Atualmente a avaliação das perdas de água, nos sistemas de distribuição, é feita com base em equações empíricas, que utilizam informações, agrupadas e totalizadas, de uma área. Isto torna necessária sua subdivisão em frações cada vez menores, na busca da fração mais crítica. Neste trabalho, é apresentada uma avaliação da eficácia do uso de modelos de simulação hidráulica na obtenção das informações necessárias para a elaboração de um diagnóstico de perdas de água, com uma metodologia prática para o uso de modelos com este objetivo. Apresenta uma classificação dos trechos de rede em três categorias A, B e C, que facilita a priorização dos trechos mais críticos facilitando a análise por meio de gráficos de pareto e mapas temáticos. Demonstra que a adoção da simulação hidráulica no estudo das causas de perdas de água, nos sistemas de abastecimento, é uma ferramenta eficaz e permitirá às empresas de saneamento, uma melhoria na gestão operacional, que garante a sustentabilidade da empresa, a economia dos recursos humanos, econômicos, e principalmente, os hídricos. / Currently water losses evaluation in distribution systems, is based on empirical equations using information, grouped and totaled, covering whole area. Thus, becomes necessary to subdivide the area into smaller and smaller fractions, searching for the most critical part. This study presents, the effectiveness evaluation of the hydraulic simulation models, use to obtain the information necessary in elaboration diagnosis of water losses, with a practical methodology for using models for this purpose. Shows a pipe classification in three categories A, B and C, its began possible analyses with pareto graphics and thematic maps. Demonstrates that hydraulic simulation adoption is an effective tool in the study of water loss in supply systems. It will allow companies an operational management improvement, ensuring the sustainability of the business and economics of human, financial, and especially, water resources.

This thesis presents a research work on the development of new methodology for near-real-time detection and localisation of pipe bursts in a Water Distribution System (WDS) at the District Meters Area (DMA) level. The methodology makes use of online hydraulic model coupled with a demand forecasting methodology and several statistical techniques to process the hydraulic meters data (i.e., flows and pressures) coming from the field at regular time intervals (i.e. every 15 minutes). Once the detection part of the methodology identifies a potential burst occurrence in a system it raises an alarm. This is followed by the application of the burst localisation methodology to approximately locate the event within the District Metered Area (DMA). The online hydraulic model is based on data assimilation methodology coupled with a short-term Water Demand Forecasting Model (WDFM) based on Multi-Linear Regression. Three data assimilation methods were tested in the thesis, namely the iterative Kalman Filter method, the Ensemble Kalman Filter method and the Particle Filter method. The iterative Kalman Filter (i-KF) method was eventually chosen for the online hydraulic model based on the best overall trade-off between water system state prediction accuracy and computational efficiency. The online hydraulic model created this way was coupled with the Statistical Process Control (SPC) technique and a newly developed burst detection metric based on the moving average residuals between the predicted and observed hydraulic states (flows/pressures). Two new SPC-based charts with associated generic set of control rules for analysing burst detection metric values over consecutive time steps were introduced to raise burst alarms in a reliable and timely fashion. The SPC rules and relevant thresholds were determined offline by performing appropriate statistical analysis of residuals. The above was followed by the development of the new methodology for online burst localisation. The methodology integrates the information on burst detection metric values obtained during the detection stage with the new sensitivity matrix developed offline and hydraulic model runs used to simulate potential bursts to identify the most likely burst location in the pipe network. A new data algorithm for estimating the ‘normal’ DMA demand and burst flow during the burst period is developed and used for localisation. A new data algorithm for statistical analysis of flow and pressure data was also developed and used to determine the approximate burst area by producing a list of top ten suspected burst location nodes. The above novel methodologies for burst detection and localisation were applied to two real-life District Metred Areas in the United Kingdom (UK) with artificially generated flow and pressure observations and assumed bursts. The results obtained this way show that the developed methodology detects pipe bursts in a reliable and timely fashion, provides good estimate of a burst flow and accurately approximately locates the burst within a DMA. In addition, the results obtained show the potential of the methodology described here for online burst detection and localisation in assisting Water Companies (WCs) to conserve water, save energy and money. It can also enhance the UK WCs’ profile customer satisfaction, improve operational efficiency and improve the OFWAT’s Service Incentive Mechanism (SIM) scores.

Interruption to water services and low water pressure conditions are commonly observed problems in water distribution systems (WDSs). Of particular concern are the unplanned events, such as pipe bursts. The current regulation in the UK requires water utilities to provide reliable water service to consumers resulting in as little as possible interruptions and of as short possible duration. All this pushes water utilities toward developing and using smarter responses to these events, based on advanced tools and solutions. All with the aim to change network management style from reactive to a proactive, and reduce water losses, optimize energy use and provide better services for consumers. This thesis presents a novel methodology for efficient and effective operational, short time response to an unplanned failure event (such as pipe burst) in a WDS. The proposed automated, near real-time operational response methodology consists of isolating the failure event followed by the recovery of the affected system area by restoring the flows and pressures to normal conditions. The isolation is typically achieved by manipulating the relevant on/off valves that are located closely to the event location. The recovery involves selecting an optimal combination of suitable operational network interventions. These are selected from a number of possible options with the aim to reduce the negative impact of the failure over a pre-specified time horizon. The intervention options considered here include isolation valve manipulations, changing the pressure reducing valve’s (PRV) outlet pressure and installation and use of temporary overland bypasses from a nearby hydrant(s) in an adjacent, unaffected part of the network. The optimal mix of interventions is identified by using a multi-objective optimization approach driven by the minimization of the negative impact on the consumers and the minimization of the corresponding number of operational interventions (which acts as a surrogate for operational costs). The negative impact of a failure event was quantified here as a volume of water undelivered to consumers and was estimated by using a newly developed pressure-driven model (PDM) based hydraulic solver. The PDM based hydraulic solver was validated on a number of benchmark and real-life networks under different flow conditions. The results obtained clearly demonstrate its advantages when compared to a number of existing methods. The key advantages include the simplicity of its implementation and the ability to predict network pressures and flows in a consistently accurate, numerically stable and computationally efficient manner under both pressure-deficient and normal-flow conditions and in both steady-state and extended period simulations. The new real-time operational response methodology was applied to a real world water distribution network of D-Town. The results obtained demonstrate the effectiveness of the proposed methodology in identifying the Pareto optimal network type intervention strategies that could be ultimately presented to the control room operator for making a suitable decision in near real-time.

Atualmente a avaliação das perdas de água, nos sistemas de distribuição, é feita com base em equações empíricas, que utilizam informações, agrupadas e totalizadas, de uma área. Isto torna necessária sua subdivisão em frações cada vez menores, na busca da fração mais crítica. Neste trabalho, é apresentada uma avaliação da eficácia do uso de modelos de simulação hidráulica na obtenção das informações necessárias para a elaboração de um diagnóstico de perdas de água, com uma metodologia prática para o uso de modelos com este objetivo. Apresenta uma classificação dos trechos de rede em três categorias A, B e C, que facilita a priorização dos trechos mais críticos facilitando a análise por meio de gráficos de pareto e mapas temáticos. Demonstra que a adoção da simulação hidráulica no estudo das causas de perdas de água, nos sistemas de abastecimento, é uma ferramenta eficaz e permitirá às empresas de saneamento, uma melhoria na gestão operacional, que garante a sustentabilidade da empresa, a economia dos recursos humanos, econômicos, e principalmente, os hídricos. / Currently water losses evaluation in distribution systems, is based on empirical equations using information, grouped and totaled, covering whole area. Thus, becomes necessary to subdivide the area into smaller and smaller fractions, searching for the most critical part. This study presents, the effectiveness evaluation of the hydraulic simulation models, use to obtain the information necessary in elaboration diagnosis of water losses, with a practical methodology for using models for this purpose. Shows a pipe classification in three categories A, B and C, its began possible analyses with pareto graphics and thematic maps. Demonstrates that hydraulic simulation adoption is an effective tool in the study of water loss in supply systems. It will allow companies an operational management improvement, ensuring the sustainability of the business and economics of human, financial, and especially, water resources.

An ideal drinking water distribution system (DWDS) must supply safe drinking water with free chlorine residual (FCR) in the form of HOCI and OCIֿ at a required concentration level. Meanwhile the FCR is consumed in the bulk liquid phase and at the DWDS pipes wall as the result of chemical reactions. Because of these, an optimized chlorine dosing for the DWDS using model-based predictive control (MBPC) is developed through the steps of modelling the FCR transport along the main pipes of the DWDS, designing chlorine dosing and implementing a multiple-input multiple-output system control scheme in Matlab 7.0.1 software. Discrete time-space models (DTSM) that can be used to predict free chlorine residual (FCR) concentration along the pipes of the DWDS over time is developed using explicit finite difference method (EFDM). Simulations of the DTSM using step and rectangular pulse input show that the effect of water flow rate velocity is much stronger than the effect of chlorine effective diffusivity coefficient on the FCR distribution and decay process in the DWDS main pipes. Therefore, the FCR axial diffusion in single pipes of the DWDS can be neglected. Investigating the effect of injection time, initial chlorine distribution, and overall chlorine decay rate constant involved in the process have provided a thorough understanding of chlorination and the effectiveness of all the parameters. This study proposed a model-based chlorine dosing design (MBCDD) based on a conventional-optimum design process (CODP) (Aurora, 2004), which is created for uncertain water demand based on the DTSM simulation. / In the MBCDD, the constraints must be met by designing distances between chlorine boosters and optimal value of the initial chlorine distribution in order to maintain the controlled variable (CV), i.e. FCR concentration with a certain degree of robustness to the variations of water flow rate. The MBCDD can cope with the simulated DWDS (SDWDS) with the conditions; the main pipe is 12 inch diameter size with the pipe length of 8.5 km, the first consumers taking the water from the point of 0.83 km, the assumed pipe wall chlorine decay rate constant of 0.45 m/day, and the value of chlorine overall decay rate constants follow Rosman's model (1994), by proposing a set of rules for selecting the locations for additional chlorine dosing boosters, and setting the optimal chlorine dosing concentrations for each booster in order to maintain a relatively even FCR distribution along the DWDS, which is robust against volumetric water supply velocity (VWS) variations. An example shows that by implementing this strategy, MBCDD can control the FCR along the 8.5 km main pipe of 12 inch diameter size with the VWS velocity from 0.2457 to 2.457 km/hr and with the assumed wall and bulk decay constants of 0.45 and 0.55 m/day, respectively. An adaptive chlorine dosing design (ACDD) as another CODP of chlorine dosing which has the same concept with the MBCDD without the rule of critical velocity is also proposed in this study. The ACDD objective is to obtain the optimum value of initial chlorine distribution for every single change in the VWS. Simulation of the ACDD on the SDWDS shows that the ACDD can maintain the FCR concentration within the required limit of 0.2-0.6 mg/1. / To enable water quality modelling for studying the effectiveness of chlorine dosing and injection in the form of mass flow rate of pure gaseous chlorine as manipulated variable (MV), a multiple-input multiple-output (MIMO) system is developed in Simulink for Matlab 7.0.1 software by considering the disturbances of temperature and circuiting flow. The MIMO system can be used to design booster locations and distribution along a main pipe of the DWDS, to monitor the FCR concentration at the point just before injection (mixing) and between two boosters, and to implement feedback and open-loop control. This study also proposed a decentralized model-based control (DMBC) based on the MBCDD-ACDD and centralized model predictive control (CMPC) in order to optimize MV to control the CV along the main pipe of the DWDS in the MIMO system from the FCR concentration at just after the chlorine injection (CVin) to the FCR concentration (CVo) before the next chlorine injection with the constraints of 0.2-0.6 ppm for both the CVin and CVo. A comparison of the performances of decentralized PI (DPI) control, DMBC and CMPC, shows that the performances of the DMBC and CMPC in controlling the MIMO system are almost the same, and they both are significantly better than the DPI control performance. In brief, model-based predictive control (MBPC), in this case a decentralized model-based control (DMBC) and a centralized predictive control (CMPC), enable optimization of chlorine dosing for the DWDS.

The purposes of this study include: (1) investigating the reasons why drinking water quality degrades during transportation in the distribution system and developing an easy and effective tool to evaluate the status of distribution system; (2) investigating residents¡¦ satisfaction with advanced treated drinking water. It is found that the main reason of drinking water degradation is that most people don¡¦t flush the drinking water storage facilities routinely. It is also found that although most respondents are satisfied with advanced treated drinking water, nearly 40% of local residents still buy bottle water instead of drinking tap water. Therefore, Taiwan Water Supply Corp. (TWSC) should let people know the importance of flushing water storage facilities routinely and what TWSC has done to improve drinking water quality. The LSI (Langelier Saturation Index) of most water samples is negative, which means that the drinking water is corrosive when too much hardness is removed to comply with the regulations. A simple, efficient and cost-effective method is developed to provide TWSC sufficient information to solve the problems regarding water quality degradations in distribution systems. By using contour maps of different water quality parameters, TWSC can easily identifies locations with potential problems and easily assesses the necessity and appropriate locations of building re-chlorination stations, even though the lack of information regarding pipeline material, hydraulic conditions, thickness of biofilm¡Ketc.

Hasankeyf, located in Upper Mesopotamia, southeastern Turkey with its environs at the floodplains of Tigris, welcomed many cultures in different periods. It has a very unique status with its difficult topography and distinctive outlook where spatial urbanization in almost every period must have been extraordinary, as well. The aim of this thesis is to study the water distribution system, specifically its relation to natural and man-made environment, at the Upper city of Hasankeyf, in order to identify the impact of utilization of water on the urban structure, with a new perspective. The thesis tries to explain the designation of urban patterns and understand possible late settlement strategies in the light of cistern-incentive and available canal data collected at the Upper city. The identification of 185 cisterns and their various characteristics helps to make different analyses to establish links between the water system and settlement areas at macro and micro levels, which go hand in hand with mapping studies. Notwithstanding the abovementioned objectives, this study endeavors to find some common denominators with Roman water practices, which are considered to be comparable to those of Hasankeyf, thus unveil some clues for Hasankeyf water features. It now appears that water and urban settlement are two sides of a coin where water can not be treated as the sole determinant on the development of settlement patterns in which case the urban settlement also has impact on the water distribution at the Upper city.

Access to clean and safe drinking water is a fundamental human requirement. However, in many areas of the world natural water sources have been impacted by a variety of biological and chemical contaminants. The ingestion of these contaminants may cause acute or chronic health problems. To prevent such illnesses, many technologies have been developed to treat, disinfect and supply safe drinking water quality. However, despite these advancements, water supply distribution systems can adversely affect the drinking water quality before it is delivered to consumers. The primary aim of this research was to investigate the effect that water distribution systems may have on household drinking water quality in Christchurch, New Zealand and Addis Ababa, Ethiopia. Water samples were collected from the source water and household taps in both cities. The samples were then tested for various physical, chemical and biological water quality parameters. The data collected was also used to determine if water samples complied with national drinking water quality standards in both countries. Independent samples t-test statistical analyses were also performed to determine if water quality measured in the samples collected from the source and household taps was significantly different. Water quality did not vary considerably between the source and tap water samples collected in Christchurch City. No bacteria were detected in any sample. However, the pH and total iron concentrations measured in source and tap water samples were found to be significantly different. The lower pH values measured in tap water samples suggests that corrosion may be taking place in the distribution system. No water samples transgressed the Drinking Water Standards for New Zealand (DWSNZ) MAVs. Monitoring data collected by the Christchurch City Council (CCC) was also used for comparison. A number of pH, turbidity and total iron concentration measurements collected by the CCC in 2011 were found to exceed the guideline values. This is likely due to structural damage to the source wells and pump-stations that occurred during the 2011 earthquake events. Overall, it was concluded that the distribution system does not adversely affect the quality of Christchurch City’s household drinking water. The water quality measured in samples collected from the source (LTP) and household taps in Addis Ababa was found to vary considerably. The water collected from the source complied with the Ethiopian (WHO) drinking water quality standards. However, tap water samples were often found to have degraded water quality for the physical and chemical parameters tested. This was especially the case after supply interruption and reinstatement events. Bacteria were also often detected in household tap water samples. The results from this study indicate that water supply disruptions may result in degraded water quality. This may be due to a drop in pipeline pressure and the intrusion of contaminants through the leaky and cross-connected pipes in the distribution network. This adversely affects the drinking water quality in Addis Ababa.

There is currently growing concern about the presence of heterotrophic plate count (HPC) bacteria in drinking water. These HPC may have potential pathogenic features, enabling them to cause disease. It is especially alarming amongst individuals with a weakened immune system. South Africa, the country with the highest incidents of HIV positive individuals in the world, mainly uses these counts to assess the quality of drinking water in terms of the number of micro-organisms present in the water. These micro-organisms may be present in the bulk water or as biofilms adhered to the surfaces of a drinking water distribution system. The current study investigated the pathogenic potential of HPC bacteria occurring as biofilms within a drinking water distribution system and determined the possible presence of these micro-organims within the bulk water. Biofilm samples were taken from five sites within a drinking water distribution system. Fifty six bacterial colonies were selected based on morphotypes and isolated for the screening of potential pathogenic features. Haemolysin production was tested for using sheep-blood agar plates. Of the 56, 31 isolates were ?-haemolytic. Among the 31 ?-haemolytic positive isolates 87.1% were positive for lecithinase, 41.9% for proteinase, 19.4% for chondroitinase, 9.7% for DNase and 6.5% for hyaluronidase. All of the ?-haemolytic isolates were resistant to oxytetracycline 30 ?g, trimethoprim 2.5 ?g and penicillin G10 units, 96.8% were resistant to vancomycin 30 ?g and ampicillin 10 ?g, 93.5% to kanamycin 30 ?g, 74.2% to chloramphenicol 30 ?g, 54.8% to ciprofloxacin 5 ?g, 22.6% to streptomycin 300 ?g and 16.1% to erythromycin 15 ?g. Nineteen isolates producing two or more enzymes were subjected to Gram staining. The nineteen isolates were all Gram-positive. These isolates were then identified using the BD BBL CRYSTALTM Gram-positive (GP) identification (ID) system. Isolates were identified as Bacillus cereus, Bacillus licheniformis, Bacillus subtilis, Bacillus megaterium, Bacillus pumilus and Kocuria rosea. 16S rRNA gene sequencing was performed to confirm these results and to obtain identifications for the bacteria not identified with the BD BBL CRYSTALTM GP ID system. Additionally identified bacteria included Bacillus thuringiensis, Arthrobacter oxydans and Exiguobacterium acetylicum. Morphological properties of the different species were studied with transmission electron microscopy (TEM) to confirm sequencing results. All the isolates displayed rod shaped cells with the exception of Arthrobacter oxydans being spherical in the stationary phase of their life cycle. Bulk water samples were taken at two sites in close proximity with the biofilm sampling sites. The DNA was extracted directly from the water samples and the 16S rRNA gene region was amplified. Denaturing gradient gel electrophoresis (DGGE) was performed to confirm the presence of the isolates from the biofilm samples in the bulk water samples. The presence of Bacillus pumilus and Arthrobacter oxydans could be confirmed with DGGE. This study demonstrated the presence of potentially pathogenic HPC bacteria within biofilms in a drinking water distribution system. It also confirmed the probable presence of two of these biofilm based bacteria in the bulk water. / Thesis (M.Sc. (Microbiology))--North-West University, Potchefstroom Campus, 2010.

There is currently growing concern about the presence of heterotrophic plate count (HPC) bacteria in drinking water. These HPC may have potential pathogenic features, enabling them to cause disease. It is especially alarming amongst individuals with a weakened immune system. South Africa, the country with the highest incidents of HIV positive individuals in the world, mainly uses these counts to assess the quality of drinking water in terms of the number of micro-organisms present in the water. These micro-organisms may be present in the bulk water or as biofilms adhered to the surfaces of a drinking water distribution system. The current study investigated the pathogenic potential of HPC bacteria occurring as biofilms within a drinking water distribution system and determined the possible presence of these micro-organims within the bulk water. Biofilm samples were taken from five sites within a drinking water distribution system. Fifty six bacterial colonies were selected based on morphotypes and isolated for the screening of potential pathogenic features. Haemolysin production was tested for using sheep-blood agar plates. Of the 56, 31 isolates were ?-haemolytic. Among the 31 ?-haemolytic positive isolates 87.1% were positive for lecithinase, 41.9% for proteinase, 19.4% for chondroitinase, 9.7% for DNase and 6.5% for hyaluronidase. All of the ?-haemolytic isolates were resistant to oxytetracycline 30 ?g, trimethoprim 2.5 ?g and penicillin G10 units, 96.8% were resistant to vancomycin 30 ?g and ampicillin 10 ?g, 93.5% to kanamycin 30 ?g, 74.2% to chloramphenicol 30 ?g, 54.8% to ciprofloxacin 5 ?g, 22.6% to streptomycin 300 ?g and 16.1% to erythromycin 15 ?g. Nineteen isolates producing two or more enzymes were subjected to Gram staining. The nineteen isolates were all Gram-positive. These isolates were then identified using the BD BBL CRYSTALTM Gram-positive (GP) identification (ID) system. Isolates were identified as Bacillus cereus, Bacillus licheniformis, Bacillus subtilis, Bacillus megaterium, Bacillus pumilus and Kocuria rosea. 16S rRNA gene sequencing was performed to confirm these results and to obtain identifications for the bacteria not identified with the BD BBL CRYSTALTM GP ID system. Additionally identified bacteria included Bacillus thuringiensis, Arthrobacter oxydans and Exiguobacterium acetylicum. Morphological properties of the different species were studied with transmission electron microscopy (TEM) to confirm sequencing results. All the isolates displayed rod shaped cells with the exception of Arthrobacter oxydans being spherical in the stationary phase of their life cycle. Bulk water samples were taken at two sites in close proximity with the biofilm sampling sites. The DNA was extracted directly from the water samples and the 16S rRNA gene region was amplified. Denaturing gradient gel electrophoresis (DGGE) was performed to confirm the presence of the isolates from the biofilm samples in the bulk water samples. The presence of Bacillus pumilus and Arthrobacter oxydans could be confirmed with DGGE. This study demonstrated the presence of potentially pathogenic HPC bacteria within biofilms in a drinking water distribution system. It also confirmed the probable presence of two of these biofilm based bacteria in the bulk water. / Thesis (M.Sc. (Microbiology))--North-West University, Potchefstroom Campus, 2010.