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Fresh and pure water has an important role to play for healthy life. Currently, in many studies higher concentrations of contaminants like calcium, sodium, nitrate, lead, chromium, arsenic, fluoride etc. have been reported that makes the water unfit for its direct consumption. Sources and release mechanism of many such pollutants is still not known. These sources can be anthropogenic or geogenic. This paper deals with one of such contaminants namely fluoride and emphasizes on its release from various minerals viz. Gypsum, fluorite, tourmaline, actinolite, plagioclase, biotite, quartz, kayanite, epidote and orthoclase under different pH environment. It has been noted that maximum fluoride has been released from the fluorite at all pH environment (acidic, normal and alkaline) of water while minimal fluoride was released from kayanite. However, orthoclase, tourmaline and biotite can release fluoride in considerable amount. The attempts were also made to compare the release of fluoride from modern sand (Ganga sediments) with ancient sand (from sandy aquifer) under different pH condition. Outcome of studies shows that maximum fluoride released from the sand at the pH range of 6.1 to 8.2. [ABSTRACT FROM AUTHOR]

This article provides updated status of the arsenic affected rural habitations in India, summarizes the policy initiatives of the Ministry of Drinking Water & Sanitation (Government of India), reviews the technologies for arsenic treatment and analyses the progress made by states in tackling arsenic problems in rural habitations. It also provides a list of constraints based on experiences and recommends suggested measures to tackle arsenic problems in an holistic manner. It is expected that the paper would be useful for policy formulators in states, non-government organizations, researchers of academic and scientific institutions and programme managers working in the area of arsenic mitigation in drinking water, especially in developing countries, as it provides better insights compared to other available information in India on mitigating arsenic problems in drinking water in rural areas. [ABSTRACT FROM AUTHOR]

This study was conducted to inspect the spatial distribution, source identification, and risk assessment of groundwater arsenic (As) in different blocks that lie on the opposite banks of river Bhagirathi (a distributary of river Ganges), Murshidabad, West Bengal, India. It has been observed that the blocks that lie towards the eastern bank of river Bhagirathi have elevated arsenic and comparatively more reducing groundwater (lower oxidation–reduction potential and high iron). About 66% of groundwater samples across the district have arsenic concentration higher than the World Health Organization (WHO) permissible limit. Speciation of groundwater arsenic reveals that about 90% of arsenic species were present as arsenic (III). Further, principal component analysis (PCA) was employed to identify the controlling factors that favor the release of arsenic. PC1 comprises EC, TDS, As, Fe, TOC, and HCO3− with moderate loadings, which suggests microbially mediated degradation of organic matter (OM), helps in reductive dissolution of arsenic-bearing Fe–Mn oxyhydroxides. Results pointed out severe groundwater arsenic poisoning; hence, a health risk assessment was performed for the exposure of arsenic in groundwater, using incremental lifetime cancer risk (ILCR) models coupled with Monte Carlo simulations. On the eastern bank of river Bhagirathi, incremental lifetime cancer risk (ILCR) due to oral exposure (5th to 95th percentile values) ranged from 1.30538E − 04 to 9.31398E − 03 with a mean of 2.84194E − 03 for adults, which is 2841 times higher than the USEPA high safety risk guidelines of one in 1 million. The outcomes of the results will be useful for the policymakers and regulatory boards in defining the actual impact and deciding the pre-remediation goals. [ABSTRACT FROM AUTHOR]

Geogenic arsenic contamination in groundwaters poses a severe health risk to hundreds of millions of people globally. Notwithstanding the particular risks to exposed populations in the Indian sub-continent, at the time of writing, there was a paucity of geostatistically based models of the spatial distribution of groundwater hazard in India. In this study, we used logistic regression models of secondary groundwater arsenic data with research-informed secondary soil, climate and topographic variables as principal predictors generate hazard and risk maps of groundwater arsenic at a resolution of 1 km across Gujarat State. By combining models based on different arsenic concentrations, we have generated a pseudo-contour map of groundwater arsenic concentrations, which indicates greater arsenic hazard (> 10 μg/L) in the northwest, northeast and south-east parts of Kachchh District as well as northwest and southwest Banas Kantha District. The total number of people living in areas in Gujarat with groundwater arsenic concentration exceeding 10 μg/L is estimated to be around 122,000, of which we estimate approximately 49,000 people consume groundwater exceeding 10 µg/L. Using simple previously published dose–response relationships, this is estimated to have given rise to 700 (prevalence) cases of skin cancer and around 10 cases of premature avoidable mortality/annum from internal (lung, liver, bladder) cancers—that latter value is on the order of just 0.001% of internal cancers in Gujarat, reflecting the relative low groundwater arsenic hazard in Gujarat State. [ABSTRACT FROM AUTHOR]

Presence of arsenic ion [As(V)] in ground water at different locations of India is a big health concern in present days. In this work, effort was made to remove As(V) ions from tap water by electrocoagulation (EC) using iron (Fe) electrodes having an effective surface area of 38.67 m2/m3. Investigation was focused on studying the effects of various process parameters of EC like solution pH, current density (CD), inter-electrode distance (IED) initial arsenic concentration (Co), electrical conductivity of water on removal of As(V) in efficient ways. Experimental results reveal that initial pH of 7, CD of 0.431 mA/cm2, IED of 0.5 cm, agitation speed of 200 rpm and NaCl dose of 0.33 g/L are optimal conditions to reduce As(V) ion concentration from 100 µg/L to below 10 µg/L. Overall, 99.4% As(V) removal was achieved at 30 minutes of EC treatment. Different quality parameters for drinking water such as TDS, turbidity, salinity, electrical conductivity were also assessed during the EC, to verify drinking water quality in several aspects. Kinetic analysis infers that As(V) removal by EC follow the first order reaction model. Present study affirms that, EC is an effective technique for efficient As(V) removal from drinking water with an estimated energy consumption of 8.33 × 10−3 Kwh/m3, electrode utilization of 0.0486 kg/m3, and operational cost of 0.0488 US$/m3. [ABSTRACT FROM AUTHOR]

A sonochemical reduction method of permanganate (MnO4−) was utilized for preparation of manganese dioxide (MnO2) coating on the surface of XAD-4 resin. Characterization of the modified MnO2-coated XAD-4 resin (MX-4) was done and sorption studies were carried out using arsenic (76As) radiotracer. The adsorption capacity for As(III) and As(V) using MX-4 were 5.5 mg/g and 7.6 mg/g, respectively. The MX-4 resin was successfully applied for quantitative removal of arsenic from two ground water samples collected from arsenic contaminated regions of North 24 Parganas, West Bengal, India. A schematic mechanism of removal of arsenic by MX-4 beads was also suggested. [ABSTRACT FROM AUTHOR]

A plethora of technologies has been developed over decades of extensive research on arsenic remediation, although the technical and financial perspective of arsenic removal plants in the field requires critical evaluation. In the present study, focusing on some of the pronounced arsenic-affected areas in West Bengal, India, we assessed the implementation and operation of different arsenic removal technologies using a dataset of 4000 spatio-temporal data collected from an in-depth field survey of 136 arsenic removal plants engaged in the public water supply. Our statistical analysis of this dataset indicates a 120% rise in the average cumulative capacity of the plants during 2014–2021. The majorities of the plants are based on the activated alumina with FeCl3 technology and serve about 49% of the population in the study area. The average cost of water production for the activated alumina with FeCl3 technology was found to be ₹7.56/m3 (USD $1 ≈ INR ₹70), while the lowest was ₹0.39/m3 for granular ferric hydroxide technology. A machine learning-based framework was employed to analyze the impact of water quality and treatment plant parameters on the removal efficiency, capital, and operational cost of the plants. The artificial neural network model exhibited adequate statistical significance, with a high F-value and R2 of 5830.94 and 0.72 for the capital cost model, 136,954, and 0.98 for the operational cost model, respectively. The relative importance of the process variables was identified through random forest models. The models indicated that flow rate, media, and chemicals are the predominant costs, while contaminant loading in influent water and a coagulating agent was important for removal efficiency. The established framework may be instrumental as a decision-making tool for water providers to assess the expected performance and financial involvement for proposed or ongoing arsenic removal plants concerning various design and quality parameters. [ABSTRACT FROM AUTHOR]