Degree

Doctor of Philosophy (PhD)

Department

Department of Civil & Environmental Engineering

Document Type

Dissertation

Abstract

Water pollution and energy depletion are two critical issues in the world that limit the sustainable development of human society. In this study, several advanced (photo) bioelectrochemical systems (BESs) were proposed for effective energy (electricity and H2) and nutrients (N and P) recovery from wastewater, solar energy, seawater, and river water. The first study demonstrated high effectiveness of a novel resource-recovery microbial fuel cell (RRMFC) for wastewater treatment and nutrient recovery from synthetic urine-containing wastewater. Over one cycle (∼3 days), 99% of urea, 97% of COD, 99% of histidine, 91% of creatinine, 99% of sodium acetate, 98% of SO42−, and 99% of PO43− were removed from the wastewater, and at the same time, 42% of total nitrogen, 37% of PO43−, 59% of SO42−, and 33% of total salt were recovered in the middle chamber. The second study explored the possibility of H2 gas production using microbial electrolysis cells (MECs) configurated with Mo2N nanobelts cathodes. The H2 production rates (0.39 vs. 0.37 m3-H2/m3/d), coulombic efficiencies (90% vs. 77%), and overall hydrogen recovery (74% vs. 70%) of MECs with the Mo2N nanobelt cathodes were comparable to those with Pt/C cathodes but the cost of Mo2N nanobelt catalyst ($ 31/m2) was much less than that of Pt/C catalysts ($ 1930/m2). Moreover, a solar microbial electrolysis cell (solar-MEC) with a Fe2O3 photoanode, a bioanode, and a black-silicon (b-Si) photocathode was proposed for self-sustainable H2 production from wastewater without external bias in the third study. The solar-MEC achieved a current density of 0.8 mA/cm2 and a H2 production rate of 5.1 µmol/h/cm2 under 1 sun irradiation. In the last study, a concentration flow cell (CFC) powered by a bioelectrochemical system(bio-CFC) was developed to recover SG energy from synthetic seawater and river water. The maximum power density of the bio-CFC reached 42 ± 2 W/m2, which was three times higher than that of a single CFC (10.6 ± 0.1 W/m2). These research studies demonstrated the prospects to achieve highly efficient electricity production, N and P recovery, and H2 generation in sustainable ways with novel system designs and cost-effective electrode materials.

Date

3-19-2021

Committee Chair

Zhu, Xiuping

Available for download on Monday, December 12, 2022

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