levels of less than 1.0 mg/L were obtained at loading rates up to 0.339 kg NH3-N/m3/d. At the highest NH3-N loading rate tested (0.852 kg NH3-N/m3/d), the nitrification performance of all the systems decreased, probably due to D.O. limitations, increased BOD loading and the consequent displacement of the nitrifiers by the heterotrophic organisms and lower detention time.