Biological elimination of volatile xenobiotic compounds in biofilters

Biofiltration is a technique which is frequently applied for the odour abatement of waste gases. This technique is based on the ability of microorganisms (generally bacteria, and to a small extent moulds and yeasts) to degrade several organic as well as inorganic compounds to mineral end-products, like water and carbon dioxide. In the case of biofiltration, microorganisms are attached to suited packing materials in the filter, which contain the inorganic nutrients necessary for microbial growth. In order to make biofiltration applicable on a larger scale in process industry, it is necessary to find microorganisms able to eliminate compounds which are strange to life, the so-called xenobiotics. At the Eindhoven University of Technology microorganisms were isolated for the elimination of a number of xenobiotics, e.g. aromatic compounds and chlorinated hydrocarbons.Both the microkinetics of the biodegradation in aqueous batch systems and the macrokinetics of biofilters were studied. Special attention was paid to the influence of the superficial gas velocity and the organic load on the filter bed's elimination capacity. Also the discontinuous operation of biofilters is discussed.Nomenclature C ₁],C _1,0,C _í mol/m³ liquid phase concentration - K _s mol/m³ saturation constant - Y kg/kmol yield coefficient - t, t d time - _md^–1 maximum growth rate - X, X ₀ g/m³ microorganism concentration - P _gPa partial vapour pressure - H Pa m³/mol Henry's law constant - m (-) distribution coefficient - C _g,C _g,max mol/m³ gas phase concentration - R J (mol K) gas constant - T K temperature - (-) gas phase- and liquid phase volume ratio - m³/(m² h) superficial gas velocity - H m height of the filter bed - h m height in the filter bed In memory of Dick van Zuidam