Alternative fuels are necessary to meet the increasing demands for fuels. Alternative fuels such as biodiesel are produced using vegetable oils, which are prominentt in the food industry. An alternate feedstock could be oil-producing microorganisms. These oleaginous microorganisms are defined as accumulating more than 20% of their weight in oil as lipids. Cultivating these microorganisms for oil production is not economical due to the high production costs from the sugars in the culture medium. Municipal wastewater could be a potential growth medium that has not previously been considered for cultivating oleaginous microorganisms. However, municipal wastewater contains a low concentration of carbon, which does not promote oil accumulation in the oleaginous microorganisms. To increase the carbon concentration in the wastewater, lignocellulosic sugars could be added to the municipal wastewater. These sugars are a potential alternative to sugars that are in the food industry. The goal of this research is to determine the efficacy of using municipal wastewater to cultivate a consortium of oleaginous microorganisms, thus, producing oil for biodiesel production. First, a consortium of oleaginous microorganisms was cultivated on autoclaved wastewater to determine if the wastewater contains any inhibiting substances for the microorganisms. In addition to the substances in the wastewater, indigenous microorganisms are possible inhibitors to the consortium. Therefore, to determine the effect these indigenous microorganisms have on the oleaginous microorganisms, the consortium was cultivated on raw municipal wastewater amended with varying amounts of sugar. Since the municipal wastewater can be used as a cultivation medium, the effect of the addition of lignocellulosic sugars was determined. During the production of lignocellulosic sugars, furfural and acetic acid, known microbial inhibitors, are formed. The effect of these inhibitors on the consortium’s growth and oil accumulation ability was ascertained, and inhibition models were developed to describe their impact. With these results, SuperPro Designer v6.0 was used to perform simulations and economic analyses to determine the efficacy of incorporating an oleaginous microorganism consortium in a wastewater treatment facility.

Pharmaceuticals and personal care products (PPCPs) are detected routinely in raw and treated municipal wastewater. Conventional wastewater treatment processes are not effective in removing PPCP; therefore, treated wastewater discharges are one of the main entry points for PPCPs into the aquatic environment, and eventually into drinking water supplies. The use of laccase-catalyzed oxidation for removing low concentrations of PPCPs from municipal wastewater after primary treatment is investigated. Oxybenzone was selected as a representative PPCP. Like many other PPCPs, oxybenzone is not recognized directly by the laccase enzyme. Therefore, mediators were used to expand the oxidative range of laccase, and the efficacy of this laccase-mediator system in primary effluent was evaluated. Eight potential mediators were investigated. The greatest oxybenzone removal efficiencies were observed when 2,2’-azino-bis(3-ethylbenzthiazoline-6sulphonic acid) (ABTS), a synthetic mediator, and acetosyringone (ACE), a natural mediator, were present. An environmentally relevant concentration of oxybenzone (10 µg/L) in primary effluent was removed below the detection limit after two hours of treatment with ABTS, and 95% was removed after two hours of treatment with ACE. Several mediator/oxybenzone molar ratios were evaluated at two different initial oxybenzone concentrations. Higher mediator/oxybenzone molar ratios were required at the lower (environmentally relevant) oxybenzone concentrations, and ACE required higher molar ratios than ABTS to achieve comparable oxybenzone removal. The oxidation mechanisms and kinetics of the ACE mediator was evaluated. A better understanding of the mediator oxidation process would lead to a better design of the laccase-mediator system. An alternative laccase-mediator treatment configuration, which allows the enzyme and mediator to react prior to coming in contact with the target PPCP, was investigated. This treatment configuration shows promise for further development since it might reduce laccase and mediator requirements. Oxidation byproducts generated by the laccase-mediator system were characterized and compared to those generated during ozonation. Enzymatic treatment generated byproducts with higher mass to charge (m/z) ratios, likely due to oxidative coupling reactions. The results of this study suggest that, with further development, a laccase-mediator system has the potential to extend the treatment range of laccase to PPCPs not directly recognized by the enzyme, even in a primary effluent matrix. / text