Abstracts Category : Other

Advancing wastewater valorization using anaerobic membrane bioreactors with bioaugmentation and ion-exchange, and bio-plastic production

by Ana Dolores Martin-Ryals

Wastewater treatment is essential for protecting human health and the environment. However, current conventional wastewater treatment, which focuses primarily on aerobic conversion of organic pollutants to CO2, requires significant energy input making it costly and less environmentally sustainable. With increasing economic development, population growth, aging infrastructure, and stricter regulations, the energy and material inputs of wastewater treatment are only expected to increase (EPA, 2006; Mo & Zhang, 2013). Meanwhile, the carbon content of wastewater has potential to be a significant renewable resource for energy and materials production that could be leveraged to offset the cost and resource demands of wastewater treatment. Thus, shifting the current paradigm from pollutant removal to resource recovery is as a promising strategy for improving the economic and environmental impacts of wastewater treatment. To that aim, this work investigated two emerging technologies for resource recovery from wastewater, namely enhanced methane recovery in a novel two-phase anaerobic membrane bioreactor (AnMBR) process incorporating bioaugmentation and ion-exchange resins, as well as bio-polymer recovery via mixed microbial culture (MMC) polyhydroxyalkanoate (PHA) production. The first study presented in this dissertation investigated the application of bioaugmentation in the acid-phase of a two-phase AnMBR treating primary sludge to improve solids removal and overall process efficiency. Bioaugmentation was carried out using a proprietary bioculture blend containing a mixture of hydrolytic, acidogenic, and acetogenic microorganisms. This mixture was added both on its own and in combination with recycled anaerobic sludge from the methane-phase of the AnMBR. These bioaugmentation strategies increased average percent hydrolysis by 25-38%, and increased average acid-phase acetic acid generation by 31-52% compared to operation without bioaugmentation. These benefits led to subsequent increases in average methane production (10-13%) and greater average overall solids reduction by 25-55%. Finally, microbial community analysis using 16S Illumina MiSeq generated sequences confirmed increased relative abundance of bioaugmented microorganism including Acetobacter, and Syntrophomonas species. Overall, bioaugmentation was found to improve conversion of primary sludge to methane by shifting the microbial community towards one better suited for hydrolysis and acetogenesis.In the second study, application of ion-exchange resins in the methane-phase of the same two-phase AnMBR system was investigated as a means for improving reactor recovery after organic shock-loading. Four commercially available anion-exchange resins were evaluated for their ability to sorb soluble organics, specifically volatile fatty acids (VFA), from AnMBR effluent. The strong-base resin, Purolite TANEX was determined the best resin for deployment in the AnMBR system having achieved the greatest removal of soluble chemical oxygen demand (COD) (up to 36%) andAdvisors/Committee Members: Schideman, Lance (advisor), Zhang, Yuanhui (Committee Chair), Mata-lvarez, Joan (committee member), Wilkinson, Henry (committee member), Gates, Richard (committee member), Guest, Jeremy (committee member).