NITROGEN REMOVAL USING POLYURETHANE FOAM SPONGE CUBE AS A BIOMASS SUPPORT MEDIUM IN A MOVING-FIXED BED BIOFILM REACTOR

A mathematical model of nitrification and denitrification in a moving-fixed bed biofilm reactor has been developed to describe ammonium utilization by nitrifying biomass as well as nitrate and organic carbon utilization by denitrifying biomass, respectively. The model incorporates the mechanisms of diffusive mass transport and Monod kinetics. The batch kinetic tests were independently conducted to determine biokinetic coefficients used in the model. A pilot-scale moving-fixed bed biofilm reactor including suspended and attached growth of nitrifying and denitrifying biomasses was set up to verify the validity of the model. The experimental results of ammonium,nitrate and organic carbon effluents show a good agreement with model prediction. The removal efficiencies of ammonium-nitrogen, nitrate-nitrogen and organic carbon (as COD) were 85%, 92% and 70%, respectively. The approach of modeling and experiments presented in this study could be employed for the design of the full-scale moving-fixed biofilm process to remove nitrogen and carbon simultaneously in waters or wastewaters.