Arsenic Groundwater Contamination-Bangladesh

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Arsenic Groundwater Contamination-Bangladesh
Encheng Zhou Xiaowen Kan
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Introduction

• Prior to the 1970s, the highest infant mortality
  rates in the world
• UNICEF and the World Bank s help(ground water
  well programme)
• Over 8 million wells constructed
• In 1993 Association of health problems with
  arsenic contamination.
• Estimated 35 to 77 million inhabitants are at
  risk of drinking contaminated water.

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Occurrence of arsenic in the world

• Bangladesh is not the only country with arsenic
  pollution of the groundwater, but pollution is
  exceptionally widespread here

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Arsenic Contamination
Country Effected Population Effected
Bangladesh 60,000,000
Vietnam 2,500,000
India 1,000,000
China 720,000
Taiwan 200,000

• A metalloid element known for its toxicity and
  carcinogenicity
• 70 million people possibly at risk
• Still now, it is difficult to resolve the
  problem

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Theories of Arsenic Mobilisation
Mechanism of Mobilization
Anthropogenic Sources
Geogenic Mechanism
Desorption from Fe(OH)3
Industry Pharm. Products, Mining
Agriculture Fertilizer, Pestizides
Pyrit Hypothesis
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Pyrit Hypothese
Pyrites minerals (FeAsS) are present in the
delta sediments Due to the lowering of the
water table (by intensified extraction for
irrigation) ?? oxidation of pyrites deposits in
so-called Vadose Arsenic adsorbs to Fe(OH)3
During recharge period ?? release of As (same
mechanisms as before)
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Health Effects
Organ System Problems
Skin Symmetric hyperkeratosis of palms and soles, melanosis or depigmentation, bowen's disease, basal cell carcinoma and squamous cell carcinoma.
liver Enlargement, Jaundice, cirrhosis, non-cirrhotic portal hypertension
Nervous System Peripheral neuropathy, hearing loss
Cardiovascular System Acrocyanosis and Raynaud's Phenomenon
Hemopoietic System Megalobastosis
Respiratory System Lung Cancer
Endocrine System Diabetes mellitus and goiter
Signs of arsenicosis spots on the hands
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Possibilities of Elimination
For removal oxidation of As(III) to As(V) is
needed Principle mechanisms oxidation
adsorption ion exchange Oxidation Oxidants
such as O2 O3 KMnO4 H2O2 Mainly in
industrialized countries. Coagulation Adsorption
- Bucket Treatment Unit (1) Precipitation by
metal salts in upper bucket (2) Coagulation by
mixing (3) Adsorption by passing sand filter
precipitation sedimentation/ filtration
membrane filtration.
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Conclusion

• The worst environmental catastrophe of the
  twentieth century.
• The government needs to conduct effective water 
• Remediation techniques are available but are
  being limited
• Every effort should be made to help the people of
  Bangladesh