Water consumption and wastewater generation depletes water resources and has a destructive impact on the environment. Recent attention has aimed at preserving water resources and preventing pollution through several routes. Restrictions on wastewater discharge into the environment, recycling, reuse and regeneration of wastewater streams are now common practices toward achieving these objectives. Membrane and integrated membrane processes have been shown to be effective at reducing water usage and recovering valuable compounds. This thesis focuses on topics related to the optimal synthesis of wastewater treatment networks by hybrid membrane systems. The use of superstructures has been a useful tool to synthesize chemical engineering process flowsheets. The approach postulates all possible alternatives of a potential treatment network. Within the representation, an optimal solution is assumed to be hidden in the given superstructure. State space is a framework to process synthesis problems which involves heat and mass exchange. In this representation, unit operations, utility units and utility streams can be embedded in such a way that all the process synthesis alternatives can be realized. Such a framework can be applied for water and wastewater synthesis problems. Several research optimization studies presented membrane and hybrid membrane process synthesis problems for wastewater treatment. Nonetheless, the problems in fact can be represented in several ways. Therefore, the mathematical programs are expected to be different for every postulated representation. Comparison between different representations and their mathematical programs are analyzed to highlight the relationship between the superstructure representation and their mathematical programming formulations. Possible improvement of these superstructures is addressed. Also, a generic representation is provided to give a systematic and clear description for assembling hybrid membrane system superstructures via the state space approach. The synthesis of reverse osmosis networks (RON) for water and wastewater treatment network is presented as a superstructure problem. The mathematical programming model describes the RON through a nonconvex mixed integer nonlinear program (MINLP). A mixed integer linear program (MILP) is derived based on the convex relaxation of the nonconvex terms in the MINLP to bound the global optimum. The MILP models are solved iteratively to supply different initial guesses for the nonconvex MINLP model. It is found that such a procedure is effective in finding local optimum solutions in reasonable time. Water desalination and treatment of aqueous wastes from the pulp and paper industry are considered as case studies to illustrate the solution strategy. The RON mathematical program is a nonconvex MINLP which contains several local optima. A deterministic branch and bound (B&B) algorithm to determine the global optimum for the RON synthesis problem has also been developed. A piecewise MILP is derived based on the convex relaxation of the nonconvex terms present in the MINLP formulation to approximate the original nonconvex program and to obtain a valid lower bound on the global optimum. The MILP model is solved at every node in the branch and bound tree to verify the global optimality of the treatment network within a pre-specified gap tolerance. Several constraints are developed to simultaneously screen the treatment network alternatives during the search, tighten the variable bounds and consequently accelerate algorithm convergence. Water desalination is considered as a case study to illustrate this approach for global optimization of the RO network. Wastewater and groundwater streams contaminated with volatile organic compounds (VOCs) require proper treatment to comply with discharge standards or drinking requirement restrictions. Air stripping and pervaporation are two common treatment technologies for water streams contaminated with VOCs. The combination of these technologies for water treatment which are representative of hybrid membrane systems may offer advantages over stand-alone treatments. Superstructure optimization uses the framework of hybridization to determine the optimal treatment network and the optimal operational requirements for the treatment units to achieve desired water qualities. Two case studies are presented to illustrate the proposed approach and sensitivity of the optimal solutions to given perturbations is analyzed.

Municipal wastewater effluent (MWWE) is an important source of pollution in the aquatic environment impacting fish. MWWE is a complex mixture of chemicals including pharmaceuticals, personal care products, industrial chemicals and pesticides. A link between reproductive endocrine disruption and MWWE exposure has been established in fish, but less is known about the effects of MWWE on non-reproductive endocrine disruption. The overall objective of this thesis was to examine the impacts of MWWE exposure on the stress response and intermediary metabolism in rainbow trout (Oncorhynchus mykiss). In fish, the primary adaptive organismal stress response involves the activation of hypothalamic-sympathetic-chromaffin axis to produce catecholamines, predominantly epinephrine, and the hypothalamic-pituitary-interrenal (HPI) axis to produce cortisol. Both of these hormones play a key role in elevating plasma glucose levels that is essential to fuel the increased energy demand associated with stress. Along with the organismal stress response, the cellular stress response, involving the synthesis of a suite of heat shock proteins (hsps), also plays an important role in protecting cellular protein homeostasis in response to stressors, including toxicants. The impact of MWWE on stress-related pathways were identified using a low-density trout cDNA microarray enriched with genes encoding for proteins involved in endocrine-, stress- and metabolism-related processes. This was further confirmed by assessing plasma hormone and metabolite levels and stress-related targeted genes and proteins expression and enzyme activities in select tissues in rainbow trout. Studies were carried out in controlled field (caging) and laboratory experiments to examine the impacts of MWWE on stress and tissue-specific metabolic responses in rainbow trout. Further in vitro studies using rainbow trout hepatocytes in primary cultures were carried out to investigate the mechanism of action of two pharmaceuticals, atenolol and venlafaxine, found in relatively high concentrations in MWWE in impacting the stress-mediated glucose response. In caged fish, MWWE exposure significantly elevated plasma cortisol and glucose concentrations, and altered the mRNA abundance of a number of stress-related genes, hormone receptors, glucose transporter 2 and genes related to immune function. When fish were exposed to an acute handling stress following a 14 d exposure to MWWE, the cortisol response was abolished and the glucose response was attenuated. The effects on cortisol did not correlate with changes in the expression of genes involved in cortisol biosynthesis, but were associated with an increase in hepatic glucocorticoid receptor (GR) protein expression. Upon further investigation in controlled laboratory studies, MWWE exposure elevated constitutive hsp 70 and hsp90 expression after 8 d exposure, which correlated with a decrease in glycogen levels in the liver in fish exposed to a high concentration of MWWE compared to control fish, pointing to a MWWE-induced increase in liver energy demand. By 14 d, glycogen stores were replenished, and this was commensurate with increases in liver gluconeogenic capacity, including increases in the activities of phosphoenolpyruvate carboxykinase (PEPCK) and alanine aminotransferase (AlaAT), along with a decrease in liver GR expression. In the heart, GR protein expression increased in treated fish, and the activity of pyruvate kinase increased, indicating an increase in glycolytic capacity. Subjecting the MWWE exposed fish to a secondary handling disturbance (acute stress) led to an attenuated plasma cortisol and glucose response compared to the control group. This corresponded with a reduced liver gluconeogenic capacity and a lower liver and heart glycolytic capacities, reflecting a disturbance in the energy substrate repartitioning that is essential to cope with stress. While it is difficult to establish causative agents from a complex mixture such as MWWE, the two pharmaceutical that were tested impacted glucose production. Specifically, atenolol and venlafaxine disrupted the epinephrine-induced glucose production, but did not modify cortisol-mediated glucose production in trout hepatocytes. The suppression of epinephrine-mediated glucose production by atenolol and venlafaxine was abolished by cAMP analogue (8-bromo cAMP) or glucagon (a metabolic hormone that increases glucose production). This suggests that both drugs disrupt β-adrenoceptor signaling, while it remains to be determined if the response is receptor isoform-specific. Altogether MWWE exposure disrupts the organismal and cellular stress responses in trout. Key targets for MWWE impact leading to the impaired cortisol and metabolic responses to stress include liver and heart GR expression, liver gluconeogenic capacity, and liver, heart and gill glycolytic capacities. Most significantly, MWWE impairs the ability to metabolically adjust to a secondary acute stressor, which is an important adaptive process that is integral to successful stress performance. From an environmental stand-point, long-term exposure to MWWE will lead to reduced fitness and will compromise the capacity of fish to cope with additional stressor, including escape from predators.

Fast paced population growth in urban areas of southern Ontario is putting increased pressure on the surrounding aquatic environment. The City of Guelph uses the Speed River to assimilate its municipal wastewater effluent. With a projected 57% population increase in the watershed by 2031, the assimilative capacity of the river may be challenged in the coming years. The Guelph Wastewater Treatment Plant uses tertiary treatment methods greatly reducing ammonia, suspended solids and phosphate concentrations in the effluent. However there are still impacts detectable related to excessive nutrients released into this relatively small river (6th order) which promotes algae and aquatic macrophyte growth. There is also concern about a variety of emerging contaminants that may enter the river and impact the health of the ecosystem. The research in this thesis examined the seasonal and spatial variability and extent of the impacts of the wastewater effluent on the riffle fish communities in the Speed River. Stable isotope signatures (δ13C and δ15N) were used to understand the changes in the dominant benthic fish species, Rainbow Darters (Etheostoma caeruleum) and Greenside Darters (E. blennioides), relative to changes in invertebrate signatures and their abundance. Rainbow Darters were extremely abundant relative to Greenside Darters at the site immediately downstream of the effluent outfall, particularly in August. The benthic invertebrate community was distinctly different downstream of the effluent outfall, especially in the summer, with a reduced abundance of Elmidae beetle larvae and increased abundance of isopods (Caecidotea intermedius) compared to upstream. δ13C and δ15N of the two darters species were similar at all sites in May and July, but in August and October Rainbow Darter signatures were more enriched in the two heavier isotopes at sites downstream of the effluent outfall. The vast majority of invertebrate taxa sampled were also enriched at the downstream sites. An analysis of Rainbow and Greenside Darter stomach contents revealed that Rainbow Darters incorporated more isopods and other invertebrates in their diet, especially at the immediate downstream sites suggesting that they are more adaptable to the altered downstream environment. The feeding habits of Greenside Darters appear to change between July and August in response to changes in habitat and food availability. They are potentially consuming food organisms with less enriched isotopic signatures, which results in their isotopic signatures not rising during these months like most of the invertebrates and other fish. Alternatively, the Greenside Darters may move across the stream to feed on invertebrates that remain unexposed to the wastewater effluent. These impacts, although subtle, may be a reflection of the Speed River ecosystem being compromised by nutrient inputs from the wastewater effluent. With the impending increase in demand on the treatment plant (e.g., population growth), ongoing treatment and infrastructure improvements may be needed in the future to maintain the current ecosystem structure.

Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments. <p>Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments.

The Sudbury, ON, Canada region has been the site of metal mining and processing operations for more than 100 years. The study site for my thesis, Junction Creek, flows southwest through the City of Greater Sudbury and receives cumulative inputs including from the Garson Mine wastewater treatment plant (WWTP), Nolin Creek WWTP (stormwater) and CVRD Inco Limited WWTP (process water) as well as effluent from municipal WWTPs and untreated urban runoff, aerial deposition and historical contamination from multiple sources. Elevated levels of ammonia, Ni, Cu, Co, Pb and As, as well as reduced benthic invertebrate community diversity and density have been observed in the Junction Creek system below certain mine inputs. In addition, the Sudbury region has cold winters, with average daily air temperatures below 0°C from November to March.<p> The winter stress syndrome hypothesis proposes that the combination of winter conditions and contaminants (acting as physiological stressors) in the aquatic environment could reduce fish condition and deplete energy (lipid) reserves to the point of decreased survival, thus negatively impacting wild fish populations. However the winter stress syndrome hypothesis has rarely been tested in the field. I hypothesized that juvenile fish challenged with a physiological stressor (treated wastewater) in combination with winter conditions would have decreased growth and energy stores as a result of increased metabolism.<p> The approach I used to examine the potential effects of treated metal mine and municipal wastewaters on bioenergetics and growth, as they related to overwinter survival potential and the winter stress syndrome, of juvenile fish was a combination of a field study and a laboratory experiment. The first objective was to test the winter stress syndrome hypothesis under field conditions. Juvenile fathead minnows (Pimephales promelas), creek chub (Semotilus atromaculatus) and white sucker (Catostomus commersoni) were collected in fall and the following spring from sites along Junction Creek, Sudbury, ON downstream of two metal mining wastewater treatment plants as well as a municipal wastewater treatment plant. The second objective was to test the winter stress syndrome hypothesis in the laboratory by determining the effect of diluted (45 percent) treated CVRD Inco Limited wastewater effluent (CCWWTP) on juvenile fathead minnow growth and energy storage under simulated summer and winter conditions of reduced temperature, photoperiod and food ration. The effect on growth and energy storage of exposure to environmentally relevant ammonia concentrations was also assessed. In both the field and laboratory portions of this study, overwinter survival potential was assessed indirectly through measurements of growth (length, weight, muscle RNA/DNA ratio, muscle proteins) and energy stores (whole body triglycerides). There were inconsistent effects between the field study and the laboratory experiment. In contrast to my hypothesis, fathead minnows in the field study were larger with greater triglyceride stores at exposure sites compared to the reference site. White suckers were smaller at exposure sites but did not differ in triglycerides among sites and creek chub had no clear trend. For the laboratory portion of this study, only fathead minnows were used. After a 90 day exposure to reference or diluted CCWWTP water under simulated winter or summer conditions, juvenile fathead minnows raised in winter CCWWTP water (4°C) had lower whole body triglyceride concentration than those raised in winter reference water. There was no difference in triglycerides in fathead minnows raised in diluted CCWWTP or reference water under summer conditions. This lends support to the winter stress syndrome hypothesis, but the traditional measures of growth showed no significant differences in any of the treatments. In a separate experiment, fathead minnows were exposed from 10-100 days post hatch to graded concentrations of ammonia (0.02 to 0.40 mg unionized NH3/L) under summer conditions only. There was no effect of ammonia exposure on growth parameters, but a significant increase in total body triglycerides at the highest exposure concentration (0.40 mg/L) was observed.<p> The results of this study emphasize that laboratory-based hypotheses must be tested in the field to determine their environmental significance. The winter stress syndrome may not apply to northern fish adapted to living and feeding in colder climates and was not strongly supported by my study.

The polluted agricultural wastewater, after reaching marine recipients, can cause eutrophication. This problem can be tackled and mitigated by using constructed wetlands as water treatment systems. The fact that constructed wetlands work through long periods of time has led many scientists to evaluate how long they can still treat their influents effectively. The development and growth of vegetation and the accumulation of nutrients on the soils in a wetland are expected to occur. These processes change the wetland efficiency to remove pollutants. In this study, a set of wetlands constructed to treat agricultural wastewater were analyzed in different periods to assess if there is a difference in removal efficiency of nitrogen and phosphorus. This assessment was performed by analyzing the retention rate, k and k20 values, which are variables that quantify the nutrients removal, in different periods of each employed wetland. Some of the observations demonstrated differences when comparing different periods of the wetlands. The nitrogen removal presented better performance in one of the employed wetlands when this was older. Another employed wetland has not shown a clear difference between different periods. In the wetlands with high vegetation densities, the nitrogen removal was more stable over consecutive years. The occurrence of oscillations in nitrogen removal was observed more often in the wetlands with the highest vegetation densities over consecutive years. The phosphorus removal presented no clear differences between different periods. The results suggest that the removal of nitrogen improves after wetland creation due to the growth of vegetation. In addition, they suggest that wetlands with high vegetation densities tend to oscillate the nitrogen removal more or less often according to the density of the vegetation due to the balance between denitrification and decomposition. Further, the results suggest that the removal of phosphorus remains unchanged over longer periods than the periods considered in this study (four to six years) due to the deposition of organic matter on the soils.

The present paper summarizes the results of an application initiated within the framework of 35 years celebration of diplomatic relations between Germany and Vietnam. Within this context, the Technische Universität Dresden (TUD) and the Academy of Managers for Construction and Cities (AMC) jointly organized in 2010 a series of four thematic workshops. The one-day events have had similar structures and focused on main subjects of interest in the water sectors of both countries. In Vietnam, the workshops took place in Ha Noi, Hai Phong, Nha Trang and Vung Tau. Best practice examples about conceptualization, operation and maintenance of municipal water works provided an insight view into the challenges currently faced by the water service providers. TUD and AMC, together with their German and Vietnamese partners, addressed these issues by organizing the consecutive workshops under the umbrella of Vietnamese Water Supply and Sewerage Association (VWSA) and in coordination with the German Water Partnership (GWP). / Bài báo trình bày tóm tắt các kết quả của một đề xuất trong khuôn khổ kỷ niệm 35 năm quan hệ ngoại giao giữa CHLB Đức và Việt Nam. Theo đó, Trường Đại học Tổng hợp Kỹ Thuật Dresden (TUD) và Học viện Quản lý Xây dựng và Đô thị (AMC) đã phối hợp tổ chức một chuỗi bốn hội thảo chuyên đề trong năm 2010. Mỗi hội thảo thực hiện trong một ngày chương trình giống nhau và tập trung vào các chủ đề chính mà cả hai quốc gia đều quan tâm trong lĩnh vực nước. Phía Việt Nam, các hội thảo được tổ chức ở các thành phố Hà Nội, Hải Phòng, Nha Trang và Vũng Tàu. Nhiều bài thuyết trình về khái niệm hóa, vận hành và bảo dưỡng các công trình cấp nước đô thị đã thảo luận sâu về những thách thức mà các dịch vụ cấp nước đang gặp phải. TUD và AMC, kết hợp với các đối tác CHLB Đức và Việt Nam, đã ghi nhận các vấn đề phát sinh thông qua việc tổ chức nhiều hội thảo liên tục dưới sự bảo trợ của Hiệp hội Cấp thoát nước Việt Nam (VWSA) và Hiệp hội nước CHLB Đức (GWP).

Since 1989, the United States Federal Government and the State of Texas have targeted water and wastewater infrastructure development spending in the colonias to improve access to safe, reliable and adequate water supplies and wastewater service. Prior to widespread installation of piped, treated water infrastructure, waterborne illnesses attained levels only seen in developing countries. Despite the hundreds of millions of dollars that have been spent since 1989 on water and wastewater infrastructure improvements, roughly a quarter of colonias still lacked basic access to water and wastewater services. Previous research and assessments of where this government spending has been targeted have not evaluated all four largest funding sources together or demonstrated the impacts of water and wastewater infrastructure spending on either public health or the local economy. This report evaluates the first of these problems by analyzing government spending of these funding sources from 1996 to 2006 in Cameron, Hidalgo, and Starr counties. The report provides the history and context of the Texas colonia problem, discusses who provides water and wastewater services to the colonias, and describes the make-up of federal and state financial assistance to the colonias to develop their water and wastewater infrastructure. Conventional understandings of where government spending is going, for what, and to whom, are challenged by the data and analysis. Analysis results indicate greater spending on wastewater infrastructure improvements than water service in addition to greater allocation to municipal systems that extended service into colonia areas historically operated by water service corporations. Further research may build on this data as well as regional economic and epidemiological data to determine outcomes of the spending in quantitative terms using various impact assessment methodologies. This report concludes with a discussion of impact assessment.

Clostridium difficile has been recognized as one of the leading causes of nosocomial diarrhea and pseudomembranous colitis in human hospitals and nursing homes since the 1970s; however, recent occurrences of community-acquired cases have led researchers to search for additional sources of these infections. Some of the possible sources being investigated include food animals and retail meat. The objective of this study was to compare the prevalence and genotypic characteristics of C. difficile isolated from a closed population in Texas consisting of both humans and swine. Implicit in this objective, we seek to investigate the possible food safety and occupational risks associated with swine and C. difficile. Isolation of C. difficile was performed utilizing an enrichment technique and restrictive media. Polymerase chain reaction (PCR) was used to test for the presence of the toxin A and B genes, the tcdC gene deletion, and the binary toxin gene. Genotypic characteristics were compared using PCR toxinotyping and pulsed-field gel electrophoresis (PFGE). Antimicrobial susceptibility was tested using commercially available tests (ETest®) for 11 different antibiotics. Statistical comparisons (both parametric and non-parametric, and appropriate to the data) were performed both between and among host species. We tested 2,292 aggregated human wastewater samples and 2,936 swine fecal samples from 2004 to 2006 and found 271 (11.8 percent) and 252 (8.6 percent) to be positive for C. difficile, respectively. The prevalence of C. difficile among swine production groups differed significantly (p<0.05); however, prevalence in the human occupational group cohorts (swine workers and non-workers) did not differ (p=0.81). The majority of the human and swine isolates were a PFGE NAP7 (a variant pattern with 90.5 percent similarity) toxinotype V strain. Antimicrobial resistance levels and multi-resistance patterns were generally similar between host species; however, there was decreased susceptibility (p<0.05) to ampicillin, clindamycin, and imipenem observed in swine isolates, whereas there was decreased susceptibility (p<0.05) to ciprofloxacin in the human isolates. The similarity in C. difficile prevalence between swine workers and non-workers suggests a low occupational hazard of working with swine as it relates to C. difficile source. We also found that there is a decreased prevalence of C. difficile in late production groups in swine suggesting a lowered risk of food-borne exposure. However, the majority of the isolates derived from the human wastewater and swine appeared to be of very similar strain types, suggesting that a common environmental point source predominates for both hosts.

Electroplating industry is one important industries in Taiwan. Its wastewater has lead to pollution of the river, ocean, and underground water. Thus, the reduction of the concentration of heavy metals such as Cu, Zn, Ni, Cr, Pb etc. from wastewater is critical. Conventional strategies to remove the heavy metals involve adding abundant chemical agents which results in largy quantity of heavy metal sludge. Secondary pollution might occur as due to the heavy metal sludge contacted with acid. Aquatic plants have been shown to uptake the heavy metals from the surrounding environment. This unique character is different from the conventional approach and could be applied for removing the heavy metals in wastewater.This study used an aquatic plant, Najas graminea Del, to remove the heavy metals from the prepared metal solution and electroplating wastewater. Our data revealed that the relationship between the specific adsorption and residual concentration of the heavy metal was best described by the Langmiur adsorption isotherm curve. The value of maximal adsorption capacity (Ymax) in copper is 58.1 mg/g. Without buffering, the sequential order for the Ymax in the prepared metal solution is Cu > Pb > Cd> Ni > Zn. The value of Ymax was with significantly reduced under buffering circumstance as compared with that no buffer. In the electroplating wastewater containnig copper from company A, the value of Ymax was 20.7 mg/g, which was much smaller in prepared copper solution (Ymax =33.1 mg/g). Our further investigation showed that the background contaminatants especially iron in the electroplating wastewater have significant contribution to this discrepancy. In other set of experiments, we found that there is no significant difference between the electroplating wastewater and prepared solution for the adsorption of Ni. Our results provide useful information the understanding the process for the Najas graminea in adsorption the heavy metals from electroplating wastewater. Futhermore, the application of Najas graminea to remove the pollution from wastewater can protect the enviroment from pollution. This innovative concept has the potential in practical application and could be trasferred into a novel technology to substitute the conventionally physical or chemical treatment for the electroplating wastewater.