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By

T. Revathi

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Bangladesh made great strides in improving coverageof its population with access to an improved watersupply.

Bangladesh -97% of rural areas having access to an

improved water. But it is reduced to 74% due to arseniccontamination.

Groundwater arsenic contamination in Bangladesh isreported to be the biggest arsenic calamity in the worldin terms of the affected population.

The Government of Bangladesh (GOB) has initiatedand implemented a number of major programmes,with support from development partners and a rangeof national and international NGOs.

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Bangladesh located in the Ganges-Brahmaputra delta.

Most regions of Bangladesh are composed of a vastthickness of alluvial and deltaic sediments which isrich in is rich in arseno-pyrite, pyrite, iron sulfate, andiron oxide as revealed by the geological investigation.

Rainfall is highly seasonal - people used to usegroundwater for drinking water supplies, which is lowcost, year-round availability, simple withdrawal

mechanism

And also the materials and manpower to sinktubewells are available throughout the country.

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An analysis of data collected in the DPHE-Unicef projectarea in 15 upazilas of Bangladesh reported that 88.1%tubewells are privately owned of which 84.8% is used fordomestic purposes.

In 1986 government to reduce the chronic shortage offood liberalise laws on sale of imported pumps doublethe area of cultivation and no. tube wells in the country.

The groundwater in Bangladesh has declined

progressively due to the excessive extraction of water forirrigation and domestic water supply, lack of watermanagement.

Excessive groundwater extraction may be the vital

reason for creating a zone of aeration in clayey and peatysediments containing arseno-pyrite. Under aerobiccondition, arseno-pyrite decomposes and releases arsenicthat mobilizes to the subsurface water. The mobilizationof arsenic is further enhanced by the compaction of

aquifers caused by groundwater withdrawal.

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Increase in no. tube wells

Large scale withdrawal of GW

Diffusion of oxygen

Oxidation of arseno-pyrite

Formation of waters oluble iron arsenate

Extraction of arsenic dissolved water duringpumping

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Impacts

on human being A large number of populatio

ns in Bangladesh aresuffering from melanosis, leuco-melanosis,

keratosis, hyperkeratosis, dorsum, non-pettingoedema, gangrene and skin cancer.

And also causes cardiac disease, cerebrovasculardisease, pulmonary disease, diabetes mellitus and

diseases of the arteries, arterioles, and capillaries. skin lesions on palm and soles

The occurrence of black foot disease after arsenicexposure has been extensively documented ashave a range of skin conditions.

The occurrence of arsenic diseases depends on theingestion of arsenic compounds and theirexcretion from the body.

The analysis shows that around 90% of people

have arsenic in their hair & nail above the normal

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In Bangladesh, 95% of the groundwater abstracted is

used for irrigation. There is no evidence that arsenic isessential for plant growth but it has phytotoxic effectson different crops and so may limit crop yields.

Wetland rice is known to be very susceptible to arsenic

toxicity The arsenic content of vegetables was found to be

higher when irrigating with arsenic contaminatedwater than those grown with arsenic free water. The

trend of arsenic accumulation in leafy vegetables ishigher and lower in fruity vegetables.

The probability of significant amount of arsenic intothe food chain has been reported in areas where thearsenic contaminated ground water is used forirrigation

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A report of analysis of soil, pond water and tubewell water showed that the soil below 2.5 feetfrom the surface has high arsenic concentration

(>400mg/l). Arsenic residues can accumulate tovery high levels in agricultural areas where arsenicpesticides or defoliants were repeatedly used.

Arsenic can move downward with leaching water,

especially in coarse-textured soil profile and insubmerged soils. The average concentration ofarsenic in Bangladesh soil was 10 mg/kg

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Illiteracy and lack ofawareness

Panicked the localpeople

Contagious killer

Suffered peopleare ostracized

Avoided ordiscouraged toappear in publicplaces

Children arebanned to attendschool

Adults lose theirjobs

Women facesostracization anddiscrimination

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The mitigation of arsenic requires interventions in

screening,

awareness-raising,

water supply provision and patient identification and management.

The primary focus of the mitigation effort in Bangladeshhas been on the provision of alternative water sources.

A significant number of projects and programmes havebeen implemented by different organizations across thecountry since the detection of the arsenic problem.

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DPHE-Unicef and BAMWSP are both specificallydesigned for arsenic mitigation. DPHE-Danida

and GOB IV are both general water supplyprogrammes that have installed water supplies inarsenic affected Upazilas.

No. of projects undertaken in different sectors.

0 10 20 30 40 50 60 70

Integrated approach

Patients identificationa and support

Awareness

Mitigation

Screening

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Communitymobilisation

Water quality testing

Safe water optionsIdentifying the

patients

Integrated

approach

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A total of 18 organizations with the help ofdevelopment partners have piloted different mitigationactivities in arsenic affected areas of the countrythrough a total of 47 projects and programmes.

The Implementation Plan for Arsenic Mitigation inBangladesh identifies a number of water supplytechnologies for use in arsenic mitigation: protected

dug well, pond sand filter, rainwater harvesting, deeptubewell and river sand filters. It also notes thedesirability of promoting piped water supplies.

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In a system of stratified aquifers, a tubewell thatcollects water from a deeper aquifer leaving one ormore water bearing aquifers above is called a deeptubewell.

The deeper aquifers are separated from contaminatedshallow aquifers by relatively impermeable strata,hence they are arsenic free.

Sealing of the annular space around the tubewell usingmudballs soft clay , cement has been emphasised in the

protocol for installation of deep hand tubewells toprotect the deeper aquifers from contamination

installation of tubewell in reddish sand, if available,should be safe from arsenic contamination.

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Arsenic removal technologies have also been distributedin different parts of the country on a pilot scale. Some of

the technologies are imported from outside the countryand some are developed inside the country.

Arsenic removal technologies introduced by differentorganizations in Bangladesh principally based on four

different processes: oxidation/precipitation; co-precipitation and adsorption; and, membrane filtration.

Most of those technologies were introduced in small andexperimental scale.

It is very important to consider several factors such astype of materials used in the system, availability ofinputs, efficiency of arsenic removal, chemical andphysical properties of the material, operating techniquesand maintenance, replacement cost of materials, and

environmental impact of the waste.

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Priniciples Technology

Oxidation/precipitation Passive sedimentationInsitu oxidation

Solar oxidationCo-precipitation andadsorption Bucket treatment unitFill and draw unit

Chemical packages

BCSIR Filter unitMembrane filtration MRT-1000 and reid

systems ltd

Low pressure

nanofiltration and

reverse osmosis

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DW PSF RWH DTWASIA ARSENICNETWORK(AAN

)38 13 0 9

BAMWSP 739 12 3001 1867BRDB 227 0 95 14DCH

81

5

11

0

DPHE-UNICEF 1552 321 7472 403IDE 268 0 804 0NGO FORUM 241 47 384 85WORL VISION 106 490 1205 0OTHERS

29

23

147

7

ARSENIC

MITIGATION

PROGRAMMES3281 91 13119 2385

DPHE-DANIDA 2 20 132 14706GOB IV 2985 2590 73 57718ALL 6268 3521 13324 74809

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The key messages provided through the campaignswere:

What arsenic is and its source; The consequences of drinking arsenic contaminated

water for long time; The alternative sources of arsenic free safe water; How the alternative source of arsenic free safe water

option is maintained; and How arsenic affected individuals can be identified

and how they can get help. The different studies all appear to show that knowledge

about arsenic has greatly increased because of theawareness-campaigns and that attitudes haveimproved.

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The policy aims to:.

providing a guideline for arsenic mitigation

providing Safe Water Supply

The main policies are Ensuring access to safe water

Diagnosis

Assessment of impacts on agriculture

Preference to surface water Promoted piped water supplies

To monitor the implemented process

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The Implementation Plan identifies three phases tomitigation:

Emergency phase (villages with over 80% of tubewellswith arsenic above 50g/l)

Medium-term response (villages with 40-80% oftubewells with arsenic above 50g/l)

Long-term response (villages with less than 40% oftubewells with arsenic above 50g/l)

Many research plans concerning health of people andimpacts on agriculture were implemented

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Future needs for arsenic mitigation

Coordination

Total water quality

Mapping and Improved Understanding of Groundwater andMobilization of Arsenic

Improved Monitoring and Evaluation

Patient Identification and Surveillance

Human Resources Development

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There is no doubt that the arsenic contamination inBangladesh is a big environmental disaster in the humanhistory and also a big challenge to a very successful publichealth story.

The complex nature of arsenic increases the severity of the

problem. Though different national and international organization

are working to provide safe drinking water to the people,but still there not enough technology which areeconomically affordable to exposed people, technicallyfeasible and environmentally sustainable. So it is important

responsibility to both national and international communityto have a sustainable technology which can save a millionsof peoples from the unlimited suffering and give them a safedrinking water sources.

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References :

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