Krishna KumarYadav et al. Fluoride contamination, health problems and remediation methods in Asian groundwater: A comprehensive review. Ecotoxicology and Environmental Safety Volume 182, 30 October 2019, 109362
In low concentration, fluoride is considered a necessary compound for human health. Exposure to high concentrations of fluoride is the reason for a serious disease called fluorosis. Fluorosis is categorized as Skeletal and Dental fluorosis. Several Asian countries, such as India, face contamination of water resources with fluoride. In this study, a comprehensive overview on fluoride contamination in Asian water resources has been presented. Since water contamination with fluoride in India is higher than other Asian countries, a separate section was dedicated to review published articles on fluoride contamination in this country. The status of health effects in Asian countries was another topic that was reviewed in this study. The effects of fluoride on human organs/systems such as urinary, renal, endocrine, gastrointestinal, cardiovascular, brain, and reproductive systems were another topic that was reviewed in this study. Different methods to remove fluoride from water such as reverse osmosis, electrocoagulation, nanoﬁltration, adsorption, ion-exchange and precipitation/coagulation were introduced in this study. Although several studies have been carried out on contamination of water resources with fluoride, the situation of water contamination with fluoride and newly developed technology to remove fluoride from water in Asian countries has not been reviewed. Therefore, this review is focused on these issues: 1) The status of fluoride contamination in Asian countries, 2) health effects of fluoride contamination in drinking water in Asia, and 3) the existing current technologies for defluoridation in Asia.
“Environmentalists are destroying environmentalism. As a subset of that destruction, creators of the Intergovernmental Panel on Climate Change (IPCC) falsified science to claim that humans are causing global warming (AGW). That false science wasted trillions of dollars and disrupted millions of lives. That is enough money to provide clean drinking water and basic sewage for every country in the world.” click here
Price JI, Heberling MT. The Effects of Source Water Quality on Drinking Water Treatment Costs: A Review and Synthesis of Empirical Literature. Ecological Economics 2018 Sep 3;151:195-209. doi: 10.1016/j.ecolecon.2018.04.014.
Watershed protection, and associated in situ water quality improvements, has received considerable attention as a means for mitigating health risks and avoiding expenditures at drinking water treatment plants (DWTPs). This study reviews the literature linking source water quality to DWTP expenditures. For each study, we report information on the modeling approach, data structure, definition of treatment costs and water quality, and statistical methods. We then extract elasticities indicating the percentage change in drinking water treatment costs resulting from a 1% change in water quality. Forty-six elasticities are obtained for various water quality parameters, such as turbidity, total organic carbon (TOC), nitrogen, sediment loading, and phosphorus loading. An additional 29 elasticities are obtained for land use classification (e.g., forest, agricultural, urban), which often proxy source water quality. Findings indicate relatively large ranges in the estimated elasticities of most parameters and land use classifications. However, average elasticities are smaller and ranges typically narrower for studies that incorporated control variables consistent with economic theory in their models. We discuss the implications of these findings for a DWTP’s incentive to engage in source water protection and highlight gaps in the literature.
T.C., Prathna; Sharma, Saroj Kumar; Kennedy, Maria. Review: Nanoparticles in household level water treatment: An overview Separation and Purification Technology 30 June 2018 199:260-270
Providing safe drinking water is a great challenge for both the developing and the developed world. Increasing demand and source water quality deterioration has led to the exploration of new technological innovations for better water management. Nanotechnology holds great promise in ensuring safe drinking water through designing innovative centralised and decentralised (household-level) water treatment systems. The paper provides an overview of recent advances in nanotechnologies for (household level) water treatment processes, such as its use as nanoadsorbents, photocatalysts, microbial disinfectants and in membranes. Extensive implementation of nanotechnology for water treatment would require overcoming the high cost of the nanomaterials by enabling their reuse and regeneration. This would also ensure minimising potential environmental exposure. Potential advances in nanotechnology must go hand in hand with environmental health to alleviate any undesirable consequences to humans.
Dhadge VL, Medhi CR, Changmai M, Purkait MK. House hold unit for the treatment of fluoride, iron, arsenic and microorganism contaminated drinking water. Chemosphere 2018 Feb 16;199:728-736. doi: 10.1016/j.chemosphere.2018.02.087.
A first of its kind hybrid electrocoagulation-filtration prototype unit was fabricated for the removal of fluoride, iron, arsenic and microorganisms contaminated drinking water. The unit comprised of 3 chambers, chamber A consisting of an inlet for the water to be treated and an outlet for the treated water along with one block of aluminum electrodes. Chamber B consisted of ceramic membrane filtration assembly at the bottom over a metallic support which filters the flocs so produced in chamber A and chamber C consisting of space to collect the treated water. Operating parameters were maintained as current density of 625 A m-2 and an electrode distance of 0.005 m. Contaminated drinking water containing mixture of fluoride (10 mg L-1), iron (25 mg L-1), arsenic (200 μg L-1) and microorganisms (35 CFU ml-1) was used for the experiment. A removal of 98.74%, 95.65%, 93.2% and 100% were obtained for iron, arsenic, fluoride and microorganisms, respectively. The apparatus and method made it possible to efficiently treat contaminated drinking water to produce drinkable water as per WHO specification. By-products obtained from the electrocoagulation bath were analyzed using SEM, EDX and XRD and explained.
Shivaraju HP, Egumbo H, Madhusudan P, Kumar KMA, Midhun G. Preparation of Affordable and Multi-functional Clay-based Ceramic Filter Matrix for Treatment of Drinking Water. Environmental technology. 2018 Jan 18:1-30. doi: 10.1080/09593330.2018.1430853.
In the present study, affordable clay-based ceramic filters with multi-functional properties were prepared using low-cost and active ingredients. The characterization results of as-prepared materials clearly revealed well crystallinity, structural elucidation, extensive porosity, higher surface area, higher stability, and durability which apparently enhance the treatment efficiency. The filtration rates of ceramic filter were evaluated under gravity and the results obtained were compared with typical gravity slow sand filter. All ceramic filters showed significant filtration rates of about 50-180 m/h, which is comparatively higher than typical slow sand filter. Further, purification efficiency of clay-based ceramic filters was evaluated by considering important drinking water parameters and contaminants. A significant removal potential was achieved by clay-based ceramic filter with 25 and 30 % activated carbon (AC) along with active agents. Desired drinking water quality parameters were achieved by potential removal of nitrite (98.5 %), nitrate (80.5 %), total dissolved solids (62 %), total hardness (55 %), total organic pollutants (89 %), and pathogenic microorganisms (100 %) using ceramic filters within short duration. The remarkable purification and disinfection efficiencies were attributed to the extensive porosity (0.202 cm3g-1), surface area (124.61 m2g-1), stability and presence of active nanoparticles such as Cu, TiO2, and Ag within porous matrix of ceramic filter. The low cost clay-based ceramic filter was found to be easily reusable, handy, durable, and effective for the treatment of drinking water at household level.
Sarkar B, Mandal S, Tsang YF, Kumar P, Kim KH, Ok YS. Designer carbon nanotubes for contaminant removal in water and wastewater: A critical review. The Science of the total environment. 2018 Jan 15;612:561-581. doi: 10.1016/j.scitotenv.2017.08.132.
The search for effective materials for environmental cleanup is a scientific and technological issue of paramount importance. Among various materials, carbon nanotubes (CNTs) possess unique physicochemical, electrical, and mechanical properties that make them suitable for potential applications as environmental adsorbents, sensors, membranes, and catalysts. Depending on the intended application and the chemical nature of the target contaminants, CNTs can be designed through specific functionalization or modification processes. Designer CNTs can remarkably enhance contaminant removal efficiency and facilitate nanomaterial recovery and regeneration. An increasing number of CNT-based materials have been used to treat diverse organic, inorganic, and biological contaminants. These success stories demonstrate their strong potential in practical applications, including wastewater purification and desalination. However, CNT-based technologies have not been broadly accepted for commercial use due to their prohibitive cost and the complex interactions of CNTs with other abiotic and biotic environmental components. This paper presents a critical review of the existing literature on the interaction of various contaminants with CNTs in water and soil environments. The preparation methods of various designer CNTs (surface functionalized and/or modified) and the functional relationships between their physicochemical characteristics and environmental uses are discussed. This review will also help to identify the research gaps that must be addressed for enhancing the commercial acceptance of CNTs in the environmental remediation industry.