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Index
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Bangladesh
is located in the midst of one of the world's largest river systems.
Although this vast amount of water provides a living for almost
1/3 of the country's population, the water quality is poor and the
abundance of this water does little to meet the drinking needs of
the people. Hence, Ddrinking water in Bangladesh is not largely
a river based water purification system but i. Instead, the most
crucial source of drinking water remains groundwater. However, the
discovery of "Arsenic" in groundwater in several areas
of Bangladesh has aroused widespread concern from the last couple
of years. The arsenic crisis in Bangladesh has been called the worst
environmental catastrophe of the twentieth century. Arsenic, a metalloid
element known for its toxicity and carcinogenicity, is soluble in
water and occurs naturally in many minerals. Arsenic contamination
of groundwater in Bangladesh is widely accepted to be of geological
origin, though the exact mechanisms remain poorly understood. Arsenic
occurs in different forms, organic and inorganic, with different
toxicity. Humans get affected by arsenic mainly through ingestion
and probably the nutritional status is important in relation to
the development of arsenicosis. The World Health Organization (WHO)
has set a provisional guideline value of 0.01 mg/l (10 ppb) for
total arsenic in drinking water. The Government of Bangladesh has
set a provisional water quality standard of 0.05 mg/l (50 ppb) arsenic
for drinking water.
The groundwater of Bangladesh provides safe drinking water to aboutover
97% of the rural population. This extensive coverage is indicative
of the country's successful attempt to provide safe drinking water
to its general population as surface water sources were often polluted
and diarrhoeal disease was widespread. This respectable public health
effort was overshadowed when in 1993 an alarming discovery confirmed
of arsenic contamination in groundwater. The discovery of arsenic
contamination was first identified in the northwestern part of the
country. But it was soon evident that the contamination was more
widespread and not confined to any one local area, but it is assumed
based on different studies so far conducted that the population
at risk may vary from 2520 million to over 360 million (using the
Bangladesh standard of 50ppb). As more chemical tests and research
work were being performed and subsequently concluded, the extent
of the problem became evident. Estimates vary on how many people
are affected. Tens of thousands of people have already been showing
skin discoloration and other more serious manifestations of arsenic
toxicity. Children below the age of ten are also now showing signs
of chronic arsenic poisoning.
Not only clinical symptoms but also a number of social and societal
problems are aggravating the situation. Dissolution of marriage,
avoidance of arsenicosis patients, arsenic panic in the affected
areas etc. have been reported in many areas.
Many national and international organizations have come forward
to work on arsenic for the mitigation of arsenic crisis in Bangladesh
from the beginning of the problem. Many organizations are doing
lot of researches on clinical, social and safe water technology
aspect. Different information, education and communication (IEC)
materials including participatory learning materials have been and
are being developed by different agencies which are very much important
for the mitigation strategy of arsenic catastrophe in Bangladesh.
The objective of this document and its subsequent updating is to
compile the mitigation and research activities of different organizations
and to make them readily accessible to all of them for information
sharing and forestalling any duplication of work which will minimize
our efforts and increase our efficiency to combat the deadly crisis
of arsenic in Bangladesh.
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Background
to the Arsenic contamination and Potential scale of the problem
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The
arsenic in ground water is of natural origin, and the distribution
of arsenic contaminated groundwater is related to the geology, with
most of the arsenic contaminated tubewells drawing water from the
Middle and Upper Holocene sediments.
The arsenic is believed to be released from soil under conditions
conducive to dissolution of arsenic from solid phase on soil grains
to liquid phase in water. Among the few hypothesis initially proposed
to explain the possible mechanism of arsenic release most scientists
have settled to two hypothesis: i) Oxidation theory - oxidation
of arsenic mineral 'Arsenopyrite' or arsenic rich 'Pyrite' resulting
in release of arsenic in ground water and ii) 'Reduction theory'
- reduction of arsenic rich iron-oxi-hydroxides leaching the arsenic
which remain at adsorbed state on its surface.
Mechanism of Arsenic release in underground water
Among the natural sources Arsenopyrite (FeAsS) is the most common
arsenic bearing mineral. In addition, many sulfide minerals, specially
pyrite (FeS2) is found to be rich in Arsenic. Chowdhury et al reported
presence of Arsenic-rich pyrite in a number of Arsenic affected
districts in West Bengal, India. Arsenic may leach into the underground
water as a result of oxidation of Arsenopyrite and Arsenic-rich
pyrite. Besides, Arsenic bearing minerals, Arsenic is often present
in sediments in association with iron oxi-hydroxides. Arsenic derived
from weathering of Arsenic-rich base metal sulfides may accumulate
in iron oxi-hydroxides because of its affinity for the latter. The
Arsenic-rich iron oxi-hydroxides can be a major source of Arsenic
in underground water.In some of the arsenic affected countries including
Bangladesh and West Bengal, India, two most probable (natural) sources
responsible for arsenic contamination of under ground water are:
i) Arsenopyrite (FeAsS) and Arsenic-rich pyrite and ii) Arsenic-rich
iron oxi-hydroxides.
Arsenic rich Iron Oxi-hydroxides (Reduction Process):
Arsenic derived from weathering of arsenic-rich base metal sulfides
isare often found to be associated with iron oxyhydroxides in downstream
sediments. Arsenic (both arsenate and arsenite and particularly
arsenate) has high affinity for iron oxyhydroxides and becomes associated
with them as a result of adsorption. Sediments in the Ganges delta
region are known to have iron oxyhydroxides grains on the mineral
coatings on the mineral grains and at many places these coatings
have been found to be rich in arsenic. Arsenic can be released from
these arsenic rich iron oxi-hydroxides as a result of dissolution
and desorption. A reducing redox environment (oxygen-deficient conditions)
in the subsurface can promote dissolution of iron oxi-hydroxides
and release of associated arsenic into under ground water. The normal
burial of the alluvial sediments during the development of the delta
leads to strongly reducing conditions due to the microbial consumption
of oxygen during the process of organic matter oxidation. Dissolution
of oxi-hydroxides can be caused by a reducing redox environment
in the subsurface. Organic matter, which is present in abundance
in alluvial sediments, can be responsible for reducing environment
in the subsurface. Introduction of organic waste into an aquifer
can also promote a reducing environment. Reducing redox environment
in the subsurface can promote dissolution of iron oxi-hydroxides
and release of associated arsenic into under ground water. In addition,
lowering of pH can also promote dissolution of iron oxi-hydroxides
and subsequent release of associated arsenic. This process in general
is known as the "Reduction Process".However, Tthe above
two hypotheses may be operative in different parts of a country
at a time. However the BGS report "Arsenic contamination of
groundwater in Bangladesh" (Ref X, 2001) strongly supports
the second hypothesis - the reduction process associated with iron
oxides, although it does state that it is still a hypothsis and
requires further study. The BGS study found that high arsenic concentrations
were associated with strongly reducing conditions rather than oxidizing
conditions. The oxidation hypothesis is not getting support in the
absence of widespread arsenopyrite in arsenic-prone areas of Bangladesh,
and arsenic concentrations showed a broad negative correlation with
sulphate concentrations. The intensity of arsenic problem has not
been found to have any relationship with ground water fluctuations.
Similarly the hot spots in Bangladesh are not located in areas of
high withdrawal of ground water for irrigation.Natural processes
of groundwater flushing would eventually wash the arsenic away,
but this will take thousands or tens of thousands of years. The
flushing is particularly slow in the Bengal basin due to the low
hydraulic gradients in such a large flat deltas.
Arsenic Catastrophe in Bangladesh: The Scale of the problem
Bangladesh is very much dependent on ground water both for drinking
and irrigation purposes. Until the discovery of Arsenic, groundwater
was considered safe for drinking. About Tubewells have, in the majority,
replaced the traditional surface water sources and diarrhoeal disease
has reduced significantly. An estimated 97% of drinking water of
the rural population in Bangladesh is now supplied by groundwater.
About 80% of the population is covered by manually operated shallow
tube wells and 6% by manually operated deep tubewells (Table 2.1
in Ref 1), 97% of the rural population of Bangladesh have been brought
under safe water out of which 95% of the drinking water source is
groundwater. It has been estimated that about 8.0 million hand pump
tube-wells have been installed under private initiatives and government
has sunk about 1.2 million tube-wells. In 1993 DPHE first identified
high concentration of arsenic in shallow tube-well in Chapai Nawabganj
adjacent to an area of West Bengal which had been found to be extensively
contaminated in 1988. Extensive contamination was confirmed in 1995
when additional surveys showed contamination of shallow tube-wells
across much of southern and central Bangladesh. WHO declared arsenic
contamination as a ' Major Public Health Issue' in 1996 and informed
Bangladesh Government to deal with emergency basis.Department of
Public Health Engineering (DPHE) , British Geological Survey (BGS)
and Mott MacDonald Ltd. survey (approximately 3500 samples) throughout
Bangladesh, but excluding the Chittagong Hill Tracts, revealed that
27% of the shallow tube-wells are contaminated with arsenic above
the level of 0.05 mg/l (50 ppb) and 46% of the shallow tube-wells
tested are contaminated with arsenic above the WHO guideline 0.01
mg/l (10 ppb). Eight of the 61 sampled districts had no samples
exceeding the Bangladesh standard for arsenic (0.05 mg/l) and all
districts except Thakurgaon had at least one well exceeding WHO
guideline value.According to the study finding the worst affected
districts (percent of sampled wells with greater than 0.05 mg/l
arsenic) were Chandpur (90%), Munshiganj (83%), Gopalganj (79%),
Madaripur (69%), Noakhali (69%), Satkhira (67%), Comilla (65%),
Faridpur (65%), Shariatpur (65%), Meherpur (60%), Bagerhat (60%)
and Lakshmipur (56%). The least affected districts were Thakurgoan,
Barguna, Jaipurhat, Lamonirhat, Natore, Nilphamari, Panchagar, Patuakhali
(and 0%), Rangpur (1%),. Dinajpur (2%), Noagoan (2%).
Most of the arsenic has been found in the shallow aquifer, with
only 1% of the deep tubewells (greater than 150m) tested in the
BGS study (Ref X) having arsenic greater than 50 ppb and 5% greater
than 10ppb. However there are some concerns regarding future arsenic
contamination of the deep aquifer, particularly where the shallow
and deep water is not separated by an aquitard.DPHE /BGS/ MML in
phase 1 studies estimated that the population exposed to arsenic
contamination more than 0.05 mg/l (>50 ppb) would lie in the
range 18.5-22.7 million. However the BGS-DPHE studies finally gave
an estimation of the number of population exposed to arsenic concentration
above 0.05 mg/l (50 ppb) and 0.01 mg/l (10 ppb) to be 35.2 million
and 56.7 million respectively. (Based on upazilla-averaged statistics
the exposure levels to arsenic exceeding 0.05 mg/l (50 ppb) and
0.01 mg/l (10 ppb) were computed as 28.1 million and 46.4 million
respectively, but the BGS report states that they consider the larger
figures to be more reliable). .School of Environmental Studies (SOES),
Jadavpur University, Calcutta and Dhaka Community Hospital Trust
tested water from 64 districts of Bangladesh. Their finding up to
February 2000 shows that in 47 districts arsenic in ground water
is above 0.05 mg/l and in 54 districts above 0.01 mg/l.Chronic exposure
to high doses of arsenic cause dermatologic, neurologic, vascular
and carcinogenic effects. The most common symptoms of arsenicosis
is dermatological which include dark/white pigmentation (melanosis)
and gradual hardening of palms and soles along with appearance of
hard nodular lesions over these areas (keratosos). Everyday new
patients of arsenicosis are being reported to be diagnosed. Exposure
to arsenic from drinking water increases the risk of skin, lung
and bladder cancer and possibly that of other sites also. In a report
WHO has predicted that in most of the southern part of Bangladesh
almost 1 in every 10 adult deaths will be a result of cancer triggered
by Arsenic poisoning in the next decade (Contamination of drinking-water
by arsenic in Bangladesh: a public health emergency - Alan H. Smith,
Elena O. Lingas & Mahfuzar Rahman). From the experience of Taiwan
it has been foforecastedrbidden that almost two million of people
are at risk of developing cancer in the next decades. An estimate
of Department of Public Health Engineering (DPHE) and DGHS reveals:
Total Arsenic Contaminated Districts: 61
Total Upazillas contaminated with Arsenic: 268
Total number of Patients: 13333 (August, 2002- DGHS)Everyday new
patients are coming in notice and the number of arsenicosis patients
so far identified in Bangladesh is just the tip of an iceberg and
the actual number is much higher than the present statistics. The
current screening efforts (of wells and people) present a "freeze-frame"
picture of the situation at one point in time. The true and dynamic
picture will only start to appear once private testing becomes accessible
to people and once the health service kicks in on the patient screening
side (if arsenicosis was declared as a reportable disease, there
would be chance that the patient numbers would more accurately reflect
reality). The current arsenic situation of Bangladesh has been considered
as the greatest environmental disaster of the world. So effective
and appropriate mitigation program is urgently warranted for tackling
this catastrophe in Bangladesh.
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Summary
of activities and developments since the Arsenic 2000 report
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Although
in 1993 the presence of Arsenic in a Bangladesh tubewell was first
detected, the magnitude and extent of the problem was not known
clearly before 1997. Various agencies conducted tests of tubewell
water sample from different districts randomly and comprehensive
testing could not be done due to lack of testing facilities in
Bangladesh. After 1997 there was lots of initiative taken by the
Government (through DPHE), various national and international
NGO's, and research institutions. In particular, in recent years
many small scale Arsenic removal technologies have been developed,
field tested and used under action research programs in Bangladesh.
Since the Arsenic 2000 report there have also been some improvements
in field test kits such as the Hach EZ and Merck Sensitive.
DPHE
with the donor agencies conducted various survey, study and mitigation
activities in the country and some of these are still continuing.
Under the assistance of DFID, DPHE and British Geological Survey
conducted systematic and comprehensive groundwater studies (1997
to March 2000) in 61 districts (except in the Chittagong Hill
Tracts), which helped identify the extent of arsenic contaminated
groundwater within Bangladesh. The DPHE / UNICEF arsenic mitigation
initiative to date consisted of several National-scale activities
and a focused action research project. Under the 'Action Research
into Community Based Arsenic Mitigation' project DPHE- UNICEF
worked in five upazillas (with BRAC, Grameen Bank, DCHT and ISDCM/Rotary)
and developed the second phase (2001 to 2003) of the project in
15 upazillas. Since the beginning of 2002 with funding received
from UNF, WHO and UNICEF, are collaborating with DPHE and DGHS
in an action-research community-based arsenic mitigation project
in three upazillas under the 15 upazilla project.
In
the second half of 2002 the program will be further expanded,
when communication and well-screening activities will commence
in further 25 upazillas. DPHE - DANIDA Arsenic Mitigation Pilot
Project has been taken up in the south- eastern part of Bangladesh
for three years and a half (up to June 2004). WHO, being an active
partner of GoB, organised a National Co-ordination Conference
(1999) and the International Workshop on Arsenic Mitigation (January
2002). From this International Workshop some short term and long-term
outline recommendations, on alternative water supply options,
hydrogeology and health were made.
The
Bangladesh Arsenic Mitigation Water Supply Project (BAMWSP) was
designed about four years ago (in August 1998)- when, the nature,
magnitude and impacts of the Arsenic contamination problem were
not adequately understood by all concerned. The US$ 44.4 million
project is co- funded by GoB, World Bank and SDC. The Arsenic
contamination problem and its mitigation strategy being a multidimensional
problem, the BAMWSP included multi- sectoral components for implementation.
A large amount of screening of tubewells has been carried out
under BAMWSP, but coming towards its proposed final date it can
be seen that a huge amount of mitigation and institutional aspects
of the problem are still to be addressed and BAMWSP alone is not
sufficient for handling such multi- sectoral issues.
DFID
funded "Rapid Assessment of Household Level Arsenic Removal
Technologies" was jointly managed by WaterAid Bangladesh
and DFID and implemented by WS Atkins International Ltd. This
study (commenced in August 2000 and ended in March 2001) was focused
on comparative assessment of the performance and acceptability
of nine household level technologies and finally came up with
seven. The study also included a comparative evaluation of field
test kit also. The report was submitted to the BAMWSP Technical
Advisory Group (TAG) and TAG reviewed the study and recommended
four technologies.
In
late 2001 ICDDR,B has started a research project in the Matlab
area to study the effects of exposure to arsenic. This project
is executed in collaboration with BRAC and supported by WHO, SIDA
and USAID. In mid 2002 an annotated overview of all health research
on arsenic undertaken in the last few years was published by the
Bangladesh Medical Research Council (BMRC).
Many organizations, NGO- Forum, BRAC, DCHT, CARE and others are
very much involved in arsenic mitigation: awareness raising, patient
identification & management and small-scale research. BUET,
DU and IDE are also involved in some research on mitigation options.
In January 2002, the DFID funded (US$ 49.3 million) Rural Hygiene,
Sanitation and Water Supply Project has been started by DPHE with
assistance from UNICEF.
Initial
studies have been undertaken to address the concern regarding
the contribution to arsenic in the food chain by water contaminated
with arsenic and used for irrigation or cooking. Studies undertaken
by FAO, CSIRO/Australia & Dhaka University and AIIHPH/Kolkata
with WHO, point to substantial contributions to the total arsenic
content in green leafy vegetables, when grown with contaminated
irrigation water. However a study by Australian National University
(ANU) in collaboration with NGO Forum "An Intervention Trial
to Assess the Contribution of Food Chain to Total Arsenic Exposure"
in May 2000, which chose exposure based on arsenic content in
irrigation water, failed to demonstrate a difference in arsenic
content in the small number of raw food samples tested from the
high and low contamination areas. Further studies investigating
the arsenic content in different types of food from areas with
high and low contamination of irrigation water, are recommended.
It
is evident that since 2000 many Government, Non Government and
Bilateral organisations are working on this issue and much action
research has been carried out, however the situation of many communities
has not improved greatly. The broad spectrum of institutional
arrangement should be such that it ensures sustainable development.
The services that are required, be it technological or financial,
need to be delivered optimally. The situation now demands to review
and reform the institutional arrangement to address sector issues
appropriately.
To develop a more coordinated response to the arsenic crisis,
GoB has taken new initiative to establish Arsenic Policy Support
Unit (APSU) in the Local Government Division (LGD) to prepare
and implement a National Arsenic Mitigation Programme (NAMP) through
a partnership approach. It is an indication that GoB and donors
wish to address the arsenic crisis in a more holistic way than
has been possible under the BAMWSP. DFID is currently designing
a Support to the National Arsenic Mitigation Programme (SNAMP)
and would assist APSU in implementing the recommendations for
action that resulted from the International Workshop held in January
2002.
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Methods
of Detection of Arsenic
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Arsenic
can be detected either at the field level using portable test kits
or by laboratory testing. Field kits are very important given the
scale of testing required but are not accurate for determining the
exact arsenic concentration in water at the low concentrations important
for human health. The Bangladesh standard of 50 parts per billion
(ppb) for arsenic in drinking water. The equivalent of ppb is micrograms/litre
or µg/l. The World Health Organisation (WHO) guideline value
for arsenic in drinking water is 10ppb. A semi quantitative result
of arsenic concentration can be obtained using the field kits, most
of which depend on comparing the colour obtained during the test
to a colour chart with the kit. Weaknesses of field testing include
the issues such as: (1) the field test kits being subject to fluctuations
in sensitivity and accuracy depending on the model of the kit;
(2) excess light and certain other water quality parameters encountered
in the field, are thought to interfere with the analysis,
(3) individual differences are inevitable when many field workers
are involved (i.e. operator error in the procedure or reading of
result, such as confusion over decimals) and reading of the colour
chart can be subjective.
(4) field storage conditions of reagents of some kits can dramatically
decrease the working life of the reagents.Field kits users are usually
from a non-technical background, and may feel pressurised to read
the resulting colour to tend towards expected results. However proper
training to the field workers does improve results. Some crosschecking
of field results is important.For the purpose of screening of the
tube wells field testing is being widely used in spite of its limitations.
Laboratory testing is much more expensive than field kit since laboratory
testing has a cost of approximately US$ 8 to US$ 15 and the cost
of field kit testing is about US$ 0.50 per sample.Field test kits
that are commercially available use the mercury bromide method or
the Silver Diphenyl Dithio Carbamate (SDDC) method. Laboratory analytical
equipment used includes atomic absorption spectrometry (AAS), ICP
(Inductively Coupled Plasma), Neutron Activation Analysis (NAA),
ICP/MS (Inductively Coupled Plasma/Mass Spectrometry) and Anodic
Stripping Voltametry, TXRF and PIXE. Field Test Kit MethodologiesMercury
Bromide stain methodMost of the current field-test kits (e.g. Merck,
Asian Arsenic Network -AAN, General Pharmaceuticals Limited -GPL,
NIPSOM, HACH) are based on the "Gutzeit" method. This
involves the reduction of arsenite and arsenate by zinc to give
arsine gas, which is then used to produce a stain on mercuric bromide
paper. There have been several studies on the sensitivity and reliability
of these kits, although some of these are rather out-of-date since
not all of these studies were carried out using the most recently
available kits. The most extensively field tested of these kits
were until recently the E-Merck, AAN and GPL kits. The evaluations
have generally shown these kits to be reasonable at detecting high
concentrations (greater than 100ppb) but less reliable at lower
concentrations. Merck and Hach therefore focussed on improving the
kits at low concentrations and have developed the Merck-Sensitive
kit and the user-friendly HACH EZ. The Arsenic Cell, NGO Forum is
intending to update their earlier conducted evaluation study on
different field kits available in Bangladesh.The newly developed
HACH EZ is a simplification of the HACH 5-stage kit, in that it
uses only 2 reagents and is therefore quicker and more straightforward
for field workers. This HACH kit has currently undergone field-testing
and to date has produced encouraging results on both reliability
and accuracy when cross-checked with laboratory testing. HACH EZ
is now recommended by Bangladesh Arsenic Mitigation Water Supply
Project (BAMWSP), UNICEF, WaterAid Bangladesh and many other organizations
for arsenic screening at field level. These organizations are currently
using this field test kit for screening purpose.The PeCo75 is a
handheld instrument developed by Professor Walter Kosmus of the
Karl Franzens University in Austria. This field kit is a development
of the standard Gutzeit method in that it replaces zinc with sodium
borohydride and so removes the problem of obtaining low-arsenic
zinc. The PeCo75 uses a calculator-style device to measure the stain
developed photometrically rather than by eye and is easily calibrated.
The PeCo75 has shown good reliability and accuracy to 5ppb in laboratory
environments. The kit is not currently in commercial production,
but Professor Kosmus has joined with Wagtech in a partnership/joint
venture to produce and market the Peco commercially. Wagtech is
intending that the product will be available for its official launch
at the Kolkatta WEDC Conference in November 2002. Presently it is
being redesigned to be more user friendly and to give digital readout
down to 2ppb. Consumables will be readily available in refill packs
(together with colour comparison charts - so the refill pack will
become a direct alternative to other kits in its own right - but
can then also be use in conjunction with the instrument for a more
accurate reading). Information on Field-test Arsenic Kit:Field Test
Kit Capital Cost (approx) Commercially & Locally available?
Manufactured by Waiting time taken per test -minutes Shelf Life
Contact
US $ Tk.
E. MerckOr Merck Sensitive 50 About 2600-2800 Taka (per 100 tests)
depending on quantity of order Yes Merck KGaA Germany 30 3 years.(150-250
C)May reduce once opened due to field storage conditions. gat@bdmail.net
GPL 43 2000-2500 depending on quantity Yes General Pharmaceuticals
Bangladesh 20 Bromide strip:1yr but when opened best to use within
45 days Other 2 chemicals: 5 years.Storage: 200-250c zac@aitlbd.net
NIPSOM 18 1000 Yes NIPSOM Bangladesh 10 Unopened: 6 monthsOpened:
1 month anon@bdcom.com
HACH 5 -stage 150 9000, (per 100 tests) less on large quantity order.
Yes(but large orders may require 6-8 weeks delivery time) HACH ,
USA 35 Reagents: 3-5 years. worth@bangla.net
HACH EZ 80 4700, (per 100 tests) less on large quantity order. Yes(but
large orders may require 6-8 weeks delivery time) HACH , USA 20
Reagents: 3-5 years. worth@bangla.netHowever it is generally recommended
that all the test kits which use strips should be used within six
months of opening.Further Contacts:Mr. T. AliProprietor, G.A. TRADERSTel:
9557299, 9559275Fax: 9562591E-mail: gat@bdmail.net Mr. Zaki Azam
ChoudhuryMarketing ManagerGeneral Pharmaceuticals LimitedTel: 9132594,
8120081, 017681072, 017811642Fax: 9120657E-mail: zac@aitlbd.net
Mohammad Abdul BatenMarketing & Technical Supports ManagerTECHNOWORTH
Associates Limited78, Motijheel Commercial Area, 1st floor,Dhaka
-1000.Phone: 9555646, 9559776, 9568461, 9567981, 9568794, 018241772Fax:880-2-9562215,
880-2-8616947E-mail: worth@bangla.net Dr. S. Akhtar Ahmad,Associate
Professor,Dept. of Occupational and Environmental HealthNIPSOM,
Mohakhali, Dhaka - 1212Phone: 602776E-mail: anon@bdcom.com
Colorimetric methodsOther field test kits use the SDDC (Silver Diphenyl
Dithio Carbamate) method which relies on arsine generation and the
colour reaction with SDDC. Arsenic hydride is absorbed into a solution
of silver diphenyl dithio carbamate; the orange to red-violet soluble
compound that is produced is analyzed by absorption spectrophotometry.
The absorption line is measured to find the arsenic concentration.
If no substances that obstruct the process are present then detection
of arsenic concentrations to below 50ppb is feasible.Two addresses
of companies that manufacture and supply field spectrophotometers
include
Spectrochem Instruments Pvt. Ltd. (AsDETECT) and HACH Company.Contact
1) Madhav TennetiManaging DirectorSpectrochem Instruments Pvt. Ltd.B-23
Huda Complex, SaroornagarHyderabad, Andhra Pradesh500 035 INDIAPh:
91-40-4053341 or 4053342Fax: 91-40-4146308Email: madhav@spectrochemindia.comWeb:
www.spectrochemindia.com HACH Company, USA(Bangladesh Distributor)Contact:
Mohammad Abdul BatenMarketing & Technical Supports ManagerTECHNOWORTH
Associates Limited78, Motijheel Commercial Area, 1st floor,Dhaka
-1000.Phone: 9555646, 9559776, 9568461, 9567981, 9568794, 018241772Fax:880-2-9562215,
880-2-8616947E-mail: worth@bangla.netWeb: www.hach.com International
Enquiries: intl@hach.com
Wagtech Portable Trace Element Analyzer (PTEA)This is a portable
device for measuring metals in water, including arsenic (but also
lead, copper, etc). The operating principle is voltaic stripping.
Due to price and complexity you cannot consider it equivalent to
a field test kit, but it can be used in the field. It can attain
the same accuracy and precision as a AAS, at a fraction of the cost
(also without need for reliable electricity, airconditioning, etc.).
Potential uses
are as system for cross-checking field kit results, or for use as
part of a mobile laboratory (e.g. setting up a temporary water supply
analysis facility at union or upazilla level). The PTEA is marketed
by Wagtech in the UK. Further details from:
Nick Price
Export Manager
Wagtech UK Ltd.
Wagtech House
137-139 Station Road
Thatcham
Berkshire RG19 4QH
nick.price@wagtech.co.uk
Laboratory Methodologies:The following are the different methodologies
for determining arsenic concentration.
a) Atomic Absorption Spectrophotometry
- Flow Injection Hydride Generation AAS
- Graphite Furnace AAS
- Flame AAS
- Electrothermal AAS
b) Neutron Activation Analysis
c) Inductively Coupled Argon Plasma Emission Spectrometry (ICP)
d) Anodic Stripping Voltametry
e) Spectrophotometry
f) X-ray spectroscopy
- Particle-induced X-ray emission spectrometry (PIXES)
- X-ray fluorescence (XRF) spectroscopy
- X-ray absorption fine structure (XAFS) spectroscopyThe minimum
detection level of Flow Injection Hydride Generation Atomic Absorption
Spectrophotometer is 0.003 mg/l and that of Spectrophotometer is
0.03 mg/l.Many governmental and non-governmental organizations and
different institutes have laboratory set up where arsenic analysis
facilities are available on commercial basis. NGO Forum for Drinking
Water Supply & Sanitation has set a laboratory where arsenic
analysis and other 30 parameters of water are tested on commercial
basis. NGO Forum analyses arsenic by spectrophotometer. Bangladesh
University of Engineering & Technology, Atomic Energy Commission,
BCSIR, Dhaka University (Soil, Water & Environment Dept.) have
AAS facilities in their laboratory. Due to the nature of laboratory
testing being remote good co-ordination is necessary with the field
to ensure correct tubewells are marked with correct concentrations
(i.e. painted red or green). Collaboration with field staff as well
as map information and efficient transportation are essential.
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Arsenic
Mitigation Options
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Safe
water is the prerequisite for improved public health situation of
a country. In addition to the arsenic problem, numerous water borne
diseases toll lot of lives every year in Bangladesh. Both the GoB
and NGOs have been working with great emphasis in this field since
last few decades for ensuring safe drinking water to the people.
Concept
of Safe Drinking Water:§ Water has no objectionable taste,
colour and odour.
§ Water that does not contain harmful biological agents,
§ Water that does not contain toxic materials & chemicals,
§ Water that contains permissible limit of minerals.Drinking
water can be obtained from groundwater, surface water or rainwater
sources. Each source has characteristics relating to quality, quantity,
reliability, user acceptability and costs that will determine use.
While it was claimed that about 95% of the total population of Bangladesh
have been brought under safe water supply, the current ground water
arsenic contamination is a severe blow to that perceived success.
Now it has become urgent to seek alternative water source other
than shallow tube-well in the arsenic contaminated areas.When considering
sources and water supply technologies for arsenic mitigation, selection
should be on the basis of avoidance or of a substantial and consistent
reduction of the ingestion of arsenic. In assessing best alternative
water options and / or arsenic removal technologies the following
basic criteria should be evaluated:· Water Quality (i.e.
does the system consistently provides bacteriologically and chemically
safe water?)
· Water Quantity (e.g. flow rate, access to water at peak
times)
· Affordability (capital, operation & maintenance)
· Reliability
· Life expectancy (e.g. how does one know when to change
filter media)
· Convenience (e.g. time & effort involved)
· Time considerations
· Gender issues (e.g. ergonomically appropriate, division
of labour)
· Environmental risks (e.g. sludge disposal, excess water
/ drainage issues)
· Operational safety (e.g. user accidental misuse, physical
and chemical safety, robustness)
· Risk substitution (e.g. introduction of bacteriological
contamination)
· Logistical sustainability of system (e.g. are reagents
available locally, life time of system, market base, involvement
of private sector)
· User acceptability
· Necessary operation and maintenance training
· Information, Education & CommunicationDifferent field
studies revealed that arsenic free alternative safe water options
should be area specific depending on the features and geological
structure of that area. Rain water Harvesting System (RWHS) or deep
tube wells will be a better source of drinking water in the coastal
areas where the shallow aquifer is contaminated with arsenic and
less potable because of high salinity. In some areas, particularly
those without an aquitard separating the shallow and deep aquifers,
there are concerns about the deep aquifer also coming contaminated
with arsenic. So many experts consider that the long-term recommendation
of an alternative water supply option should be aimed at the best
proper use of surface water, but this must consider the treatment
of typically high pathogen loadings.
Alternative Safe Water OptionsAlternative safe water options can
be provided at either household or community level. The household
level options include:· accessing water by sharing safe (green)
tubewells,
· using protected dug wells,
· rainwater harvesting,
· treating surface water (e.g by use of household filter
or solar disinfection).Community level alternative options include:
· Deep tube well with hand pump,
· Deep tube well with motorized pump, overhead tank and series
of stand posts (below tank or distributed in the area),
· Rainwater harvesting,
· Surface water treatment through pond sand filters,
· Other surface water filters or treatment technologies,
· Disinfection systemsArsenic Removal technologiesHousehold
and community level arsenic removal technologies should be subjected
to rigorous testing in idealized field conditions, in real household
conditions, and in laboratory conditions. It is imperative that
the performance of the technologies is adequate and as anticipated
in the household or the community - not only in the laboratory or
in supervised field conditions. They should produce an adequate
quality and quantity of water even when the technology is subject
to a certain degree of "misuse" such as may be caused
by improper mixing, use beyond assumed safe removal capacity of
a filter, shortcuts, etc. Removal technologies should be such that
their presentation (sachet, pill or adsorbent layer), operation
and functioning (mixing, settling), storage and abstraction, favour
the adequate operation at the household and community level to ensure
provision of safe water. There are four main methods of arsenic
removal:· co-precipitation (coagulants form flocs that bind
arsenic and are then filtered out)
· adsorption (arsenic adsorbed onto surface of media)
· ion-exchange (arsenic ions attracted to charged polymer
resins)
· membrane filtration (selectively permeable membranes remove
arsenic by filtration)Some stakeholders have expressed doubts about
the viability of household arsenic units, and suggested that community
level arsenic removal units are preferable. They note the difficulties
associated with persuading millions of households to use arsenic
removal units, and in ensuring that they are used correctly, and
the advantages of centralized operation and maintenance, including
arsenic testing, by trained caretakers. They also express concern
about the effect of private sector involvement, with its emphasis
on commercial viability, on the poor. However, these compelling
arguments ignore history. The failure of concerted efforts to provide
community water supplies for all is what led to the massive growth
in private hand pump tubewells in the first place, and existing
investments in community water treatment units, such as pond sand
filters, or iron removal plants, have rarely produced safe or sustainable
water supplies.This listing of technologies does not indicate that
they are safe technologies to use or that they consistently remove
arsenic to below 50ppb. This listing should be used as an information
point and organisations are encouraged to seek further detail either
from organisations testing the technologies or the technology proponents.
The responsibility for safe implementation lies with the respective
implementing organization.
Household level Arsenic Removal TechnologiesRapid Assessment of
Household Level Arsenic Removal Technologies:The DFID funded the
project 'Rapid Assessment of Household Level Arsenic Removal Technologies'
which comparatively evaluated the first nine of the household level
technologies listed below and was carried out as part of the Bangladesh
Arsenic Mitigation Water Supply Project (BAMWSP) with management
support of WaterAid Bangladesh. It was carried out by WS Atkins
International with the assistance of the Bangladesh Engineering
and Technological Services (BETS) , the Intermediate Technology
Development Group (ITDG) and Imperial College, London.The study
was conducted in two phases. Phase I sought to answer the question
"Does the technology consistently reduce arsenic concentration
below the Bangladesh Guideline Standard of 0.05 mg/l". Seven
of the nine technologies passed and were included in Phase II.Phase
II was concerned with:
¨ Arsenic removal under normal conditions
¨ Fourteen other water quality parameters
¨ Bacteriological contamination
¨ Breakthrough
¨ User acceptability
¨ Affordability
¨ An evaluation of field based arsenic testing kits.The household
level arsenic removal technologies that were considered during Phase
I are:1. Passive Sedimentation
2. DPHE / DANIDA Bucket Treatment Unit
3. Stevens' Institute Technology
4. Adarsha Filter
5. GARNET home-made filter
6. SONO- 3 kolshi method
7. BUET Activated Aluminium Filter
8. Alkan Activated Aluminium Filter
9. Tetra Hedron
10. Ion exchange resins
11. Rajshahi University / New Zealand iron hydroxide slurry
12. SORAS (Solar Oxidation and Removal of Arsenic)
The seven technologies that passed to second stage (Phase II) are
the following:¨ Alcan Enhanced Activated Alumina
¨ BUET Activated Alumina
¨ Sono 3 - kolsi
¨ Stevens Institute Filter
¨ DPHE/DANIDA Two Bucket
¨ GARNET Home-made Filter
¨ Tetrahedron Ion Exchange Resin Filter.The first four were
consistently good at removing arsenic, with no apparent negative
impact on any of the other key water quality variables. The last
three were most unpredictable, two of them struggling to cope with
high arsenic concentration in ground water. Of the four consistent
technologies, the Alcan and the Sono were the most acceptable to
householders, whilst the BUET and Stevens were less so. Key factors
for acceptability were cost, ease of use, waiting time and flow
rate. The full report is available on-line at the WaterAid web site
(http://www.wateraid.co.uk) under 'Research and campaigns' and the
Arsenic Crisis Information Centre site (http://bicn.com/acic/) .
Household level arsenic removal technologies:Household level arsenic
removal technology options include the following (see Annexe 5 for
further details of the technologies):1. Passive Sedimentation
No proponent
2. DPHE / DANIDA Bucket Treatment Unit
Contact: DPHE-Danida Water Supply and Sanitation Components, Arsenic
Mitigation Component, 2888, Central Road, Harinarayanpur, Maijdee
Court, Noakhali. Ph. 0321 5582
3. Stevens' Institute Technology
Professor Meng, Center for Environmental Engineering, Stevens Institute
of Technology, Hoboken, NJ 07030. E-mail: xmeng@stevens-tech.edu
Ms. Nasrine R. Karim, Director General,Earth Identity Project, F
6/1 House 2, Road 17, Block - C, Banani, Dhaka-1213. Tel: 8812049-53
4. Ardasha Fliter
Mr. Sounir Mojumdar, CRS-Ardasha Filter Industries, Chagalnaya Bazar,
Chagalnaya, Feni.
5. GARNET home-made filter
Mr. Tofael Ahmed, Programme Officer/, GARNET-SA, 1/7, Block-E, Lalmatia,
Dhaka-1207, Tel: 9117421
6. SONO- 3 kolshi method
Professor A.H. Khan, Department of Chemistry, University of Dhaka,
Dhaka-1000, E-mail: ahkhan@udhaka.net
Dr. A.K.M. Munir, Director, SDC-Environment Initiative, College
More, Courtpara, Kushtia 7000 Ph: 07153144
7. BUET Activated Aluminium Filter
Dr. M.A. Jalil, Department of Civil Engineering, BUET, contact:
e-mail:majalil@ce.buet.edu
8. Alcan Activated Alumina Filter
M. Saber Afzal, MAGC Technologies Ltd, House 15, Road 5 Dhanmondi,
Dhaka-1205. Tel: 861 5279, 989 3747 Fax: 861 5279 E-mail: magc@bdmail.net
Website: www.magctech.com
9. Tetra Hedron
US: Dr. Waqi Alam, tetrahedron@prodigy.net
Bangladesh: Wazir Alam or Md. Masud Rana
9882770, 601852, 017171376 10.
10. Ion exchange resins
Contact: BAMWSP, email: pdamwsp@bol-online.com??
11. Rajshahi University / New Zealand iron hydroxide slurry
Contact: BAMWSP, email: pdamwsp@bol-online.com??
12. SORAS (Solar Oxidation and Removal of Arsenic)
Contact: Martin Wegelin, Daniel Gechter and Stefan Hug,
Swiss Federal Institute for Env. Science and Technology (EAWAG),
Dept. of Water & Sanitation in Developing Countries (SANDEC),
8600 Duebendorf, Switzerland
internet: www.eawag.ch, www.sandec.ch
Abdullah Mahmud and Abdul Motaleb,
Swiss Agency for Development and Cooperation (SDC), GPO Box 928,
Dhaka, Bangladesh
13. Shapla Filter
Contact:David B Nunley,Country Director, International Development
Enterprises (IDE) - Bangladesh, House 15, Road 7, Dhanmondi, Dhaka
1205, Phone: 8614485, 8619258, Fax: 8613506
E-mail: dbnunley@agni.com Webpage: www.ide-bangladesh.org Community
Level Arsenic Removal Technologies:Community level arsenic removal
technology options include the following (see Annexe 6 for further
details on the technologies):1. Arsenic / Iron Removal Plants
18 District Towns Project,
Rotary International / UNICEF,
DPHE / DANIDA,
NGO Forum for safe drinking water and sanitation.
2 SIDCO
Mir Moaidul Huq, General Manager, Sidko Limited
Paragon House (7th Floor), 5, Mohakhali C/A., Dhaka-1212
Phone: 880-2-9881794 / 8827122
Fax: 880-2-9883400
E-Mail: sidko@neksus.com3 Alcan
M. Saber Afzal, MAGC Technologies Ltd, House 15, Road 5 Dhanmondi,
Dhaka-1205. Tel: 861 5279, 989 3747 Fax: 861 5279 E-mail: magc@bdmail.net
Website: www.magctech.com4 Arsen-X System
Contact: Ostertech Inc. 37 North Forge Drive, Phoenixville, Pennsylvania
19460, USA
Phone / fax: +610 935 066
Email: lewo@att.net5 Tetra Hedron
US: Dr. Waqi Alam, tetrahedron@prodigy.netBangladesh: Wazir Alam
or Md. Masud Rana
9882770, 601852, 017171376 E-Mail:6 Nirapad
PROSHIKA / Altech7 Apyron System
Contact: Forrest Cookson, American Chamber of Commerce Dhaka (c/o.
Sheraton Hotel)
Phone: 0118523378 READ-F
Contact: Brota Services International, Al-Islam Chamber (2nd Floor),
91
Agrabad, Chittagong. Phone: 031-712183, 725865. Dhaka Office: 262/KA
Fakirapool,
Dhaka 1000. Phone: 9350390
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