Groundwater In Bangladesh Research Articles

Iron Cycling Potentials of Arsenic Contaminated Groundwater in Bangladesh as Revealed by Enrichment Cultivation

ABSTRACTThe activities of iron-oxidizing and reducing microorganisms impact the fate of arsenic in groundwater. Phylogenetic information cannot exclusively be used to infer the potential for iron oxidation or reduction in aquifers. Therefore, we complemented a previous cultivation-independent microbial community survey covering 22 arsenic contaminated drinking water wells in Bangladesh, with the characterization of enrichments of microaerophilic iron oxidizers and anaerobic iron reducers, conducted on the same water samples. All investigated samples revealed a potential for microbial iron oxidation and reduction. Microbial communities were phylogenetically diverse within and between enrichments as was also observed in the previous cultivation-independent analysis of the water samples from which these enrichments were derived. Enrichment uncovered a larger diversity in iron-cycling microorganisms than previously indicated. The iron-reducing enrichments revealed the presence of several 16S ribosomal RNA (16S rRNA) gene sequences most closely related to Acetobacterium, Clostridium, Bacillus, Rhizobiales, Desulfovibrio, Bacteroides, and Spirochaetes, in addition to well-known dissimilatory iron-reducing Geobacter and Geothrix species. Although a large diversity of Geobacteraceae was observed, they comprised only a small part of the iron-reducing consortia. Iron-oxidizing gradient tube enrichments were dominated by Comamonadaceae and Rhodocyclaceae instead of Gallionellaceae. Forty-five percent of these enrichments also revealed the presence of the gene encoding arsenite oxidase, which converts arsenite to less toxic and less mobile arsenate. Their potential for ferric (oxyhydr)oxides precipitation and arsenic immobilization makes these iron-oxidizing enrichments of interest for rational bioaugmentation of arsenite contaminated groundwater.

Evidence of decoupling between arsenic and phosphate in shallow groundwater of Bangladesh and potential implications

Reductive dissolution of iron oxyhydroxides and reduction of arsenic are often invoked as leading causes of high dissolved As levels in shallow groundwater of Bangladesh. The second of these assumptions is questioned here by comparing the behavior As and phosphate (P), a structural analog for As (V) which also adsorbs strongly to Fe oxyhydroxides but is not subject to reduction. The first line of evidence is provided by a detailed groundwater time-series spanning two years for three wells in the 6–9 m depth range showing removal of As(III) from shallow groundwater during the monsoon without of loss of P. The data indicate a loss of ∼90% of the dissolved As from groundwater in the intermediate well relative to a level of 3 μmol/L As predicted by conservative mixing between groundwater sampled from the shallower and the deeper well. In contrast, P concentrations of ∼30 μmol/L in the intermediate well closely match the prediction from conservative mixing. Reduction therefore appears to inhibit the release of As to groundwater at this site relative to P instead of enhancing it. A re-analysis of existing groundwater As and P data from across the country provides a broader context for this finding and confirms that, without reduction, elevated concentrations of As would probably be even more widespread in shallow aquifers of Bangladesh. Without providing definite proof, X-ray absorption spectroscopy of sediment from the time-series site and elsewhere suggests that the loss of As from groundwater may be coupled to precipitation of As sulfide. Further study is needed to assess the implications of these observations for shallow aquifers that have been subjected to increased withdrawals for irrigation in recent decades.

Removal of Arsenic (III) Present in Ground Water of Bangladesh with Polymer Supported Hydrated Fe(III) Oxides

In the present study, a technique to remove arsenic has been developed with a polymer-supported hydrated Fe(III) oxide (HFO) by using a strongly basic anionic exchanger IRA-420 as the host material and FeCl3-HCl-NaCl solution as the reaction environment. The optimized conditions were applied to a sample collected from Sonargaon, Dhaka. The removal efficiency of this method was more than 80%, which indicates that this method can be used as an efficient method for arsenic removal in Bangladesh. IRA-420-HFO exhibits more preferential adsorption of arsenic ions which is attributed to the Donnan membrane effect exerted by the host resin (IRA-420) as well as to the loaded HFO particles for specific interaction toward arsenic (III) ions. All the results indicated that HFO polymer derivative is an attractive adsorbent for efficient arsenic (III) removal from contaminated groundwater of Bangladesh.Dhaka Univ. J. Sci. 63(2):85-89, 2015 (July)

Concentrations of arsenic and other elements in groundwater of Bangladesh and West Bengal, India: Potential cancer risk

We investigated the concentrations of 23 elements in groundwater from arsenic (As) contaminated areas of Bangladesh and West Bengal, India to determine the potential human exposure to metals and metalloids. Elevated concentrations of As was found in all five study areas that exceeded the World Health Organization (WHO) guideline value of 10μg/L. The mean As concentrations in groundwater of Noakhali, Jalangi and Domkal, Dasdia Nonaghata, Deganga and Baruipur were 297μg/L, 262μg/L, 115μg/L, 161μg/L and 349μg/L, respectively. Elevated concentrations of Mn were also detected in all areas with mean concentrations were 139μg/L, 807μg/L, 341μg/L, 579μg/L and 584μg/L for Noakhali, Jalangi and Domkal, Dasdia Nonaghata, Deganga and Baruipur, respectively. Daily As intakes from drinking water for adults and the potential cancer risk for all areas was also estimated. Results suggest that mitigation activities such as water treatment should not only be focused on As but must also consider other elements including Mn, B and Ba. The groundwater used for public drinking purposes needs to be tested periodically for As and other elements to ensure the quality of drinking water is within the prescribed national guidelines.

Sustainability of arsenic mitigation interventions—an evaluation of different alternative safe drinking water options provided in Matlab, an arsenic hot spot in Bangladesh

The wide spread occurrence of geogenic arsenic (As) in Bangladesh groundwater drastically reduced the safe water access across the country. Since its discovery in 1993, different mitigation options tested at household and community scale have resulted in limited success. In an arsenic hotspot of southeastern Bangladesh, 841 arsenic removal filter (ARF), 190 surface water filter membrane, 23 pond sand filter (PSF), 147 rain water harvester (RWH) and 59 As-safe tubewell were distributed among the severely exposed population by AsMat, a Sida supported project. After three-four years of providing these safe water options, this study was carried out during 2010-2011 for performance analysis of these options, in terms of technical viability and effectiveness and thus to evaluate the preference of different options to the end users. Household and community based surveys were done to make an assessment of the current water use pattern as impact of the distributed options, overall condition of the options provided and to identify the reasons why these options are in use and/or abandoned. In total, 284 households were surveyed and information was collected for 23 PSF, 147 RWH and 59 tubewells. None of the filters was found in use. Among other options distributed, 13% of PSF, 40% RWH and 93% of tubewell were found functioning. In all cases, tubewells were found As-safe. About 89% of households are currently using tubewell water which was 58% before. Filter was abandoned for high cost and complicated maintenance. The use of RWH and PSF was not found user friendly and ensuring year round water quality is a big challenge. Arsenic-safe tubewell was found as a widely accepted option mainly because of its easy operation and availability of water, good water quality and negligible maintenance. This study validated tubewell as the most feasible option and holds significance for planning water supply projects, improving mitigation policy as well as developing awareness among users.

Multiple inorganic toxic substances contaminating the groundwater of Myingyan Township, Myanmar: Arsenic, manganese, fluoride, iron, and uranium

In South Asia, the technological and societal shift from drinking surface water to groundwater has resulted in a great reduction of acute diseases due to water borne pathogens. However, arsenic and other naturally occurring inorganic toxic substances present in groundwater in the region have been linked to a variety of chronic diseases, including cancers, heart disease, and neurological problems. Due to the highly specific symptoms of chronic arsenic poisoning, arsenic was the first inorganic toxic substance to be noticed at unsafe levels in the groundwater of West Bengal, India and Bangladesh. Subsequently, other inorganic toxic substances, including manganese, uranium, and fluoride have been found at unsafe levels in groundwater in South Asia. While numerous drinking water wells throughout Myanmar have been tested for arsenic, relatively little is known about the concentrations of other inorganic toxic substances in Myanmar groundwater. In this study, we analyzed samples from 18 drinking water wells (12 in Myingyan City and 6 in nearby Tha Pyay Thar Village) and 2 locations in the Ayeyarwaddy River for arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. Concentrations of arsenic, manganese, fluoride, iron, or uranium exceeded health-based reference values in most wells. In addition, any given well usually contained more than one toxic substance at unsafe concentrations. While water testing and well sharing could reduce health risks, none of the wells sampled provide water that is entirely safe with respect to inorganic toxic substances. It is imperative that users of these wells, and users of other wells that have not been tested for multiple inorganic toxic substances throughout the region, be informed of the need for drinking water testing and the health consequences of drinking water contaminated with inorganic toxic substances.

Assessment of Health Hazard of Metal Concentration in Groundwater of Bangladesh

The study was to assess health hazard of metal concentation in groundwater of Bangladesh for drinking purposes. A number of 13 deep tube wells were selected purposively for collecting groundwater samples from the different sampling location of the study area. The study was carried out by laboratory analysis of chemical parameters which were analyzed by ion Chromatograph (IC) and atomic absorption spectrophotometer methods (AAS). The result shown that the concentration of iron and manganese were found to be more than permissible limit according to Bangladesh and WHO standard. The descriptive statistics revealed that most of the heavy metal concentrations like As, Cd, Fe and Mn were found to be range from 0.00 to 0.02 mg/l, 0.00 to 0.20 mg/l, 0.11 to 24.20 mg/l, 0.06 to 16.00 mg/l respectively within accessible limit for drinking Original Research Article Islam et al.; ACSj, 5(1): 41-49, 2015; Article no.ACSj.2015.006 42 according to Bangladesh and WHO standard except some water sampling locations were exceed the permissible limits. Pearson correlation matrix results were depicted that a strong positive correlation between the parameters such as Na + and SO4 2and K + and NH3 while low negative correlation were existed between Dissolved Oxygen and Mn + . From the analysis of result, it suggests that using groundwater for drinking purposes in the study area is slightly detrimental to human health hazard and thier surrouding environment.

Integrating Arsenic-Related Environmental Topics into the Education of the Next Generation of Citizens for Arsenic-Hit Communities: Awareness and Mobilization

Several programs, organized by Chemists without Borders or the University of Massachusetts Amherst, in which secondary school or college students are introduced to the impact of arsenic contamination of the environment, and in particular of groundwater in Bangladesh, are described. A common feature is that students are recruited as members of a research group or investigative team and take ownership of the work by making relevant chemical measurements and participating in discussion of the implications of their findings. Leadership is provided in a hierarchical model in which, very often, more experienced students acting as near-peer mentors guide the activities of the newly recruited members of the groups. In some of the programs, the students work with teachers who have been trained by researchers on the university campus. Both in-school and out-of-school programs are described. A feature common to all is that chemical measurements are provided by low-cost field test kits based on the Gutzeit-Marsh reaction, the modification of which has provided a driving force for a considerable number of research projects for the college students. Many hundreds of students have been impacted and the programs, particularly that in Bangladesh, have considerable potential for empowering the students as agents of change in their communities as they not only take specific action as a result of their engagement but also educate other members of their families and communities about the potential hazards of consuming arsenic-contaminated water and rice and how these can be mitigated. Readers are invited to contribute to sustaining the program in Bangladesh and to initiate their own activities with students.

Sustainable Management for Arsenic (As) Free Safe Drinking Water in Bangladesh: A Review

The presence of elevated levels of naturally occurring arsenic in groundwater of Bangladesh has severely impaired the decade long effort of providing safe water to its population. Most of the recognized stages of arsenic poisoning have been identified in Bangladesh and the risk of arsenic poisoning in the population is increasing every day. The severity of arsenic contamination is demanding extensive research in this field. Many studies have been carried out in Bangladesh, West Bengal in India and other countries as well, but the situation is still out of sound control. In order to minimize arsenic exposure, a work to provide various alternate safe drinking water options to the exposed population has been initiated. This article implies to look at the sustainable management for safe drinking water in Bangladesh by reviewing different measures to remedy the arsenic contamination in groundwater.

Situation of arsenic contamination in groundwater and mitigation in southwestern Bangladesh

Situation of arsenic contamination in groundwater and mitigation in southwestern Bangladesh

A generalized regression model of arsenic variations in the shallow groundwater of Bangladesh.

Localized studies of arsenic (As) in Bangladesh have reached disparate conclusions regarding the impact of irrigation‐induced recharge on As concentrations in shallow (≤50 m below ground level) groundwater. We construct generalized regression models (GRMs) to describe observed spatial variations in As concentrations in shallow groundwater both (i) nationally, and (ii) regionally within Holocene deposits where As concentrations in groundwater are generally high (>10 μg L−1). At these scales, the GRMs reveal statistically significant inverse associations between observed As concentrations and two covariates: (1) hydraulic conductivity of the shallow aquifer and (2) net increase in mean recharge between predeveloped and developed groundwater‐fed irrigation periods. Further, the GRMs show that the spatial variation of groundwater As concentrations is well explained by not only surface geology but also statistical interactions (i.e., combined effects) between surface geology and mean groundwater recharge, thickness of surficial silt and clay, and well depth. Net increases in recharge result from intensive groundwater abstraction for irrigation, which induces additional recharge where it is enabled by a permeable surface geology. Collectively, these statistical associations indicate that irrigation‐induced recharge serves to flush mobile As from shallow groundwater.

Removal of Arsenic (III) from groundwater applying a reusable Mg‐Fe‐Cl layered double hydroxide

AbstractBACKGROUNDLayered double hydroxide compounds (LDHs) have been applied for the removal of oxyanions including arsenate (As(V)). However, the aim of this present research is to develop a LDH to treat arsenite (As(III)). Both batch and column sorption studies were conducted to assess the effect of LDH dosage, contact time, solution pH and initial As(III) concentrations on the As(III) removal performance. The potential re‐use of this sorbent was also investigated.RESULTSFor 2 g L−1 of Mg‐Fe‐Cl LDH, As(III) in test solution can be reduced from 400 µg L−1 to <10 µg L−1 after a contact time of 2 h. High As(III) concentration in Bangladesh groundwater can be reduced to meet the national drinking water standards (<50 µg L−1). The maximum adsorption capacity of As(III) by Mg‐Fe‐Cl LDH is 14.6 mg g−1‐LDH. Further, reusability of this sorbent was at least 20 cycles of regeneration with effective As(III) removal between 93.0 and 98.5%. Moreover, As(III) removal was unaffected by the solution pH but affected by the co‐existing competing anions and concentration of As(III). Finally, the main mechanism of As(III) removal by Mg‐Fe‐Cl LDH was suggested to be chemical sorption together with anion and ligand exchange with interlayer Cl− and OH− ions.CONCLUSIONHigh efficiency of sorption of As(III) by the developed Mg‐Fe‐Cl LDH was demonstrated in this study which is generally not the case for most other sorbent materials. Pilot‐scale trials are needed to explore the suitability of full application of the developed Mg‐Fe‐Cl LDH for the removal of As(III). © 2014 Society of Chemical Industry

Toxic injustice in the Bangladesh water sector: a social inequities perspective on arsenic contamination

Arsenic contamination of groundwater in Bangladesh poses a major environmental health hazard to millions. The efforts of public health programmes to address the problem have often been short-lived and unevenly distributed. The crisis represents a failure of governance and a structural injustice of global dimensions. Rights-based approaches to development have been proposed to address such problems. This paper explores the implications of framing the arsenic problem in terms of social justice and human rights. It describes the efforts of the Arsenic Mitigation and Research Foundation to implement drinking water supplies and health support schemes with marginalised communities. The approach was never explicitly framed as rights-based, but focuses instead on social mobilisation and on securing fundamental human needs. We argue that this will be conducive to social justice, which in turn creates the necessary space for pursuing human rights claims.

Parental decisions, child health and valuation of avoiding arsenic in drinking water in rural Bangladesh.

Arsenic contamination of groundwater in Bangladesh is a widespread public health hazard. Water sources without high arsenic levels are scarce, affecting people's availability for work and other activities when they have to seek safe water to drink. While children are particularly susceptible to chronic arsenic exposure, limited information and heavy constraints on resources may preclude people in developing countries from taking protective actions. Since parents are primary decision-makers for children, a model of stochastic decision-making analytically linking parent health and child health is used to frame the valuation of avoiding arsenic exposure using an averting behavior model. The results show that safe drinking water programs do work and that people do take protective actions. The results can help guide public health mitigation policies, and examine whether factors such as child health and time required for remediation have an effect on mitigation measures.

Source and Characteristic of Fluorescence Humic Substances in Arsenic Polluted Groundwater of Bangladesh

AbstractFluorescence characteristic and molecular size distribution of groundwater humic substance (HS) from arsenic contaminated (AsCon) and uncontaminated (nAsCon) areas of Bangladesh indicated that source of HS in aquifers are different with specific molecular size distributions. AsCon area showed signature of microbial degraded HS with small molecular size (0.65 KDa) whereas nAsCon area has minor signature of microbial originated HS with relatively high molecular size (1.24 KDa).

Biogeochemical Process-Based Design and Performance of a Pilot-Scale Constructed Wetland for Arsenic Removal from Simulated Bangladesh Groundwater

A pilot-scale constructed wetland treatment system (CWTS) was designed and built to produce biogeochemical conditions promoting processes targeted for removal of arsenic from simulated Bangladesh groundwater. Two CWTS series were designed to promote coprecipitation and sorption of arsenic with iron oxyhydroxides under oxidizing conditions, and two series were designed to promote precipitation of arsenic sulfide and coprecipitation of arsenic with iron sulfide under reducing conditions. Arsenic removal performance was greater in series with oxidizing conditions than in series with reducing conditions (mean outflow concentrations of 64 and 108 μg L−1, respectively). Additions of zero-valent iron (ZVI) to oxidizing series and to reducing series enhanced arsenic removal (mean removal efficiencies of 72 and 42 %, respectively) compared to unamended series (27 and 20 %, respectively). Arsenic removal performance was significantly greater (α = 0.05) in the oxidizing series amended with ZVI than in the other series, with removal extents, efficiencies, and rate coefficients ranging from 6 to 79 μg L−1, 40 to 95 %, and 0.13 to 0.77 day−1, respectively. Results from this pilot-scale study demonstrate that a CWTS can decrease concentrations of arsenic in arsenic-contaminated water to below the World Health Organization (WHO) drinking water quality guideline of 10 μg L−1.

Predicting arsenic concentration in groundwater of Bangladesh using Bayesian geostatistical model

The pattern of the spatial variation in arsenic concentration in groundwater of Bangladesh is usually needed for the planning of safe drinking water. Often a model-based prediction is required for this purpose. In this paper, we fit a Bayesian hierarchical geostatistical model by utilizing data from the project, ‘Groundwater studies of arsenic concentration in Bangladesh’ conducted by the British Geological Survey and the Department of Public Health Engineering of Bangladesh. We also develop a predictive model for arsenic concentration at different levels of well-depth using the same approach. The resulting predictive model has been cross-validated by appropriate statistical tools. Finally, we obtained reliable spatially continuous predictive maps and predictive probability maps showing the areas with high probability of arsenic concentration for different levels of well-depth. Results indicate that our model fits the data well and captures a substantial amount of spatial variation. Moreover, well-depth is found to have a significant contribution in explaining the observed variation in arsenic concentration. The predictive maps that have been produced are observed to be different for various levels of well-depths and are expected to be helpful to the policy makers in preparing proper regional planning for safe drinking water.

Arsenic removal from groundwater using iron electrocoagulation: Effect of charge dosage rate

We demonstrate that electrocoagulation (EC) using iron electrodes can reduce arsenic below 10 μg/L in synthetic Bangladesh groundwater and in real groundwater from Bangladesh and Cambodia, while investigating the effect of operating parameters that are often overlooked, such as charge dosage rate. We measure arsenic removal performance over a larger range of current density than in any other single previous EC study (5000-fold: 0.02 – 100 mA/cm2) and over a wide range of charge dosage rates (0.060 – 18 Coulombs/L/min). We find that charge dosage rate has significant effects on both removal capacity (μg-As removed/Coulomb) and treatment time and is the appropriate parameter to maintain performance when scaling to different active areas and volumes. We estimate the operating costs of EC treatment in Bangladesh groundwater to be $0.22/m3. Waste sludge (∼ 80 – 120 mg/L), when tested with the Toxic Characteristic Leachate Protocol (TCLP), is characterized as non-hazardous. Although our focus is on developing a practical device, our results suggest that As[III] is mostly oxidized via a chemical pathway and does not rely on processes occurring at the anode. Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Environmental Science and Health, Part A, to view the free supplemental file.

Transformation of arsenic in the presence of cow dung and arsenic sludge disposal and management strategy in Bangladesh

Summary With increasing use of arsenic (As) removal units for treatment of As-contaminated groundwater in rural Bangladesh, concerns have been raised regarding safe disposal of the As-rich wastes from such units and possible contamination of the environment. In the absence of any clear guideline for safe disposal of wastes generated from As removal units, the wastes are usually disposed of in the open environment, often on cow dung beds in the backyard. Short term (up to 6 weeks) batch experiments performed in this study suggest that bio-chemical (e.g., bio-methylation) processes in the presence of only fresh cow dung may lead to a significant removal of As, both from aqueous solution and As-rich treatment wastes. Arsenic removal appears to increase with decreasing As to cow dung weight ratio. This study also suggests that arsenate transforms to arsenite before removal from aqueous As solution in the presence of cow dung. In most cases majority of As removal takes place during first few days. Removal of As under cap-open (to facilitate aerobic condition) and cap-closed conditions (to facilitate aerobic condition) were found to be similar. No significant variation was observed in the removal As from aqueous solution and from treatment wastes (As bound to iron solids). This study concludes that disposal of As-rich treatment wastes to cow dung pits could be an effective option of As sludge disposal and management in rural areas of Bangladesh.

Advection of surface-derived organic carbon fuels microbial reduction in Bangladesh groundwater

Chronic exposure to arsenic (As) by drinking shallow groundwater causes widespread disease in Bangladesh and neighboring countries. The release of As naturally present in sediment to groundwater has been linked to the reductive dissolution of iron oxides coupled to the microbial respiration of organic carbon (OC). The source of OC driving this microbial reduction--carbon deposited with the sediments or exogenous carbon transported by groundwater--is still debated despite its importance in regulating aquifer redox status and groundwater As levels. Here, we used the radiocarbon ((14)C) signature of microbial DNA isolated from groundwater samples to determine the relative importance of surface and sediment-derived OC. Three DNA samples collected from the shallow, high-As aquifer and one sample from the underlying, low-As aquifer were consistently younger than the total sediment carbon, by as much as several thousand years. This difference and the dominance of heterotrophic microorganisms implies that younger, surface-derived OC is advected within the aquifer, albeit more slowly than groundwater, and represents a critical pool of OC for aquifer microbial communities. The vertical profile shows that downward transport of dissolved OC is occurring on anthropogenic timescales, but bomb (14)C-labeled dissolved OC has not yet accumulated in DNA and is not fueling reduction. These results indicate that advected OC controls aquifer redox status and confirm that As release is a natural process that predates human perturbations to groundwater flow. Anthropogenic perturbations, however, could affect groundwater redox conditions and As levels in the future.