title: Measuring and modeling the oxygen profile in a nitrifying Moving Bed Biofilm Reactor.
abstract: In this paper we determine the oxygen profile in a biofilm on suspended carriers in two ways: firstly by microelectrode measurements and secondly by a simple mathematical model. The Moving Bed Biofilm Reactor is well-established for wastewater treatment where bacteria grow as a biofilm on the protective surfaces of suspended carriers. The flat shaped BiofilmChip P was developed to allow good conditions for transport of substrates into the biofilm. The oxygen profile was measured in situ the nitrifying biofilm with a microelectrode and it was simulated with a one-dimensional mathematical model. We extended the model by adding a CSTR equation, to connect the reactor to the biofilm through the boundary conditions. We showed the dependence of the thickness of the mass transfer boundary layer on the bulk flow rate. Finally, we estimated the erosion parameter lambda to increase the concordance between the measured and simulated profiles. This lead to a simple empirical relationship between lambda and the flow rate. The data gathered by in situ microelectrode measurements can, together with the mathematical model, be used in predictive modeling and give more insight in the design of new carriers, with the ambition of making process operation more energy efficient.
authors.affiliation: Centre for Technological Studies, Malmö University, SE-20506 Malmö, Sweden. alma.masic@mah.se
authors.forename: Alma
authors.initials: A
authors.lastname: Masić
authors.forename: Jessica
authors.initials: J
authors.lastname: Bengtsson
authors.forename: Magnus
authors.initials: M
authors.lastname: Christensson
mesh_terms: D000465:Algorithms; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D003198:Computer Simulation; D004058:Diffusion; D008839:Microelectrodes; D008954:Models, Biological; D009566:Nitrates / Q000378:metabolism; D058465:Nitrification; D009573:Nitrites / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012212:Rheology; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D009566:Nitrates; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D010100:Oxygen