http://idea.library.drexel.edu/handle/1860/729 http://idea.library.drexel.edu/retrieve/4828 http://idea.library.drexel.edu/handle/1860/729 Search the Channel search http://idea.library.drexel.edu/simple-search http://idea.library.drexel.edu/handle/1860/3171 Title: Economic analysis of decentralized options for providing water service to low-income settlements <br/> <br/>Authors: Martinez, Victor; Gurian, Patrick L.; Cook, Steve R. <br/> <br/>Abstract: The U.S.-Mexico border region has large numbers of unincorporated settlements lacking basic services, which are known as colonias. Sanitation and health conditions in colonias can be compared to those in third world countries. El Paso County has approximately 200 known colonias. Despite large-scale investments to extend water supply to the colonias, approximately 3500 colonia residents still lack piped water service. Extending service to these remaining residents would be prohibitively expensive. A previous study estimated that providing piped water supply would cost an average of $119,000 per lot. In this study, a representative colonia with an estimated population of 558 residents is evaluated to determine the costs of de-centralized approaches to water supply. A survey was administered to document the costs the residents currently pay for delivery by truck. Household water bills were found to average $808 annually, confirming that the predominantly low-income colonia residents pay more for water than do households served by piped water supplies. A cost comparison of the current water supply delivery cost vs. the proposed cost of well drilling was performed to determine if it is economically feasible to construct wells. The well construction option is estimated to have an initial investment of $13,980 and a capital recovery period of 6 years. Therefore, the construction of wells appears to be an appropriate option for colonia residents. <br/> <br/>Description: A version of this paper appeared in the Proceedings of the AWWA 2009 Annual Conference and Exhibition, San Diego, CA http://idea.library.drexel.edu/handle/1860/3169 Title: Spatial Trends in Groundwater Arsenic Concentrations <br/> <br/>Authors: Bradshaw, Jonathan L.; Gurian, Patrick L.; Kumar, Arun; Breen, David E. <br/> <br/>Abstract: Arsenic presents complex spatial occurrence trends that can be difficult to identify and understand. This project sought to understand geographic trends in arsenic occurrence using a visualization technique. The approach taken was to link geospatially referenced arsenic concentration information from a water quality database with elevation data contained in Digital Terrain Elevation Data (DTED) files. DTED files are available for all land masses across the world for public download. This allows for the development of three-dimensional plots of arsenic concentration and topography. The plots developed in this manner show that high arsenic is associated with the transition from plains to piedmont on the western side of the Delaware River Valley in New Jersey. In Oklahoma high arsenic is found along the North Canadian River Valley. In New Mexico high concentrations are generally high in the Rio Grande Valley but with an area of low concentration in the southern portion of this valley. In California, arsenic concentrations are high in the middle of the Central Valley but moderate somewhat toward the edges. These results are consistent with mobilization of arsenic by reductive processes in the organic-rich sediments of river valleys, but further statistical analysis is required to confirm the significance of this association. The visualization software used here is broadly applicable and a user guide for this software is available on request. <br/> <br/>Description: A version of this paper appeared in the Proceedings of the AWWA 2009 Annual Conference and Exhibition, San Diego, CA http://idea.library.drexel.edu/handle/1860/3168 Title: Microfiltration Cost Benchmarking for Large Facilities <br/> <br/>Authors: Gurian, Patrick L. <br/> <br/>Abstract: A number of models of the cost of microfiltration treatment exist, but these models generally do not address, or are not validated for, larger facilities (facilities with design flow of 5 mgd or greater). In the past, microfiltration was not cost-competitive for larger facilities, but it is now being adopted at plants with design flows as large as 20 mgd. Accordingly, there is a need to extend these cost models to include larger facilities. Data for the larger facilities is still somewhat sparse, as only a few have yet been constructed. Nevertheless, the information that is available on these facilities can provide a valuable guide as to the economies of scale that may be available to larger treatment plants. In this study a survey of costs at large microfiltration plants was conducted. Data was obtained for 10 facilities, including 3 facilities with design flows greater than 9 mgd. The results indicate that large systems can achieve economies of scale, despite the modular nature of most microfiltration units. The three largest facilities (design flows of 9 to 20 mgd) have costs of less than 50 cents/thousand gallons. The cost estimates for facilities with flows of less than 5 mgd closely match a previous survey of small microfiltration plants. In addition, this study provides a basis for extending the predictions of existing cost models up to design flows of 20 mgd. Results indicate that costs vary among systems of the same capacity with 95% of all systems being within roughly a factor of two of the mean cost. <br/> <br/>Description: A version of this paper appeared in the Proceedings of the AWWA 2009 Annual Conference and Exhibition, San Diego, CA http://idea.library.drexel.edu/handle/1860/3151 Title: Cost-effectiveness of arsenic adsorbents <br/> <br/>Authors: Kumar, Arun; Bucciarelli-Tieger, Robin H.; Gurian, Patrick L. <br/> <br/>Abstract: A great deal of effort has been devoted to the development of new arsenic removal technologies. This study assesses the cost-effectiveness of different technologies based on literature reports from different studies. Assessing performance based on literature reports is challenging because (1) different studies use different levels of background ions, (2) different studies use different arsenic concentrations, and (3) low-cost, low adsorption density materials must be compared with high-cost, high adsorption density materials. In this evaluation, technologies were compared using the cost of removing one gram of arsenic at an equilibrium arsenic concentration of 20 μg/L. Comparisons of different arsenic adsorbents indicate that the removal costs of the proprietary media (estimated at $2.3-$5.1/g arsenic removed) overlapped those of iron oxide-coated-sand (estimated at $3.3-4.2/g), which supports the current trend toward the use of metal hydroxide media. However, the close comparability of alternative approaches such as iron oxide-coated materials, zero-valent iron, etc. with them also suggests that continued research in a variety of directions is justified. http://idea.library.drexel.edu/handle/1860/3150 Title: Innovative inland brine disposal options <br/> <br/>Authors: Hoque, Shamia; Alexander, Terry; Gurian, Patrick L. <br/> <br/>Abstract: Growing demand, concerns over droughts, over-allocation of surface water resources, and depletion of freshwater aquifers have all made desalination of brackish groundwater an increasingly important option for inland communities. However, these communities must find a means to dispose of the concentrated saline residual waste stream in an environmentally sound manner. Evaporation ponds are one of the primary options, but this technology has a large land requirement, which makes it costly. A concern for large facilities is that this technology is one of the few treatment methods that offers decreasing returns to scale due to increasing boundary layer resistance for larger ponds. This study evaluated a number of innovative options for improving the performance of evaporation ponds. Viable methods identified from the literature are: 1) fabric evaporators, 2) wetted boundary layer breakers, 3) salt-tolerant plants, and 4) droplet spraying. Two cost models are developed, one for boundary layer breakers and one for droplet spraying. Incremental costs and incremental evaporation enhancements are compared with site-specific cost information for a wastewater treatment facility in California's Central Valley. Results indicate that both boundary layer breakers and spray technologies are cost-effective compared to a simple expansion of the pond area. Boundary layer breakers appear to be more cost-effective per gallon incremental capacity but have a lower evaporation enhancement capacity compared to droplet spraying (24% enhancement vs. 35% enhancement). For a new facility, an example calculation with preliminary cost information indicates that spray evaporation is more cost-effective because of avoided pond excavation and lining costs. Boundary layer breakers are preferred as a retrofit to an existing facility, if they provide sufficient additional capacity to avoid the need for an expansion of the pond. http://idea.library.drexel.edu/handle/1860/3149 Title: Iron Oxide Phase Transformation of a Commercial Granular Iron Oxyhydroxide Based Arsenic Adsorbent: A Mineralogical Explanation <br/> <br/>Authors: Kumar, Arun; Gurian, Patrick L.; Nickolov, Zhorro S. <br/> <br/>Abstract: The objective of this research work was to understand the combined effects of pH, ion types and time on phase transformation of a commercially available granular iron hydroxide media, Bayoxide E33, exposed to a synthetic groundwater at pH 6 and pH 8 for 90 days in batch experiments, using X-ray diffraction (XRD) technique. No new iron/arsenic bearing mineral was observed for spent E33 media indicating that arsenic was not incorporated within the crystalline structure of the media. However, XRD peaks of spent media at 2θ = 21.62° and 36.9° were observed to widen compared to fresh media. Greater widening of peaks was observed for samples exposed to pH 6 solutions than that exposed to pH 8 solutions. Observed changes in peak-widths of spent media suggest the possibility of structural changes in media over time, which may also influence its arsenic adsorptive capacity over time. These findings are relevant to small utilities that treat groundwater with high arsenic and ferrous iron concentrations. Concerns appear to be greater for reduced, alkaline groundwater as the pH 8 sample with ferrous iron present showed the greatest structural change. Further experiments are underway to collect more information about changes in degree of crystallinity and arsenic adsorption capacity of iron oxide media over time, which could be useful in understanding the combined effects of different environmental factors on its stability and time-dependent arsenic removal effectiveness. http://idea.library.drexel.edu/handle/1860/2687 Title: A quantitative microbial risk assessment model for Legionnaires' disease: animal model selection and dose-response modeling <br/> <br/>Authors: Armstrong, T.W.; Haas, Charles Nathan <br/> <br/>Abstract: Legionnaires’ Disease (LD), first reported in 1976, is an atypical pneumonia caused by bacteria of the genus Legionella, and most frequently by L. pneumophila (Lp). Subsequent research on exposure to the organism employed various animal models, and with Quantitative Microbial Risk Assessment techniques, the animal model data may provide insights on human dose-response for LD. The present report focuses on the rationale for selection of the guinea pig model, comparison of the dose-response model results, comparison of projected low-dose responses for guinea pigs, and risk estimates for humans. Based on both in vivo and in vitro comparisons, the guinea pig (Cavia porcellus) dose-response data were selected for modeling human risk. We completed dose-response modeling for the β-Poisson (approximate and exact), exponential, probit, logistic and Weibull models for Lp inhalation mortality and infection (end point elevated body temperature) in guinea pigs. For mechanistic reasons, including low-dose exposure probability, further work on human risk estimates for LD employed the exponential and β-Poisson models. With an exposure of 10 Colony Forming Units (retained dose), the QMRA model predicted a mild infection risk of 0.4 (as evaluated by seroprevalence) and a clinical severity LD case (e.g., hospitalization and supportive care) risk of 0.0009. The calculated rates based on estimated human exposures for outbreaks used for the QMRA model validation are within an order of magnitude of the reported LD rates. These validation results suggest the LD QMRA animal model selection, dose-response modeling, and extension to human risk projections were appropriate. http://idea.library.drexel.edu/handle/1860/2683 Title: Using a global positioning system to measure tidal currents in Absecon Inlet, Atlantic City, NJ <br/> <br/>Authors: Weggel, J. Richard; Walz, James K.; Lomax, Joseph; Sray, Mark <br/> <br/>Abstract: As a permit requirement for the development of a marina within Absecon Inlet, Atlantic City, NJ, tidal current measurements were required. Maximum ebb and flood currents determine the forces to which the structural elements of the marina will be subjected as well as sediment transport patterns near the marina. Currents also influence the maneuverability of small craft attempting to enter or exit the marina. Consequently, current velocities and directions during maximum ebb and flood tides (spring tides) were measured on 10 March 2005 in the vicinity of the proposed marina using the Global Positioning System (GPS). The location of the proposed marina in the inlet is shown in Figure 1. Current patterns are affected by the presence of Clam Creek (on southwest side of the study area) and the Route 87 Bridge over the inlet. The marina site is also subject to locally generated wind waves as well as waves entering the inlet from the Atlantic Ocean. http://idea.library.drexel.edu/handle/1860/2641 Title: Application of zonal model on indoor air sensor network design <br/> <br/>Authors: Chen, Y. Lisa; Wen, Jin <br/> <br/>Abstract: Growing concerns over the safety of the indoor environment have made the use of sensors ubiquitous. Sensors that detect chemical and biological warfare agents can offer early warning of dangerous contaminants. However, current sensor system design is more informed by intuition and experience rather by systematic design. To develop a sensor system design methodology, a proper indoor airflow modeling approach is needed. Various indoor airflow modeling techniques, from complicated computational fluid dynamics approaches to simplified multi-zone approaches, exist in the literature. In this study, the effects of two airflow modeling techniques, multi-zone modeling technique and zonal modeling technique, on indoor air protection sensor system design are discussed. Common building attack scenarios, using a typical CBW agent, are simulated. Both multi-zone and zonal models are used to predict airflows and contaminant dispersion. Genetic Algorithm is then applied to optimize the sensor location and quantity. Differences in the sensor system design resulting from the two airflow models are discussed for a typical office environment and a large hall environment. http://idea.library.drexel.edu/handle/1860/2596 Title: Evaluating in-home water purification methods for communities in Texas on the border with Mexico <br/> <br/>Authors: Gurian, Patrick L.; Camacho, Gema; Park, Jun-young; Cook, Steve R.; Mena, Kristina D. <br/> <br/>Abstract: This study evaluated user preferences among three alternative in-home water treatment technologies suitable for households relying on trucked water in El Paso County, Texas, which is on the border with Mexico. The three technologies were: chlorination of household storage tanks, small-scale batch chlorination, and point-of-use ultraviolet disinfection. Fifteen households used each of the three technologies in succession for roughly four weeks each during April through June of 2004. Data were collected on treated water quality, and a face-valid survey was administered orally to assess user satisfaction with the technologies on a variety of attributes. Treatment with a counter-top ultraviolet disinfection system received statistically significantly higher ratings for taste and odor and likelihood of future use than the other two approaches. Ultraviolet disinfection and small-scale batch chlorination both received significantly higher ratings for ease of use than did storage tank chlorination. Over-chlorination was a common problem with both batch chlorination and storage tank chlorination. Water quality in the households using trucked water is now higher than was reported by a previous study, suggesting that water quality has improved over time.