Biodegradation of methanol and alpha-pinene using thermophilic bacteria and its application in thermophilic biofiltration systems

The overall goal of this study was to recover and characterize thermophilic bacteria that can degrade the VOCs methanol and α-pinene and to develop a bench-scale thermophilic biofiltration system for the removal of these VOCs.; Thermophilic bacterial mixtures that degrade both methanol and α-pinene were obtained via enrichment techniques. Two tested bench-scale thermophilic biofiltration systems utilizing these bacteria were designed to treat VOCs under conditions, particularly temperatures between 50 and 60°C, commonly found in the waste stream of forest product industries such as oriented strand board mills. The first system had removal efficiencies of >98% for methanol but only 23% for α-pinene. α-Pinene removal was poor, likely because of mass transfer limitation (i.e., α-pinene is essentially immiscible). The second system, having the same parameters as the first system except being larger in size, was designed and operated to evaluate residence time and the effects of surfactants on VOC removal. A nonionic surfactant mixture (having concentrations of 0.05% w/v for Triton X-100, 0.1% w/v for Brij 35 and 0.05% for Brij 58) when added to system resulted in increased α-pinene removal, indicating that the surfactants may increase mass transfer and bioavailability of α-pinene.; An additional study was conducted to further investigate the effects of nonionic surfactants on α-pinene solubility and on the thermophilic biodegradation of methanol and α-pinene in liquid systems. A test of solubility enhancement of α-pinene by surfactants utilized the same surfactants mixture as was used in the second bïofiltration system, as well as each surfactant in the mixture individually and at various concentrations. All three nonionic surfactants were able to linearly increase α-pinene concentrations in water, although each did so to a different extent. When testing thermophilic biodegradation, over 99.9% of the α-pinene was degraded within 8 h (k of 0.27/h) with surfactants. In contrast, only 4% of the α-pinene was degraded without surfactants (k of 0.08/h). Maximum degradation rates of α-pinene with and without surfactants were 50.6 mg/l/h and 0.15 mg/l/h, respectively. The surfactants did not affect growth rates on methanol nor methanol degradation. Tests also showed that the surfactants neither served as nutrient sources nor were toxic to the bacteria. Therefore the results indicate that nonionic surfactants may be successfully employed to enhance α-pinene degradation under thermophilic conditions by increasing its solubility, mass transfer, and bioavailability, while not adversely affecting methanol degradation.; The final phase of this thesis focused on the characterization of the thermophilic methanol-utilizing facultative methylotrophs by using both phenotypic and molecular techniques. The major recoverable isolates of both methanol and α-pinene bacterial mixtures appeared similar. The bacteria were able to utilize both methanol and multicarbon compounds, thus the recovered bacteria were considered to consist of facultative methylotrophs. Phenotypic and molecular (i.e., 16S rRNA gene sequences) characteristics revealed that none of isolates matched closely to any published thermophilic or methylotrophic species. At least two new thermophilic methanol-utilizing methylotrophs have been found. One isolate should belong to the Deinococus-Thermus phylum, the other two isolates should belong to Gammaproteobacterium class and in the Proteobacterium phylum.