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EEWR Brown Bag Seminar with Emily Sun and Weitao Shuai, Graduate Students

Speaker: Emily Wei-Hsin Sun and Weitao Shuai, Graduate Students
Series: EEWR Brown Bag Seminars
Location: Engineering Quad E225
Date/Time: Friday, October 26, 2018, 12:00:00 p.m. - 01:00:00 p.m.

Abstract:

Emily Wei-Hsin Sun: Molecular dynamics simulation  prediction of wettability and multiphase flow of water and supercritical CO2 in quartz nanopores

Emily Wei-Hsin SunFundamental physical and chemical features governing multiphase flow in water-CO2-quartz nanopore systems directly impact the mobility and trapping of supercritical CO2 injected into the subsurface as part of Carbon Capture and Sequestration (CCS). CCS is a potentially important approach to mitigating anthropogenic emissions, and depends largely on the capillary trapping capacities of subsurface formations. However, published experimental data on relevant properties, such as water-CO2 contact angles (CA), vary widely. The fundamental basis of this variability remains poorly known, though surface contamination, heterogeneity, and roughness are hypothesized to be significant sources. Molecular dynamics (MD) simulations have shown significant promise in elucidating CA at the nanoscale and we have been able to predict trends with respect to changes in pressure in ideal systems. In this study, we carry out and analyse a series of MD simulations to probe equilibrium CAs with and without the presence of organic molecules.

Weitao Shuai: The influence of water table fluctuations on ammonium oxidation coupled to iron reduction process in constructed wetland mesocosms

Weitao ShuaiEffective ammonium removal has been challenging since aeration for  nitrification is energy intensive during the wastewater treatment processes. The efficiency of ammonium oxidation in natural systems is also limited by oxygen  transfer in water and sediments. Feammox process is a novel process that can oxidize ammonium under an aerobic conditions coupled to ferric iron reduction.  The change of water table in wetlands can alter dissolved oxygen level and redox potential of the sediments, which plays an important role in iron cycling as well as the Feammox process in wetland systems. The potential influence of water table fluctuations was examined by monitoring the redox potential, iron concentration as well as ammonium  profiles before and after drying and rewetting of the constructed wetland mesocosms. The application of Feammox process in constructed wetlands for wastewater treatment can be improved in light of the results from this study.