MODELLING NITRIFYING TRICKLING FILTERS / Modellering av nitrifierande biobäddar
Nitrifying trickling filters (NTFs) have attained renewed attention due to increasing demands on nitrogen re moval in municipal waste-water treatment. For improved control of wastewater treatment plants (WWFPs), using NTFs, models of the filters are almost indispensable. Furthermore, models may be used to improve the understanding of the process and for studying new operational strategies and process configurations. In this study a few models of increasing complexity are presented. Data from a pilot plant at the Rya WW’FP in Goteborg have been used to validate model assumptions and to estimate model parameters. From comparisons between experimental data and model simulations a few conclusions are made: The fast dynamics have transients in the order of minutes, and can be separated from the slow bacterial dynamics that have transients of several days. The response time of the bacteria to changes in substrate bulk concentrations is in the order of a few minutes. An increase in flow enhances the substrate flux into the biofilm, probably due to increased turbulence in the bulk water. It is also shown how the control of the addition of hydrocarbons in a subsequent denitrifying process stage can possibly be improved by using a model of the fast NTP-dynamics.