This publication provides guidance to water-sector decision makers and planners on how to deal with the quality dimension of groundwater resources management in the World Bank's client countries. There is growing evidence of increasing pollution threats to groundwater and some well-documented cases of irreversible damage to important aquifers. This guide has been produced in the belief that groundwater pollution hazard assessment must become an essential part of environmental best practice for water supply utilities. The guide is particularly relevant for the World Bank's Latin American and Caribbean Region, where many countries have initiated major changes to modernize their institutional and legal framework for water resources management, but may not yet have considered groundwater at the same level as surface water, because of lack of awareness and knowledge of groundwater issues and policy options.

El proyecto de investigación evalúa la remoción de manganeso en el sistema de tratamiento convencional de agua potable del municipio de Tocancipá, ya que este elemento químicos ha generado dificultad para ser removido y cumplir permanentemente con el valor máximo permisible de conformidad con la resolución 2115 de 2007, que es de 0.1 mg Mn/l; se realizaron análisis de las condiciones actuales de tratamiento del sistema, considerando las características del agua cruda, agua tratada y se evaluó el proceso de oxidación del manganeso con peróxido de hidrógeno que es el método utilizado actualmente. | The research project evaluates the removal of manganese in a conventional drinking water treatment Plant of the municipality of Tocancipá, since this chemical element has generated difficulty to be removed and permanently keep under the maximum permissible value in accordance with resolution 2115 of 2007 , which is 0.1 mg Mn/l; several analysis of the current treatment conditions of the system were analysed, including the characteristics of raw water, treated water and finally evaluated the oxidation process of manganese with hydrogen peroxide that is the method currently used. | Maestría | Magíster el Ingeniería Civil con Énfasis en Ingeniería Ambiental

Artículo original escaneado para el Repositorio (archivo delegado) | La presencia de hierro y manganeso en las aguas de abastecimiento público supone un grave problema para el mantenimiento de unos niveles óptimos de calidad. La oxidación de los estados solubles de los dos metales da lugar a la formación de precipitados que confieren mal sabor y color al agua, y pueden llegar abstruir las tuberías. La limpieza química de la red de distribución utilizando H2O2 es un método adecuado para la eliminación de las deposiciones de Fe y Mn, y para el control de las concentraciones de ambos metales disueltas en el agua. En este trabajo se presentan los resultados de la aplicación de este tratamiento para la mejora de la calidad del agua potable en la localidad de Valencia del Ventoso (Badajoz). Así, se proponen medidas para el adecuado mantenimiento de dicha calidad basadas en el ajuste del sistema de potabilización actualmente en funcionamiento en el pueblo. | Chemical cleaning of supply pipes. Presence of iron and manganese in drinking water means a serious problem for the maintenance of water quality. Oxidation of both metals produces precipitates that give the water bad taste and colour, and may block the supplying pipes. Chemical cleaning of the water supply network using hydrogen peroxide is an effective method for removing Fe and Mn, and for controlling concentrations of both metals in the water. In this paper, results of H2 O2 application for the improvement of drinking water in Valencia del Ventoso (Badajoz) are presented. Moreover, a set of steps based on the adjustment of treatment processes in the Municipal Water Treatment Plant are proposed to achieve an appropriate maintenance of water quality.

Managed aquifer recharge (MAR) refers to intentional infiltration of surface water to an aquifer for facilitating natural water treatment and storage. MAR is often used as a treatment to remove natural organic matter from water in drinking water production. The sustainability of MAR depends on how the aquifer capacity to remove organic matter will evolve over the long term. This report explores the behavior of MAR systems by using a natural lake–aquifer system as a surrogate. Natural infiltration of lake water to groundwater has been going on for millennia at the research site in Finland chosen for this study. According to the measurements, the mean concentration of total organic carbon (TOC) in lake water was 3.0 mg/L. Within the distance of 3 m from the lake bank (retention time 7–15 days), already 46% of TOC was removed. At greater distances along the flow paths within the aquifer, 80–90% of TOC was removed. The observed TOC removal in the aquifer was slightly higher than the reported values at MAR sites, indicating that MAR can be an effective solution to the problem of removing natural organic matter in the long term. Signs of accumulation of organic matter were not observed in the aquifer, which suggests that biodegradation was the main removal method, and the role of sorption was minor. Several processes had an impact on oxygen levels in the aquifer, which led to spatial and seasonal changes in the redox conditions and in the iron and manganese concentrations in groundwater.

As part of a province-wide groundwater characterization program, a detailed groundwater geochemistry survey was undertaken in the Outaouais Region (Québec, Canada) in order to identify the primary processes responsible for groundwater quality and to develop a conceptual model for groundwater flow and geochemical evolution. During the summers of 2011 and 2012, 139 samples were collected from municipal and private wells which were analysed for major ions, nutrients, trace elements and sulphides. About 70 % of the samples were obtained from bedrock wells, mainly in the silicate rocks of the Canadian Shield and the remainder from wells screened in Quaternary deposit aquifers. Hydrogeochemical facies distributions were determined from 127 of these samples which had anion-cation charge balance errors within ±10 %. The classification by facies was also supported by a multivariate statistical analysis, namely factor analysis combined with hierarchical cluster analysis. The study identified Champlain Sea invasion, cation exchange and freshwater recharge as the main geochemical processes affecting groundwater chemistry in this region. Secondary processes, related to the bedrock geology, are responsible for exceedances of Canadian drinking-water standards, namely for fluoride, uranium, iron and manganese.

Urban groundwater has often been over-exploited for industrial uses. Now, this usage tends to be reduced or the resource abandoned due to pollution and/or changes in land use. The use and the subsequent disuse of groundwater has resulted in rising water tables that damage underground structures (e.g., building basements and underground car parks and tunnels), leading to the need for additional pumping in urban areas. In the case of the underground parking lot of Sant Adrià del Besòs (Barcelona, NE Spain), large amounts of urban groundwater are pumped to avoid seepage problems. Can this pumped groundwater be used for other purposes (e.g., drinking water and urban irrigation) instead of wasting this valuable resource? To answer this question, it was necessary to quantify the groundwater recharge and to assess the evolution of groundwater quality. The limiting factor at this study site is the groundwater quality because ammonium and some metals (iron and manganese) are present at high concentrations. Hence, further treatment would be needed to meet drinking water requirements. The pumped groundwater could also be used for supplementing river flow for ecological benefit and/or for mitigating seawater intrusion problems. Currently, only a small amount of this urban groundwater is used for cleaning public areas and watering public gardens. This situation highlighted the urgent need to manage this resource in a responsible and more efficient manner, especially in moments of high water demand such as drought periods.

Anthropogenic sources of carbon from landfill or waste leachate can promote reductive dissolution of in situ arsenic (As) and enhance the mobility of As in groundwater. Groundwater from residential-supply wells in a fractured crystalline-rock aquifer adjacent to a Superfund site in Raymond, New Hampshire, USA, showed evidence of locally enhanced As mobilization in relatively reducing (mixed oxic-anoxic to anoxic) conditions as determined by redox classification and other lines of evidence. Redox classification was determined from geochemical indicators based on threshold concentrations of dissolved oxygen (DO), nitrate (NO 3 – ), iron (Fe2+), manganese (Mn2+), and sulfate (SO 4 2– ). Redox conditions were evaluated also based on methane (CH4), excess nitrogen gas (N2) from denitrification, the oxidation state of dissolved As speciation (As(III) and As(V)), and several stable isotope ratios. Samples from the residential-supply wells primarily exhibit mixed redox conditions, as most have long open boreholes (typically 50–100 m) that receive water from multiple discrete fractures with contrasting groundwater chemistry and redox conditions. The methods employed in this study can be used at other sites to gauge redox conditions and the potential for As mobilization in complex fractured crystalline-rock aquifers where multiple lines of evidence are likely needed to understand As occurrence, mobility, and transport.

Poyang Lake is the largest freshwater lake in China and is well known for its ecological and economic importance. Understanding the contribution of groundwater to Poyang Lake is important for the lake’s protection and management. In this study, stable isotopes (δD and δ¹⁸O), ²²²Rn measurements, and corresponding models (²²²Rn and ¹⁸O mass balance models) were employed to evaluate the groundwater discharge and associated chemical inputs to Poyang Lake. The results showed that the distribution of δ¹⁸O in the lake water reflects the groundwater discharge into the lake. The groundwater discharge estimated using the ²²²Rn mass balance model was in reasonable agreement with the groundwater discharge derived from the ¹⁸O mass balance model. The ²²²Rn mass balance model showed that the groundwater discharge rate was 24.18 ± 6.85 mm/d with a groundwater discharge flux of (2.24 ± 0.63) × 10⁷ m³/d, which accounts for 6.52–11.14% of river-water input in the Poyang Lake area. The groundwater discharge flux estimated using the ¹⁸O mass balance model was 3.17 × 10⁷ m³/d, and the average groundwater discharge rate was 26.62 mm/d. The estimated groundwater discharge was used to estimate the associated chemical fluxes. It was found that groundwater-derived heavy metals such as iron and manganese are potential threats to the lake ecological system because of their large inputs from groundwater discharge.