Performance of Actively-Aerated Biofilters Using a Multiple-Level Air Injection System to Enhance Biological Treatment of Methane Emissions
Abstract
The present research is intended to remove methane from a gas stream by converting it into carbon dioxide by means of aerobic methane-oxidizing microorganisms. Such technology can be useful when dealing with biogas from landfills, or solution gas from natural gas wells. Taken that methane oxidation is an aerobic process, a major enhancement in efficiency is observed by the active introduction of oxygen throughout the biofilter profile. Thus, with the aim of improving conventional biofilters, in this study a multiple-level aeration biofilter design is proposed.
Laboratory column experiments were run to study three different actively-aerated methane biofilter configurations. Columns were aerated at one, two, or three levels along the bed thickness. Inlet methane loading rates were increased at five stages between 6 mL/min to 18 mL/min. A first set of columns were operated introducing air at flow rates calculated based on the oxidation reaction stoichiometry. The effects of methane feeding rate, levels of aeration, and residence time were evaluated. Based on the results obtained from a mixed Analysis of Variances, the response surface, and laboratory observations, it was suggested that the biofilter column with two aeration levels has the most even performance over time, maintaining an average oxidation efficiency of 85.1% over the 195 days of experiments.
A second set of columns with the same aeration designs were run for varying air to methane flow rates. Air flow rates were changed inlet air flow rates between ¼ of stoichiometric levels to 1.5 times higher than stoichiometric values. The performance of columns was recorded for 90 days. With air flow rates set at ¼ of the stoichiometric value, an average 13.8% reduction in performance of the biofiltration designs was observed. However, more experiments are required to evaluate the long-term performances of aerated biofilters operated under low air to methane flow rate ratios.
Description
Keywords
Engineering--Civil, Engineering--Environmental
Citation
Farrokhzadeh, H. (2016). Performance of Actively-Aerated Biofilters Using a Multiple-Level Air Injection System to Enhance Biological Treatment of Methane Emissions (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27298