Scaling is a major problem in cooling water circuits as it reduces water flow and therefore affects the efficiency of the circuit. The natural organic matter has been suggested in earlier studies to limit the formation of calcium carbonate scaling by complexing the calcium ion. It was therefore the aim of this study to characterize the natural organic matter in the cooling water circuits at Lethabo power station (Vereeniging) and to investigate its potential to complex with calcium. The cooling water and raw water samples were comprehensively analyzed for major metal ions, anions and dissolved organic carbon using AAS, ICP-OES, IC and TOC analyzer and the results entered into MINTEQA2 speciation program to determine the precipitation potential of aragonite and calcite in the water samples. The natural organic matter from the cooling water and raw water were isolated initially through the cross-flow ultrafiltration using a polysulfone membrane with a molecular weight cut-off of 45 kDa. The collected isolates were characterized by ultraviolet-visible spectrophotometer, Fourier transform-infrared spectroscopy and (carbon, hydrogen and nitrogen) elemental analysis. The natural organic matter was also fractionated on ultrafiltration stirred cells using membranes with molecular weight cut-off of 1 kDa, 10 kDa and 100 kDa and then characterized using high performance size-exclusion chromatography. The isolated fractions were also titrated with sodium hydroxide and with calcium chloride to determine the amounts of carboxylic and phenolic groups available for complexation and the extent of the complexation of the fractions with calcium respectively. The speciation results from MINTEQA2 indicated that the raw water had a potential to be corrosive and the cooling water had a potential to scale. Higher concentrations of the natural organic matter were detected in the permeate from the cross-flow ultrafiltration process which suggested that it had predominantly a low molecular weight fraction. This low molecular weight fraction was further confirmed by the results from the high performance size-exclusion chromatography analysis of the fractions obtained from the fractionation process using ultrafiltration stirred cells. The specific ultraviolet absorbance and ratios of 465 to 656 nm absorbances results indicated that the organic compounds were mostly aliphatic in character. Titration of the concentrated organic isolates with sodium hydroxide solution revealed that the fractions had a high content of titratable acidic groups and titrating with calcium chloride showed that there is considerable complexation with calcium to affect calcium carbonate precipitation. / Dr. M. Shumane

Recently the uniqueness of the vernal pool habitat has been recognized by several groups of biologists. A survey of the literature reveals that interest of botanists, but one notes a lack of information of plankton which are so fundamental in the food web. Therefore, a taxonomic survey of the plankton seems appropriate. In the present study, the abundance of the predominant species of plankton were studied during a seasonal and also diurnal cycle. A possible correlation of this information with some physicochemical factors was also tested. Because of time constraints this study was limited to one pool but hopefully other researchers will extend this work in the future.

Groundwater contamination and soil salinisation are a major environmental problem worldwide. Living organisms depend largely on groundwater for their survival and its pollution is of course of major concern. It therefore goes without saying that remedial processes and understanding of the mathematical models that describe contaminant transport is of great importance. The theory of contaminant transport requires understanding of the water ow even at the microscopic level. In this study we focus on macroscopic deterministic models based on di erential equations. Here contaminant will refer to nonreactive contaminant. We aim to calculate Lie point symmetries of the one-dimensional Advection-di usion equation (ADE) for various forms of the di usion coe cient and transport velocity. We aim to employ classical Lie symmetry techniques. Furthermore, reductions will be carried out using the elements of the optimal systems. In concluding, the ADE is analyzed for selected forms of the the di usion coe cient and transport velocity via the potential symmetry method. For the potential symmetries obtained, we investigate the associated invariant solutions.

The population and industrial complexes of Choctaw County obtains much of its water from an aquifer system in the Tertiary age Wilcox unit of the Mississippi Embayment. Utilizing 20 years of physical chemistry (P-Chem) analysis, potentiometric groundwater records of Choctaw County public water wells as well as industrial P-Chem analysis and surface and ground water level records from an industrial complex, this study examined the changes to the hydrosphere that has taken place since 1995. Analysis of the hydrosphere shows that over the last 20 years, there has been a drop in the potentiometric surface of the Wilcox aquifer system. The analysis also shows changes in the P-Chem of the hydrosphere, changes such as a decrease in the concentration of free CO2 and chloride, and fluctuations of Alkalinity. Comparisons between groundwater records taken from the industrial complex and other locations around Choctaw County, show little variation in the physical chemistry.

No description available.

In this study an effort was made to determine by analysis the principal minerals that are dissolved in the water of the Little Wichita River.

No description available.

Precipitation of solids in plumbing systems (i.e., scaling) is a major problem in both traditional tank (electric and gas) and tank-less building hot water systems. Scaling can cause energy inefficiencies, flow reduction, pressure loss, and erosion corrosion damage. Consumers are also concerned with unsightly soap scum, cloudy water, discolored glassware, and failing infrastructure including appliances and fixtures. There are many treatments available that claim to ameliorate scaling problems, and several efforts have been made to develop standardized test protocols to verify and quantify their performance. This work critically evaluated previous testing efforts and revealed limitations in terms of reproducibility and a need to measure all key aspects of scale deposition including quantity, location, aesthetic and other issues. A Standardized Scaling Test Protocol (SSTP) was conceived and vetted to address these deficiencies and measure key parameters of calcium carbonate scaling throughout a model premise plumbing system, while using a synthesized test water that could provide reproducible results in any laboratory. This synthetic water and methodology was able to produce significant scaling in a model hot water system within the targeted 5-day experimental time frame. The average amount of scale recovered for the triplicate control tests (with no scale reduction device) was 25.1 grams of calcium carbonate with a 95% confidence interval of 20.3-29.8 grams of calcium carbonate. The approach also worked in recreating scaling in natural waters and was used to verify the performance of a wide array of scale reduction technologies including cation exchange softeners, electrochemical deionization, physical magnets or electric field generators, media induced precipitation, sacrificial media (phosphate), and sacrificial media (citric acid). While calcium carbonate precipitation within a water distribution system is generally undesirable; it was recently discovered that calcium carbonate particles are sometimes naturally clogging leaks in pipes and extending the lifetime of aging infrastructure. Corrosion inhibitors, mainly phosphates, have been increasingly dosed (up to 3.0 mg/L as PO4) into water to inhibit the corrosion of lead and copper pipelines in potable water systems since the advent of the Lead and Copper Rule (LCR) in 1991 by US Environmental Protection Agency (EPA). Phosphate corrosion inhibitors are now used at over 50% of water utilities in the United States and they can affect calcium carbonate scaling kinetics. In bench-scale experiments, the critical concentrations of phosphates that could inhibit leak repair over the short-term in one water tested were: tripolyphosphate (0.05 mg/L as P) < hexametaphosphate (0.1 mg/L) < orthophosphate (0.3 mg/L). The results prove that dosing of phosphates for corrosion control will also affect the kinetics and likelihood of calcium carbonate precipitation, with both beneficial and adverse consequences for pipes and consumers. Specifically, increased use of inhibitors for corrosion control is expected to reduce the likelihood of all calcium carbonate scaling problems while reducing the likelihood of autogenous pipe leak repair. In Providence, RI the dosing of orthophosphate at relatively high pH to control a lead corrosion problem, caused formation of a white precipitate, consumer reports of white water, clogging of aerators and loss of the added soluble phosphate corrosion control inhibitor due to precipitation. The precipitate was identified as a calcium phosphate solid. Field and lab scale tests suggest that at doses below 2 mg/L as PO4, precipitation did not occur in water at pH 10.4 even when the water was heated to 48°C. However, if the water was dosed above 2 mg/L as PO4 precipitation occurred within 5 minutes, and once pre-existing particles were formed precipitation tended to continue even at much lower phosphate doses. Virtually all of the phosphate precipitated within 4 hours at the upper range of 60°C that is commonly found in water heaters. Thus, dosing of phosphate can actually increase scaling problems in some circumstances. Prior work has highlighted a need for a simplified bench-scale test that can be used to rapidly screen for qualitative trends in scaling. The SSTP and practical experience showed that the vast majority of scaling occurred in the water heater. Therefore, a simplified bench-scale test consisting of a heating element in a small volume of water could be used to focus on the most sensitive aspect of scaling. A 3-hour bench-scale test was developed to quickly examine scaling with orders of magnitude less volume, time, labor, cost, and space requirements. This approach was used to evaluate aspects of scaling in water heaters for the following illustrative examples: (1) scale impacts of combined phosphate corrosion inhibitor addition and partial water softening at centralized treatment plants, (2) role of silica concentration in scaling propensity and deposit durability, (3) effects of phosphate addition on scaling in a water known to cause erosion corrosion pipe damage. This dissertation reveals the complexity of scaling for consumers and water utilities and provides tools to systematically study and resolve these practical problems. Dosing of phosphate corrosion control inhibitors can increase scaling from calcium phosphate, decrease scaling of calcium carbonate, and in other cases will have little or no effect on scaling. Both calcium carbonate and calcium phosphate can contribute to scaling as controlled by pH, temperature, hardness, phosphate dose, and other circumstances. The standardized bench and pilot scale approaches developed herein, can serve as a basis for building knowledge reproducibly in any modern laboratory. These methods can also be used to verify performance claims for a wide range of scale reduction technologies, test treatments that could be applied at centralized treatment plants, and optimize water heater design dependent on water chemistry. / Doctor of Philosophy / Precipitation of solids in plumbing systems (i.e., scaling) is a major problem in both traditional tank (electric and gas) and tank-less hot water systems. In addition to scale build up within the hot water system, consumers are also concerned with unsightly soap scum, cloudy water, discolored glassware, and failing infrastructure including appliances and fixtures. There are many treatments available that claim to mitigate scaling problems, and several efforts have been made to develop standardized test protocols to verify and quantify their performance. This work evaluated previous testing efforts to determine limitations in their methodology. A Standardized Scaling Test Protocol (SSTP) was developed to address these deficiencies and measure key parameters of calcium carbonate scaling throughout a model home plumbing system, while using a test water that could provide reproducible results in any laboratory. The test water was able to produce significant scaling within a 5-day test period with reproducible results. While calcium carbonate precipitation within a water distribution system is generally undesirable; it was recently discovered that calcium carbonate particles are sometimes naturally repairing leaks in pipes and extending the lifetime of aging plumbing systems. An increasing number of water treatment plants are adding corrosion inhibitors to water to prevent the corrosion of lead and copper pipelines. Small scale lab experiments were run to determine how effective this natural leak repair was when there were corrosion inhibitors in the water. The results showed that most corrosion inhibitors also prevented or delayed calcium carbonate precipitation which reduced the likelihood of pipe repair through clogging leaks. In Providence, RI the addition of a corrosion inhibitor caused a white precipitate to form in the water which led to consumer complaints of white water and clogging of aerators. This was due to the uniquely high pH of the water. The precipitate was identified as a calcium phosphate solid. Field and lab scale tests suggest that there is a critical inhibitor dose, below which no precipitation occurred in the high pH water. However, if the water was dosed above this critical limit, precipitation occurred immediately and continued as time went on. Prior work has highlighted a need for a simplified bench-scale test that can be used to rapidly screen for qualitative trends in scaling. A 3-hour bench-scale test was developed to quickly examine key aspects of scaling with orders of magnitude less volume, time, labor, cost, and space requirements. This dissertation reveals the complexity of scaling for consumers and water utilities and provides tools to systematically study and resolve these practical problems.

Eight identical and independent pilot scale recirculating aquaculture production systems were populated with fingerling hybrid striped bass <i>(Morone chrysops</i> female x <i>Morone saxatilis male</i>). Three population densities were established with two replicates at 132 fishlm3 and three replicates each at 66 and 33 fishlm3. Water chemistry and water quality characteristics were monitored throughout the 228 day growth trial for all eight systems. A system component performance analysis was done for both the multi-tube solids clarifier and rotating biological contactor (RBC). Water chemistry and water quality analysis included dissolved oxygen (DO), alkalinity, ions, carbonaceous biochemical oxygen demand (CBODS), chemical oxygen demand (COD), dissolved organic carbon (DOC), total suspended solids (TSS), volatile suspended solids (VSS), total ammonia nitrogen (TAN) , nitrite and nitrate. The major ions present were chloride, nitrate, sulfate, phosphate, sodium, calcium, magnesium and potassium. Trace levels of TAN, nitrite, iron and copper were also observed. Sodium, calcium and chloride levels were controlled based on a preplaned water exchange and chemical management method. TAN, nitrite and nitrate levels increased over time with increasing feed rates but never reached levels toxic to the fish population. CBODS,COD, DOC, TSS and VSS increased over time increasing as a function of increasing feed rates. No correlation was observed between fish mortality or fish growth rates for the range of organic and solids parameters observed during this study. On average 67% of the TSS present was between 1.5 and 30 microns in size. Diurnal cycles were observed for DO, TAN and alkalinity. The magnitude of these cycles were population dependent. Multi-tube clarifiers removed an average 56% of all suspended solids in a single pass with 81 % removal efficiency for particles above 70 microns in size. Analysis of the system effluent generated by the clarifier indicates a high degree of similarity between the aquaculture effluent and standard municipal waste on a nutrient basis but with much higher levels of nitrogen and phosphate species. RBC nitrification performance was fitted to an empirical equation. A nearly constant TAN removal rate was observed over the range of mass loading experienced in this growth trial. This implies that within a reasonable range higher flow rates resulting in higher mass loading will yield higher TAN removal rates for a given RBC. / Master of Science

The building plumbing microbiome has important implications, especially in terms of its role as a reservoir and conduit for the spread of opportunistic pathogens (OPs), such as Legionella pneumophila. This dissertation applied next-generation DNA sequencing tools to survey the composition of building plumbing microbiomes and assessed hypothetical factors shaping them. A challenge to identifying key factors shaping building plumbing microbiomes is untangling the relative contributions of influent water quality, provided by drinking water utilities, and those of building-level features, such as pipe materials. To this end, standardized pipe rigs were deployed at the treatment plants and in distal portions of the water distribution system at five water utilities across the eastern U.S. Source water and treatment practices appeared to be the overarching factors shaping the microbial taxonomic composition at the tap, with five key water chemistry parameters identified (total chlorine, pH, P, SO42- and Mg2+). Hot water plumbing is of particular interest because OPs tend to proliferate in warm water environments and can be inhaled in aerosols when showering. Two identical lab-scale recirculating hot water rigs were operated in parallel to examine the combined effects of water heater temperature set point, pipe orientation, and water use frequency on the hot water plumbing microbiome. Our results revealed distinct microbial taxonomic compositions between the biofilm and water phases. Importantly, above a threshold of 51 °C, water heater temperature, pipe orientation, and water use frequency together incurred a prominent shift in microbiome composition and L. pneumophila occurrence. While heat shock is a popular means of remediating L. pneumophila contamination in plumbing, its broader effects on the microbiome are unknown. Here, heat shock was applied to acclimated lab-scale hot water rigs. Comparison of pre- versus post- heat shock samples indicated little to no change in either the microbial composition or L. pneumophila levels at the tap, where both water heater temperature and water use frequency had the most dominant effect. Overall, this dissertation contributes to advancing guidance regarding where to most effectively target controls for OPs and also advances research towards identifying the features of a 'healthy' built environment microbiome. / PHD / Drinking water is often misconceived to be “sterile,” whereas in reality the water distribution and plumbing systems that convey the water to the consumer represent a robust microbial habitat. While it is not possible, or even desirable, to kill all of the microbes present in drinking water, the Safe Drinking Water Act in the U.S. enforces measures to purify and disinfect water at the treatment plant and keep bacterial numbers low in water mains and up to the consumer property line. However, current regulatory frameworks are designed to protect against fecal- (e.g., raw sewage and manure) derived pathogens, whereas recently opportunistic pathogens (OPs), including Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa have come to the forefront as the leading source of tap-water related illness in the U.S. and other developed countries. In contrast to traditional fecal pathogens, building plumbing systems are a natural habitat for OPs, where they can readily proliferate. Currently there are no provisions within the Safe Drinking Water Act or other regulations to protect consumers specifically from OPs. There are also no “silver bullet” remedial measures that consistently and reliably defend against OPs colonizing building building plumbing, particularly when aiming to protect against multiple types of OPs. A major challenge in preventing and remediating OP proliferation in building plumbing is that they tend to be protected from disinfectants, such as chlorine, inside amoeba hosts and within the slimy layer that forms on the surface of pipe walls called “biofilm”. With the recent advent over the past decade of next-generation DNA sequencing, there are new reasons to take interest in the microbial composition of tap water. In particular, next-generation DNA sequencing has provided new insight into the composition of the human microbiome, e.g., the microbes that naturally inhabit our skin, gut, and lungs, and has revealed striking relationships with human health (e.g., obesity, diabetes, asthma, autism, allergies). The question naturally arises with respect to the factors shaping the human microbiome, with role of the “built environment” being of fundamental interest. The built environment; including homes, offices, schools, hospitals, and vehicles, is where most humans in developed countries spend > 90% of their time. Tap water is likely an important feature shaping the microbiome of the built environment, serving as a conduit for microbes into tiny droplets called aerosols, which can be inhaled into the lungs or otherwise inoculate the skin during showering or be transferred onto food during food preparation. Thus, there is interest in mapping out the microbiome of tap water and the factors that shape it, not only because of its potential to harbor OPs, but because of its potential general effect on built environment and human microbiomes. Long-term research could lead towards identifying which microbes serve a beneficial, or “probiotic,” role in preventing pathogen growth and benefiting human health. The purpose behind the body of research described in this dissertation was to apply newly available next-generation DNA sequencing tools towards mapping out the microbial composition characteristic of tap water, with emphasis on implications for preventing proliferation of OPs. Of particular interest was the relative role of what water utilities and building operators can do to protect public health. To this end, the DNA sequencing approach was applied to carefully controlled and replicated field- and laboratory-scale plumbing rigs to gain insight into the relative roles and interactions of the water quality provided by drinking water utilities and practical building-level engineering controls. Specific factors investigated included: stagnation (i.e., the tendency of water to sit unused in pipes in 8 hour cycles), pipe material (e.g., metallic versus plastic), pipe configuration (i.e., up or down flow to induce convective mixing vs stratification, respectively), water heater temperature set point (i.e., balancing hotter temperatures needed to kill pathogens versus lower temperatures desirable to save energy or prevent scalding), and heat-shock treatment (i.e., temporarily elevating the water heater temperature and flushing the system to kill off pathogens). There were several general findings that can be highlighted based on this research. First, based on comparison of standardized plumbing rigs installed at five water utilities in the U.S., the nature of the water provided by the local water utility was the overarching factor shaping the microbiome composition at the tap, moreso than pipe material or stagnation. Second, there exists an ideal threshold water heater temperature setting (51 °C based on the conditions of this study) above which there is a concordant shift in microbiome composition and decrease in L. pneumophila occurrence. Third, consistent water heater temperature setting above this threshold has a stronger long-term influence on the microbiome composition and L. pneumophila control than temporarily elevating the temperature for heat-shock treatment. Finally, biofilm and bulk water microbial compositions are extremely diverse in composition (e.g., thousands of species of microbes in each) and functional markers, and distinct from one anaother in terms of their characteristics under different operational conditions. In sum, this study takes a step towards better understanding building plumbing microbiome and identifies several promising engineering and control factors that can ultimately inform intentional engineering of the building plumbing microbiome, particularly with respect to protecting public health against OPs and potentially other microbiome-related ailments in the future.