Scholarly Works, Civil and Environmental Engineering

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Relating Geotechnical Sediment Properties and Erodibility at a Sandy Beach
Brilli, Nicola C.; Stark, Nina; Castro-Bolinaga, Celso (ASCE, 2024-07-01)
Geotechnical sediment properties, morphological change, and hydrodynamics were measured as part of the During Nearshore Event Experiment (DUNEX) in October 2021 at the sandy Atlantic side beach in Duck, North Carolina. In this study, direct relationships were explored between in situ soil properties and direct erodibility measurements in the context of morphological change. Moisture content, grain size, total density, relative density, void ratio, and sediment strength were compared to bed-level change using ground-based LiDAR and erodibility parameters from laboratory jet erosion tests (JETs) conducted along a cross-shore transect stretching from the dune toe to the lower intertidal zone. Directly relating changes in sediment properties to changes in morphology from LiDAR proved inconclusive due to the complex interactions between sediments, hydrodynamics, and morphology, even on a local scale, but initial observations and possibly impacting factors were discussed. Void ratio and total unit weight correlated well with the detachment rate coefficient from JETs, with denser sediments testing as less erodible. In situ sediment strength measurements related-as expected-to total unit weight, void ratio, and water content, with increases in firmness factor associated with increases in total unit weight, void ratio, and water content. These strength measurements were also found to have a correlation with the detachment coefficient from the JET, with stronger/firmer sediments being less erodible than weaker ones.
Simulating landslides with the material point method: Best practices, potentialities, and challenges
Ceccato, Francesca; Yerro, Alba; Di Carluccio, Gaia (Elsevier, 2024-08-01)
Advances in numerical methods have provided useful tools for investigating the complex behaviour of landslides, which can be a valuable support for landslide hazard assessment, planning, and design of mitigation measures. Among different methodologies, the Material Point Method (MPM) has recently grown in popularity, thanks to its ability to simulate large displacements and has been applied to simulate an increasing number of real cases. Despite the success, there are still several challenges to be addressed. This paper aims to present the current state of the art in the modelling of real landslide case histories with MPM. The key numerical features used to capture the evolution of different types of landslides are discussed, such as constitutive models, soil-water interaction, and triggering mechanisms, thus providing insight into the computational aspects of using MPM to serve as guidelines for future applications. Limitations and future perspectives are also mentioned to encourage the development of new solutions for current numerical challenges and further extend the applicability of the methodology in this field.
Metatranscriptomic Analysis Reveals Synergistic Activities of Comammox and Anammox Bacteria in Full-Scale Attached Growth Nitrogen Removal System
Johnston, Juliet; Vilardi, Katherine; Cotto, Irmarie; Sudarshan, Ashwin; Bian, Kaiqin; Klaus, Stephanie; Bachmann, Megan; Parsons, Mike; Wilson, Christopher; Bott, Charles; Pinto, Ameet (American Chemical Society, 2024-07-13)
Leveraging comammox Nitrospira and anammox bacteria for shortcut nitrogen removal can drastically lower the carbon footprint of wastewater treatment facilities by decreasing aeration energy, carbon, alkalinity, and tank volume requirements while also potentially reducing nitrous oxide emissions. However, their co-occurrence as dominant nitrifying bacteria is rarely reported in full-scale wastewater treatment. As a result, there is a poor understanding of how operational parameters, in particular, dissolved oxygen, impact their activity and synergistic behavior. Here, we report the impact of dissolved oxygen concentration (DO = 2, 4, 6 mg/L) on the microbial community's transcriptomic expression in a full-scale integrated fixed film activated sludge (IFAS) municipal wastewater treatment facility where nitrogen removal is predominantly performed by comammox Nitrospira and anammox bacterial populations. 16S rRNA transcript compositions revealed anammox bacteria and Nitrospira were significantly more active in IFAS biofilms compared to suspended sludge biomass. In IFAS biofilms, anammox bacteria significantly increased hzo expression at lower dissolved oxygen concentrations and this increase was highly correlated with the amoA expression levels of comammox bacteria. Interestingly, the genes involved in nitrite oxidation by comammox bacteria were significantly more upregulated, relative to the genes involved in ammonia oxidation with decreasing dissolved oxygen concentrations. Ultimately, our findings suggest that comammox Nitrospira supplies anammox bacteria with nitrite via ammonia oxidation and that this synergistic behavior is dependent on dissolved oxygen concentrations.
Zinc Orthophosphate Can Reduce Nitrate-Induced Corrosion of Lead Solder
Lopez, Kathryn G.; Xiao, Jinghua; Crockett, Christopher; Lytle, Christian; Grubbs, Haley; Edwards, Marc A. (American Chemical Society, 2024-07-30)
Nitrate-induced spallation of lead-bearing solder particles into drinking water is not sufficiently controlled by phosphate-based inhibitors, although adding zinc can improve their performance. Studies using copper coupons coated with new lead-tin solder in water with up to 12 mg/L nitrate demonstrated that zinc orthophosphate reduced lead release by more than 90% and outperformed orthophosphate alone. Lead release and spallation from harvested pipes with decades-old lead-tin solder in a high nitrate water were improved but not eliminated with zinc orthophosphate over a period of months. When applied at a water utility with high source water nitrate, monthly in-home field sampling showed that 90th percentile lead levels dropped below the action level after dosing zinc orthophosphate at full scale for 6 months. Scanning electron microscopy (SEM) analysis of pipe scales revealed that zinc and orthophosphate codeposit at the copper-solder interface and may act as a mixed inhibitor, with zinc inhibiting the cathodic reaction on the copper pipe, phosphate limiting the anodic reaction, and an added benefit of zinc orthophosphate preferentially precipitating at the galvanic interface between the anode and the cathode. Updates to corrosion control guidance for waters with higher nitrate due to seasonal runoff or source water changes are needed.
Knowledge sources, narratives, and living in social-ecological systems
Cockerill, Kristan; Glynn, Pierre; Cerrutti, Estefania Santamaria; Little, John C. (Springer, 2024-08-01)
Humans exist as part of social-ecological systems (SES) in which biological, physical, chemical, economic, political and other social processes are tightly interwoven. Global change within these systems presents an increasingly untenable situation for long-term human security. Further, knowledge that humans possess about ourselves and SES represents a complex amalgamation of individual and collective factors. Because of various evolutionary pressures, people often reject this complex reality in favor of more simplistic perceptions and explanations. This thought paper offers an overview of how and where people acquire knowledge and how that knowledge acquisition process reflects and influences narratives, which subsequently affect efforts to address challenges in SES. We highlight three narratives as examples of constraints on finding ways forward toward a more resilient future. Our focal narratives include tendencies to conflate tame and wicked problems; to posit a false human-nature duality; and to resist the explanatory evidence from biocultural evolution. We then discuss the human cognitive propensity to create narratives to think about how we might intentionally develop narratives that are more appropriate for living in coevolving SES.
Guidance for Residents Addressing Copper Problems in Drinking Water: Opportunities and Challenges
Kriss, Rebecca; Edwards, Marc A. (American Chemical Society, 2024-08-12)
Residents and their pets may experience aesthetic or health concerns resulting from elevated copper in their drinking water. The United States Environmental Protection Agency Lead and Copper Rule focuses on addressing systemwide corrosion issues, but gaps in the rule leave some municipal water consumers and residents with private well water vulnerable to high cuprosolvency. We developed guidance to aid residents in understanding, detecting, and addressing cuprosolvency issues in their drinking water. Three types of at-home test kits for copper and one for pH were determined to be accurate enough (R-2 > 0.9 (lab, based on average values from n = 5 replicates each) and >0.7 (field)) to detect concerns related to high cuprosolvency and inform selection of intervention options. Case study results indicate that, although water treatments such as increasing pH on-site may be effective, long-term treatment (>36 weeks or permanently) may be needed to maintain reductions in cuprosolvency. A decision tree is provided to help residents and citizen scientists navigate these concerns for both public water systems and private wells.
Ventilation does not affect close-range transmission of influenza virus in a ferret playpen setup
Rockey, Nicole C.; Le Sage, Valerie; Shephard, Meredith; Vargas-Maldonado, Nahara; Vu, Michelle N.; Brown, Cambria A.; Patel, Krishna; French, Andrea J.; Merrbach, Grace A.; Walter, Sydney; Ferreri, Lucas M.; Holmes, Katie E.; Vaninsberghe, David; Clack, Herek L.; Prussin II, Aaron J.; Lowen, Anice C.; Marr, Linsey C.; Lakdawala, Seema S. (National Academy of Sciences, 2024-08-13)
Sustained community spread of influenza viruses relies on efficient person-to-person transmission. Current experimental transmission systems do not mimic environmental conditions (e.g., air exchange rates, flow patterns), host behaviors, or exposure durations relevant to real- world settings. Therefore, results from these traditional systems may not be representative of influenza virus transmission in humans. To address this pitfall, we developed a close-range transmission setup that implements a play-based scenario and used it to investigate the impact of ventilation rates on transmission. In this setup, four immunologically naive recipient ferrets were exposed to a donor ferret infected with a genetically barcoded 2009 H1N1 virus (H1N1pdm09) for 4 h. The ferrets interacted in a shared space that included toys, similar to a childcare setting. Transmission efficiency was assessed under low and high ventilation, with air exchange rates of similar to 1.3 h-1 and studies were similar between ventilation conditions. The presence of infectious virus or viral RNA on surfaces and in air throughout the exposure area was also not impacted by the ventilation rate. While high viral genetic diversity in donor ferret nasal washes was maintained during infection, recipient ferret nasal washes displayed low diversity, the frequency and duration of ferret physical touches revealed no link between these interactions and a successful transmission event. Our findings indicate that exposures characterized by frequent, close-range interactions and the presence of fomites can overcome the benefits of increased ventilation.
Prediction of retrogressive landslide in sensitive clays by incorporating a novel strain softening law into the Material Point Method
Urmi, Zinan Ara; Yerro, Alba; Saeidi, Ali; Chavali, Rama Vara Prasad (Elsevier, 2024-10-01)
Sensitive clays, when subjected to large strains, exhibit a unique strain-softening behavior, transforming into a remolded liquid with remarkably low shear strength. When a slope fails, this behavior leads to the remolded clay moving away from its original position, triggering subsequent failures and catastrophic outcomes. To accurately predict such scenarios, it is crucial to incorporate realistic strain-softening characteristics into the constitutive soil model. This paper presents a novel yet practical strain-softening law developed by the authors that effectively captures the post-peak behavior of sensitive clays down to their remolded strength. The softening law is implemented in an elastoplastic Mohr-Coulomb model and incorporated into Anura3D, an open-source software that uses the Material Point Method to simulate large deformations. The constitutive model is calibrated by simulating the stress-strain behavior through direct shear tests conducted at three sensitive clay landslide locations. The accuracy of the overall numerical framework is assessed by predicting the post-failure movements of these landslides. Notably, two of the landslides, Sainte-Monique (1994) and Saint-Jude (2010), have previously been analyzed using other numerical tools, allowing for a comparative analysis with the method presented here. The third landslide, the Saint-Luc-de-Vincennes landslide, representing a composite flow slide and spread, has been numerically simulated for the first time. The post-failure behavior observed in the landslide events is compared with field observations and other numerical analyses. The results show that the MPM models with the proposed strain-softening law can reasonably predict post-failure retrogression and runout distance, which are crucial parameters for determining the risk of landslides in sensitive clays.
Ecosystem service values support conservation and sustainable land development: Perspectives from four University of California campuses
Fausey, Kaitlin; Rippy, Megan A.; Pierce, G.; Feldman, D.; Winfrey, B.; Mehring, A. S.; Levin, L. A.; Holden, P. A.; Bowler, P. A.; Ambrose, R. (Elsevier, 2024-11-01)
Urban landscapes homogenize our world at global scales, contributing to "extinction of experience", a progressive decline in human interactions with native greenspace that can disconnect people from the services it provides. College age adults report feeling disconnected from nature more than other demographics, making universities a logical place to explore interventions intended to restore a connection with nature. This study surveyed 1088 students and staff across four university campus communities in Southern California, USA and used multicriteria decision analysis to explore their landscape preferences and the implications of those preferences for combatting extinction of experience. Our results suggest that perspectives of, and preferences for, different greenspace forms vary significantly (i.e., they are not perceived as substitutable). Support for native ecosystems, particularly coastal sage scrub (top ranked landscape) was generally high, suggesting that disaffection with wild nature is not particularly widespread. Programs for replacing turf grass lawns (lowest ranked landscape) with native plants were also well supported, but support for stormwater bioswales was more moderate (and variable). This may reflect their relative newness, both on university campuses and in urban spaces more generally. Not all members of campus communities preferred the same landscapes; preferences differed with degree of pro-environmentalism and university status (undergraduate student, graduate student, staff). Even so, all respondents exhibited landscape preferences consistent with at least one approach for combatting extinction of experience, suggesting that ecologists, engineers and urban planners have a viable set of generalizable tools for reconnecting people with nature.
Decentralized Cycle-Free Game-Theoretic Adaptive Traffic Signal Control: Model Enhancement and Testing on Isolated Signalized Intersections
Shafik, Amr K.; Rakha, Hesham A. (MDPI, 2025-10-14)
This research enhances and evaluates the performance of a Decentralized Nash Bargaining (DNB) adaptive traffic signal controller that operates a flexible National Electrical Manufacturers Association (NEMA) phasing and timing scheme responding dynamically to fluctuating traffic demands. The DNB controller is enhanced to (1) use traffic density estimates instead of queues to optimize signal timings; (2) to consider the eight-phase two-ring NEMA controller configuration within the game-theoretic approach; and (3) to consider dynamically adaptable control time steps. The enhanced DNB controller is benchmarked against (1) a fixed-time traffic signal control using the state-of-practice Webster’s method and an emerging Laguna-Du-Rakha (LDR) method for computing the optimum cycle length; (2) a state-of-the-practice actuated traffic signal control; and (3) a state-of-the-art reinforcement learning (RL) traffic signal controller presented in the literature. The controller is tested on two isolated signalized intersections, demonstrating enhanced overall intersection performance compared to the baseline pretimed and actuated controllers at various demand levels, and offers better performance than a previously developed RL controller. Specifically, the DNB controller results in a decrease in the average vehicle delay and queue size by up to 54% and 63%, respectively, compared to Webster’s state-of-the-practice pretimed control. Unlike the RL controller, the DNB controller requires no pre-training while adapting to fluctuating traffic conditions, thereby providing a flexible framework for reducing traffic congestion at signalized intersections. As such, this research contributes to the development of smarter and more responsive urban traffic control systems.
Metagenomic Profiling of Internationally Sourced Sewage Influents and Effluents Yields Insight into Selecting Targets for Antibiotic Resistance Monitoring
Garner, Emily; Maile-Moskowitz, Ayella; Angeles, Luisa F.; Flach, Carl-Fredrik; Aga, Diana S.; Nambi, Indumathi; Larsson, D. G. Joakim; Bu''rgmann, Helmut; Zhang, Tong; Vikesland, Peter J.; Pruden, Amy (American Chemical Society, 2024-09-04)
It has been debated whether wastewater treatment plants (WWTPs) primarily act to attenuate or amplify antibiotic resistance genes (ARGs). However, ARGs are highly diverse with respect to their resistance mechanisms, mobilities, and taxonomic hosts and therefore their behavior in WWTPs should not be expected to be universally conserved. We applied metagenomic sequencing to wastewater influent and effluent samples from 12 international WWTPs to classify the behavior of specific ARGs entering and exiting WWTPs. In total, 1079 different ARGs originating from a variety of bacteria were detected. This included ARGs that could be mapped to assembled scaffolds corresponding to nine human pathogens. While the relative abundance (per 16S rRNA gene) of ARGs decreased during treatment at 11 of the 12 WWTPs sampled and absolute abundance (per mL) decreased at all 12 WWTPs, increases in relative abundance were observed for 40% of the ARGs detected at the 12th WWTP. Also, the relative abundance of mobile genetic elements (MGE) increased during treatment, but the fraction of ARGs known to be transmissible between species decreased, thus demonstrating that increased MGE prevalence may not be generally indicative of an increase in ARGs. A distinct conserved resistome was documented in both influent and effluent across samples, suggesting that well-functioning WWTPs generally attenuate influent antibiotic resistance loads. This work helps inform strategies for wastewater surveillance of antibiotic resistance, highlighting the utility of tracking ARGs as indicators of treatment performance and relative risk reduction.
A Possible Nocebo Effect in Children Following the Flint Water Crisis: Evidence From Schoolteacher Perceptions and Neuropsychological Evaluations
Roy, Siddhartha; Edwards, Marc A.; Petrie, Keith J.; Gamble, Greg D.; Jacques, Ellie (Cambridge University Press, 2024-09-18)
Objective: Special education enrollment increased in Flint following the 2014-2015 Flint Water Crisis, but lead exposure is not plausibly responsible. Labeling Flint children as lead poisoned and/or brain damaged may have contributed to rising special education needs (ie, nocebo effect). To better document this possibility, we surveyed schoolteachers and reviewed neuropsychological assessments of children for indications of negative labeling. Methods: A survey of Flint and Detroit (control) public schoolteachers using a modified Illness Perception Questionnaire was conducted 5 years post-crisis. We also examined neuropsychological assessments from a recently settled class lawsuit. Results: Relative to Detroit (n = 24), Flint teachers (n = 11) believed that a higher proportion of their students had harmful lead exposure (91.8% Flint vs 46% Detroit; P = 0.00034), were lead poisoned (51.3% vs 24.3%; P = 0.018), or brain damaged (28.8% vs 12.9%; P = 0.1), even though blood lead of Flint children was always less than half of that of Detroit children. Neuropsychological assessments diagnosed lead poisoning and/or brain damage from water lead exposure in all tested children (n = 8), even though none had evidence of elevated blood lead and a majority had prior learning disability diagnoses. Conclusion: Teachers' responses and neuropsychological assessments suggest Flint children were harmed by a nocebo effect.
Integrating Data Science Into Undergraduate Science and Engineering Courses: Lessons Learned by Instructors in a Multiuniversity Research-Practice Partnership
Naseri, Md. Yunus; Snyder, Caitlin; Perez-Rivera, Katherine X.; Bhandari, Sambridhi; Workneh, Habtamu Alemu; Aryal, Niroj; Biswas, Gautam; Henrick, Erin C.; Hotchkiss, Erin R.; Jha, Manoj K.; Jiang, Steven; Kern, Emily C.; Lohani, Vinod K.; Marston, Landon T.; Vanags, Christopher P.; Xia, Kang (IEEE, 2025-02-01)
Contribution: This article discusses a research-practice partnership (RPP) where instructors from six undergraduate courses in three universities developed data science modules tailored to the needs of their respective disciplines, academic levels, and pedagogies. Background: STEM disciplines at universities are incorporating data science topics to meet employer demands for data science-savvy graduates. Integrating these topics into regular course materials can benefit students and instructors. However, instructors encounter challenges in integrating data science instruction into their course schedules. Research Questions: How did instructors from multiple engineering and science disciplines working in an RPP integrate data science into their undergraduate courses? Methodology: A multiple case study approach, with each course as a unit of analysis, was used to identify data science topics and integration approaches. Findings: Instructors designed their modules to meet specific course needs, utilizing them as primary or supplementary learning tools based on their course structure and pedagogy. They selected a subset of discipline-agnostic data science topics, such as generating and interpreting visualizations and conducting basic statistical analyses. Although instructors faced challenges due to varying data science skills of their students, they valued the control they had in integrating data science content into their courses. They were uncertain about whether the modules could be adopted for use by other instructors, specifically by those outside of their discipline, but they all believed the approach for developing and integrating data science could be adapted to student needs in different situations.
What is the Difference between Conventional Drinking Water, Potable Reuse Water, and Nonpotable Reuse Water? A Microbiome Perspective
Blair, Matthew F.; Garner, Emily; Ji, Pan; Pruden, Amy (American Chemical Society, 2024-09-11)
As water reuse applications expand, there is a need for more comprehensive means to assess water quality. Microbiome analysis could provide the ability to supplement fecal indicators and pathogen profiling toward defining a "healthy" drinking water microbiota while also providing insight into the impact of treatment and distribution. Here, we utilized 16S rRNA gene amplicon sequencing to identify signature features in the composition of microbiota across a wide spectrum of water types (potable conventional, potable reuse, and nonpotable reuse). A clear distinction was found in the composition of microbiota as a function of intended water use (e.g., potable vs nonpotable) across a very broad range of U.S. water systems at both the point of compliance (Betadisper p > 0.01; ANOSIM p < 0.01, r-stat = 0.71) and point of use (Betadisper p > 0.01; ANOSIM p < 0.01, r-stat = 0.41). Core and discriminatory analysis further served in identifying distinct differences between potable and nonpotable water microbiomes. Taxa were identified at both the phylum (Desulfobacterota, Patescibacteria, and Myxococcota) and genus (Aeromonas and NS11.12_marine_group) levels that effectively discriminated between potable and nonpotable waters, with the most discriminatory taxa being core/abundant in nonpotable waters (with few exceptions, such as Ralstonia being abundant in potable conventional waters). The approach and findings open the door to the possibility of microbial community signature profiling as a water quality monitoring approach for assessing efficacy of treatments and suitability of water for intended use/reuse application.
Free Chlorine Can Inhibit Lead Solder Corrosion via Electrochemical Reversal
Mazzola, Frank A.; Lopez, Kathryn G.; Edwards, Marc A. (American Chemical Society, 2024-10-18)
Galvanic corrosion of lead-tin solder in copper plumbing can be a major contributor to water lead contamination. Here, we report the electrochemical reversal of the copper-solder galvanic couple, in which the normally anodic solder becomes cathodic to copper via a reaction with free chlorine. This reversal occurred after a few months of exposure to continuously circulating water with relatively low pH and low alkalinity, causing dramatically decreased lead release and the formation of a Pb(IV) scale. Chloramine did not similarly inhibit solder corrosion over the 4-9 month test duration, resulting in up to 100 times more lead contamination of the water relative to free chlorine. These findings have major implications for corrosion control and public health and can help explain anomalously low levels of lead contamination in some waters with free chlorine that are normally considered corrosive to solder.
Community-based propagation to scale up educational innovations in sustainability
Rooney-Varga, Juliette N.; Kapmeier, Florian; Henderson, Charles; Ford, David N. (Nature Portfolio, 2024-12-01)
Many high-quality educational innovations are freely available, and some are known to motivate evidence-based climate and sustainability action. Typically, efforts to propagate educational innovations rely on outreach and word-of-mouth diffusion, but these approaches tend to achieve little. We develop and analyse a dynamic computational model to understand why and to test other propagation strategies. Our analysis reveals that outreach has limited impact and does little to accelerate word-of-mouth adoption under conditions typical in higher education. Instead, we find that community-based propagation can rapidly accelerate adoption, as is also shown by a small number of successful real-world scaling efforts. This approach supports a community of 'ambassadors', facilitating and rewarding their sharing the innovation with potential adopters. Community-based propagation can generate exponential growth in adopters, rapidly outpacing outreach and word-of-mouth propagation. Without it, we are unlikely to rapidly scale the educational innovations needed to build urgently needed capacity in sustainability. Innovative educational methods can be difficult to spread across universities and instructors. This study examines the best routes to rapidly scale new methods in sustainability education.
Evaluation of groundwater travel time through a multilayered aquifer using multiple tracers and a novel transport approximation
Martinez, Meredith B.; Widdowson, Mark A. (Springer, 2024-12-01)
Aquifer long-term replenishment (ALTR) is a managed aquifer recharge (MAR) strategy by which reclaimed water is continuously delivered by injection wells to depleted, confined aquifer systems to increase groundwater storage and increase the potentiometric surface over space and time. One implication of large-scale continuous recharge is a large radial impact and the need to quantify transport in radially extensive strata. The use of an artificial tracer can be cost-prohibitive as the radial front moves further from the injection well. This investigation employs a novel approximation for radial transport to track the radial front of recharge, injectate constituents and simulation of tracer breakthrough concentrations under transient recharge rates, variable depth-dependent flow distributions over time, and variable influent concentrations. Six constituents-sulfate, chloride, total organic carbon (TOC), fluoride, 1,4-dioxane and N-nitrosodimethylamine (NDMA)-were chosen to evaluate conservative transport and semiqualitatively assess attenuation of nonconservative constituents relative to conservative tracers. Results indicate that sulfate acted as the most effective conservative tracer for characterization of transport and travel times at the study site. The analytical model was modified to account for variable operations at the MAR demonstration facility and was effective in simulating breakthrough curves over the period of performance, particularly sulfate concentrations at a monitoring well located 104 m from the injection well. The behavior of the remaining constituents is discussed, and the qualities of an effective intrinsic tracer for future ALTR projects are identified.
Influenza virus infection and aerosol shedding kinetics in a controlled human infection model
Shetty, Nishit; Shephard, Meredith J.; Rockey, Nicole C.; Macenczak, Hollie; Traenkner, Jessica; Danzy, Shamika; Vargas-Maldonado, Nahara; Arts, Peter J.; Le Sage, Valerie; Anderson, Evan J.; Lyon, G. Marshall; Fitts, Eric Charles; Gulick, Dalia A.; Mehta, Aneesh K.; El-Chami, Mikhael F.; Kraft, Colleen S.; Wigginton, Krista R.; Lowen, Anice C.; Marr, Linsey C.; Rouphael, Nadine G.; Lakdawala, Seema S. (American Society for Microbiology, 2024-12-17)
Establishing effective mitigation strategies to reduce the spread of influenza virus requires an improved understanding of the mechanisms of transmission. We evaluated the use of a controlled human infection model using an H3N2 seasonal influenza virus to study critical aspects of transmission, including symptom progression and the dynamics of virus shedding. Eight volunteers were challenged with influenza A/Perth/16/2009 (H3N2) virus between July and September 2022 at Emory University Hospital. Viral shedding in the nasopharynx, saliva, stool, urine, and respiratory aerosols was monitored over the quarantine period, and symptoms were tracked until day 15. In addition, environmental swabs were collected from participant rooms to examine fomite contamination, and participant sera were collected to assess seroconversion by hemagglutination inhibition or microneutralization assays. Among the eight participants, influenza virus infection was confirmed in six (75%). Infectious virus or viral RNA was found in multiple physiological compartments, fecal samples, aerosol particles, and on surfaces in the immediate environment. Illness was moderate, with upper respiratory symptoms dominating. In participants with the highest viral loads, antibody titers rose by day 15 post-inoculation, while in participants with low or undetectable viral loads, there was little or no increase in functional antibody titers. These data demonstrate the safety and utility of the human infection model to study features critical to influenza virus transmission dynamics in a controlled manner and will inform the design of future challenge studies focused on modeling and limiting transmission. CLINICAL TRIALS This study is registered with ClinicalTrials.gov as NCT05332899.
A machine learning framework to predict PPCP removal through various wastewater and water reuse treatment trains
Choi, Joung Min; Manthapuri, Vineeth; Keenum, Ishi; Brown, Connor L.; Xia, Kang; Chen, Chaoqi; Vikesland, Peter J.; Blair, Matthew F.; Bott, Charles; Pruden, Amy; Zhang, Liqing (Royal Society Chemistry, 2025-01-30)
The persistence of pharmaceuticals and personal care products (PPCPs) through wastewater treatment and resulting contamination of aquatic environments and drinking water is a pervasive concern, necessitating means of identifying effective treatment strategies for PPCP removal. In this study, we employed machine learning (ML) models to classify 149 PPCPs based on their chemical properties and predict their removal via wastewater and water reuse treatment trains. We evaluated two distinct clustering approaches: C1 (clustering based on the most efficient individual treatment process) and C2 (clustering based on the removal pattern of PPCPs across treatments). For this, we grouped PPCPs based on their relative abundances by comparing peak areas measured via non-target profiling using ultra-performance liquid chromatography-tandem mass spectrometry through two field-scale treatment trains. The resulting clusters were then classified using Abraham descriptors and log Kow as input to the three ML models: support vector machines (SVM), logistic regression, and random forest (RF). SVM achieved the highest accuracy, 79.1%, in predicting PPCP removal. Notably, a 58-75% overlap was observed between the ML clusters of PPCPs and the Abraham descriptor and log Kow clusters of PPCPs, indicating the potential of using Abraham descriptors and log Kow to predict the fate of PPCPs through various treatment trains. Given the myriad of PPCPs of concern, this approach can supplement information gathered from experimental testing to help optimize the design of wastewater and water reuse treatment trains for PPCP removal.
Water Heater Type, Temperature Setting, Operational Conditions, and Insulation Affect Ecological Niches for Legionella Growth
Roman, Fernando A. Jr.; Martin, Rebekah L.; Rhoads, William J.; Pearce, Annie; Smeltz, Rania E.; Pruden, Amy; Edwards, Marc A. (American Chemical Society, 2024-12-23)
Residential water heating represents an important nexus of energy/water conservation, waterborne disease, hygiene, and consumer preference. Here, we examine attributes of two off-the-shelf 151-L tank water heaters, one with hot water recirculation (recirculating) and another without recirculation (standard), compared to a tankless on-demand heater (on-demand). Energy efficiency decreased in the order on-demand > standard > continuous recirculation. However, the electric on-demand water heater repeatedly malfunctioned and could not consistently achieve target temperatures >48 degrees C. At a temperature setting of 48 degrees C, the volume of water in the pipe and tank within a temperature range at very high risk for Legionella growth (38-47 degrees C) decreased from recirculating (150 L) > standard (40 L) > on-demand (similar to 0.47 L). However, at a temperature setting of 66 degrees C, the standard tank was stratified, and the bottom 13 L fell within the very high-risk temperature range, whereas the recirculating tank system maintained 100% of its volume >55 degrees C, which is not suitable for Legionella growth. Addition of insulation was found to markedly increase the temperature throughout the tank. In the standard tank set at 66 degrees C with insulation, no volume was maintained within the very high-risk range. Insulation can holistically increase energy efficiency and reduce health risks at a sufficiently elevated temperature setting.

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