Date of Award
Civil and Environmental Engineering
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The focus of this thesis was on the production of methane from black liquor (BL) using a two-step degradation process; that being, photocatalytic pretreatment of BL followed by anaerobic digestion. Photocatalytic degradation efficiency was optimised based on the following factors: lignin type (BL, black liquor with sulfide removal (BL-S), alkaline lignin (AL), and sodium lignosulfonate (LS)), lignin concentration (500 and 1000 mg COD/L), catalyst type (titanium dioxide (TiO2) and reduced graphene oxide titanium dioxide nanotubes (RGO TNT)), and initial concentration of strong oxidizing agent (0, 0.001, 0.005, and 0.01 mol/L of H2O2). The process efficiency was evaluated based on biodegradation as measured by TOC and TP reduction and structural modification as measured by FTIR and LC-MS analysis. Next, biomethanation potential for the photocatalytic degradation byproducts was evaluated using anaerobic digestion serum bottle studies. In terms of the photocatalytic degradation efficiency, a comparison of the lignin types showed the best TOC removal for LS. Evaluation of the lignin concentration yielded higher degradation at lower initial concentrations. Statistical analysis showed the two catalyst type performed the same in terms of TOC removal. Assessment of the H2O2 photocatalysis showed increased degradation rates with an increase of initial H2O2 concentration. In terms of the biomethanation potential, the maximum methane production was observed for the BL-S. Statistical comparison of the TiO2 and RGOT TNT catalyst showed the two catalyst type performed the same in terms of methane production. The addition of H2O2 to the photocatalysis resulted in increased methane production in anaerobic digestion.
Jung, Christina Joy, "Methane Production Using Photocatalytic Degradation Byproducts from Black Liquor" (2019). Electronic Theses and Dissertations. 7812.