Investigation of Oxygen Profile in a Nitrifying Moving Bed Biofilm Process. Theory and Validation of a Mathematical Model

Several mathematical models can be used to reproduce and predict the behaviour of biofilms. Depending on conditions like substrate concentrations or temperature, there are many models representing the variety of processes. The AnoxKaldnesTM MBBR technology is well-established for wastewater treatment where a bacterial biofilm grows on the protective surfaces of suspended carriers [1]. Previous studies on the KaldnesTM K1 carrier have shown that the nitrification rate was close to first order kinetics with respect to DO when oxygen limiting conditions were established [2]. Thus, higher DO gives higher nitrification rates but at the expense of increased energy consumption. The flat shaped BiofilmChipTM P was developed to increase the available protective surface area and to allow good conditions for transport of substrates into the biofilm. We present the oxygen profile of the biofilm within the BiofilmChipTM P carriers based on two different methodologies: Firstly, the oxygen profile was measured on actual carriers that have been used in a Moving Bed Biofilm Reactor and secondly, the oxygen profile was estimated, based on a mathematical model.