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Edmonton, Canada

Chen Z.,Concordia University at Montreal | Han S.,Concordia University at Montreal | Zhou F.-Y.,Environmental Planning | Wang K.,Dalian University of Technology
Water Resources Management | Year: 2013

The design of the urban sewage system is site specific, and it makes the use of three-dimensional (3D) model an alternative to a field study or a laboratory experiment. However, the use of 3D computational fluid dynamics (CFD) in the study of the urban sewage system has been generally limited to the study of a single structural component with simplified assumptions. In this study, the 3D model that adopted the renormalized group (RNG) k-ε turbulence model, the volume of fluid (VOF) free water surface model and the particle tracking approach was verified comparing the predicted flow field data with the measurements in laboratory scale experiments. Then, the model was applied to optimize the design of the combined sewer system (CSS) in the city of Edmonton with multiple hydraulic structures. Considering the details of predicted flow characteristics and the behaviors of the suspended solids, the final design was chosen and implemented to reduce the water pollution induced by the direct combined sewer overflow (CSO) discharge to the receiving water body. It is shown that the proposed 3D CFD modeling approach is a cost-effective tool to design the municipal sewer system. © 2013 Springer Science+Business Media Dordrecht. Source

Craig A.P.,University of New South Wales | Hanger J.,Australia Zoo Wildlife Hospital | Loader J.,Australia Zoo Wildlife Hospital | Ellis W.A.H.,University of Queensland | And 6 more authors.
Vaccine | Year: 2014

Background: Many koala populations around Australia are in serious decline, with a substantial component of this decline in some Southeast Queensland populations attributed to the impact of Chlamydia. A Chlamydia vaccine for koalas is in development and has shown promise in early trials. This study contributes to implementation preparedness by simulating vaccination strategies designed to reverse population decline and by identifying which age and sex category it would be most effective to target. Methods: We used field data to inform the development and parameterisation of an individual-based stochastic simulation model of a koala population endemic with Chlamydia. The model took into account transmission, morbidity and mortality caused by Chlamydia infections. We calibrated the model to characteristics of typical Southeast Queensland koala populations. As there is uncertainty about the effectiveness of the vaccine in real-world settings, a variety of potential vaccine efficacies, half-lives and dosing schedules were simulated. Results: Assuming other threats remain constant, it is expected that current population declines could be reversed in around 5-6 years if female koalas aged 1-2 years are targeted, average vaccine protective efficacy is 75%, and vaccine coverage is around 10% per year. At lower vaccine efficacies the immunological effects of boosting become important: at 45% vaccine efficacy population decline is predicted to reverse in 6 years under optimistic boosting assumptions but in 9 years under pessimistic boosting assumptions. Terminating a successful vaccination programme at 5 years would lead to a rise in Chlamydia prevalence towards pre-vaccination levels. Conclusion: For a range of vaccine efficacy levels it is projected that population decline due to endemic Chlamydia can be reversed under realistic dosing schedules, potentially in just 5 years. However, a vaccination programme might need to continue indefinitely in order to maintain Chlamydia prevalence at a sufficiently low level for population growth to continue. © 2014 Elsevier Ltd. Source

Han S.-S.,Concordia University at Montreal | Chen Z.,Concordia University at Montreal | Zhou F.-Y.,Environmental Planning | Lu X.-Q.,Huazhong University of Science and Technology
Water Resources Management | Year: 2014

Surface flow constructed wetlands (SFCWs) have been widely used to treat various types of wastewater and stormwater due to the advantages such as low costs for operating and maintenance compared with conventional treatment systems. In SFCW, the flow pattern, which is determined by the geometric features including bed morphology and vegetation distribution, significantly influences the removal processes of suspended solids and other pollutants. In this study, a three-dimensional computational fluid dynamics model, that integrates hydrodynamic model and the Lagrangian particle tracking model, is applied to determine the effectiveness of a SFCW in removing suspended solids based on the predicted flow characteristics and distribution of suspended solids in the wetland. After the validation, the three-dimensional numerical model is applied to illustrate the three-dimensional internal flow pattern in the wetland. The predicted concentrations of suspended solids at several cross-sections in downstream direction are compared with the field sampling data and also the results from a traditional first-order decay model. The results show that the 3D model performs reasonably well predicting complex flow fields associated with complex wetland geometry. This study indicates that the 3D model is an effective tool to support the management and operation of field SFCWs. Also, it can help to improve the design of SFCWs providing better understanding of interactions among the geometric features, the flow characteristics and the contaminants behaviors. © 2014 Springer Science+Business Media Dordrecht. Source

Wang K.,Dalian University of Technology | Zhang X.,Dalian University of Technology | Chen Z.,Concordia University at Montreal | Zhou F.,Environmental Planning | Nie X.,Transport planning and research institute
Water Resources | Year: 2015

Mathematical model analysis is very important in investigating the water exchanges and tidal prism in the reconstruction engineering projects around coastal bay. Based on the accurate simulation of tides, the mathematical model method is more economical and efficient than traditional measurement method and physical experiment model in the first evaluation of initial design. A robust numerical model with high accuracy is explored in this study for a systematic consideration of hydraulic interactions within different water zones in coastal reconstruction project. Application of the developed tidal model to a reconstruction project in the Dalian Laohutan Bay of China is presented in details. The developed tidal model with a refined meshing algorithm has been validated through measured field data with reasonable agreement. Then, the validated model is used to examine water exchanges and the tidal prism under different engineering reconstruction scenarios. The engineering solutions that satisfy the requirements of both project demands and environmental protection have been obtained. © 2015, Pleiades Publishing, Ltd. Source

News Article
Site: http://news.mit.edu/topic/mitenvironment-rss.xml

Amid a changing climate, population growth, rapid development, and pervasive urbanization, an unprecedented threat to the world’s food and water supply is more apparent than ever before. In fact, it is predicted that 70 percent more food will be needed by 2050 and the demand for water will triple. "To date, we’ve met the food and water challenge to a significant extent through technology, as exemplified in the 'green revolution,' but there are still significant problems to solve. We’re optimistic that MIT will have a major role in meeting the world’s challenges around food and water supply," John Lienhard, director of the Abdul Latif Jameel World Water and Food Security Lab (J-WAFS) at MIT, said in the opening remarks at the third annual MIT Water Summit held Nov. 13-14 on campus. "Workshops such as this are critical to raise awareness and build momentum towards solving the grand water challenges of our world," said Elfatih Eltahir, associate department head and a professor in the Department of Civil and Environmental Engineering (CEE). "The Water Summit was a wonderful opportunity for open and transparent discussions that helped in reaching better definitions of water problems and paved the way for new and innovative solutions." An MIT Water Club team — comprised of MIT graduate students Reetik Kumar Sahu, Anjuli Jain Figueroa, Alexis Fischer, Matthew Willner, Brendan Smith, and Isadora Cruxen — organized this year’s Water Summit into three conversation panels: Interpret, Innovate, and Implement. The team brought together more than 200 members of the MIT and non-MIT communities to discuss the role of climate change in global water challenges. Over the course of two days, several representatives from academia, government, and industry were invited to present. "The biggest risk to our water systems is our social norms," Col. John Henderson of the U.S. Army Corps of Engineers said. "We, as a society, may not be adapting fast enough." Of course, the path leading to full adaptation to climate change is far from clear, he added. The Interpret panel included Henderson, Camille Touton of the U. S. Department of the Interior, Scott Doney of the Woods Hole Oceanographic Institute (WHOI), Manoj Fenelon of the Aspen Institute, and MIT graduate student Jordon Hemingway as moderator. One major hindrance that Fenelon said prevents climate adaptation is the way the problem is framed. "How do you explain the challenge in a way that causes people to realize it is bigger than their individual interests?" he asked. To emphasize, Touton said that 50 percent of the world is in severe drought — a negative impact of climate change that many do not directly experience. Using open water data to visualize the impact of drought and climate change on water resources, she said, is one aspect of the problem that her department investigates and reports to the public. "The world is teeming with answers, but are we asking the right questions?" Fenelon added. Perspectives unrelated to science — such as considering water as a right rather than a luxury — may result in interesting and efficient approaches to the challenge. Leveraging branding, for instance, was one such approach explored by the panel. "I would be interested to see brands engage in civil work," Fenelon said. "Consumers would be buying not just a brand, but a movement." In agreement, Doney added it’s not the destination that matters, but rather how quickly society manages to get there. When it comes to climate change and the global water supply, the rate of change heavily impacts the natural ecosystems. However, the panelists agreed, the key to truly engaging open interest is to pitch the science behind climate change in a way that attracts stakeholders and, more importantly, the general public. The future is about radical transparency In their remarks on how technological innovations and research have led to more resilient water systems, the Innovate panelists — Noel Bakhtian, lead strategic coordinator on Energy-Water Nexus activities for the U.S. Department of Energy; Marcus Quigley, founder of OptiRTC; Anarug Bajpayee, co-founder and CEO of Gradiant Corporation; Mark Ellison, U.S. affiliate of IDE Technologies; and MIT graduate student and panel moderator Divya Panchanathan — offered a hopeful, yet guarded, perspective. For Quigley, the world needs a future of “radical transparency” of data. With an open explanation of the reality of water, he postulated that this approach will transform the manner in which we act and develop regulations around water management. "We need to be creative with data science and make water information more meaningful for the public to digest," he said. Noting society’s hesitancy to trust new innovations in the water sector, Bajpayee suggested some of the challenge may also lie with people’s misconception of the value of water. "People think water is free when it’s not," he said. "Something is paying for it. Explaining this openly and clearly may help people appreciate how important it is to conserve energy and water." When it comes down to it, Quigley continued, our perception on what we think the world should look like is irrelevant. The gateway to water management is about delivering the outcomes people expect, and furthermore educating them on why they should expect those outcomes from a political perspective. The panelists contended that the world would benefit from focusing more on a transparent understanding of the projected outcome and less on what society portrays as an ideal world. One way to achieve this may be for water businesses to expand their reach beyond one idea and emphasize an entire market or specialized sector. "The most successful companies are those who have evolved along the way," Bajpayee said. "Water entrepreneurs should build businesses around an entire platform, not just one innovation." Climate change is no longer about belief, but fact To close the Water Summit on the second day, keynote speaker Curt Spalding of the U.S. Environment Protection Agency (EPA) for New England introduced the Implement panel with a discussion on the hard evidence and implications of climate change. Spalding said 70 percent of the population accepts that climate change is happening, and, because of this, progression is being made to both mitigate and adapt to the reality. "Adaptation is a priority and is integrated into every decision made by the EPA," he said. However, it’s not always as high a priority as it should be for others, he added. Spalding emphasized the need to communicate complex data to the implementers for real movement to be made in the fight against climate change. This notion was further explored in the panel, moderated by MIT graduate student Alice Alpert, and comprised of Edgar Westerhof of ARCADIS U.S. Inc., Stephen Estes-Smargiassi of the Massachusetts Water Resources Authority, Dennis Carlberg of Boston University, and Larry Susskind, the Ford Professor of Urban and Environmental Planning at MIT. According to Susskind, the hindrance to true innovation in policy implementation is mainly the lack of collaboration between leaders and the public. "No decision is ever going to be completely correct, so we will have to collaboratively adapt as things evolve," he said. Estes-Smargiassi agreed, and added that it is equally important to embrace any potential opportunity to build resiliency — even if the timing or innovation is not perfect. "Each opportunity that we fail to grasp, puts us further behind," he said. "Let’s figure out which steps we should take now to continue to move ahead later." Particularly, participatory planning is a crucial part of resiliency planning; otherwise, he explained, there may not be buy-in. Corporation mitigation efforts and sponsoring of events, such as the international Sustainable Innovation Forum 2015 in Paris, has a powerful effect in changing the public image of what’s being done today. While concrete conclusions may not necessarily be drawn from efforts such as these, confidence is built for the long-term. And this, the panelists agreed, is effective in the process of managing water in a time of a changing climate. "The MIT community is deeply motivated to contribute," Lienhard said. "Our students and faculty are bringing their insight, innovation, and technical excellence to bear on the challenge of water management." Sponsors for this year's Water Summit included Arcadis, Association of Student Activities, MIT's Department of Urban Studies and Planning, CEE, the Coop at MIT, Desalitech, Environmental Policy and Planning Group, Gradiant Corporation, J-WAFS, MIT International Science and Technology Initiatives, MIT Brazil, the WHOI, Pepsico, and WRI Brazil.u

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