Tesi sul tema "Drinking water"

4 pp.
Gasses, minerals, bacteria, metals and chemicals suspended or dissolved in water can influence the quality of the water and hence affect our health. Therefore, EPA, the U.S. Environmental Protection Agency, has established limits on the concentration of certain drinking water contaminants allowed in public water supplies. This publication discusses drinking water standards and how these standards are set.

This dissertation involves two different studies. The first concerns the real-time detection of microbial contamination in drinking water using intrinsic fluorescence of the microorganisms. The prototype, “Blinky”, uses LEDs that emit light at 365nm, 590nm, and 635nm for ultraviolet, amber, and red light, respectively. At 365 nm, the cellular components excited include reduced pyridine nucleotides (RPNs), flavins, and cytochromes to distinguish viable bacteria; at 590 nm, the cellular components excited include cytochromes for non-viable bacteria; at 635 nm, the cellular components excited include calcium dipicolinic acid (DPA) for spores. By using these three different wavelengths, the prototype can differentiate between viable and non-viable organisms and also has the potential to detect spores. The aim of this study was to improve the detection limit by modifying the design of the instrument and to establish the detection limit of viable and non-viable bacteria and spores. The instrument was modified by replacing existing LEDs with LEDs that had 50% more intensity. Two additional LEDs were added for amber and red light, bringing the total to four LEDs for each. The LEDs were also positioned closer to the photomultiplier tube so as to increase sensitivity. For UV, only two LEDs were used as previous. The detection limit of the viable bacteria was ~50 live bacteria/L. No change in the intrinsic fluorescence below the concentration of ~10⁸ dead bacteria/L was observed. The results for spore measurements suggested that most of the spores had germinated before or during the measurements and could not be detected. The instrument was successful in detection of viable bacteria and also differentiating viable and non-viable bacteria. The instrument was not successful in detection of spores. The second study was designed to assess the water quality of well construction in southeastern Tanzania. Three designs were tested: Msabi rope pump (lined borehole and covered), an open well converted into a closed well (uncovered well into a covered and lined well), and an open well (uncovered and may or may not be lined). The study looked at the microbial and chemical water quality, as well as turbidity. The survey included 97 water collection points, 94 wells and three rivers. For microbial analysis, heterotrophic plate count (HPC), total coliforms and E. coli tests were performed. Fifteen of these wells were further analyzed for microflora and diversity for wells comparison purposes, using culture methods, followed by polymerase chain reaction (PCR) and genome sequencing. Ten wells out of the fifteen were analyzed for calcium (water hardiness), potassium, nitrates, nitrites, chloride, fluoride, bromide, sulfate, iron, and arsenic. Two water collection points were also selected for organic compound analysis (gasoline components). All samples tested positive for coliforms. Two samples tested positive for Escherichia coli for the lined borehole (Msabi rope pump) and four samples from closed wells. All open wells tested positive for E. coli. There was more microbial diversity in open wells than the closed wells and Msabi rope pumps. Potential bacterial pathogens were detected in seven wells out of the fifteen examined. The wells that tested positive were one Msabi rope pump, one closed well; the rest were from open water sources. Open wells had high turbidity followed by closed wells. Msabi rope pumps had low turbidity comparing to the two wells designs. No traces of gasoline components were detected in any of the water sources. One well out of ten had high amounts of nitrates-nitrogen (> 10 mg/L). The results of this study showed that the Msabi rope pumps performed comparably to the closed wells in terms of microbial quality but performed better with regard to turbidity. The open wells performed poorly in terms of microbial water quality as well and turbidity. There was a statistical difference in HPC, total coliforms, E.coli numbers and turbidity between open wells, closed wells and the Msabi rope pumps. However, there was no statistical difference in HPC, total coliforms and E.coli numbers between the closed wells and Msabi rope pumps. Msabi rope pumps performed better in turbidity

2 pp.
Arsenic is the twentieth most abundant element in the earth's crust and frequently occurs in rock formations of the Southwestern United States. Arsenic remains in the environment over long periods and when it occurs in high concentrations, it can be toxic to many life forms, but it also has been shown to be an essential nutrient for many animal species and may be to humans, too. This publication provides information about the impact arsenic in drinking water has over human and plant health and the ways to remove it.

Thesis (Master)--İzmir Institute Of Technology, İzmir, 2005.
Keywords:Trihalomethane, volatile organic compounds, drinking water, risk assessment, exposure. Includes bibliographical references (leaves. 64-70).

In light of substantial medical evidence of the detrimental effect of lead on the body, the use of lead in pipe networks, and the subsequent lead emissions into drinking water is now a major concern. As a result, the new European Union 'drinking water' directive requires the standard for lead in drinking water to be tightened from 50pg/l to 25pg/l by December 2003 and to 10pg/l by December 2013. It is anticipated that these standards will be achieved by a combination of water treatment, which must be optimised, and selective lead pipe replacement where necessary. In order to optimise corrective treatment, accurate monitoring of lead emissions across a water supply zone must be achieved. The severe limitations of traditional monitoring methods have provided the motivation to develop a computational model to facilitate the optimisation of corrective treatment as well as to investigate lead emissions at individual houses. The development of a model to assess lead emissions in drinking water at a single house and across a water supply zone is described. The model has been used to investigate the daily variation of lead emissions at a single house and to determine the influence of factors, such as pipework geometry and water usage, on the daily average concentration of lead in drinking water. The ability to simulate traditional sampling methodologies on simulated water supply zones has enabled the model to be validated for a wide range of real water supply zones. This has allowed the model to be used successfully for the purposes of assessing zonal compliance and facilitating the optimisation of corrective treatment. Additionally, the model has enabled a detailed assessment of the use of the Random Day Time sampling method, for the optimisation of plumbosolvency control.

Human demand for clean water has increase drastically in the past centuries, mainly due its demographic growth. The sources of clean drinking water have been continuously reduced due to depletion or contamination with one example being the extensive use of fertilizers in agriculture, which can lead to leaching of nitrates into groundwater and hence into surface water. The gravity of the situation was expressed by European Environmental Agency in 1998, revealing that, 87% of agricultural areas in the European Union (EU) have nitrate concentrations in groundwater above the guide level (25 ppm). Catalytic hydrogenation is one potential solution if an appropriate active, selective catalyst could be identified. One of the major drawbacks of the hydrogenation approach is the absence of robust studies which clearly describe what happens during reaction, essential for full understanding of the process. It was decided to use FTIR under operando conditions to try to disclose what happens in the catalyst surface during reaction. Pd/TiO2 catalysts were selected one. Upon adsorption at Lewis acid sites (oxygen vacancies), the nitrates are reduced by the electron enriched titania species, most likely Ti4O7 as identified by electron microscopy, which lead to the formation of nitrites, generally detected in solution during the hydrogenation tests and expected assuming a stepwise mechanism exists. The rather weak adsorption of nitrate onto the catalysts surface allied to their stability might be the reasons for their low reactivity, i.e., limiting step of the hydrogenation process. The nitrite reduction occurs essentially on Pd sites however their adsorption site is Lewis acid sites. NO is adsorbed and reduced exclusively on the noble metal. The order of reactivity of the surface species decreases with the decrease in the oxidation state of the nitrogen, i.e., NO3- NO2- NO. High surface concentration of nitrite leads to the formation of N2O, while ammonia is formed via consecutive hydrogenation of Nads. originating from the dissociation of NO. Ammonia formation takes place over Pd and is dependent on the hydrogen availability and presence of water. Ever since Becquerel discovered the photoelectric effect back 1839, researchers and engineers have been infatuated with the idea of converting light into electric power or chemical fuels. Photocatalysis is also particularly suitable for the abatement of contaminants since it offers potentially high conversions at low cost. Two aspects have dominated the research of photocatalysts, namely improvement of catalytic performances under visible light and the minimization of charge recombination. The latter can be improved by a decrease in the particle size and/or by the addition of small metal clusters of elements such as Cu that operate as electrons sinks thus allowing the system to be employed in processes such as N03- reduction. The addition of metal to TiO2 P25, led to a significant enhancement in the photocatalytic activity of the catalyst. The overall process was found to be dependent on the temperature of reaction media, and the nature and concentration of the hole scavenger, and on the metal loaded. In the case of Hombikat, the metal-free support appeared to operate better possibly as a consequence of its greater surface area as this would hinder, to a certain extent, the charge recombination process. EPR and FTIR experiments under UV irradiation carried out using the metal clusters (Au, Ag and Cu) supported on TiO2, revealed that the presence of the metal leads to the loss of signal related to the stabilized electrons on the pure TiO2 when a hole scavenger such as hydrogen is present. The Fermi level equilibration process, in a semiconductor - metal nanocomposite system, is a clear indication of the presence of electron transfer process between support and metal. Addition of the metal did not, however, modify the band gap energy of the studied semiconductor. In the generality of the cases studied, the photocatalytic approach was found to have much higher activities when compared to the hydrogenation process.

Thesis (M.F.A.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of English. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Water resources in many parts around the world are becoming critical because of human activity. This leads many countries around the world to rely more on their groundwater as an essential source of drinking water. The situation in Libya is critical because there is no access to surface fresh water. The rainfall rate is very low, but there is a huge quantity of ground water with good quality (average TDS around 1030 mg/l) and this leads the country to rely on this water source. The Great Man-Made River Authority (GMRA) was established to produce and transfer water from the southern part of the country (desert) where ground water is available to the northern coastal strip where most of the population is concentrated. However, the water in some wells in the East Japal Hassouna (EJH) well-field has a high nitrate concentration, more than 50 mg/L as NO3-. To solve this problem and reduce the nitrate content to less than the limits of WHO Guidelines (50 mg/l as NO3- and10 mg/L NO3--N), one of the available techniques of nitrate removal has to be applied. Previous studies have assessed techniques for nitrate removal from drinking water including analysis of their efficiency, ease of operation, impact on the environment and cost of production. Moreover, the characteristics of ground water (good quality) in the EJH well-field and the potential to use solar energy during the whole year was considered. Experimental trial investigated the use of reverse osmosis (RO) powered by solar energy to remove nitrate from synthetic water similar to water in EJH wellfield by operating a RO unit in a closed system and using a single solar pump to deliver feed water to the RO unit and through the unit as well. A range of nitrate concentrations treated by applying different pressures for each nitrate concentration. Nitrate removal percentages ranged between 78% to 90% depending on the initial nitrate concentration of feed water and the applied pressure. An ion exchange experiment was also conducted to remove nitrate from synthetic water similar to water in the EJH wellfield and from a nitrate solution by performing column and batch test experiments. Several nitrate concentrations and contact times were applied. Nitrate removal for the synthetic water were excellent (100% nitrate removal) but chloride concentration in the produced water increased over the limits of WHO guidelines. When the same nitrate concentration (20 mg/L NO3--N) in feed water was applied in both techniques, both of them gave a good result in terms of nitrate removal capacity as mentioned above. However, the produced water by ion exchange still contained chloride concentrations over the limits of WHO guidelines in contrast to reverse osmosis which did not produce this unintended effect.

4 pp.
This short fact sheet is taken from "Arizona Well Owner's Guide to Water Supply" currently in print. We plan to complete part 2 of this fact sheet by the end of July, 2009. Please note that the text has already been incorporated into the eXtension Community of Practice web page - - I am the author for the COP/Drinking Water group text on chemistry of naturally occurring water contaminants.
Arizona well water is often contaminated with elevated concentrations of naturally occurring constituents that are a human health concern. This short fact sheet is the first in a two-part series about what naturally occurring contaminants may be found in your water supply well and includes a brief discussion on environmental pollutants that originate from land use activities. If you own a well in Arizona, you have the sole responsibility for checking to see if your drinking water is contaminated. Arizona state law does not require private well owners to test or treat their water for purity. The second part of this series outlines what to sample for and how to understand your analytical results.

1 pp.
Infants and certain elderly people are the most susceptible to nitrates found in water. When these individuals drink water or eat foods that contain high levels of nitrates, their blood can lose the ability to effectively carry oxygen. This condition is called methemoglobinemia or blue baby syndrome. This article discusses the health problem caused by nitrates found in your drinking water, and the way to test for those nitrates.

Approximately 80% of Virginians with private drinking water (PDW) sources are unaware of the quality of their drinking water. Strontium is a water quality contaminant gaining recognition at the federal level. At concentrations >1.5 mg/L, strontium substitutes calcium in the bones leading to bone density disorders (e.g. rickets). This is particularly problematic for children and individuals with low calcium and low protein diets. Because most Virginians do not know the quality of their PDW and since strontium poses a public health risk, this study investigates the sources of strontium in PDW in Virginia and identifies the areas and populations most vulnerable. Physical factors such as rock type, rock age, and fertilizer use have been linked to elevated strontium concentrations in drinking water. Meanwhile, social factors such as poverty, poor diet, and adolescence also increase social vulnerability to health impacts of strontium. Thus, this study identifies both physically and socially vulnerable regions in Virginia using water quality data from the Virginia Household Water Quality Program and statistical and spatial analyses conducted in RStudio 1.0.153 and ArcMap 10.5.1. Physical vulnerabilities were highest in the Ridge and Valley province where geologic formations with high strontium concentrations (e.g., limestone, dolomite, sandstone, and shale) are the dominant the aquifer rocks. The complex relationship between agricultural land use and strontium concentrations made it difficult to determine the impact of fertilizer use on strontium concentrations in PDW in Virginia. In general, the spatial distribution of social vulnerability factors was distinct from physical factors with the exception of food deserts. This study provides information and analysis to help residents of Virginia understand their risk of strontium exposure in PDW.
Master of Science
There are 1.7 million residents in Virginia that rely on private drinking water supplies in their homes. Those individuals are responsible for knowing how often to test their water, what to test their water for, and how to treat their water, if needed, to achieve safe drinking standards. Unfortunately, approximately 80% of Virginians with private drinking water sources (e.g., wells, cisterns, and springs) do not know if their water is safe to drink. Strontium, an element closely related to calcium, is a contaminant that the federal government recognizes as dangerous because in high quantities (>1.5 mg/L of water) it can replace calcium in bones making them brittle (e.g. rickets). These health impacts are more extreme in children and individuals with low calcium and low protein diets. Since strontium poses a public health risk, this study identified areas and populations in Virginia that have higher chances of being exposed to strontium and higher chances of their health being impacted by high levels of strontium. Physical factors such as rock type, rock age, and fertilizer use have been linked to elevated strontium concentrations in drinking water, indicating various physical vulnerabilities. Meanwhile, social factors such as poverty, poor diet, and adolescence also increase social vulnerability to the health impacts of strontium. This paper investigates regions in Virginia that are likely to contain high strontium levels and thus potential health impacts from strontium. Statistical and spatial analyses of water quality data from Virginia Cooperative Extension’s Virginia Household Water Quality Program combined with risk factor data identified vulnerable areas in Virginia. The highest chance of exposure was in counties near the western border of the state (e.g., Augusta, Fredrick, Highland, Montgomery, Shenandoah, and Wythe) due to the presence of limestone, dolomite, sandstone, and shale, all of which naturally contain high amounts of strontium. The land use data indicated that there were no strong patterns of strontium occurrence relative to fertilizer use. In general, the spatial distribution of social vulnerability factors was distinct from physical factors with the exception of food deserts occurring at high rates in the same areas as the samples with high strontium levels (e.g., Augusta, Fredrick, Highland, Montgomery, Shenandoah, and Wythe). The presence of food deserts prevents individuals from obtaining a high calcium and high protein diet, which makes them more vulnerable to the impacts of strontium. Overall, this study can help people in Virginia who are not on public water systems understand their risk of from being exposed to strontium.

Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2008.
A thesis submitted for the degree of Doctor of Philosophy, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2008. Typescript. Includes bibliographical references: p. 263-278.

Perceived drinking water quality is a factor known to cause the failure of drinking water schemes in developing countries. This leads to the loss of health benefits which are the main aims of such schemes. This thesis examines the relationship between perceived and actual drinking water quality and the factors which feed into perceived drinking water quality in a developing countries context. A mixed methodology approach was used which included the use of the following methods: a questionnaire (n=96), participant observations, interviews, a media study, analysis of other texts, sanitary surveys, and analysis of source (2006 n=32, 2007 n=70) and household (2006 n=58, 2007 n=91) water samples for thermotolerant coliforms, chlorine, pH, turbidity and colour. The drinking water situation was found to be more complex than originally thought and drinking water practices were found to be supply driven. The quality of water at the source had little influence on the quality of water drunk in the household, as water was becoming contaminated during collection and in the home. Household water managers prioritised the importance of the different water sanitation and hygiene interventions as the water situation changed, but the rating of drinking water quality remained consistent and was rated as the most important intervention in both periods. The factors that were associated with perceived drinking water quality significantly changed from 2006 to 2007, but the importance of perceived drinking water quality remained consistent. Therefore the factors that influenced the perception of drinking water quality were not fixed and were responsive to changes in the water situation in the community. A surprising relationship was found between perceived and actual drinking water quality, which can be attributed to chlorine being associated with ‘good’ drinking water.

El agua de consumo subministrada a través de las redes de distribución deviene alterada durante su circulación en el mismo debido a la actividad microbiana. Estos cambios en la calidad a menudo afectan al sabor, color y al olor. En otros casos, la calidad sanitaria de agua es alterada debido al recrecimiento bacteriano. La masa del agua, es el mayor hábitat de un sistema de aguas potables, aunque la mayoría de cambios significativos en sus propiedades tienen lugar en las superficies de contacto las cuales están colonizadas por microorganismos creciendo en diferentes comunidades microbianas adaptadas a los bajos niveles de nutrientes, altos niveles de cloro, formando biopelículas. Este trabajo demuestra que el agotamiento de cloro en el suministro de agua es clave para la proliferación microbiana en todo el sistema. Un nivel adecuado de cloro (~ 0,5 mg / l) es suficiente para garantizar la ausencia de biopelículas incluso después de eventos de contaminación microbiana o la entrada de carbono orgánico en el sistema. Sin embargo, la reducción de los niveles de cloro, incluso sin la adición de carbono o el aumento de la carga microbiana suspendida, permite el desarrollo de una comunidad unida en aproximadamente 2 semanas. En este escenario, la liberación de células microbianas en la fase acuosa se incrementó 10 veces en la ausencia de cloro. Episodios posteriores de agotamiento del cloro pueden acelerar el desarrollo de las comunidades microbianas con susceptibilidad reducida a la desinfección en los sistemas de agua potable real. Se necesitan enfoques alternativos de desinfección, no sólo para la distribución de agua potable, sino también para el control del crecimiento de biopelículas En este trabajo se ha evaluado la aplicabilidad de una nueva familia de desinfectantes llamados tiol bismuto (BT), que representan una nueva generación de agentes antibacterianos. Estos agentes están basados en el Bismuto, pero su actividad antibacteriana se ha mejorado notablemente en combinación con ciertos compuestos de tiol lipófilos. BTs exhiben efectos residuales más persistentes que el cloro a pesar de su acción relativamente lenta. BTs podrían ser especialmente útiles para los ecosistemas de agua artificiales en las que es muy difícil mantener un nivel constante de cloro libre, tales como sistemas de agua caliente o torres de refrigeración. Los BT tienen efectos residuales más persistentes que el cloro y la hiper-calefacción en los sistemas de agua. Eficiencia del BT aumentó con la temperatura, pero, al igual que los iones de cobre y plata, su acción es relativamente lenta. La combinación de efectos bactericidas y residuales puede prevenir la acumulación de limo en sistemas de agua caliente.
The water supply released into the distribution system is altered during its passage through the system due to a large extent to microbial activity. These quality changes most often result in complaints about taste, odour, and colour. In other cases, the sanitary quality of water is altered due to bacterial regrowth. The water body is the major habitat of drinking water systems, though the most significant changes in drinking water properties are at contact surfaces, which are colonized by microorganisms growing in diverse microbial communities adapted to low nutrient and high chlorine levels, forming biofilms. This work demonstrates that chorine depletion in the water supply is key to microbial proliferation throughout the system. An adequate level of chlorine (~0.5 mg/l) is enough to ensure the absence of biofilms, even after microbial contamination events or the input of organic carbon into the system. However, reducing chlorine levels, even without adding carbon or increasing the suspended microbial load, allows the development of an attached community in approximately 2 weeks. In this scenario, the release of microbial cells into the water phase increased 10-fold in the absence of chlorine. Subsequent episodes of chlorine depletion may accelerate the development of microbial communities with reduced susceptibility to disinfection in real drinking water systems. Alternative disinfection approaches are needed, not only for the distribution of safe water, but also for the control of biofilm growth. In this job has been evaluated the applicability of a new family of disinfectant called bismuth thiol (BT), which represents a new generation of antibacterial agents. These agents are bismuth based, but their antibacterial activity has been enhanced markedly in combination with certain lipophilic thiol compounds. BTs exhibit more persistent residual effects than chlorine despite their relatively slow action. BTs could be especially useful for artificial water ecosystems in which it is very difficult to maintain a constant level of free chlorine, such as hot water systems or cooling towers. BTs have more persistent residual effects than chlorine and hyper-heating in water systems. BT efficiency increased with temperature but, like copper–silver ions, its action is relatively slow. The combination of bactericidal and residual effects may prevent slime build-up in hot water systems.

The following report is the result of a literature study of published documents presenting the current water supply situation in Sub-Saharan Africa, in combination with a field trip to the Mpagne village in Cameroon. The objective of the project has been to study and discuss the current theoretical approach on sustainable water supply, as well as to generate possible technical solutions and present administrative changes required. A thorough background analysis demonstrates the need for improvement on a local village level as well as on a regional, national and international level. Key findings are high failure rates as a consequence of the absence of evaluation of past projects, as well as the fact that many agencies do not work in line with existing policies and theoretically developed approaches to solve the problem. Further, there is a general need to cultivate local political will for long-term commitment and funding of the sector. Although some of the organizations engaged in the sector have started to realise that there is a need for an alteration of approach angle, thus far there is little evidence of the change required to move towards universal coverage. A needs assessment and a requirement specification were developed based on the findings in the background analysis. This was then used to generate possible technical solutions to be further studied. In the process of deciding upon technical solutions, the information gathered in the village, especially that related to the previously implemented system, has been important. After analysing the data collected in Mpagne and studying available technology the following alternatives were developed: Alternative 1: Groundwater exploitation with flywheel handpump, elevated storage tank and gravity based distribution to community tap standAlternative 2: Rainwater harvesting with swale-trench filtration and flywheel handpump, elevated storage tank and gravity based distribution to community tap standAlternative 3: Combination of groundwater exploitation and rainwater harvesting, similar to alternative 1, with the addition of RWH at the village school. In order to systematically compare these options and decide upon a best suited solution, the indicator comparison methodology developed during the fall project was used in combination with a SWOT-analysis of each concept. The final results obtained indicate that alternative 3 was slightly better than the other two alternatives. A description of the technology required for the new water supply facility in Mpagne was then presented to the level it is possible with the information available at this stage. The intention is for this to serve as an initial suggestion to be presented to the villagers for further discussion. The report continues with a discussion of an implementation strategy with an enhanced focus on how the technical system can be installed in Mpagne in a social, economic and environmentally sound context. The discussion covers the following four phases: 1.Planning2.Construction3.Operation and maintenance4.Follow-up and evaluation This process will be especially important considering the past failed project in Mpagne, and an agency should give special attention to including the villagers in all levels from an early stage. This to avoid the deficiency between the solution implemented and the actual needs resulting from the past project. Further findings are the current situation of downgrading external factors such as the availability and reliability of spare part supply networks as well as lack of general technical support. This is a primary cause of project failure today. The lack of coordination amongst the sector operators, including NGO’s, donor agencies, and local and international government entities, is also an important factor which slows down the progress of developing an efficient and effective water supply sector. Lastly, until internal village level factors as well as external regional and national aspects are adequately satisfied, the agencies operating in the rural water supply sector today have a great responsibility in terms of creating an enabling environment for sector development. Project conduction should be done in adherence with existing policies until the local governments and/or private partners have succeeded in developing an institutional framework to support a well-functioning water supply sector.

Thesis (PhD)--Stellenbosch University, 2004.
ENGLISH ABSTRACT: Microorganisms show a tendency to accumulate on surfaces in aqueous environments to form biofilms. Microbial biofilms represent a significant problem in public health microbiology as the development of these microbial communities, especially in water distribution systems, may lead to (i) the enhanced growth of opportunistic pathogens, (ii) the development of organoleptic problems, (iii) the reduction in the flow rate and (iv) the regrowth of microorganisms. In this project, biofilm monitors were installed in a large water distribution system to study biofilm phenomena in drinking water systems, and to deduce the biological stability and quality of the potable water. Measurements of biofilm formation potential showed that biofilms did not reach a steady state after 100 to 150 days. The microbial cells in these biofilms were mostly non-culturable. The contribution of the heterotrophic colony count to active biomass, as determined with cell numbers based on ATP measurements were often < 1%, while the ratio of heterotrophic plate counts and direct acridine orange counts were also <1%. The ratio between cell numbers based on ATP measurements and direct acridine orange counts were often < 100%. Results also showed that under certain conditions, such as those investigated in the present study, 1 pg of ATP may not be equal to approximately 104 active bacteria/cells, as stipulated by previous investigations, and that the average ATP content per active bacterial cell is indeed less than 10-16 - 10-15 g. It was calculated that threshold values for assimilable, and dissolved organic carbon below -5 IJg Gil and -0.5 mg Gil, respectively, should be target values for the control of biofilm formation in this system. It was shown that polyethylene, polyvinylchloride, teflon, plexiglass, copper, zinc-coated steel and aluminium provide favourable attachment surfaces that allowed primary colonisation and subsequent biofilm formation. Significant (p < 0.05) differences in surface colonisation on the materials were observed, indicating that the composition of the material has a direct influence on microbial colonisation. The two grades of stainless steel evaluated in this study were the least favourable materials for biofilm formation. It was further demonstrated that the nature of the surface of these materials, flow conditions and water type all had a direct influence on biofilm formation. While modification of the attachment surface did not result in significant differences (p > 0.05) in disinfection efficiency of two commonly used biocides, the concentration of the biocide, as well as the material to which the biofilm is attached, greatly influenced biocidal efficiency. The results show that biofilm monitoring needs to be implemented at the water treatment plants in addition to common biostability measurements.
AFRIKAANSE OPSOMMING: Mikro-organismes neig om te akkumuleer aan oppervlaktes in akwatiese omgewings om biofilms te vorm. Mikrobiese biofilms verteenwoordig In betekenisvolle probleem in publieke gesondheidsmikrobiologie omdat die ontwikkeling van hierdie mikrobiese gemeenskappe in waterverspreidingsisteme mag lei tot (i) die verhoogde groei van opportunistiese patogene, (ii) ontwikkeling van organoleptiese probleme, (iii) die vermindering in die vloeitempo en (iv) die hergroei van mikro-organismes. In hierdie projek was biofilm monitors geïnstalleer in In groot waterverspreidingsisteem om biofilm fenomene in drinkwatersisteme to bestudeer, en om die biologiese stabiliteit en kwaliteit van drinkwater af te lei. Bepalings van biofilmvormingspotensiaal het aangetoon dat biofilms nie In stabiele stadium na 100 tot 150 dae bereik nie. Die mikrobiese selle in hierdie biofilms was meestal niekweekbaar. Die bydrae van die heterotrofiese kolonie tellings tot aktiewe biomassa, soos bepaal deur seltellings gebaseer op ATP metings was dikwels < 1%, terwyl die verhouding van die heterotrofiese plaatteIIings en direkte akridien oranje tellings ook < 1% was. Die verhouding tussen seltellings, gebaseer op ATP metings en direkte akridien oranje tellings was dikwels < 100%. Resultate het ook aangetoon dat onder sekere omstandighede, soos dié wat ondersoek was in die huidige studie, 1 pg ATP nie gelyk is aan min of meer 104 aktiewe bakterieë/selle soos gestipuleer deur vorige ondersoeke nie, en dat die gemiddelde ATP inhoud per aktiewe bakteriële sel inderdaad minder as 10-16 tot 10-15 g is. Dit was bereken dat die drempelwaardes vir assimileerbare en opgeloste organiese koolstof onder -51-1g C/l en -0.5 mg C/l, onderskeidelik, teikens moet wees vir die beheer van biofilmvorming in hierdie sisteem. Dit was aangetoon dat polyetileen, polyvinielchlroried, teflon, plexiglas, koper, sink-bedekte staal en aluminium gunstige aanhegtings oppervlaktes voorsien wat primêre kolonisering en daaropvolgende biofilmvorming toelaat. Betekinisvolle (p <0.05) verskille in oppervlak kolinisering op die materiale was waargeneem, wat aandui dat die samestelling van die materiaal In direkte invloed op mikrobiese kolonisering het. Die twee tipes vlekvryestaal wat geëvalueer was in hierdie studie, was die minder gunstige materiale vir biofilmvorming. Dit was verder gedemonstreer dat die aard van die oppervlak van hierdie materiale, vloeitoestande, en water tipe almal In direkte invloed het op biofilmvorming. Terwyl die aanpassing van aanhegtingsoppervlak nie die ontsrnettinqsdoeltreffendheid resultaat van die twee algemeen-gebruikte biosiede betekinisvol (p > 0.05) beïnvloed het nie, het die konsentrasie van die biosiede doeltreffendheid grootliks beïnvloed. asook die aanhegtings-materiaal, biosied Die resultate het aangetoon dat biofilm monitering geïmplementeer moet word by waterbehandelingsaanlegte as In alternatief vir algemene biostabiliteit metings.

2 pp.
Chemical contaminants occur in drinking water supplies throughout the United States, ranging from barely detectable amounts to levels that could possibly threaten human health. Determining the health effects of these contaminants is difficult, especially since researchers are still learning how chemicals react to the damaged cells. This publication addresses the issue of chemical contaminants in drinking water, topics include; acute and chronic health effects, setting standards, and treatment techniques.

The current computer models used for simulating water quality in potable water distribution systems assume perfect mixing at pipe junctions and non-dispersive solute transport in pipe flows. To improve the prediction accuracy, the present study examines and expands these modeling assumptions using transport phenomena analyses. Whereas the level of solute mixing at a cross-type junction is evaluated numerically via Computational Fluid Dynamics (CFD), the axial transport in laminar flows is investigated with both CFD simulations and corresponding experimental runs in a single pipe. The findings show that solute mixing at junctions is rather incomplete owing to the limited spatio-temporal interaction that occurs between incoming flows with different qualities. Incomplete mixing shifts the expected propagation patterns of a chemical or microbial constituent from widely-spread to narrowly-concentrated over the service area. On the other hand, solute dispersion is found to prevail over advective transport in laminar pipe flows. Thus, this work develops axial dispersion rates through parameter optimization techniques. By accounting for axial dispersive effects, the patterns of solute delivery shifted from high concentrations over short time periods to lower doses at prolonged exposure times. In addition, the present study integrates the incomplete mixing model into the optimal placement of water quality monitoring stations aimed at detecting contaminant intrusions.

The formation of an objectionable "swampy" odour in drinking water distribution systems in Perth, Western Australia, was first described by Wajon and co-authors in the mid-1980s (Wajon et al., 1985; Wajon et al., 1986; Wajon et al, 1988). These authors established that the odour, variously described as "swampy", "sewage" or "cooked vegetable" was caused by dimethyltrisulfide (DMTS) which has an odour threshold concentration of 10 nanograms per litre (ng/L). Investigations described in the present Thesis extend the work of Wajon and co-workers in attempting to establish the origin and cause of DMTS formation in Perth drinking water distribution systems.The DMTS problem appeared to be confined to water originating from a particular type of groundwater, specifically groundwater sourced from shallow, unconfined aquifers, which contain relatively high concentrations of sulfide, dissolved natural organic matter (NOM) and dissolved iron. DMTS was not present in the groundwater, but only formed in the distribution system, after treatment of groundwater via alum coagulation-filtration and oxidation processes. One objective of the present work was to determine the reasons for the observed association between DMTS formation and this specific groundwater type. A primary focus was to investigate the chemistry and biochemistry of sulfur species and NOM which might act as precursors to DMTS. The work was driven by the view that increased understanding of the problem might lead to more effective and acceptable treatment solutions than those presently in use.The observation that DMTS forms in distributed water that originates from groundwater, but not in water from surface sources has led to the hypothesis that groundwater NOM may contain precursor(s) to DMTS For example, it was proposed that methyl esters and ethers within humic substances might be a source of methyl groups that could participate in DMTS formation in distributed water (Wajon and Heitz, 1995; Wajon and Wilmot, 1992). Further, comparison of levels of reduced sulfur with levels of dissolved organic carbon (DOC) in groundwaters feeding Wanneroo GWTP revealed that a positive correlation between these two parameters existed. This observation provided further impetus to examine the nature of NOM in these groundwater systems. In the present study (discussed in Chapter 3), NOM from two Perth drinking water sources was isolated and characterised, with the aim of identifying major differences in structure and/or functional groups that might influence DMTS formation. NOM was isolated from water samples using ultrafiltration, and characterised using pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) and offline- thermochemolysis/methylation (TCM). Pyrolysis of groundwater NOM yielded a high proportion of organosulfur compounds, primarily methyl thiophenes and sulfur gases, but did not yield detectable amounts of methoxy-aromatic compounds. Analysis by TCM yielded sulfur compounds tentatively identified as the methyl esters of methylthiopropanoate and methylthiobutanoate, compounds that may arise as degradation products of dimethylsulfoniopropionate (DMSP), an algal odmoregulator Compounds such as DMPS could potentially undergo reactions to form DMTS in distributed water.The task of investigating the formation of nanogram-per-litre concentrations of DMTS demanded the development of new analytical procedures that could be used to determine similarly low concentrations of DMTS precursors. Evidence existed to suggest that inorganic polysulfides could be plausible precursor compounds, and since no technique existed to analyse and quantify individual polysulfide homologues a new technique needed to be developed and verified. The technique, first used in a semiquantitative manner by Wajon and Heitz (1995), utilizes methyl iodide to derivatise polysulfides in-situ. The technique was developed further and shown to be quantitative and specific for inorganic polysulfides. Further, a new procedure for the determination of d i methyl polysulfides (DMPSs; CH3SnCH3, where n = 2-5), based on purge and trap was developed. In this new procedure analytes were trapped on a "Grob" activated charcoal tube, which was integrated into a commercially available, automated purge and trap instrument. Perdeuterated analogues of the DMPS analytes were synthesized and used as internal standards. These modifications resulted in a more rapid and robust procedure than the previously used procedures, vii which were based on closed loop stripping analysis (CLSA). Validation of the precision, accuracy, linearity and robustness of the new procedures for both inorganic polysulfides and dimethylpolysulfides is described in Chapter 4.Previous authors (Wajon and Heitz, 1995; Wajon and Wilmot, 1992; Wilmot and Wajon, 1997) hypothesized that DMTS could arise in the distribution system from residual polysulfides or other reduced sulfur compounds originating from groundwater. The latter authors showed that a small proportion of sulfide in the groundwater was not completely oxidised to sulfate during the water treatment process and proposed that this residual reduced sulfur fraction, which they referred to as non-sulfide reduced sulfur (NSRS) could contain precursors to DMTS. In a review of the chemistry of sulfide oxidation (Chapter 2) it was shown that the most likely forms of sulfur comprising the NSRS that enters the Wanneroo distribution system are organosulfur compounds and elemental sulfur, probably associated with organic matter in the form of a sulfur sol.Analysis of inorganic polysulfides in treated water, using the newly described method in Chapter 4, revealed that small amounts of these compounds (20-80 ng/L) were occasionally present in some samples. However, it was concluded that, since inorganic polysulfides could not survive water treatment processes, these compounds probably arose from traces of biofilm or pipe sediment that may have entered the water during sampling. It was proposed that the presence of biofilm particulates in water samples probably also accounted for observations that DMTS appeared to form in some water samples during storage of the sample. These studies are discussed in Chapter 5.The primary method of control of DMTS formation in the distribution system has been to maintain free chlorine residuals. However, the mechanisms by which this occurs have not been studied; the effectiveness of DMTS oxidation by chlorine, or how chlorine affects microbial processes that might form DMTS is not known. These issues are addressed in the final section of Chapter 5. Experiments to determine the effectiveness of oxidation of dimethyldisulfide (DMDS) and DIVITS (5 mu g/L) by free chlorine (0.2 to 0.6 mg/L) in distributed water showed that these substances are rapidly and completely oxidised in water containing a chlorine residual of more than 0.4 mg/L. However, slow regeneration of traces of DMDS and DIVITS after dissipation of free chlorine to non-detectable levels showed that these compounds were incompletely oxidised at the lower chlorine concentrations~ This provides some rationale for field observations that DIVITS occurs even where low, but measurable, chlorine residuals appear to exist (<0.2 mg/L).As was established in a review of the chemistry of reduced sulfur compounds Chapter 2), reducing conditions not present in the oxic bulk water are required for DMTS to form and to persist. It was therefore proposed that microbial reduction processes could generate anoxic microniches in the distribution system, within which DMTS production could occur. This hypothesis was investigated in Chapter 6; the new methods for analysis of organic and inorganic polysulfides were applied to the study of biofilms and deposits of colloidal material found in distribution pipes and storage reservoirs. The study demonstrated that these materials contained concentrations of methylated and inorganic polysulfides four to six orders of magnitude higher than those ever found in the bulk water phase. The results indicated that reducing conditions most probably exist within the biofilms and pipewall deposits, where these polysulfides were formed. The iron-rich pipe slimes appeared to protect the sulfur compounds against the oxidative effects of chlorine and dissolved oxygen. It was concluded that the organic and inorganic polysulfides most probably arise through microbial sulfate reduction processes that occur in anoxic microenvironments within the slimes and deposits.Microbial processes that lead to the formation of polysulfides and dimethylpolysuifides under conditions approximately representative of those in distribution systems were investigated in work described in Chapter 7. The aim of this work was to investigate the role of biofilms in the formation of DMTS and to determine the nature of chemical precursors which might stimulate these processes. Biofilms, artificially generated on synthetic supports within chambers filled with water from Wanneroo GWTP, were exposed to compounds thought to be potential DMTS precursors. The response of the systems in terms of production of methylated sulfur compounds was monitored. Conclusions of the study were that, under the test conditions, production of DMDS and DMTS could occur via several mechanisms and that these dimethyloligosulfides could be formed even without the addition of compounds containing sulfur or methyl moieties. DMTS did not form in the absence of biofilms and it was therefore concluded that minimisation of biofilm activity was a key in preventing DMTS formation. Outcomes of the work imply that environments within distribution systems are complex and dynamic, as perhaps manifested by the intermittent nature of the DMTS problem.Finally, in Chapter 8 the conclusions to the present studies are summarised. It is shown how they underpin the rationale for proposed new treatment solutions aimed at preventing DMTS problems in the Wanneroo zone, primarily by minimising microbial activity and biofilm formation within distribution systems.

The formation of an objectionable "swampy" odour in drinking water distribution systems in Perth, Western Australia, was first described by Wajon and co-authors in the mid-1980s (Wajon et al., 1985; Wajon et al., 1986; Wajon et al, 1988). These authors established that the odour, variously described as "swampy", "sewage" or "cooked vegetable" was caused by dimethyltrisulfide (DMTS) which has an odour threshold concentration of 10 nanograms per litre (ng/L). Investigations described in the present Thesis extend the work of Wajon and co-workers in attempting to establish the origin and cause of DMTS formation in Perth drinking water distribution systems.The DMTS problem appeared to be confined to water originating from a particular type of groundwater, specifically groundwater sourced from shallow, unconfined aquifers, which contain relatively high concentrations of sulfide, dissolved natural organic matter (NOM) and dissolved iron. DMTS was not present in the groundwater, but only formed in the distribution system, after treatment of groundwater via alum coagulation-filtration and oxidation processes. One objective of the present work was to determine the reasons for the observed association between DMTS formation and this specific groundwater type. A primary focus was to investigate the chemistry and biochemistry of sulfur species and NOM which might act as precursors to DMTS. The work was driven by the view that increased understanding of the problem might lead to more effective and acceptable treatment solutions than those presently in use.The observation that DMTS forms in distributed water that originates from groundwater, but not in water from surface sources has led to the hypothesis that groundwater NOM may contain precursor(s) to DMTS For example, it was proposed that methyl esters and ethers within humic substances might be a source of methyl groups that ++
could participate in DMTS formation in distributed water (Wajon and Heitz, 1995; Wajon and Wilmot, 1992). Further, comparison of levels of reduced sulfur with levels of dissolved organic carbon (DOC) in groundwaters feeding Wanneroo GWTP revealed that a positive correlation between these two parameters existed. This observation provided further impetus to examine the nature of NOM in these groundwater systems. In the present study (discussed in Chapter 3), NOM from two Perth drinking water sources was isolated and characterised, with the aim of identifying major differences in structure and/or functional groups that might influence DMTS formation. NOM was isolated from water samples using ultrafiltration, and characterised using pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) and offline- thermochemolysis/methylation (TCM). Pyrolysis of groundwater NOM yielded a high proportion of organosulfur compounds, primarily methyl thiophenes and sulfur gases, but did not yield detectable amounts of methoxy-aromatic compounds. Analysis by TCM yielded sulfur compounds tentatively identified as the methyl esters of methylthiopropanoate and methylthiobutanoate, compounds that may arise as degradation products of dimethylsulfoniopropionate (DMSP), an algal odmoregulator Compounds such as DMPS could potentially undergo reactions to form DMTS in distributed water.The task of investigating the formation of nanogram-per-litre concentrations of DMTS demanded the development of new analytical procedures that could be used to determine similarly low concentrations of DMTS precursors. Evidence existed to suggest that inorganic polysulfides could be plausible precursor compounds, and since no technique existed to analyse and quantify individual polysulfide homologues a new technique needed to be developed and verified. The technique, first used in a semiquantitative manner by ++
Wajon and Heitz (1995), utilizes methyl iodide to derivatise polysulfides in-situ. The technique was developed further and shown to be quantitative and specific for inorganic polysulfides. Further, a new procedure for the determination of d i methyl polysulfides (DMPSs; CH3SnCH3, where n = 2-5), based on purge and trap was developed. In this new procedure analytes were trapped on a "Grob" activated charcoal tube, which was integrated into a commercially available, automated purge and trap instrument. Perdeuterated analogues of the DMPS analytes were synthesized and used as internal standards. These modifications resulted in a more rapid and robust procedure than the previously used procedures, vii which were based on closed loop stripping analysis (CLSA). Validation of the precision, accuracy, linearity and robustness of the new procedures for both inorganic polysulfides and dimethylpolysulfides is described in Chapter 4.Previous authors (Wajon and Heitz, 1995; Wajon and Wilmot, 1992; Wilmot and Wajon, 1997) hypothesized that DMTS could arise in the distribution system from residual polysulfides or other reduced sulfur compounds originating from groundwater. The latter authors showed that a small proportion of sulfide in the groundwater was not completely oxidised to sulfate during the water treatment process and proposed that this residual reduced sulfur fraction, which they referred to as non-sulfide reduced sulfur (NSRS) could contain precursors to DMTS. In a review of the chemistry of sulfide oxidation (Chapter 2) it was shown that the most likely forms of sulfur comprising the NSRS that enters the Wanneroo distribution system are organosulfur compounds and elemental sulfur, probably associated with organic matter in the form of a sulfur sol.Analysis of inorganic polysulfides in treated water, using the newly described method in Chapter 4, revealed that small ++
amounts of these compounds (20-80 ng/L) were occasionally present in some samples. However, it was concluded that, since inorganic polysulfides could not survive water treatment processes, these compounds probably arose from traces of biofilm or pipe sediment that may have entered the water during sampling. It was proposed that the presence of biofilm particulates in water samples probably also accounted for observations that DMTS appeared to form in some water samples during storage of the sample. These studies are discussed in Chapter 5.The primary method of control of DMTS formation in the distribution system has been to maintain free chlorine residuals. However, the mechanisms by which this occurs have not been studied; the effectiveness of DMTS oxidation by chlorine, or how chlorine affects microbial processes that might form DMTS is not known. These issues are addressed in the final section of Chapter 5. Experiments to determine the effectiveness of oxidation of dimethyldisulfide (DMDS) and DIVITS (5 mu g/L) by free chlorine (0.2 to 0.6 mg/L) in distributed water showed that these substances are rapidly and completely oxidised in water containing a chlorine residual of more than 0.4 mg/L. However, slow regeneration of traces of DMDS and DIVITS after dissipation of free chlorine to non-detectable levels showed that these compounds were incompletely oxidised at the lower chlorine concentrations~ This provides some rationale for field observations that DIVITS occurs even where low, but measurable, chlorine residuals appear to exist (<0.2 mg/L).As was established in a review of the chemistry of reduced sulfur compounds Chapter 2), reducing conditions not present in the oxic bulk water are required for DMTS to form and to persist. It was therefore proposed that microbial reduction processes could generate anoxic microniches in the distribution system, within which ++
DMTS production could occur. This hypothesis was investigated in Chapter 6; the new methods for analysis of organic and inorganic polysulfides were applied to the study of biofilms and deposits of colloidal material found in distribution pipes and storage reservoirs. The study demonstrated that these materials contained concentrations of methylated and inorganic polysulfides four to six orders of magnitude higher than those ever found in the bulk water phase. The results indicated that reducing conditions most probably exist within the biofilms and pipewall deposits, where these polysulfides were formed. The iron-rich pipe slimes appeared to protect the sulfur compounds against the oxidative effects of chlorine and dissolved oxygen. It was concluded that the organic and inorganic polysulfides most probably arise through microbial sulfate reduction processes that occur in anoxic microenvironments within the slimes and deposits.Microbial processes that lead to the formation of polysulfides and dimethylpolysuifides under conditions approximately representative of those in distribution systems were investigated in work described in Chapter 7. The aim of this work was to investigate the role of biofilms in the formation of DMTS and to determine the nature of chemical precursors which might stimulate these processes. Biofilms, artificially generated on synthetic supports within chambers filled with water from Wanneroo GWTP, were exposed to compounds thought to be potential DMTS precursors. The response of the systems in terms of production of methylated sulfur compounds was monitored. Conclusions of the study were that, under the test conditions, production of DMDS and DMTS could occur via several mechanisms and that these dimethyloligosulfides could be formed even without the addition of compounds containing sulfur or methyl moieties. DMTS did not form in the absence of ++
biofilms and it was therefore concluded that minimisation of biofilm activity was a key in preventing DMTS formation. Outcomes of the work imply that environments within distribution systems are complex and dynamic, as perhaps manifested by the intermittent nature of the DMTS problem.Finally, in Chapter 8 the conclusions to the present studies are summarised. It is shown how they underpin the rationale for proposed new treatment solutions aimed at preventing DMTS problems in the Wanneroo zone, primarily by minimising microbial activity and biofilm formation within distribution systems.

Source water quality plays a critical role in maintaining the quality and supply of drinking water, yet it can be negatively affected by human activities. In Pennsylvania, coal mining and treatment of conventional oil and gas drilling produced wastewaters have affected source water quality for over 100 years. The recent unconventional natural gas development in the Marcellus Shale formation produces significant volumes of wastewater containing bromide and has the potential to affect source water quality and downstream drinking water quality. Wastewater from coal-fired power plants also contains bromide that may be released into source water. Increasing source water bromide presents a challenge as even small amounts of bromide in source water can lead to carcinogenic disinfection by-products (DBPs) in chlorinated finished drinking water. However, bromide is not regulated in source water and is not removed by conventional drinking water treatment processes. The objective of this work is to evaluate the safe bromide concentration in source water to minimize the cancer risk of trihalomethanes - a group of DBPs - in treated drinking water. By evaluating three years of water sampling data from the Monongahela River in Southwestern Pennsylvania, the present analysis reached three conclusions. First, bromide monitoring for source water quality should be taken at drinking water intake points. Water sample types (river water samples vs drinking water intake samples) can lead to different water quality conclusions and thus affect regulatory compliance decision-making. Second, bromide monitoring at drinking water intake points can serve as a predictor for changes in heavily brominated trihalomethanes concentrations in finished water. Increasing bromide in source water can serve as an early warning sign of increasing formation of heavily brominated trihalomethanes and their associated cancer risks in drinking water. Finally, this work developed a statistical simulation model to evaluate the effect of source water bromide on trihalomethane formation and speciation and to analyze the changing cancer risks in water associated with these changing bromide concentrations in the Monongahela River. The statistical simulation method proposed in this work leads to the conclusion that the bromide concentration in source water must be very low to prevent the adverse health effects associated with brominated trihalomethanes in chlorinated drinking water. This method can be used by water utilities to determine the bromide concentration in their source water that might indicate a need for process changes or by regulatory agencies to evaluate source water bromide issues.

Tap water collected according to standard methods was examined for microbial presence. Epifluorescent diagnoses using redox probe 5-cyano-2,3ditolyl tetrazolium chloride (CTC), 4',6-diamidino-2-phenylindole (DAPI), and acridine orange (AO) were employed for direct evidence of microorganisms. Evidence of total (DAPI or AO), respiring (CTC) bacteria, and heterotrophic plate count (HPC) was determined on multiple occasions during the summer, fall, and winter 1996-1997. Pseudomonas aeruginosa, Acinetobacter sp., Bacillus licheniformis, and Methylobacterium rhodinum were isolated and identified by the API and Biolog system using GN and GP procedures. On the basis of comparisons presented in this study between the CTC method and the standard HPC procedure, it appeared that the number of CTC-reducing bacteria in the tap water samples was typically higher than that determined by HPC, indicating that many respiring bacteria detected by the CTC reduction technique fail to produce visible colonieson the agar media used. In the seasonal data obtained by the CTC method, no difference was shown among respiring bacterial counts obtained from June through January. In the examination of P. aeruginosa viability in presence of chlorine, the number of CTC-positive bacteria exceeded the number of CFU by more than 2 logs after exposure to chlorine, suggesting that reliance on HPC overestimate the efficacy of disinfection treatment. In inactivation assays using the Biolog MT plate, no sensitivity to chlorine or chloramine disinfectants was noted even at high concentration levels (5 mg/liter). Following initial drop, bacterial activities increased as contact time increased. Thus, it appears that the MT microplate provides too low a cell concentration, too great a contact time, and/or too low a concentration of tetrazolium dye within the well for successful analysis of disinfectant capability to selected bacterial strains isolated from distribution water.
Department of Biology

This thesis documents the relationship among the major water quality parametersduring a nitrification episode. Nitrification unexpectedly occurred in a chloraminated pilotdrinking water distribution system practicing with a 4.0 mg/L as Cl[subscript 2] residual dosed at 4.5:1Cl[subscript 2]:NH[subscript 3]-N. Surface, ground and sea water were treated and disinfected withmonochloramines to produce finished water quality similar to regional utility water quality.PVC, galvanized, unlined cast iron and lined iron pipes were harvested from regionaldistribution systems and used to build eighteen pilot distribution systems (PDSs). The PDSswere operated at a 5-day hydraulic residence time (HRT) and ambient temperatures.As seasonal temperatures increased the rate of monochloramine dissipation increaseduntil effluent PDS residuals were zero. PDSs effluent water quality parameters chloraminesresidual, dissolved oxygen, heterotrophic plate counts (HPCs), pH, alkalinity, and nitrogenspecies were monitored and found to vary as expected by stoichiometry associated withtheoretical biological reactions excepting alkalinity. Nitrification was confirmed in thePDSs. The occurrence in the PDSs was not isolated to any particular source water.Ammonia for nitrification came from degraded chloramines, which was common among allfinished waters. Consistent with nitrification trends of dissolved oxygen consumption,ammonia consumption, nitrite and nitrate production were clearly observed in the PDSs bulkwater quality profiles. Trends of pH and alkalinity were less apparent. To controlnitrification: residual was increased to 4.5 mg/L as Cl[subscript 2] at 5:1 Cl[subscript 2]:NH[subscript 3]-N dosing ratio, and theHRT was reduced from 5 to 2 days. Elimination of the nitrification episode was achieved after a 1 week free chlorine burn.
M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering

Drinking water distribution systems (DWDSs) account for the majority of the infrastructure for transporting water from treatment plants to customers’ tap. During the transportation, water quality deteriorates due to the unavoidable accumulation of biofilm within the pipelines. The microbial activity and ecology within the biofilm have great impact on the water quality degradation process. Within DWDSs using chloramine as disinfectant, nitrification caused by nitrifying bacteria is increasingly becoming a concern as it poses a great challenge for maintaining water quality. In order to control nitrification in DWDSs, it is essential to consider both the nitrifying bacteria and their shelter. Hence, the overall aim of this study is to investigate nitrification properties under different operational conditions, in addition to biofilm characteristics in chloraminated water distribution systems. To achieve the aim, nitrifying biofilm was firstly incubated within a flow cell experimental facility. A total of four test phases were conducted to investigate the effects on the extent of nitrification of five flow rates (2, 4, 6, 8 and10 L/min) and four disinfection strategies (total chlorine=1mg/L, Cl2/NH3=3:1; total chlorine=1mg/L, Cl2/NH3=5:1; total chlorine=5mg/L, Cl2/NH3=3:1; and total chlorine=5mg/L, Cl2/NH3=5:1). Physico-chemical parameters and nitrification indicators were monitored during the tests. The main results from the study indicate that nitrification is affected by hydraulic conditions and the process tends to be severe when the fluid flow transforms from laminar to turbulent (2300 < Reynold number < 4000). Increasing disinfectant concentration and optimizing Cl2/NH3 mass ratio were found to have limited efficacy for controlling nitrification. Furthermore, several nitrification indicators were evaluated for their prediction efficiency and the results suggest that the change of nitrite, together with total organic carbon (TOC) and turbidity can indicate nitrification potential more efficiently. At the end of the tests, genomic DNA from biofilm and bulk water from each flow cell unit running at different operational conditions were subjected to a next generation sequencing (NGS) analysis by Illumina MiSeq. The results obtained showed that the microbial community and structure was different between biofilm and water samples. There was no statistical difference in microbial community in biofilm identified between different hydraulic regimes, suggesting that biofilm is a stable matrix to environment. Results further showed that Cl2/NH3 mass ratio had obvious effect on microbial structure in biofilm. This suggests that excessive ammonia is an influencing factor for microbial activity within biofilm. Within bulk water, species richness and diversity tended to be higher at lower hydraulic regimes. This confirms the influence of hydraulic condition on biofilm mechanical structure and further material mobilization to water. Opportunic pathogens such as Legionella and Mycobacterium were detected in abundance in the experimental system. This confirms that nitrification can lead to a decrease of water quality and microbial outbreaks. The characteristics of extracellular polymeric substance (EPS) from biofilm conditioned under different operational conditions were also analysed. Carbohydrate was found to be the main components within biofilm’s EPS. EPS composition and structure were found to be governed by operational conditions, but no simple linear relationship was found. This suggests the interactive effects of EPS properties, hydraulics and disinfectant strategies. EPS effects on disinfection were evaluated via disinfectant decay tests. EPS was confirmed to have an influencing in biofilm overcoming disinfection.

Thesis (PhD) - Faculty of Life and Social Sciences, Swinburne University of Technology, 2009.
Submitted in full requirement for the degree of Doctor of Philosophy, Faculty of Life and Social Sciences, Swinburne University of Technology - 2009. Typescript. Includes bibliographical references (p. 137-160)

Drinking water suppliers face challenges associated with changing populations, evolving economies, aging infrastructure, and shifting consumer demands. In small drinking water systems (SDWSs), these challenges are amplified by the pressure created from financial shortfalls and limited human resources. SDWSs are prone to higher rates of drinking water quality failure, are more vulnerable to spatiotemporal variability in water quality, and may be more susceptible to waterborne disease outbreaks than larger systems. Despite these challenges, SDWSs are overlooked in traditional academic and industrial studies, which often place a focus on larger, more complex drinking water supply systems (DWSSs) and the exploration, development, and implementation of new treatment technologies. Given the current state of SDWSs, the main objectives identified for this research were to incentivize continuous performance, improve data resolution and water quality assessment practices for decision-making, and propose an improved drinking water quality management approach for SDWSs. This was accomplished in four distinct steps. The first step was to review the current state of practice of quality management systems and drinking water management systems and approaches in different parts of the world and within Canada to identify management gaps and potential areas for improvement. The second step was to explore the concept of continuous performance improvement and incentivize implementation through functional performance benchmarking. The third step was to improve on current drinking water quality assessment and benchmarking practices by implementing risk through quantifying degrees of compliance/non-compliance and spatial (i.e. location in the distribution system) and temporal (i.e. seasonal) variability through fuzzy rule-based modeling. The fourth and final step was to propose an improved drinking water management framework that fits within the bounds of Canada’s current decentralized governance system. The results of this research have the potential to be used by drinking water utility managers, operators, and planners to improve drinking water quality management in SDWSs at the federal, provincial/territorial, and municipal levels and improve on the current drinking water quality assessment and decision-making processes in place.
Graduate Studies, College of (Okanagan)
Graduate

The provision of clean drinking water typically involves treatment processes to remove contaminants. The conventional process involves coagulation with hydrolysing metal salts, typically of aluminium (‘alum’) or trivalent iron (‘ferric’). Along with the product water this also produces a waste by-product, or sludge. The fact of increasing sludge production — due to higher levels of treatment and greater volume of water supply — conflicts with modern demands for environmental best practice, leading to higher financial costs. A further issue is the significant quantity of water that is held up in the sludge, and wasted.
One means of dealing with these problems is to dewater the sludge further. This reduces the volume of waste to be disposed of. The consistency is also improved (e.g. for the purpose of landfilling). And a significant amount of water can be recovered. The efficiency, and efficacy, of this process depends on the dewaterability of the sludge.In fact, good dewaterability is vital to the operation of conventional drinking water treatment plants (WTP’s). The usual process of separating the particulates, formed from a blend of contaminants and coagulated precipitate, relies on ‘clarification’ and ‘thickening’, which are essentially settling operations of solid–liquid separation.WTP operators — and researchers — do attempt to measure sludge dewaterability, but usually rely on empirical characterisation techniques that do not tell the full story and can even mislead. Understanding of the physical and chemical nature of the sludge is also surprisingly rudimentary, considering the long history of these processes.
The present work begins by reviewing the current state of knowledge on raw water and sludge composition, with special focus on solid aluminium and iron phases and on fractal aggregate structure. Next the theory of dewatering is examined, with the adopted phenomenological theory contrasted with empirical techniques and other theories.The foundation for subsequent analyses is laid by experimental work which establishes the solid phase density of WTP sludges. Additionally, alum sludges are found to contain pseudoböhmite, while 2-line ferrihydrite and goethite are identified in ferric sludges.
A key hypothesis is that dewaterability is partly determined by the treatment conditions. To investigate this, numerous WTP sludges were studied that had been generated under diverse conditions: some plant samples were obtained, and the remainder were generated in the laboratory (results were consistent). Dewaterability was characterised for each sludge in concentration ranges relevant to settling, centrifugation and filtration using models developed by LANDMAN and WHITE inter alia; it is expressed in terms of both equilibrium and kinetic parameters, py(φ) and R(φ) respectively.This work confirmed that dewaterability is significantly influenced by treatment conditions.The strongest correlations were observed when varying coagulation pH and coagulant dose. At high doses precipitated coagulant controls the sludge behaviour, and dewaterability is poor. Dewaterability deteriorates as pH is increased for high-dose alum sludges; other sludges are less sensitive to pH. These findings can be linked to the faster coagulation dynamics prevailing at high coagulant and alkali dose.Alum and ferric sludges in general had comparable dewaterabilities, and the characteristics of a magnesium sludge were similar too.Small effects on dewaterability were observed in response to variations in raw water organic content and shearing. Polymer flocculation and conditioning appeared mainly to affect dewaterability at low sludge concentrations. Ageing did not produce clear changes in dewaterability.Dense, compact particles are known to dewater better than ‘fluffy’ aggregates or flocs usually encountered in drinking water treatment. This explains the superior dewaterability of a sludge containing powdered activated carbon (PAC). Even greater improvements were observed following a cycle of sludge freezing and thawing for a wide range of WTP sludges.
Further aspects considered in the present work include deviations from simplifying assumptions that are usually made. Specifically: investigation of long-time dewatering behaviour, wall effects, non-isotropic stresses, and reversibility of dewatering (or ‘elasticity’).Several other results and conclusions, of both theoretical and experimental nature, are presented on topics of subsidiary or peripheral interest that are nonetheless important for establishing a reliable basis for research in this area.
This work has proposed links between industrial drinking water coagulation conditions, sludge dewaterability from settling to filtration, and the microstructure of the aggregates making up that sludge. This information can be used when considering the operation or design of a WTP in order to optimise sludge dewaterability, within the constraints of producing drinking water of acceptable quality.

Household water treatment technologies provide an interim solution to drinking water provision in areas which are not yet serviced by a continuous piped connection to a communal treated source. This is a critical problem in Amerindian communities in the Guyanese hinterland region, where remote location and low population density make improving environmental health infrastructure challenging. Biosand filtration is one promising household water treatment technology available for this purpose. The overall goal of this research was to better understand, and thus improve, the biosand filter for field operation. A field study was performed in the Amerindian community of St. Cuthbert's, Guyana. A questionnaire was implemented to determine risk factors for diarrhoeal disease, and water samples were taken from creeks and standpipes in the village and from stored drinking water in households. Serving drinking water by scooping from a bucket as opposed to pouring or using a tap or spigot was found to be a risk factor for illness, while having water piped to the household was associated with lower diarrhoeal disease rates. Post-collection water contamination was found to cause a significant decline in drinking water quality. Adoption and sustained use of biosand filters were compared to two other prominent household water treatment methods, that being the addition of hypochlorite solution and use of a safe water storage container, and ceramic candle filtration. It was found that in St. Cuthbert's bios and filters had moderate adoption (36%) but usage was not sustained (4%). Closing interviews revealed that people found the filters too large and heavy, did not trust them, and found them too difficult to use. The issue of the biosand filter's size and ease of use could be partially mitigated if it were possible to reduce the height of the sand column in the filter. The filter would also be easier to use if it was not necessary to add water every day. Experiments on laboratory columns representing biosand filters determined that although the sand layer in the filters was 55 cm deep, there is little additional benefit to each centimeter over 30 cm of filter depth, making a significant height reduction possible without compromising filter performance. Further column experiments determined that the common field practice of extending residence periods of biosand filters from the recommended one day to two or three days did not lead to a statistically significant reduction in the filter's ability to remove E. coli, but did lead to anaerobic conditions within the filter and a modified nitrogen profile in filter effluent. This may impact the taste of the filtered water. In cases where influent water has high initial nitrogen content this could lead to an exceedance of World Health Organization guidelines for nitrate and nitrite in drinking water. Although the design of biosand filters was based on the theory that a low standing head would cause intermittent operation of slow sand filters to match that of continuous operation, this research found that continuous operation of the biosand filter led to significantly improved removal of bacterial and viral indicators (3.7 log10 versus 1.7 log10 for E. coli, and 2.3 log10 versus 0.9 log10 for bacteriophage MS2).
Les technologies de traitement de l'eau à domicile offrent une solution temporaire pour alimenter en eau potable les zones non encore reliées à un réseau d'apport et de traitement de l'eau communautaire. C'est un problème critique pour les communautés de l'arrière-pays montagneux de la Guyane, où l'isolation géographique et la faible densité démographique rendent l'amélioration des infrastructures hydriques et sanitaires difficile. Le filtre à biosable est une technologie prometteuse pour le traitement de l'eau à domicile qui serait disponible pour pallier ces contraintes. L'objectif de cette recherche a été de mieux comprendre et d'améliorer le filtre à biosable pour son opération sur le terrain. Une étude sur le terrain, incluant la distribution des questionnaires dans la communauté et la prise d'échantillons d'eau, a été réalisée dans la communauté de St Cuthbert's en Guyane. Puiser de l'eau potable directement d'un sceau avec un récipient improvisé par opposition à avoir accès à de l'eau à partir d'un robinet s'est avéré comme étant un facteur à risque pour tomber malade. En revanche, l'accès à l'eau courante au domicile amenée par un réseau de tuyaux a été associé à des taux de maladies diarrhéiques plus faibles. La contamination de l'eau après sa collecte initiale s'est avérée comme étant un facteur causant une baisse significative de la qualité de l'eau potable. L'adoption et l'utilisation à long terme des filtres à biosable ont été comparées à celles de deux autres technologies répandues: l'ajout dans l'eau d'une solution hypochlorique combiné à l'utilisation de récipients sécuritaires d'entreposage de l'eau et la filtration à base de bougies céramiques. L'étude a montré que les filtres à biosable ont connu un taux d'adoption modéré (36%) mais que leur utilisation n'a pas été à long terme (4%). Des entrevues de fin d'étude ont indiqué que les habitants de ont trouvé les filtres à biosable larges et lourds, qu'ils ne leur ont pas fait confiance et, qu'ils ont trouvé leur utilisation difficile. Le problème des dimensions du filtre à biosable et de sa facilité d'utilisation pourrait être atténué s'il était possible de réduire la hauteur de la colonne de sable dans le filtre. Il serait aussi plus facile d'utiliser le filtre s'il n'était pas nécessaire d'y ajouter de l'eau chaque jour. Des essais en laboratoire ont déterminé que, même si la couche de sable dans le filtre a une profondeur de 55 cm, les bénéfices pour chaque centimètre additionnel de sable au-dessus de 30 cm sont minimes. Cela permettrait une réduction significative de la hauteur du filtre sans compromettre sa performance. D'autres essais ont déterminé que la pratique usuelle sur le terrain de prolonger le temps de résidence de l'eau dans les filtres à biosable, de la période recommandée d'un jour à deux ou trois jours, ne conduit pas à une diminution significative de la capacité du filtre à enlever les E. coli. Toutefois, cette pratique conduit à des conditions anaérobiques à l'intérieur du filtre et à un profil d'azote modifié dans l'effluent du filtre à cause de la nitrification. Cela pourrait avoir un impact sur le goût de l'eau filtrée. Dans les cas, où l'eau utilisée a un contenu initial d'azote élevé, les conditions anaérobiques pourraient conduire à un dépassement des recommandations de l'Organisation mondiale de la santé concernant le nitrate et le nitrite dans l'eau potable. La conception initiale des filtres à biosable a été basée sur la théorie que le maintien d'une charge hydraulique minimale permettrait aux filtres à sable lent opérant par intermittence de performer aussi bien que ceux opérant en continue. Toutefois, cette recherche a montré que l'opération continue des filtres à biosable a permis d'améliorer significativement la diminution des indicateurs bactériens et viraux (3.7 log10 versus 1.7 log10 pour E. coli, et 2.3 log10 versus 0.9 log10 pour MS2 bactériophage) par rapport aux filtres à sable lent à opération intermittente.

Thirteen volunteer panelists were trained according to Standard Method 2170, flavor profile analysis (FPA). Following training these panelists underwent triangle test screening to determine whether or not they could detect the odorants used in this study. Following triangle testing, panelists underwent directional difference testing to determine if temperature affected odor perception when presented with two water samples. Following directional difference testing, panelists used FPA and evaluated water samples that contained odorants at either 25°C or 45°C. Samples containing geosmin cooled to 5°C were also evaluated.

Sensory analyses experiments indicate that odor intensity is a function of both aqueous concentration and water temperature for geosmin, MIB, nonadienal, n-hexanal, free chlorine, and 1-butanol. The higher water temperature resulted in an increase in odor intensity for some, but not all, concentrations of geosmin, 2-methylisoborneol, trans-2, cis-6-nonadienal, n-hexanal, free chlorine, and 1-butanol. Additionally, above 400 ng/L of geosmin, 400 ng/L of MIB, and 100 ng/L the odor intensity was equal to or less than the odor intensity at 600, 600, and 200 ng/L, respectively. Henry's Law should predict that an increase in concentration would increase the amount of odorant the panelist comes into contact with; however, results demonstrated that at specific aqueous odorant concentrations odor perception did not follow Henry's Law. Odor response to drinking water containing isobutanal was affected by concentration but not water temperature.

Master of Science

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The Environmental Protection Agency (EPA) recently issued a new law limiting lead and copper concentrations in drinking water. In large enough amounts, lead can damage your brain, kidneys and central nervous system. This publication briefly discusses; what damages can be caused by the lead in your drinking water, where it comes from, and how to remove it.