Abstract This paper presents an analysis of the challenges associated with discoloration risk management and the impact of hydraulic transients on water quality within distribution systems. Focusing on the Metropolitan Region of Curitiba, Paraná, Brazil, the study employs a comprehensive methodology that combines the Characteristic Method for simulating hydraulic transients and real-time monitoring of water quality parameters, such as turbidity and chlorine levels. A framework for managing discoloration risk is proposed, highlighting strategies for identifying potential causes, assessing risk severity, developing prevention and mitigation strategies, and implementing continuous improvement processes. The experimental section details the impact of hydraulic transient events on water quality, with significant findings indicating a direct correlation between flow dynamics and water quality degradation, particularly in terms of increased turbidity and decreased chlorine levels during pump deactivation. The study contributes valuable insights into effective water distribution system management, emphasizing the importance of advanced monitoring and risk management techniques to maintain high-quality water standards. systems Curitiba Paraná Brazil realtime real time parameters proposed causes severity processes degradation deactivation highquality high standards

Resumo Este artigo apresenta uma análise dos desafios associados ao gerenciamento do risco de descoloração e o impacto dos transientes hidráulicos na qualidade da água dentro dos sistemas de distribuição. Concentrando-se na Região Metropolitana de Curitiba, Paraná, Brasil, o estudo emprega uma metodologia abrangente que combina o Método das Características para simular transientes hidráulicos e o monitoramento em tempo real de parâmetros de qualidade da água, como os níveis de turbidez e cloro. É proposto um quadro para o gerenciamento do risco de alteração de qualidade da água, destacando estratégias para identificar causas potenciais, avaliar a severidade do risco, desenvolver estratégias de prevenção e mitigação e implementar processos de melhoria contínua. A seção experimental detalha o impacto dos eventos transientes hidráulicos na qualidade da água, com achados significativos indicando uma correlação direta entre a dinâmica do fluxo e a degradação da qualidade da água, particularmente em termos de aumento da turbidez e diminuição dos níveis de cloro durante a desativação das bombas. O estudo contribui com insights valiosos para o gerenciamento eficaz de sistemas de distribuição de água, enfatizando a importância de técnicas avançadas de monitoramento e gerenciamento de riscos para manter padrões elevados de qualidade da água. Concentrandose Concentrando se Curitiba Paraná Brasil potenciais contínua bombas

The Atlantis Water Supply Scheme (AWSS, Western Cape, South Africa) has been in operation for about 40 years as a means to supply and augment drinking water to the town of Atlantis via managed aquifer recharge (MAR). In this study, the numerical model MODFLOW for groundwater flow and contaminant transport was used in support of the management of the AWSS. The aims were: (i) to calibrate the MODFLOW model for the MAR site at Atlantis; (ii) to run realistic scenarios that cannot be replicated through experiments; and (iii) to make recommendations in support of efficient and sustainable management of the aquifer. MODFLOW was calibrated through comparison of observed and simulated groundwater levels (R² between 0.663 and 0.995). Scenario simulations indicated possible drawdowns between < 5 m (low groundwater abstraction and low artificial recharge of groundwater through infiltration basins) and > 20 m (high abstraction and high artificial recharge) at localized areas of the Witzand wellfield. At Silwerstroom, large drawdown levels were not predicted to occur, so this wellfield could be exploited more without affecting the sustainability of the groundwater resource. Groundwater moves from the infiltration basins towards the Witzand wellfield at a rate of 120-150 m-a-1. The modelling results supported recommendations for balancing groundwater abstraction and artificial recharge volumes, monitoring the water balance components of the system, the potential risks of groundwater contamination and the delineation of groundwater protection zones.

Abstract: Fluoride in drinking water has been a major concern in many parts of the world as it diminishes the acceptable good quality of groundwater sources. In Mexico this health hazard has been mainly identified along the Sierra Madre Occidental (of felsic nature) and neighbouring territory. Little concern has been given in other parts of the country, as in the State of Morelos in which groundwater is considered by the Ministry of Health fluoride-free. The water supply to the population in the quantity and quality required for human consumption is a public policy issue in Mexico; fluoride (F-) natural content in groundwater varies from 0.001 to 25 mg/L. The highest concentrations are reported in studies carried out in the central, northern, north-western, and areas in the north-eastern part of the country, where a high rate of dental and skeletal fluorosis has been reported. In the southern part of the country, there are very few studies on fluoride; however, there are cases of dental fluorosis, reported in some communities. This study was carried out in the Tenextepango region in the state of Morelos, located just to the south of Mexico City. Groundwater consumed by the population in this region has a fluoride concentration from 0.5 to 1.9 mg/ L, causing a dental fluorosis condition; infants up to 7 years of age and senior citizens being the most vulnerable. Localities with the highest presence of fluorosis are: Tenextepango, La Longaniza, El Salitre and Xalostoc, where dental fluorosis occurs with a concentration of 0.9 mg/L of fluoride, only. The aim of this work was to define fluoride levels in groundwater, their distribution in the region of Tenexpenango, its origin, as well as to document its presence and control in the water through the concept of the groundwater flow systems. The hydrogeological conceptual model was established with information on the geological context, water-level monitoring in boreholes, and chemical analyses. Analytical information was obtained from groundwater samples collected on a plain (17 boreholes and five springs) where field (pH, alkalinity, EC and water temperature) parameters were measured at borehole-head. Major cations and anions, as well as trace element content were determined by ICP-MS. These physicochemical data were useful in deducing hydrogeochemical processes, a possible chemical stratification of the water and to comparatively derive the depth travelled by water within the geological environment of reference. Results suggest that fluoride concentration and groundwater temperature are higher in boreholes pumping continuously, and lower in boreholes taping water only nine hours a day. This response proposes former boreholes to be inducing up-coning of deeper groundwater flows of regional nature Any scheme proposing an increase in water extraction (either in time or in quantity) is to enhance vertical ascending flow to reach the production level permitting such boreholes to capture deeper and warmer regional flow systems with higher fluoride content than that in other boreholes tapping in an intermittent basis. This hydrodynamic result of extraction time as a continuous decrease in the piezometric surface, is also showing as a decrease of the hydraulic head in the vertical direction just below the extraction level of the borehole, resulting in a deep water ascending flow, whose fluoride content is higher than in the cooler system above (shallow local flow). Also, the calcium content in the warm groundwater is lower than in the cool one, and vice versa. Also a high fluoride concentration corresponds with a high sodium content supporting evidence of a large flow path and long travelling time. Due to affinity of fluoride to calcium in water these ions bind to form fluorite mineral, which precipitates. Regarding fluoride origin in groundwater, it is meant to be released from rocks of rhyolitic nature primarily by the chemical weathering through hydrolysis processes. The resulting dissolution is from minerals containing fluoride as albite, biotite, amphibole, phlogopite and fluorite, which are widely present in the felsic igneous rocks in the area; once in the groundwater, fluoride will move through hydrodynamic dispersion. It was concluded that the origin of fluoride in groundwater in this region is result of chemical processes enhanced by travelling time and the high temperature on the regional flows generated beyond the surrounding plain, mainly through felsic rock formations located in the surrounding mountains at the northeast of the study area. The temperature value and fluoride content in the extracted water in the area vary depending on the extraction time (ie, the longer and/or higher extraction rate). The increase of these parameters show that a continue extraction induces the arrival of water from a deeper regional flow containing fluoride in a significant high content as compared to the shallow water. The control of water extraction with low fluoride content requires conducting control tests on the boreholes allowing to improve the natural quality of the extracted water, allowing a reduction of the fluoride content by setting fluoride vs. temperature at different time intervals after extraction started; and fluoride vs. extraction rate. It becomes important to test different extraction rates (produce different hydraulic gradients in the extraction borehole) to define the extraction rate (or extraction time) with the least fluoride content possible to achieve a fluoride control. The understanding of the groundwater functioning under extraction may avoid additional side-effects of fluoride induction. This could take advantage of the natural system without installing unnecessary and high cost treatment plants which would require costly maintenance, and specialized personnel, which, however, will produce a hazardous sludge that need to be properly managed to avoid additional health risks. It was found advisable that the inhabitants of this region decrease by natural means the fluoride inflow from boreholes containing high fluoride, while a diet with high calcium content should be implemented.

Resumen: El agua subterránea que consume la población en la región de Tenextepango, Morelos, contiene fluoruro en concentración que varía de 0.5 a 1.9 mg/L, causando problema de fluororis dental a la población. El objetivo de este trabajo es conocer los niveles de fluoruro en el agua subterránea, su distribución y su procedencia en la región de Tenexpenango, Morelos, México. Para esto se elaboró el modelo hidrogeológico soportado con análisis químicos del agua obtenida en 17 pozos y cinco manantiales; el pH, alcalinidad, CE y temperatura del agua se registraron en campo. La concentración de cationes, aniones y elementos traza se determinó por ICP-MS. Los resultados indican que la concentración de fluoruro, y temperatura del agua subterránea, son mayores en los pozos que extraen agua sin interrupción y menor en aquéllos que bombean solo nueve horas-día. La variación de estos parámetros sugiere que los primeros extraen agua de un flujo con mayor profundidad de recorrido con respecto al agua de otros pozos, indicando que el incremento en el tiempo de extracción induce un flujo vertical de agua (ascendente) permitiendo que en tales pozos se descargue un sistema de flujo más profundo, cuyo contenido de fluoruro y valor de temperatura son sensiblemente mayores al resto de los demás pozos. Como conclusión, la fuente del fluoruro al agua subterránea en esta región está en las rocas que conforman del relieve que rodea la planicie y principalmente en aquel ubicado fuera de la planicie hacia el noreste (Sierra Nevada). El fluoruro es liberado al agua subterránea por el proceso del intemperismo químico de rocas ígneas intermedias y félsicas.

ResumenEn este artículo se presentan los resultados de un estudio para determinar el potencial uso de cuatro técnicas para la cuantificación de nitratos en muestreo continuo: cromatografía iónica, espectrofotometría de absorción ultravioleta utilizando un equipo de mesa y dos miniespectrofotómetros con inyección de la muestra en flujo continuo, uno para mediciones en el ámbito de radiación visible y el otro optimizado para mediciones de absorción de radiación ultravioleta. Las variables consideradas son el consumo de reactivos y accesorios, la toxicidad de los desechos, la respuesta al analito, el límite de detección (LD), el límite de cuantificación (LC), la linealidad en el ámbito de interés y la sensibilidad.La espectrofotometría de detección de absorción ultravioleta con inyección de la muestra en flujo continuo resultó ser la mejor de las técnicas evaluadas para análisis en línea; su respuesta es lineal entre 0-10 mg/L, que es el ámbito recomendado por la OMS para la concentración de nitratos en agua potable; tiene un bajo consumo de reactivos y accesorios, no genera residuos peligrosos, tiene LD 0,002 mg/L y LC 0,006 mg/L y una sensibilidad adecuada para responder rápidamente a la concentración del analito sin saturación de la señal, cumpliendo con las características deseables para un sistema de análisis en línea.

AbstractThe potential of four analytical methods for the quantification of nitrate is determined to be used in a continuous sampling set up: ion chromatography and the ultraviolet spectrophotometric screening, both in their benchtop version, Cadmium reduction with post-reaction and visible light absorption measurement and the direct ultraviolet spectrophotometric absorption screening but using mini-spectrophotometers and in flow injection of the sample and analysis (FIA) techniques. Accessories, toxicity of the reaction products, response, detection and quantification limits, linearity in the range of interest and sensitivity are considered for the evaluation. The direct measurement of ultraviolet absorption with flow injection was the best of the evaluated techniques. It has a linear response in the 0-10 mg/L range, WHO recommended range for drinking water, low reagents and accessories consuming, LOD 0,002 mg/L, LOQ 0,006 mg/L, and good sensitivity in the investigated range, meeting the required characteristics for in-line monitoring systems.

In South Africa, the management and monitoring of drinking water quality is governed by policies and regulations based on international standards. Water Service Authorities, which are either municipalities or district municipalities, are required to submit information regarding water quality and the management thereof regularly to the national Blue Drop System (BDS). Since 2009, a trend has emerged in which urban municipalities have been shown to consistently improve their water quality management whilst some of the rural and under-resourced municipalities are falling behind. A major concern has been that rural municipalities are failing to report the required information and are not complying with some of the regulator's requirements that speak to the overall management of water quality monitoring rather than the actual water quality itself. This paper reflects on a case study undertaken in four rural municipalities in South Africa where a cellphone-based information system was implemented to collect information relevant to the municipality. The study was conducted by the Information for Community Oriented Municipal Services (iCOMMS) research team based at the Department of Civil Engineering at the University of Cape Town. The hypothesis for the research was that improved information flow within rural municipalities - from water supplies in outlying areas to the municipal government office - can improve the efficiency of existing monitoring, if the design, development and implementation of such a system are based on collecting appropriate and locally relevant information. Water service authorities at the four field sites managed the process of monitoring in very different ways due to limited resources as well as structural challenges within each government department. The variety of stakeholders involved in water quality monitoring programmes, and the alternative methods and processes used, challenges the current understanding of information system design as well as the notion of developing a single national information system. The decentralisation of national water quality monitoring to municipal level was assessed in this research, which concluded that the BDS was of limited usefulness to water quality monitoring in the rural municipalities partaking in this research.

Arsenic (As) is a natural contaminant that affects a large area of Argentina. Quantification of As in drinking water has been used to evaluate the source of exposure and As in urine to assess exposure to this toxic. This study aimed to optimize and validate a methodological technique for the quantification of As [As sum = inorganic As (AsI) + methylated species: monometilarsonic acid (MMA) and dimetilarsinic acid (DMA)], product of AsI metabolism by flow injectionhydride generation-atomic absorption spectrometry (FI-GH-AAS), after derivatization with L-cysteine. The recovery of the studied species: AsI (AsIII and AsV), MMA and DMA was close to 100% in all cases. The limits of detection and quantitation were found for water and urine: 2 and 3 μg/L; 5 and 8 μg/L respectively and a linear working range from 5 to 75 μg/L, allowing quantify As in water close to international standards of maximum As values for drinking water and urine samples with levels comparables with those found in people non exposed ocupacionally . This methodology is a valid alternative for assessing exposure to As in water and urine samples without the need of prolonged pre-treatment sample, more quickly and inexpensively.

El arsénico (As) es un contaminante natural que afecta una amplia zona de Argentina. El nivel de As en agua de consumo es utilizado para evaluar la fuente de exposición y en orina para evaluar exposición a este tóxico. El presente trabajo tuvo como objetivo la optimización y validación metodológica de una técnica para la cuantificación de As [As suma = As inorgánico (AsI) + especies metiladas: ácido monometilarsónico (MMA) y ácido dimetilarsínico (DMA)], producto del metabolismo del AsI, por inyección en flujo- generación de hidruros- espectrometría de absorción atómica (IF-GH-EAA), previa derivatización con L-cisteína. La recuperación de las especies estudiadas: AsI (AsIII y AsV), MMA y DMA fue cercana al 100% en todos los casos. Los límites de detección y cuantificación encontrados fueron para agua y orina: 2 y 3 μg/L; 5 y 8 μg/L respectivamente y el rango dinámico de trabajo establecido fue desde 5 a 75 μg/L, permitiendo cuantificar As en muestras de agua cercanos a los estándares internacionales vigentes para valores máximos de As en agua de consumo y en orina en niveles comparables con los establecidos en población laboralmente no expuesta. Esta propuesta metodológica es una alternativa para evaluar la exposición al As en muestras de agua y orina, sin necesidad de utilizar prolongados pre-tratamientos de muestra, de forma más rápida y económica.