The objective of this study was to determine how the key features of bioreactor landfills; increased temperature, moisture and microbial activity, affect the biological stability of the landfill material. In the first part of the study the solubilization and degradation of lignin in paper exposed to these bioreactor landfill conditions are explored. The solubility of the lignin in paper was observed at different temperatures and over 27 weeks at 55°C and the anaerobic bioconversion of office paper, cardboard and Kraft lignin was observed in bench-scale reactors over 8 weeks. As the temperature rose, lignin solubility increased exponentially. With extended thermal treatment, the dissolution of lignin continues at a constant rate. This rate increases 15 times for paper and 1.5 times for cardboard in the presence of rumen inoculum compared to un-inoculated systems. At around 6 weeks the inter-monomeric linkages between the solubilized lignin molecules began breaking down, releasing monomers. In cardboard and Kraft lignin, a significant amount of the monomers mineralize to CO₂ and CH₄ during this time period. The results indicate that small, but significant rates of lignin solubilization and anaerobic lignin degradation are likely to occur in bioreactor landfills due to both higher temperature and microbial activity. In the second part of the study, field data from the Outer Loop Recycling and Disposal Facility in Louisville, Kentucky was evaluated to determine the effectiveness of an anaerobic-aerobic landfill bioreactor (AALB) vs. the control landfill that is managed as a traditional landfill. Moisture, temperature, elevation and the amount of time the MSW has spent in the landfills (age) were measured and compared to determine the factors that affect the biological stability of the landfill. The results showed that the MSW in the AALB is more biologically stable than the MSW in the control landfill, indicating that they are more degraded. Additionally, elevation or location of the MSW was the key factor in determining the extent of MSW stability within the AALB and temperature is the key factor in determining the biological stability of the MSW in the control landfill. Higher temperatures correlated with a more biologically stable waste. The cellulose to lignin ratio (C/L ratio) and biochemical methane potential (BMP) were the main biological stability parameters used. / Master of Science

Beech (<u>Fagus grand1folia</u> Ehrh.> bark contains appreciable quantities of Z- (cis) con1feryl and Z-s1napyl alcohols and not the corresponding E- (trans) alcohols. Previous rad1otracer experiments suggested that the Z-coniferyl alcohol in beech bark is formed by isomerization of E-coniferyl alcohol which proceeds either directly or through the corresponding aldehydes. In the work conducted in this thesis, is has been found that crude cinnamy1 alcohol dehydrogenase isolated from beech bark shows a strong substrate preference for E-coniferyl alcohol (as opposed to Z-coniferyl alcohol) thereby suggesting that the E to Z isomerization described occurs directly at the alcohol level. Administration of (2-¹⁴C) ferul1c acid to feland wheat (<u>Triticum aest1yum</u> L.) over extended durations (21 days) and subsequent isolation of the lignin from the root tissue as its acetal derivative demonstrated the incorporation of the labelled feru1ic acid into the lignin component of the tissue. Through sim1lar administrations of (1-¹³C, 2-¹³C and 3-¹³C) ferul1c acid and subsequent analysis of the root tissues by solid state ¹³C nuclear magnetic resonance (NMR) spectroscopy, it was possible to determine the bonding patterns of lignin in situ. The lignin component of each ¹³C feru1ic acid enriched root tissue was then isolated as its acetal derivative and analyzed by solution state ¹³C NMR. Through comparison it was shown that the enhanced resonances observed in the solution state ¹³C NMR spectra of the ¹³C ferulic acid enriched acetal lignins corresponded to the enhanced resonances in the respective spectra of the intact root tissues. This indicated that minimal changes to the lignin bonding patterns occurred during the isolation procedure. The dominant presence of ¹³C NMR resonances corresponding to hydroxycinnamic acid functionalities in the solid and solution state NMR spectra demonstrates the important role of hydroxyc1nnamic acids in wheat root lignin. However, no evidence of the formation of dimers such as 4,4'-dihydroxytruxillic acid was noted. Thus, such structures do not represent an important bonding pattern in wheat root lignin. / Master of Science

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by Sham Mai-har. / Bibliography: leaves 149-176 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1983

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