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ARSENIC MITIGATION AND SURFACE WATER PURIFICATION
ARTICLE ARSENIC MITIGATION AND SURFACE WATER PURIFICATION Shyamal Chowdhury Email: sssupervision@yahoo.com, ssfoundationbd@gmail.com ABSTRACT: Scarcity of safe drinking water is a fundamental problem of poor people of developing countries. About 77 million poor rural people out of 160 million people of Bangladesh are the victims of Arsenic poison and crisis of safe drinking water. There is no facility for scientific water purification in rural villages like urban areas. Water of urban areas may also be contaminated by harmful bacteria due to defective supply system. So, many people, especially children, die if water borne diseases every year. A research work aimed at inventing water filtering complex compound for absorbing arsenic and other toxic minerals of water, to use this filtering medium in low-cost modern scientific water purification filter composite and traditional filtering systems. It has been demonstrated that this filtering compound (Patented) acts as an efficient absorptive medium for Arsenic and other Toxic Minerals, but it let to flow the essential minerals of water within permissible limits. Analytical measurements of Arsenic, Iron, Calcium, Magnesium, Potassium, Sodium, etc. of mitigated water and respective crude water samples of arsenic contaminated tube-well of Sitakunda, Chittagong, Bangladesh, were performed in Bangladesh University of Engineering and Technology (BUET), and Nutrition and Food Science Institution of Dhaka University. Test reports of BUET indicated that 173.5 micrograms/liter (0.1735 ppm) arsenic of crude water was reduced to 1.30 micrograms/liter (0.0013 ppm) after filtration through the new Arsenic and toxic minerals absorptive filter medium. Recent analysis report of Japanese environmental laboratory, Asia Arsenic Network, has indicated that an Arsenic contaminated deep-well water sample of BRAC-WASH of Satkheera has been mitigated by the filtering compound and treatment process, from 0.082 ppm Arsenic to less than 0.001 ppm Arsenic. Permissible limit of the Government is 0.05 ppm and World Health Organization (WHO) accepts 0.01 ppm Arsenic for drinking purpose. Safe drinking water can be produced from water of reserved ponds, rivers, hilly springs or flood by using the same modern filter composite with this filtering compound. Calculated quantity of sodium or calcium hypochlorite and dirt coagulant should be used for this surface water purification before filtration. Almost all absorptive media become exhausted after several days. Consequently, questions of longevity and effectiveness have been arisen about many imported and local Arsenic mitigation projects. To make this new Arsenic Mitigation plant as a permanent and cost-effective project, a simple and environmentally friendly regeneration process for this exhausted absorptive medium has been developed. To carry on self-supported and transparent arsenic mitigation work, cheap and effective arsenic test kit has also been developed. This kit can be used by the rural users and in rural school laboratories. Bangladesh Government has given patent for this invention. BACKGROUND: Bangladesh is a riverine country; in respect of area it has one of the largest valuable fresh-water resources of the world. But access to safe water has been very difficult due to arsenic contamination in groundwater and pollution in surface water. Many people, especially children, used to die of water borne diseases every year by drinking surface water. So, extraction of underground water started during British colonial era. But recently it has been known that underground aquifer layers of Bangladesh are highly contaminated with Arsenic poison. About 77 million poor rural people out of 160 million people of Bangladesh are the victims of Arsenic poison and crisis of safe drinking water. There is no facility for scientific water purification in rural villages like urban areas. Rivers, ponds, hilly springs and other surface water sources are contaminated with fecal bacteria, household and industrial wastes. Many shallow tube-wells of 62 districts out of 64 are contaminated with higher concentration of Arsenic than the selected permissible limit of the Government (0.05 ppm) and World Health Organization (0.01 ppm). In many areas deep wells are also contaminated. Poor rural people do not afford deep tube-wells. Besides this, underground water layers of some other countries of the world are contaminated with Arsenic. Bangladesh has extended coastal areas in the southern part. Soil and water of rivers of this part are saline. So, underground aquifer layers contain salinity exceeding the permissible limit of salt for drinking water. Consequently the underground water of these regions is unfit for drinking and cooking purposes. Salinity is increasing day by day with increasing sea level as an affect of global warming. So, Bangladesh is facing an environmental disaster and crisis of safe drinking water in rural villages Recent epidemiological studies have indicated that there is an association between relatively high and lengthily exposure to Inorganic Arsenic compounds and cancer. Symptoms of arsenic poisoning (arsenicosis) are the development of dark spots on the skin, hardening of palms and soles. Internal organs including the livers, kidneys and lungs can be affected. In the most severe cases cancer may occur in the skin and internal organs. Limbs can be affected by gangrene. It has posed a dangerous challenge to development and has been raised as a new health hazard.

EXPERIMENTAL SECTION: During arsenic mitigation and detection testing period since mid of 2000, arsenic contaminated water samples of Laxmipur, Comilla, Langalkot (Comilla), Companygonj (Comilla) and Sitakunda (Chittagong) of Bangladesh had been used. For field test and regular work, arsenic contaminated shallow tube-wells water of Sitakunda (College Road and Amirabad) were used. Sitakunda is located in Chittagong. It is a coastal area, so the taste of shallow tube-wells water is slightly saline. Test reports indicate that 80 percent shallow tube-wells water of this area are highly contaminated with arsenic. It has been demonstrated that one kilogram of the medium can mitigate more than 500 litres of arsenic contaminated tute-well water of Sitakunda. A process of regeneration-sludge management has also been developed to save the environment. These filter composites can be used as a flood water, reserved ponds, river and spring water treatment plants by using coagulant and sodium or calcium hypochlorite for bacteria free, clear drinking water. The plant of the cost USD 2500 (except civil work and tube-well) may fulfill the demand of Arsenic free safe potable water of a school, college, orphanage or small village community of rural areas. For fulfillment of the demand of a large community the design of this plant can be enlarged. The filter medium can also be used in different types of small traditional household gravity filters.

RESULT AND DISCUSSION: Bangladesh and other developed countries accept 0.05 milligram/litre of arsenic in drinking water, World Health Organization (WHO) accepts (from 1993) 0.01 milligram/litre. By using the new filter medium the samples of mitigated water and the respective crude water of Sitakunda (arsenic content: 173.5 microgram or 0.1735 milligram/litre) had been analysed in Civil Engineering Department of Bangladesh University of Engineering and Technology (BUET) and Micro-nutrient Lab of Nutrition and Food Science of Dhaka University. The test reports of the two institutions indicate that arsenic and some other heavy metallic minerals of crude water have been reduced to a minimum quantity by the new filter medium. Concentrations of some of these elements of crude and mitigated water and PH value of each sample are discussed below. From the test results it is clear that, the newly invented Absorptive filtering medium is very effective for Arsenic and Toxic minerals mitigation. EFFICIENCY OF ARSENIC REMOVAL: Test report of BUET shows that arsenic of crude water has been almost completely removed, i.e, in crude water concentration of arsenic is 173.5 microgram/litre (0.1735 mg/l. or 0.1735 ppm) and in respective mitigated water the concentration of arsenic become 1.3 microgram/litre (0.0013 mg/l or 0.0013 ppm). The permissible limit of arsenic in developed countries and Bangladesh is 50 microgram (0.05 mg/l or 0.05 ppm) and WHO accepts 10 microgram (0.01 gm/l or 0.01 ppm). The result shows that the new filter medium is very efficient to remove arsenic and the concentration of arsenic in mitigated water is much lower than WOH's acceptable limit of arsenic. TOXIC AND HEAVY METALLIC MINERALS MITIGATION:(Qualitative tests) Prepared solutions of poisonous mercury, manganese, chromium, barium and lead compounds had also been mitigated by the new filter medium. Mercury, chromium, barium, lead and some other heavy metals are very poisonous and occur in ground and surface water of some localities. HARDNESS AND IRON REMOVAL CAPACITY: Water containing bicarbonates, sulphates and chlorides of calcium and magnesium are termed hard water. Test report shows that the new filter medium is very efficient to mitigate calcium, magnesium and iron. It reduces magnesium 53.05 mg/l. to 0.12 mg/l calcium 18.56 mg/l to 1.62 mg/l and iron 0.8 gm/l. to 0.05 mg/l. PH OF WATER: PH is used to express the intensity of acidic and alkaline condition of water or solution. The desirable pH range for drinking water is 6.5 to 8.5 (WHO). In test report, the pH value of crude water is 7.06 and that of mitigated water is 6.87.

NEW ARSENIC TEST KITS: The new indigenous test of arsenic is performed in a glass test tube by converting the arsenic compounds (soluble or insoluble) of water into a gaseous arsenic compound, Arsine. Arsine stains on a freshly prepared white test strip within 20 to 30 minutes. The intensity of colour (light yellow to black) of stain is the indication of arsenic concentration of the water sample. It has been observed that some imported field test kits are not able to detect arsenic of old water samples, although the samples contained high concentration of arsenic (As III or As V or both). After opening the seals these Test Kits lose their activities rapidly in tropical regions, like Bangladesh, due to the reason of hot and humid conditions. The newly innovated arsenic test kits detect sharply the arsenic of fresh and old water samples without preservation and the kit is ever fresh. This kit can be used by the users and the school students of rural villages.

FILTER REGENERATION AND ARSENIC WASTE MANAGEMENT: It has been reported in newspapers that many local and imported filters became exhausted and lost their activities after working for some days. But the suppliers of the projects did not arrange any regeneration system, so, these costly projects had been rejected with a great loss of the users. To save the cost of repeated use of the projects a cheap filter regeneration method and to save the environment an effective waste management system has been developed.

ANTAGONISTS OF ARSENIC POISONING: During World War-II, an intensive effort was made to develop an antidote to vesicant arsenical war gas (lewisite). Knowing that arsenicals reacted with--SH (Sulpho-Hydral) group-containing molecules, Stocken and Thompson, at Oxford University, initiated a systemic study of thiol compounds to find one that would successfully compete with the tissue --SH groups (of Amino Acids, like Cystine, Cysteine and Methionine of our body proteins). for the arsenicals. Their investigation indicated that the arsenicals would form a very stable and relatively non-toxic chealatering with dithiol compound, Dimercaprol (2,3- Dimercaptopropanol). Pharmacological investigations revealed that this compound would protect against the toxic effects of other heavy metals, such as mercury, gold, bismuth, thallium and antimony.

CONCLUSION: Water is the largest part of human body. So, to save our lives, use of arsenic and toxic minerals free tube-wells water is very essential. Surface water also contains various man-made contaminants and pathogens. Ground water can also be contaminated with polluted surface water by infiltration through soil. All Community persons have right to use pathogen free, arsenic and harmful materials free drinking water. A number of Government and Non-Government Organizations, United Nations, Donor Agencies, World Bank etc. are working on the aspect of arsenic mitigation in drinking water. About 76% people of the total population of Bangladesh live in the rural villages and they depend on water of shallow aquifers for drinking purpose. Nearly 77 million (Report: World Bank) rural people of Bangladesh, out of 160 million, are in the grip of arsenic contamination and crisis of safe drinking water. Besides this, in many countries poor rural people are the victim of Arsenic poison. To import the equipment of these filters composites, to erect water purification projects in arsenic contaminated areas and to manufacture the invented absorptive filtering medium and arsenic test kit for poor rural villagers, United Nations, Donor Agencies and the Governments have to co-operate. These initiatives will ensure sustainable living environment in rural villages with arsenic contamination.

REFERENCES: 1. Encyclopedia of Chemical Technology - Kirk-Othmer. 2. Pharmacology - Louis L. Goodman and Alfred Gilman. 3. Industrial Chemistry with Chemical Engineering-B.K.Sharma. 4. Arsenic Mitigation Programme - UNICEF, Media Brief. 5. Arsenic Mitigation in Bangladesh - UNICEF, Media Brief. 6. Safe Drinking Water and the Arsenic Problem in Bangladesh - Shafiqul Islam. 7. Arsenic Contamination in Drinking Water in Kachua Upazila of Chandpur District: Problems and Programs for its Remedy - Golam Rahaman and M.A. Mation Miah

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