Biotrickling filters have been extensively studied for treatment of a wide variety of organic and inorganic contaminants in gaseous emissions from wastewater treatment plants, industrial manufacturing operations and sludge handling systems. Biotreatment offers an economically attractive, ambient temperature and pressure system for treating contaminant emissions than incineration, catalytic oxidation or chemical treatment. The challenge in biotrickling filters is developing a suitable media that can be used to immobilize the active bacteria as biofilms on its surface that delivers high surface area, ability to retain the attached biofilms, low bulk density to reduce the weight of the media beds, and prevent clogging due to biomass growth. Currently, no suitable media that can deliver all of the above characteristics has been developed.

Randomly packed inorganic foam structures, manufactured by a unique process, will be studied as possible support media for biotrickling filters removing Sulfur Reduced Compounds (SRC) from air at different working conditions of concentration and contact time in the filter. Foams offer high surface areas, ability to retain biofilms, low bulk density due to high porosity, and depending on size and geometry, ability to slough-off excess biomass growth to prevent clogging. While polyurethane foams have been studied as biofilter media, they have been used as monoliths, cylindrically wrapped sheets to form a single bed that have been shown to clog due to biomass growth. In this research, computer simulation studies will be conducted to develop a better understanding of gas and liquid hydrodynamics in randomly packed beds using foam structures. Hydrodynamic models will be coupled to biokinetics to model biomass growth and contaminant biodegradation in airstreams containing Hydrogen Sulfide, Methyl Mercaptan, Dymethyl Mercaptan and Carbon Disulfide.

Detailed computer simulation studies have shown that the pore size and porosity of the foam structure as well as the nominal size of the randomly packed foam pieces controls the extent of gas flow through the foam as compared to between the foam pieces. Results of the computer simulation studies and experimental data will be presented to offer some unique insights towards the development of an “optimum” support media for biotrickling filters.

Keywords: Biotrickling filter, solid foam, removal efficiency, model, biofilm growth.