Comprehensive modelling of gas-phase biofilters treating volatile organic and inorganic compounds

Resumen

In the last decades biofiltration has become an attractive alternative to physicochemical methods for treating low concentration of biodegradablecompounds in waste gases. The advancements in this technology have currently focused on attaining a better understanding of kinetics and physical removal mechanisms and determining the optimal operating conditions. In this thesis mathematical models describing gas-phase biofilters werestudied. As a first step, biofiltration fundamentals and modelling approaches used for representing the phenomena taking place in biofiltration were revisedin chapter 1 and 3. The inherent physical and kinetic modelling limitations of these systems were also discussed in detail. In this sense, mathematicalbases to build a general dynamic model describing air pollutant abatement by biofiltration were provided. The model equations were solved by means ofa discretization procedure in which discretizing values are optimized in order to achieve an accurate representation of the reactor behaviour. A general description of materials methods employed is this thesis was provided in chapter 4. In chapter 5 a broad study was conducted to determine the influence of the most relevant physicochemical and kinetic parameterson model predictions. Model was implemented and solved using Berkeley Madonna. Additionally, phenomenon related to oxygen limitation in the biofilm,dispersion in the gas phase, and mass transfer limitation in the gas interface were studied in order to provide a support framework to decide which phenomena should be included in a general biofiltration model. According to results obtained with a general biofiltration model, a dynamic modeldescribing ammonia removal by biofiltration was developed in chapter 6. Nitrification process (i.e. the oxidation of ammonium to nitrate) was described by means of two-step reactions including inhibitory effects caused by free ammonia and free nitrous acid.