Coal-tar was commonly used as an internal lining for corrosion protection of water pipes from the 19th century up to the present. It is reported that these coatings can lead to elevated concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) in the distributed drinking water. The aim of the project was to investigate the processes and mechanisms responsible for the occurrence of these substances in drinking water distribution systems. The results presented in this project showed that the occurrence of PAHs in a distribution system was linked to the presence of the disinfectants chlorine and chlorine dioxide. This dependence could be shown in the laboratory, in a pilot-scale pipe rig as well as in field investigations in a real distribution system. Generally, hostile environmental conditions for microbiological activity such as stagnation periods and anaerobic conditions could be identified as the most important factors to favour the occurrence of PAHs in the drinking water. It was clearly shown that disturbances in the hydraulic regime such as water hammers, operation of valves and rapid increases in flow velocity can result in enhanced PAH concentrations. Immediately after stagnation periods PAH concentrations increased to levels which exceeded the prescribed concentrations of the EC-guideline of 200 ng/l. In laboratory experiments it was demonstrated that the coal-tar is a substrate for the growth of biofilms. Batch experiments and reactor experiments showed that the removal of biofilm resulted in a higher leaching rate of the PAHs into the water. Experiments concerning the potential for the formation of chlorinated PAHs as disinfection by-products from the PAHs prevalent in water distributed through coal-tar lined pipes showed that their occurrence is very unlikely under conditions prevalent in water distribution systems. A theory is presented which indicates that particles adhering to the pipe walls which can be sometimes embedded in the biofilm matrix represent a major factor in the process of the mobilisation of PAHs. The destabilisation of the biofilm matrix by hostile environmental conditions (disinfectants, aerobic conditions, oxygen limitation during stagnation periods) or enhanced shear forces on the biofilm, results in the release of particles highly contaminated with PAHs.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15346号 / 工博第3225号 / 新制||工||1485(附属図書館) / 27824 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 伊藤 禎彦, 教授 津野 洋, 教授 田中 宏明 / 学位規則第4条第1項該当

Safe drinking water is a basic need; and risk assessment tools may assist in prioritizing actions to improve water safety. The objective of this research was to determine the appropriateness of current risk assessment approaches for First Nations drinking water systems. Criteria to evaluate risk assessment approaches were developed by combining common elements from literature, key informant interviews, and surveys. The criteria were compared against selected tools for drinking water risk assessment, including tools developed by Australia, Montana, Indian and Northern Affairs, and the University of Guelph. None of the tools, as available, met all of the criteria. Important considerations were found to include the operator, monitoring and recordkeeping, maintenance, technical considerations, emergency response plans, and source water protection. The tools were generally weak in assessing some potential challenges facing small, remote, and First Nations communities; including financial constraints, and taking a holistic view of water. / Note: this thesis was also submitted in hard-copy to Graduate Services

Thesis (M. Sc.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 65-68).

Ferrihydrite in a suspension has been studied as a solution for purification of arsenic contaminated water. Many development countries, amongst them Burkina Faso, have arsenic in their groundwater and the current methods for purification are too expensive. Measurements have shown extremely high levels of arsenic in the groundwater in several places in Burkina Faso. Since the availability of surface water is limited, the groundwater is still used as drinking water.   A suspension of ferrihydrite has capacity to adsorb arsenic in water due to its chemical characteristics. Small-scale laboratory work with ferrihydrite suspensions has been performed in parallel in Uppsala, Sweden, and Ouagadougou, Burkina Faso. To purify the water with regard to the economical and practical circumstances in Burkina Faso, a column with safety filter was made out of simple materials such as plastic bottles, plastic tubes and glass wool. The contaminated water was flowing upwards through the column to prevent the filter from clogging.   In Uppsala it was discovered that a 1 L ferrihydrite suspension containing 10 g ferrihydrite can adsorb 0.7 g arsenic while it was shaken and centrifuged well. In Ouagadougou it was possible, in the setup, to clean 2 L arsenic contaminated water with the concentration of 100 µg/L. The conclusions from the experiments in this project are that ferrihydrite can adsorb arsenic in contaminated water but that the setup used needs to be further evaluated and developed

INTRODUCTION: Diarrheal disease contributes to an estimated 1.5 million deaths each year, including 760,000 deaths among children under the age of five. Of those, approximately 500,000 are attributable to inadequate drinking water. In areas where piped water is unsafe, unreliable or economically impossible, packaged water sold by private vendors can play an important role in meeting the water needs of these populations. As the activity and importance of packaged water vendors grow, more data is needed to assess the quality of water sold, and to inform policies that regulate the private water sector throughout the world. AIM: This pilot study seeks to identify factors that may contribute to the deterioration of packaged water quality. METHODS: Small packaged water enterprises (SWEs) operating in the following cities were visited twice between May 2014 and September 2015: La Paz, Bolivia; Tegucigalpa, Honduras; and Muisne and Tena, Ecuador. A brief survey was conducted with each distributor, and a facility tour was completed. Water samples were collected directly from the purification system and water packaged in both reusable and disposable containers were purchased. Samples were tested for total coliform and E. coli bacterial contamination on the day of collection and over the course of 28 days. Data was analyzed using descriptive statistics, including median as the measure of central tendency, and frequency where the main outcome was presence or absence of either total coliform bacteria or E. coli. To determine the factors that were most associated with water quality deterioration, logistic regression was performed. RESULTS: A total of 616 samples were collected. This study found that 52% of the packaged water examined was contaminated with total coliform bacteria. Raw, untreated water and treated water packaged in reusable containers were most likely to be contaminated with total coliform bacteria and E.coli compared to treated water taken directly from the system. There was no significant association between water treatment or bottle disinfection protocols and total coliform or E. coli contamination. DISCUSSION: The study succeeded in identifying at what stage and in what type of container water is most likely to be contaminated with bacterial water-quality indicators. Furthermore, it highlights the heterogeneity that exists in terms of types of water sold, water treatment systems, and sanitizing protocols among SWEs in Central and South America. Reusable containers are vulnerable to contamination with total coliform bacteria and E. coli, even when filled with clean water, thus the contamination may be due to inadequate disinfection between uses. These results may have implications for national or international policies that regulate private water enterprises, and can inform guidelines for packaged water distributors in particular. Further research is needed to identify optimal cleaning methods for reusable containers that are practical for use in lower resource settings.

No description available.

The central aim of this thesis is to develop an understanding of variation in access to domestic water supply in a semi-arid, non-riverain area of Sudan. En Nahud District, in North Kordofan Province, was selected for study because it has existing water supply problems and contains distinct spatial variations in geology, which affects the potential for development of underground water resources. Fieldwork in Sudan was carried out between July and December 1988, and information was collected from a range of sources using a variety of methods. The latter included: semi-structured household interviews conducted with women; key informant interviews; observation; and various published and unpublished articles and data sets. In the thesis, the first chapter introduces the national and international context of this study. Past and present water supply development policies and projects in the Sudan are outlined, and set against the goals of the International Drinking Water Supply and Sanitation Decade. In the second chapter, the research methodology is discussed. Attempt was made to overcome the several spatial, temporal social and economic biases which have occurred in other studies. In the third chapter, the thesis is placed in the physical and socio-economic context of the Province, and the dynamic relationship between water supply and demand is outlined. The following three chapters focus upon the primary constraints which limit access to domestic water supply: water availability; at-source costs; and transportation costs. The components of each, and the way in which they operate to restrict access, are investigated in relation to varying family resources and requirements. The borrowing of carriage resources and the purchase of transportation services are examined as strategies for overcoming families' internal collection-capacity constraints. Finally, seasonal outmigration is discussed as an important response to inadequate access to water supply. In its conclusion, this thesis shows clearly the importance of examining access to water at the family scale: inter-household variations, such as the ownership of carriage animals and varying labour resources, are shown to be influential in affecting household water supply strategies.

Dissolution of arsenic bearing minerals in groundwater (used as drinking water) can lead to concentrations of >0.05 mg/L of arsenite in many countries, causing serious health effects. Several existing technologies rely on coagulation and adsorption to remove the less toxic form of arsenate (As (V)) (easier to remove from solution than As (III) due to its anionic charge) and the use of harsh oxidants (e.g. ozone). In this work nanocrystalline titanium dioxide (TiO₂) has been used as a photocatalytic oxidant (PCO) to oxidise As (III) which also functions as an adsorbent with a high surface area to remove the As (V) from solution. Most previous research has monitored only As (III) removal from solution and the mechanism of PCO is a controversial topic.  The main aim of this work was to use X-ray Photoelectron Spectroscopy (XPS) to study the adsorption and speciation of arsenic adsorbed on TiO₂ following PCO.  Aims also included finding a suitable commercial TiO₂, characterisation of adsorption of As (V), PCO reactions under different conditions, speciation of arsenic adsorbed by XPS and preliminary studies of the mechanism of PCO and the binding of arsenic species to the surface.

CIVINS / Systems on modern naval vessels are becoming exclusively dependent on electrical power. One example of this is the replacement of distilling and evaporator plants with reverse osmosis units. As the system is in continuous operation, it is critical to have remote real-time monitoring and diagnostic capabilities. The pressure to reduce shipboard manning only adds to the difficulties associated with monitoring such systems. One diagnostic platform that is particularly well suited for use in such an environment is the non-intrusive load monitor (NILM). The primary benefit of the NILM is that it can assess the operational status of multiple electrical loads from a single set of measurements collected at a central point in a ship's power-distribution network. This reduction in sensor count makes the NILM a low cost and highly reliable system. System modeling, laboratory experiments, and field studies have all shown that the NILM can effectively detect and diagnose several critical faults in shipboard fluid systems. For instance, data collected from the reverse osmosis units for two U.S. Coast Guard Medium Endurance Cutters indicate that the NILM can detect micron filter clogging, membrane failures, and several motor-related problems. Field-tested diagnostic indicators have been developed using a combination of physical modeling and laboratory experiments. / CIVINS