Centrate Treatment using MBBR with High Purity Oxygen (HPO) - Pilot Studies

Treatment of sludge dewatering liquors (centrate) by nitrification in a dedicated side-stream nitrification tank is an effective means of removing up to 25% of the ammonia nitrogen entering a wastewater treatment system. This paper presents a novel approach based on the Moving Bed Bioreactor technology oxygenated with High Purity Oxygen (HPO-MBBR). The paper discusses the results obtained in a lab scale pilot plant fed with centrate produced in a municipal WWTP with anaerobic digestion. Extensive experimentation has been carried out including analytical measurements, online data collection and estimations of real-time OUR, AUR batch tests, microbiological analysis and the application of modeling tools. The results indicate that the process can reliably provide up to 95% oxidation of ammonia with a notable effect of the DO level and Temperature on the Ammonia uptake rate. Microbiological results have demonstrated the capacity of the process to totally acclimate the biomass for high rate ammonia removal and no inhibitions have been found for a wide range of operational conditions. Results obtained at lab scale suggest that the HPO with the MBBR technology is a powerful combination for the treatment of high ammonia loaded streams.