Energy recovery from waste nitrogen through N₂O decomposition : the coupled aerobic-anoxic nitrous decomposition operation (CANDO)
- Human alteration of the global nitrogen cycle poses one of the greatest threats to the environment today. Anthropogenic production of reactive forms of nitrogen, namely ammonia (NH4+) via the Haber Bosch process, has nearly doubled the rate of terrestrial nitrogen deposition and resulted in an array of public health and environmental problems including ammonia toxicity to aquatic life, eutrophication of nutrient limited natural water bodies, oxygen depletion (hypoxia), and over 400 documented "dead zones" worldwide. As a result, dual pressures of increasingly stringent nitrogen discharge regulation and rising energy costs have made efficient removal of nitrogen polluted water streams one of the most pressing water quality issues facing treatment facilities. While many processes recover energy from waste organics, no known process recovers energy from waste nitrogen. This research work introduces a new process that improves the efficiency of nitrogen (NH4+) removal from wastewater by lowering energy inputs and enabling energy recovery from waste nitrogen itself. This process is termed the Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO) and is based on three principal steps: (1) biological oxidation of NH4+ to NO2-; (2) biological or chemical reduction of NO2- to N2O gas; and (3) N2O conversion to N2 with energy recovery via decomposition or combustion with a fuel (biogas). The development of CANDO was inspired by prior research on the use of N2O as a "green" propellant in propulsion applications and the realization that N2O could be a renewable feedstock, generated by waste nitrogen. This research is presented in three parts: (1) development of thrusters based on N2O catalytic decomposition that achieve high performance and a self-sustaining reaction; (2) theoretical studies of N2O decomposition over Rh2O3 catalyst, using Density Functional Theory (DFT), that reveal high reactivity of stable surfaces of Rh2O3 and key N2O reaction mechanisms; and (3) experimental studies on the conversion of NO2- to N2O (the novel and previously unexplored step in CANDO) via two pathways - biotic partial denitrification by oxidation of intracellular polyhydroxybutyrate (PHB), and abiotic chemical reaction driven by Fe(II).
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Scherson, Yaniv Dror
|Stanford University, Department of Mechanical Engineering
|Wilcox, Jennifer, 1976-
|Wilcox, Jennifer, 1976-
|Statement of responsibility
|Yaniv Dror Scherson.
|Submitted to the Department of Mechanical Engineering.
|Thesis (Ph.D.)--Stanford University, 2012.
- © 2012 by Yaniv Dror Scherson
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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