Doctor of Philosophy (PhD)
Civil and Environmental Engineering
Biological processes are increasingly used for treatment of air streams contaminated by biodegradable volatile organic compounds (VOCs). The research described in this dissertation involves systematic investigation of various facets of applying biological processes dominated by fungi to remove mixtures of VOCs representative of emissions from paint application and manufacturing. Screening studies were first conducted to assess the ability of multiple fungal species to degrade various industrially important VOCs. In the following phases of the research, studies were conducted to evaluate performance of laboratory-scale bioreactors inoculated with fungi for treatment of mixtures of VOCs representative of emissions from paint spray booths and reformulated paint manufacturing under various steady loading and discontinuous loading conditions. The performance of biofilters operated at neutral and low pH conditions treating simulated off-gas generated from manufacture of reformulated paint were also evaluated. Finally, the relative contribution of fungi and bacteria to toluene degradation in biofilters was investigated. Experimental results indicate that fungal consortia are capable of biodegrading a wide range of VOCs including esters, ketones, and aromatic hydrocarbons. A biofilter inoculated with a pure fungal culture provided promising VOC treatment performance under both continuous and discontinuous loading conditions. Substrate competition or inhibition occurred in the biofilter when loaded with a VOC mixture with ketones preferentially utilized relative to aromatic hydrocarbons. When inoculated with compost-derived enrichment cultures, both neutral and low pH biofilters successfully removed hazardous air pollutants combined with high loading of acetone present in a synthetic waste gas stream intended to simulate off gas emitted from manufacture of reformulated paint. Large quantities of fungal biomass developed over time in biofilters operated at neutral and low pH following inoculation with undefined mixed enrichment cultures derived from compost. Biofilters subjected to intermittent loading (8 ht/day) during startup reached high removal efficiency relatively slowly in comparison to these subjected to continuous loading during startup. Experimental results also demonstrated that fungi played an important role in toluene biodegradation in neutral pH biofilters inoculated with an undefined mixed culture. Maximum toluene elimination capacity decreased significantly after fungi were inhibited by antibiotics, while performance was essentially unchanged when bacterial inhibiters were added.
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Qi, Bing, "Biofiltration for treatment of gas-phase VOC mixtures" (2005). LSU Doctoral Dissertations. 1531.
William M. Moe