| Biofiltration is an emerging technology for VOC control. It has been described as low-cost, effective for easily degradable organics, reliable and environmentally benign. In this thesis, fundamental investigations of biofiltration have been presented, with emphasis on experimental studies and development of mathematical models.; Experimental studies were conducted on the treatment of iso-pentane in air using peat and compost packed beds. High removal efficiencies were achieved at relatively low contaminant concentrations and high empty bed gas retention time. There was an "optimal" water content that gave the highest removal efficiency. For higher water content, mass transfer outside of the packing particle controlled the removal efficiency. At low water content, changes in the bioactivity of peat and compost occurred, resulting in an irrecoverable loss of removal efficiency. Increases in biofilter bed temperature also resulted in improving the removal efficiency. A mathematical model incorporating the effects of water content and temperature was developed. Inlet and outlet carbon dioxide measurements were made to show the attainment of "biological equilibrium". Later, this concept was used for designing biofilters with no net biomass growth.; Mathematical models were developed for biofilm under different operating conditions, such as single substrate limitation, interactive and non-interactive dual limitations. A critical biofilm thickness was defined when the substrate concentration reached zero at the biofilm-support interface. Experimental studies were conducted using a plate micro-biofilter to quantify the dynamics of biofilm growth.; Experimental studies were also conducted to determine the intrinsic biokinetics for different contaminants. A novel micro-biofilter system was developed to quantify biofiltration rates. Monod biokinetics for the contaminants were obtained using a mathematical model. These biokinetics were used to successfully predict bench scale biofilter performance.; Biofilter studies on BTEX compounds were conducted with two types of support media: non-adsorbing ceramic monoliths and activated-carbon coated monoliths. It was shown that continuous adsorption and back-diffusion of substrates into the immobilized biofilm resulted in enhanced biofiltration when using adsorbing support media.; Finally, a systematic methodology for designing biofilter systems has been presented. The design procedure incorporated uses of naturally bioactive and synthetic support media. Insights attained in this research work have been incorporated in the overall design methodology. |
