Previous efforts to apply risk analysis for water distribution systems (WDS) have not typically included explicit hydraulic simulations in their methodologies. A risk classification scheme is here employed for identifying vulnerable WDS components subject to an intentional water contamination event. A Monte Carlo simulation is conducted including uncertain stochastic diurnal demand patterns, seasonal demand, initial storage tank levels, time of day of contamination initiation, duration of contamination event, and contaminant quantity. An investigation is conducted on exposure sensitivities to the stochastic inputs and on mitigation measures for contaminant exposure reduction. Mitigation measures include topological modifications to the existing pipe network, valve installation, and an emergency purging system. Findings show that reasonable uncertainties in model inputs produce high variability in exposure levels. It is also shown that exposure level distributions experience noticeable sensitivities to population clusters within the contaminant spread area. The significant uncertainty in exposure patterns leads to greater resources needed for more effective mitigation.

Although recent brownfields redevelopment research using theories of real estate valuation and neighborhood change have indicated negative effects on surrounding residential housing, little evidence exists to show price impacts and sociodemographic change after remediation. This study examines the extent and size of the economic impact of Superfund sites on surrounding single-family residential properties before and after remediation in Miami-Dade County and examines trends for contemporaneous sociodemographic changes. The study combines the economic impact from changes in environmental quality with contemporaneous sociodemographic changes within the purview of environmental and social justice. This study uses spatial hedonic price modeling on a comprehensive dataset of property-level data, with corresponding sales prices of housing transactions while controlling for other structural, neighborhood, and submarkets characteristics for assessing economic impact. Findings revealed that housing sales prices for single-family residential properties significantly increases as distance to the nearest contaminated Superfund increases. Following remediation, this negative impact declined and housing values increased significantly in neighborhoods with remedied Superfund sites albeit more so in low housing submarkets than premium submarkets. Spatial hedonic models outperformed traditional OLS models in presenting unbiased efficient parameter estimates, correcting for spatial dependence. Although no evidence for gentrification was observed, there existed significant differences between certain sociodemographic characteristics of neighborhoods around contaminated Superfund sites and those of properties located elsewhere leading to concerns of environmental and social justice. Findings suggest that low-income minority populations are more likely to be living in neighborhoods around contaminated Superfund sites and experience a greater negative effect on housing sales prices; these sites are also less likely to be remedied as compared to sites located elsewhere. The findings highlight not only the revealed preferences of homeowners with respect to environmental disamenities, but also help inform policymakers and researchers of the impact of brownfields redevelopment on economic and sociodemographic characteristics of a growing urban region with evolving cultural and social diversity. Incorporating influences of housing submarkets, neighborhood amenities, and spatial dependence help provide a holistic and comprehensive model for examining environmental disamenities and provide a better understanding for neighborhood change.

The beef industry has made tremendous strides in reducing pathogen contamination on carcasses. Multiple antimicrobial interventions have been validated for their use during harvesting. Information in regards to cross-contamination with pathogens in the post-harvest environment is limited. Surrogate microorganisms for enteric pathogens are commonly used to validate antimicrobial interventions and might allow for the simulation of cross-contamination through the post-harvest environment. The purpose of this study was to determine how the post-harvest environment impacts the direct and indirect transmission of pathogens. This was achieved by using fluorescent protein-marked surrogate strains of Escherichia coli O157:H7 and Salmonella spp. from inoculated carcasses to the adjacent ones and to the equipment and facility in three different abattoirs. Thirteen hide-on carcasses were inoculated using a gelatin-based slurry containing three nonpathogenic fluorescent protein-marked strains of E. coli biotype I. In order to determine direct and indirect cross-contamination, inoculated and adjacent carcasses were sampled (300 cm2) during the harvesting process at different stages: after hide opening (AHO), prior to evisceration (PE), after evisceration (AE), after splitting (AS), and after final intervention (AFI). Environmental samples consisting of the floor, walls, and air were tested as well as personal equipment including gloves, boots, and aprons. Equipment including hand knives, air knives, meat hooks, hide puller and split saw were also sampled. Results showed evidence of cross-contamination between inoculated carcasses and the adjacent non-inoculated ones for all abattoirs. Although this occurred in all abattoirs, surrogate counts on carcasses were below detectable levels (<1.4 log CFU/cm2) after antimicrobial interventions. Surrogates were found in low levels for all environmental samples. However surrogate counts from equipment such as knives, split saws, meat hooks, and hide puller were more frequently detected (15 percent) than those found on the floor, air and walls samples (10 percent). In the case of aprons, boots, and gloves, the prevalence of countable surrogate samples was 7 percent.

The objective of this research was to evaluate the treatment efficiency of a trichloroethylene (TCE) contaminated soil by combined technologies of the suspension of palladized nanoiron and electrokinetic remediation process. First, nanoiron and palladized nanoiron were prepared using the chemical reduction method. Then they were characterized by various methods. Micrographs of scanning electron microscopy have shown that a majority of these nanoparticles were in the range of 50-80 nm. Specific surface areas were determined to be 76.88 m2/g and 100.61 m2/g for the former and latter, respectively. Results of X-ray diffractometry have shown that both types of nanoiron were poor in crystallinity. Three anionic dispersants were employed for evaluating their performance in stabilizing various nanoiron. Results have demonstrated that an addition of 1 wt% of Dispersant E during nanoiron preparation would result in a good stabilization of nanoiron. If the system pH was adjusted to 2.99, nanoparticles would settle rapidly. Batch tests were carried out to investigate the effects of various operating parameters on degradation of TCE in aqueous solutions. Experimental results have indicated that palladized nanoiron outperformed nanoiron in treatment of TCE in this study. The employment of Dispersant E would enhance the treatment efficiency further. Test results also showed that a linear increase of reaction rate constant was found with an increasing dose of palladium from 0.05 wt% to 1 wt% based on the mass of nanoiron. Further, an exponential increase of reaction rate constant would be obtained with an increasing pH. As for mixing intensity, it was found to be insignificant to the treatment efficiency of TCE in aqueous solutions. The final stage of this study was to evaluate the treatment efficiency of combined technologies of the suspension of palladized nanoiron and electrokinetic remediation process in treating a TCE-contaminated soil. Test conditions used were given as follows: (1) initial TCE concentration: 160-181 mg/kg; (2) electric potential gradient: 1 V/cm; (3) daily addition of 20 mL of suspension of palladized nanoiron (2.5 g/L) to the electrode reservoir; and (4) reaction time: 6 days. Test results have shown that addition of palladized iron suspension to the cathode reservoir yielded the lowest residual TCE concentration in soil. Namely, about 92.5% removal of TCE from soil. On the other hand, addition of palladized iron suspension to the anode reservoir would enhance the degradation of TCE therein. Based on the above findings, the treatment method employed in this work was proven to be a novel and efficient one in treating TCE-contaminated soil.

Abstract This research was to evaluate the treatment efficiency for in-situ treatment of pentachlorophenol (PCP) contaminated soil by electrokinetics-Fenton process combined with biodegradation. An electric gradient of 1V/cm, and graphite electrodes were employed in all experiments. Soil types, catalyst types and dosage, hydrogen peroxide concentration, cathode reservoir liquid species and reaction time were employed as the experimental factors in this study. In this study, no matter electrokinetics-Fenton process or the electrokinetics-biodegradation in the latter, prolong the reaction time can promote the removal and destruction efficiency (DRE) of target pollutant from soil. By using 0.0196 M FeSO4 with 3.5% H2O2, the DRE was only lower 2% than 0.098 M FeSO4 with 3.5% H2O2.It showed that using 0.0196 M FeSO4 can provide enough Fe2+ to react with H2O2. By increasing H2O2 concentration from 0.35% to 3.5%, a DRE rised from 68.34% to 79.77%. When iron powder was used as catalyst, the residual pentachloroplenol concentration near to anode reservoir lower than 0.0196 M FeSO4 was used. But the DRE was 56.58% lower than the 68.34% of using 0.0196 M FeSO4.As the influences of soil types to electrokinetics-Fenton process, the residual concentration of pollutant for Soil No. 2 was higher than Soil No. 1. A DRE of only 59.22% was obtained. It is postulated that a much higher content of organic matter with Soil No. 2 whereas lower the treatment efficiency because of consumption of hydroxyl radicals by the organic matter of soil. For the influence of different reservoir liquid species, in this study 0.1M acetic buffer solution was used as cathode reservoir liquid, expected to promote the removal efficiency. From the result of experiment that could not reach the expected treatment efficiency of increasing the removal efficiency from soil. From the experiment of electrokinetics process combined with cometabolism, a treatment efficiency of only 25.67% was obtained. The content of pollutant within every section of soil column were still higher than predict. But by using electrokinetics-Fenton process to pretreat the pollutant within soil first, the increasing efficiency of biodegradation was found. Even when reaction time was prolonged, the pollutant could be completely eliminated from soil. If only used iron minerals to proceed electrokinetics-Fenton process naturally exited in the soil, a DRE of only 20

This research was to evaluate the treatment efficiency of a chlorinated hydrocarbons contaminated site by combined technologies of electrokinetic processing-Fenton process-catalytic iron wall. The L9 orthogonal arrays were utilized to investigate the effects of four experimental factors (i.e., H2O2 concentration, size fraction of iron particles, mass of iron particles and elapsed time) on the treatment efficiency. The experimental results were further subjected to the analysis of variance (ANOVA) and regular analysis. According to the ANOVA of results of nine experiments conducted under an electric gradient of 1 V/cm, the H2O2 concentration, mass of iron particles and elapsed time were determined to be very significant parameters for the destruction and removal efficiency (DRE) of 1,1,2,2-tetrachloroethane (TeCA) . In this system, the optimal conditions with respect to the DRE of TeCA would be 2¢MH2O2, 50-100 mesh iron, 0.2 wt% iron and 20-day treatment time. Under this optimal conditions, it was able to obtain a DRE of 69.56% and the corresponding operating cost would be 672.9 NT$/m3. Aside from the constant voltage operation, the constant current operation also was employed in this study. The latter was found to be superior to the former in terms of electroosmotic flow quantity and DRE. Experimental results of soil column tests showed that TeCA was transformed to trichloroethylene (TCE). TCE could be regarded as a daughter product of TeCA degradation. Results of Tests 17 and 18 showed that destruction dominated the DRE of TeCA, whereas removal played a much more important role in the DRE of Test 19. Regarding the treatment efficiency of a 9-day pilot test using the same combined treatment technologies, it was found to be very satisfactory. DREs of vinyl chloride, dichloroethane, and TCE were found to be >96%, >96%, and >94%, respectively in the anode and cathode wells. The concentrations of TCE in both anode and cathode wells were found to be lower than the regulatory threshold (i.e., 2£gg/L) and the operating cost was determined to be about NT$57.5/m3.

Abstract This study aims to understand the influence of weathering and human perturbation on spatial and temporal variability of major and trace element distributions in the Kaoping River basin. The collected data are used to elucidate the production, transport and export of major and trace elements from the Kaoping River basin. Experimental results show that the weathering index of the Kaoping River basin is rather high. The significant loss of major ions and enrichment of iron and aluminum from river suspended matter indicate the characteristic of high weathering rate in most tropical rivers. Particulate Si/Al mole ratios range from 1 to 2 showing that the distributions of dissolved and particulate matter are largely controlled by the weathering process of kaolinite and /or smectite formation. During the study period (2002), the physical and chemical weathering rates were estimated about 655.8 and 416.2 g/m2/yr, respectively. Both physical and chemical weathering rates are much lower than those estimated by Yang (2001) during the period of 1999-2000 [3601 g/m2/yr (physical weathering rate), 1146 g/m2/yr (chemical weathering rate)], due to significant difference in river discharge. However, the estimated physical and chemical weathering rates are still much higher than the world averages of physical (150 g/m2/yr) and chemical (33-40 g/m2/yr) weathering rates. The marked difference between this and Yang¡¦s estimates is caused from large difference in river discharge. Silicate weathering was estimated about 97.09 ¡Ó 2.41% of total chemical weathering in the Kaoping River basin. The temporal variations of enrichment factor (EF) for most particulate trace metals (Mn, Zn, Cu, Cr, Pb, Cd, and Hg) reveal a greater pollution status in the dry season than in the wet season. Spatial variations of EF also reveal a greater pollution in the downstream zone than in the upstream zone. Time-series observation showed that concentrations of particulate trace elements were inversely correlated with discharge. The significant correlation between the fluxes of dissolved and particulate trace elements and discharge suggesting that river discharge controlled largely the fluxes of major and trace elements. The annual variations of elemental fluxes were determined critically by the annual difference of river discharge. The distributions of particulate organic carbon (POC) and particulate nitrogen (PN) were similar between suspended matter in the Kaoping River and surface sediments in the Kaoping Canyon. The data of £_13Corg show that about 77.2% of organic matter derived from the Kaoping River basin deposit in the Kaoping Canyon. The Kaoping Canyon appears to play an important role on the transport and deposition of organic matter from the Kaoping River basin.

Effects of a 10% xylitol solution (X) on adhesion of Escherichia coli O157:H7 and Salmonella serotype Typhimurium to meat surfaces were examined utilizing three approaches. In Experiment 1, rifampicin-resistant strains of E. coli O157:H7 and S. Typhimurium were dispersed in xylitol or a peptone solution (containing approximately 8.9 mean log per ml of each pathogen) and used to inoculate beef outside round meat surfaces. Samples were then rinsed with water or not rinsed in a 2X2 factorial arrangement. No interaction existed between inoculum type and post-inoculation treatments (P > 0.84). Incubation of pathogens in peptone or xylitol had minimal impact on pathogen adhesion (P > 0.76). Rinsing reduced counts by approximately 0.5 log CFU/cm2 (P < 0.01). Experiment 2 meat samples received a pretreatment of a water rinse, xylitol, or no rinse, followed by inoculation with pathogens dispersed in peptone solution (containing approximately 8.6 log mean log per ml of each pathogen). Samples received a post-inoculation treatment of a water rinse, xylitol rinse or no rinse in a 3X3 factorial arrangement. No interactions between pre- and post-inoculation factors were observed for surface pathogen load (P > 0.50). Post-inoculation rinsing reduced counts by approximately 0.5 log CFU/cm2 (P < 0.01) with no difference between water and xylitol (P > 0.64). Experiment 3 carcass surfaces were inoculated with pathogens at an initial level of 5.5 log CFU/cm2 and received a hot (35°C) water wash, 2.5% L-lactic acid spray, 10% xylitol spray, lactic acid + xylitol or hot water + xylitol. Pathogen counts were taken at 0 and 24 h post treatment. Lactic acid treatments reduced Salmonella by 3.3 log CFU/cm2 at 0 h (P < 0.01) and by 2.6 log CFU/cm2 after 24 h (P < 0.02). Hot water treatments reduced Salmonella by 1.5 log CFU/cm2 at 0 h (P < 0.07). Xylitol did not minimize pathogens (P > 0.62) nor did it increase effectiveness of other treatments. These data indicate that xylitol is ineffective at preventing E. coli O157:H7 and S. Typhimurium adhesion to meat surfaces.

Reproduction de : Thèse de doctorat : Sciences : Océanologie biologique. Environnement marin : Toulon : 2005. / Titre provenant du cadre-titre. Bibliographie p. 277-301.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 63-67).