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Assessing the performance of polyphosphate accumulating organisms in a full-scale side-stream enhanced biological phosphorous removal
(Wiley, 2024-01-11) Aghilinasrollahabadi, Khashayar; Ghandehari, Shahrzad Saffari; Kjellerup, Birthe Veno; Nguyen, Caroline; Saavedra, Yerman; Li, Guangbin
Phosphorous (P) removal in wastewater treatment is essential to prevent eutrophication in water bodies. Side-stream enhanced biological phosphorous removal (S2EBPR) is utilized to improve biological P removal by recirculating internal streams within a side-stream reactor to generate biodegradable carbon (C) for polyphosphate accumulating organisms (PAOs). In this study, a full-scale S2EBPR system in a water resource recovery facility (WRRF) was evaluated for 5 months. Batch experiments revealed a strong positive correlation (r = 0.91) between temperature and C consumption rate (3.56–8.18 mg-COD/g-VSS/h) in the system, with temperature ranging from 14°C to 18°C. The anaerobic P-release to COD-uptake ratio decreased from 0.93 to 0.25 mg-P/mg-COD as the temperature increased, suggesting competition between PAOs and other C-consumers, such as heterotrophic microorganisms, to uptake bioavailable C. Microbial community analysis did not show a strong relationship between abundance and activity of PAO in the tested WRRF. An assessment of the economic feasibility was performed to compare the costs and benefits of a full scale WRRF with and without implementation of the S2EBPR technology. The results showed the higher capital costs required for S2EBPR were estimated to be compensated after 5 and 11 years of operation, respectively, compared to chemical precipitation and conventional EBPR. The results from this study can assist in the decision-making process for upgrading a conventional EBPR or chemical P removal process to S2EBPR.
Miniaturized Capsule System Toward Real-Time Electrochemical Detection of H2S in the Gastrointestinal Tract
(Wiley, 2023-11-20) Stine, Justin M.; Ruland, Katie L.; Beardslee, Luke A.; Levy, Joshua A.; Abianeh, Hossein; Botasini, Santiago; Pasricha, Pankaj J.; Ghodssi, Reza
Hydrogen sulfide (H2S) is a gaseous inflammatory mediator and important signaling molecule for maintaining gastrointestinal (GI) homeostasis. Excess intraluminal H2S in the GI tract has been implicated in inflammatory bowel disease and neurodegenerative disorders; however, the role of H2S in disease pathogenesis and progression is unclear. Herein, an electrochemical gas-sensing ingestible capsule is developed to enable real-time, wireless amperometric measurement of H2S in GI conditions. A gold (Au) three-electrode sensor is modified with a Nafion solid-polymer electrolyte (Nafion-Au) to enhance selectivity toward H2S in humid environments. The Nafion-Au sensor-integrated capsule shows a linear current response in H2S concentration ranging from 0.21 to 4.5 ppm (R2 = 0.954) with a normalized sensitivity of 12.4% ppm−1 when evaluated in a benchtop setting. The sensor proves highly selective toward H2S in the presence of known interferent gases, such as hydrogen (H2), with a selectivity ratio of H2S:H2 = 1340, as well as toward methane (CH4) and carbon dioxide (CO2). The packaged capsule demonstrates reliable wireless communication through abdominal tissue analogues, comparable to GI dielectric properties. Also, an assessment of sensor drift and threshold-based notification is investigated, showing potential for in vivo application. Thus, the developed H2S capsule platform provides an analytical tool to uncover the complex biology-modulating effects of intraluminal H2S.
Understanding the Effects of Aerosols on Electrification and Lightning Polarity in an Idealized Supercell Thunderstorm via Model Emulation
(Wiley, 2023-12-29) Sun, Mengyu; Li, Zhanqing; Wang, Tao; Mansell, Edward R.; Qie, Xiushu; Shan, Siyu; Liu, Dongxia; Cribb, Maureen
Aerosol effects on the lightning intensity and polarity of a continental supercell storm were investigated using a three-dimensional lightning scheme within the Weather Research and Forecasting model. We find that both intra-cloud (IC) and cloud-to-ground (CG) flashes are enhanced by the increasing number of cloud condensation nuclei (CCN), especially the percentage of positive CG (+CG) strokes peaking at 42%. Electrical characteristics of the storm varied in different aerosol scenarios through microphysical processes. Added aerosols increase the number of cloud droplets and ice-phase hydrometeors. The greater ice-crystal concentration and larger graupel size ensure sufficient charge separation, leading to higher charge density and more lightning discharges. In addition, an inverted polarity charge structure with a strong positive-charge region in the mid-levels was formed mainly due to the positively charged graupel in the presence of higher supercooled cloud water content. Positive lightning channels originating from this positive-charge region propagated to the ground, producing more +CG strokes. When the aerosol concentration was low, the charge density in the upper positive-charge region was much lower due to smaller ice-particle content. Consequently, there were barely any +CG strokes. Most of the negative CG flashes deposited positive charge in the lower negative-charge region.
Mitigating Electronic Conduction in Ceria-Based Electrolytes via External Structure Design
(Wiley, 2023-12-22) Robinson, Ian A.; Huang, Yi-Lin; Horlick, Samuel A.; Obenland, Jonathan; Robinson, Nicholas; Gritton, J. Evans; Hussain, A. Mohammed; Wachsman, Eric D.
Doped ceria electrolytes are the state of the art low-temperature solid oxide electrolytes because of their high ionic conductivity and good material compatibility. However, cerium tends to reduce once exposed to reducing environments, leading to an increase in electronic conduction and a decrease in efficiency. Here, the leakage current is mitigated in ceria-based electrolytes by controlling the defect chemistry through an engineered cathode side microstructure. This functional layer effectively addresses the problematic electronic conduction issue in ceria-based electrolytes without adding significant ohmic resistance and increases the ionic transference to2- number to over 0.93 in a thin 20 µm ceria-based electrolyte at 500 °C, compared to a
of to2- 0.8 for an unmodified one. Based on this design, solid oxide fuel cells (SOFCs) are further demonstrated with the remarkable peak power density of 550 mW at 500 °C and excellent stability for over 2000 h. This approach enables a potential breakthrough in the development of ceria-based low-temperature solid oxide electrolytes.
Quantifying modeling uncertainties in seismic analysis of dams: Insights from an international benchmark study
(Wiley, 2023-12-19) Hariri-Ardebili, Mohammad Amin
Advances in nonlinear dynamic analysis of dams have not completely resolved concerns over modeling confidence and analysis accuracy. Verification and validation offer accuracy assessment, but uncertainties persist during performance evaluation due to both epistemic (modeling) and aleatory (parametric) sources. Epistemic uncertainties arise from simplifications and modeling techniques. This paper addresses epistemic uncertainties in a gravity dam seismic analysis using data from the International Comnission on Large Dams (ICOLD) benchmark study. While the benchmark formulation included the finite element model of the dam, mechanical material properties, and dynamic loads, participants retained the flexibility to opt for best-practice modeling assumptions, simplifications, and other specifics. Notable response variability emerged, particularly in crack profiles and damage predictions. This study examines sources of variability, quantifying modeling uncertainty for the benchmark problem. More specifically, the modeling variability is quantified using the logarithmic standard deviation, also known as dispersion. This metric enables its incorporation into other seismic risk assessment and fragility studies. Under relatively low-intensity motion (peak ground acceleration [PGA] of 0.18 g in this case), modeling dispersion of 0.45, 0.30, 0.32, and 0.30 were calculated for the maximum dynamic crest displacement, maximum hydrodynamic pressure at the heel, heel and crest maximum acceleration, respectively. Additionally, the dispersion of the failure PGA was determined to be 0.7. Findings underscore the need for systematic seismic response modeling in dam engineering to enhance prediction accuracy. A better understanding of the sources and magnitudes of modeling uncertainties can help improve the reliability of dam seismic analysis and contribute to the development of more effective risk assessment and mitigation strategies.