-
Safe handling and disposal of arsenic bearing
drinking water treatment wastes in Bangladesh
Raghav Reddy, Ahammadul Kabir, Shamim Uddin, Abu
Shamim Khan, Wali Ullah, Abdul Haqim, Tara M. Webster,
James Tan, Kim F. Hayes, Lutgarde Raskin
September 22, OU WaTER conference
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Problem context: Arsenic in Bangladesh
• Arsenicosis, WHO and Bangladesh DW standard
• > 20 million people exposed to elevated arsenic levels
Smith et al. Bulletin of the WHO, 2000
Metral et al. Geochemical Transactions, 2008
Child collecting water in Chowgacha, Bangladesh.
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Water supply in arsenic affect rural Bangladesh
Manzurul Hassan, 2010
Deep tube wells
Arsenic removing
filters
Ramana & Sen Gupta, 1992
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Current waste disposal practices and cause
for concern
Lack of regulation on disposal
Direct disposal into the environment
Potential for arsenic mobilization
0%
20%
40%
60%
80%
100%
A1 A2 A3 A4 S1 S3
Distribution of Arsenic between solid and liquid phases in the
filter sludge
(backwash) from different sites
Liquid Solid
What is the fate of this waste stream?
-
Aims of our study
1. Assess the impact of current disposal practices on
• Surrounding soils
• Plants grown in such soils
2. Field evaluation of alternate disposal options: incorporation
in building materials such as
brick and concrete
• Performance of the material
• Long term monitoring in environmental conditions
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Sampling protocol
8 different filter sites employing two common arsenic
removal technologies
Collected surface (top 6 inches) soils in the vicinity of
the filter and along the drain path
Collected plant samples where applicable
Typical site map with sampling locations
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Effect on surrounding soils
0
5
10
15
20
25
30
35
S3
surroundingsoil (~5m)
centre point
pit tank
drain (1.5-9m)
Ars
en
ic (
mg/
kg)
0
5
10
15
20
25
30
A1
surroundingsoil (~5m)
centre point
pit tank
drain (1.5-9m)
Ars
en
ic (
mg/
kg)
0
30
60
90
120
150
180
210
A2
surroundingsoil (~5m)centre point
pit tank
drain (1.5-9m)
Ars
en
ic (
mg/
kg)
Localised elevation in soil arsenic seen
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Effect on surrounding soils
0
20
40
60
80
100
120
140
160
180
200
C1 A1 A2 A3 A4 A5 S1 S2 S3
April 2014
surrounding soil(~5m)
centre point
pit tank
drain (1.5-9m)Ars
en
ic (
mg/
kg)
Similar trend seen across all various sampling sites
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Effect on surrounding soils
0
10
20
30
40
50
60
70
80
C1 C2 A1 A4 S1
Ars
en
ic (
mg
/kg)
August 2014 surrounding soil(~5m)centre point
pit tank
drain (~2.5 m)
drain (~5.0 m)
drain (~7.5 m)
drain (~10 m)
Also at different sampling times in the year
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Effect on plants in the vicinty
0
0.5
1
1.5
2
2.5
3
3.5
4
Stem Leaf
Ars
en
ic (
mg
/kg)
Kachu plant
surrounding
drain
0
0.5
1
1.5
2
2.5
3
3.5
4
Stem Leaf
Ars
en
ic (
mg
/kg)
Kachu plant
surrounding
drain
Control 2 drain
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Plant uptake studies in the lab
8.3
5.1
22.2 7.7 12.0
4.0
28.5
62.6
19.4
26.8
35.8
0
1
2
3
4
5
6
Ars
en
ic (
mg
/kg)
Red amaranth
soil from filter surroundings soil from high arsenic
controls
Plant arsenic level correlates with the arsenic content of the
soil
Literature values lie
between 0.1- 0.4 mg/kg
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Plant uptake studies in the lab
Correlation not as clear but elevated evels compared to the
control
8.3
5.1
22.2
7.7 12.0
4.0
28.5 62.6
19.4 26.8
35.8
0
1
2
3
4
5
Ars
en
ic (
mg
/kg)
Spinach
soil from filter surroundings soil from high arsenic
controls
Literature values lie
between 0.1- 0.3 mg/kg
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Future research directions
Controlled studies to understand stability of the wastes in
environmental
conditions
Cost analysis for collecting, incorporation of waste into
building materials
accounting for potential uses of the material
Sustainability of water supply options: need for educations,
maintenance
and monitoring.
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Acknowledgements
Dr. Tara M. Webster, Dr. Lut Raskin, Dr.
Kim Hayes, James Tan, Raskin research
group
Dr. Ahammadul Kabir, Dr. Shamim
Uddin, Abu Shamim Khan, Wali Ullah,
Abdul Haqim
