Essay on Contamination of Drinking-Water by Arsenic in Bangladesh

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Introduction:

There are metal substances which have mixed up with the river water of Bangladesh. The substance is known as Arsenic in Bangladesh. It was first found in the West Bengal ten years ago (1995-96). Arsenic is both toxic and carcinogenic. It is in inorganic forms, dissolved in drinking water which is the most significant forms of natural exposure. Organic forms of arsenic that may be present in food are much less toxic to humans. Clinical manifestations of arsenic poisoning begin with various forms of skin diseases, which lead to damage of internal organs, ultimately to cancer and death.

Cause of Arsenic:

This toxic element is found in tub-well water. People are affected by it only when
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Technologies used in Arsenic

There are a lot of processes of purifying contaminated water. Many International organizations and NGO's have tested in different ways to purify the contaminated water. .
The technologies under review performed most effectively when treating arsenic in the form of As(V). As (III) may be converted through pre-oxidation to As(V). Data on oxidants indicate that chlorine, ferric chloride, and potassium permanganate are effective in oxidizing As(III) to As(V). Pre-oxidation with chlorine may create undesirable concentrations of disinfection by-products. Ozone and hydrogen peroxide should oxidize As(III) to As(V), but no data are available on performance

Coagulation/Filtration (C/F), is an effective treatment process for removal of As(V) according to laboratory and pilot-plant tests. The type of coagulant and dosage used affects the efficiency of the process. Within either high or low pH ranges, the efficiency of C/F is significantly reduced. Alum performance is slightly lower than ferric sulfate. Other coagulants were also less effective than ferric sulfate. Disposal of the arsenic-contaminated coagulation sludge may be a concern especially if nearby landfills are unwilling to accept such a sludge.

Lime Softening (LS) operated within the optimum pH range of greater than 10.5 is likely to provide a high

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