DEVELOPMENT OF A DYNAMIC-MODEL DESCRIBING NITRITIFICATION AND NITRATIFICATION IN TRICKLING FILTERS

A dynamic model which describes nitritification and nitratification in trickling filters has been developed. The model predicts the concentr ation profiles of ammonia, nitrite and nitrate along the filter depth and along the biofilm depth, as a function of the operating parameters , in batch as well as in continuous operation. The model can also pred ict the biofilm thickness as a function of filter depth and time. The batch version of the model predicts that the best moment to start the continuous operation is the moment when Nitrobacter concentration is m aximum and nitrite concentration is minimum, while the continuous vers ion of the model predicts that nitrite accumulation would be observed only when a significant ammonia concentration is observed at the filte r outlet. A pilot-scale trickling filter was used in order to verify t he predicted results. In all cases there was very good agreement betwe en predicted and experimental results. (C) 1997 Elsevier Science Ltd.