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RAHMAN et al 2005 Appraisal of Two Indigenous Household Groundwater Arsenic Removal Technologies for Bangladesh under Field Conditions

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RAHMAN et al 2005 Appraisal of Two Indigenous Household Groundwater Arsenic Removal Technologies for Bangladesh under Field Conditions
JOURNAL OF AGRICULTURE & SOCIAL SCIENCES
1813–2235/2005/01–4–361–365
http://www.ijabjass.org
Appraisal of Two Indigenous Household Groundwater Arsenic
Removal Technologies for Bangladesh under Field Conditions
I.M.M. RAHMAN1, M.M. HOSSAIN†, M. HELAL UDDIN, M. NAZIMUDDIN AND M.A. MAJID
Applied Research Laboratory, Department of Chemistry and †Institute of Forestry and Environmental Sciences, University of
Chittagong, Chittagong-4331, Bangladesh
1
Corresponding author’s e-mail: [email protected]
ABSTRACT
Performance of two indigenous arsenic (As) removal techniques-Safi filter and Home-based filters (Chari / Pitcher filter)designed to serve household drinking water requirement have been evaluated at field conditions and compared with those
reported in literature. Moderate to good As removal efficiency (> 73%) with the diminution of its concentrations below
Bangladesh standard of 0.05 mg L-1 were observed. Results revealed occurrence of gradual decrease in removal efficiency
with the increase of As concentration in the feed water. Though these filters are rated as user friendly and readily available,
lessening in flow rate of water with the progression of time is a major hindrance to the efficiency of the techniques as observed
by the users.
Key Words: Arsenic; Removal; Evaluation; Home-based filters; Safi Filter
INTRODUCTION
MATERIALS AND METHODS
In Bangladesh, the idea of drinking tube-well water for
avoiding the threat of water-borne diseases have instead put
millions at risk from one of the world's most deadly
poisons–the arsenic (As) (Dhar et al., 1997; Smith et al.,
2000; Rahman et al., 2001; Alam et al., 2002; Bhattacharya
et al., 2002 & Khan et al., 2003). Drinking As-free water is
no doubt the best option to alleviate its toxicity and several
options been proposed in this regard, viz. treatment of
surface water by low-cost methods, rain water harvesting,
drinking water from deep aquifers and treatment of Ascontaminated tube-well water etc. All these options require
major technological innovation in water supply except the
latter one, through which huge number of tube-wells likelyabandoned can easily be revitalized. Methods for removal of
As from water have been highlighted in a number of papers
(Cheng et al., 1994; Joshi & Chaudhury, 1996; Hering et
al., 1996; 1997; Hug et al., 2001 & Zaw et al., 2002) and
reviews (Jekel, 1994; Kartinen & Martin, 1995; Ahmed,
2001). During the last few years a number of low-cost
household As removal technologies in context of
Bangladesh have been developed (Safiullah et al., 2000;
Khan et al., 2000a; 2000b; Crisp & Chowdhury, 2001 &
Meng et al., 2001) and some field based evaluation have
also been done (Tahura et al., 2001; Munir et al., 2001;
Sutherland et al., 2001; 2002). In this study, we have
evaluated the performance of two indigenous As removal
filters namely Safi filter and Home-based filter at field
conditions installed at Bera Thana of Pabna District and
compared their performance with some other available
filters.
Overview of the Investigated Filters
Safi filter. This comprises of two different sized concrete
buckets-one being placed inside the other (Fig. 1). Water to
be treated flows from the upper bucket through permeable
‘candle’ containing As adsorbing chemical substance. The
lower bucket collects the treated water from which it can be
fetched by a tap.
Home-based filters. These are assemblage of earthen Chari
/ Pitcher and are called Chari filters (Fig. 2a) or Pitcher
filters (Fig. 2b). As adsorbing medium, brick pellets (locally
called 'khoa') are used to fill second Chari / Pitcher, while
sand for third Chari / Pitcher. Water to be filtered is poured
into the first Chari / Pitcher; passed through the adsorbents
and flow-regulators (made from old cloths) and then stored
at the last Chari / Pitcher.
Collection, preservation and treatment of water samples
for As estimation. Water samples were collected from
randomly selected Safi filter and Home-based filters
installed at ten different localities of Bera Thana of Pabna
District. Samples were preserved in pre-washed
polyethylene bottles, adding 0.01% HNO3 L-1 of water and
kept at 4°C (Anonymous, 1974). All other As forms were
reduced to trivalent by adding stannous chloride (SnCl2) and
potassium iodide (KI) solution and then converted to Arsine
(AsH3) by zinc (Zn) in acid solution in a Gutzeit generator.
AsH3, made free of hydrogen sulfide gas (H2S), was
estimated by visible spectrophotometer (UV-visible-160,
Shimadzu, Japan), using silver diethyldithiocarbamate (AgDDTC)
dissolved
in
chloroform
containing
hexamethylenetetramine as absorbent. This is a modified
RAHMAN et al. / J. Agri. Soc. Sci., Vol. 1, No. 4, 2005
form of EPA recommended Ag-DDTC-pyridine method.
Detailed procedure and instrumentation has been described
elsewhere (Rahman et al., 2003; Chatterjee et al., 1993). For
cross check, total As content of few samples were also
measured using atomic absorption spectrophotometer
(Model–Shimadzu, AA-6401F).
Statistical analysis. SPSS for Windows (version 11) was
used for all statistical analyses. Statistical significance was
considered valid only at 5% level of probability.
Fig. 2a. Home-based filters: Chari filter
RESULT AND DISCUSSION
The efficiency of Safi filter (SF) and Home-based
filters (HBF) were 86 to 100% and 73 to 82%, respectively
(Table I) in bringing down the As level in water down to
Bangladesh safe limit of 0.05 mg L-1. Pearson’s correlation
coefficient between initial As concentration and percentage
removal for Safi filter and Home-based filters were 0.803
and 0.806 (P < 0.01) (Table II). This indicated gradual
decrease in the removal efficiency of the filters with
increasing initial As concentration (Table I). The
observation corresponds with the behavior of some other
filters at field conditions (Bhattacharyya et al., 2002;
Petrusevski et al., 2002; Sarkar et al., 2005).
As reported by Neku and Tandukar (2003), a local
version of ‘Pitcher filter’ (locally named ‘3-Gagri filter’)
have also been tried for arsenic removal in some As-prone
areas of Nepal and 76.5% (Day 0) to 85.2% (Day 14)
removal have been observed. The iron and turbidity removal
efficiency of these filters are found very promising, also.
Though, present study does not include any such
observation, we can assume that Home-based filters may
Fig. 2b. Home-based filters: Pitcher filter.
Fig. 1. Safi filter
also have the efficiency of removing iron or other impurities
of the water.
Sutherland et al. (2001) assessed nine As removal
technologies i.e. Alcan Enhanced Activated Alumina (AL),
Aradsha Filter (AR), BUET Activated Alumina (BUET),
DPHE / Danida 2-bucket System (DPHE / DANIDA),
GARNET Home-made Filter (GARNET), Passive
Sedimentation (PASSIVE SEDIM.), Sono 3-kolshi Method
(SONO), Stevens Institute Method (STEVENS) and
Tetrahedron (TETRA) at household level in Bangladesh
context. Performances of those technologies were judged
against some pre-set criteria, on the basis of, which they
362
APPRAISAL OF TWO ARSENIC REMOVAL TECHNIQUES UNDER FIELD CONDITIONS / J. Agri. Soc. Sci., Vol. 1, No. 4, 2005
Table I. Removal of As by Safi filter and Home-based filters depending on initial concentrations
Sl. N.
01.
02.
03.
04.
05.
06.
07.
08.
09.
10.
Safi filter
Initial As conc. (mg Residual As conc.
-1
(mg L-1)
L )
0.090
<0.01
0.091
<0.01
0.097
<0.01
0.100
<0.01
0.115
0.010
0.119
0.011
0.132
0.013
0.143
0.015
0.207
0.024
0.231
0.030
As removal (%)
~100
~100
~100
~100
91.30
90.76
90.15
89.50
88.67
86.96
Home-based filters
Initial As conc. (mg L-1) Residual As conc. (mg L- As
removal
1
)
(%)
0.060
0.010
83.33
0.060
0.013
78.33
0.060
0.011
81.67
0.070
0.010
85.71
0.080
0.015
81.25
0.090
0.015
83.33
0.110
0.027
75.45
0.115
0.029
74.78
0.119
0.031
73.95
0.120
0.033
72.50
Table II. Correlation between initial as concentrations and percentage removal by Safi filter and Home-based filters
Initial As conc.
Initial As conc.
Pearson Correlation
1
Sig. (2-tailed)
.
%As Removal
Pearson Correlation
-.803**
Sig. (2-tailed)
.005
**
Correlation is significant at the 0.01 level (2-tailed).
Safi filter
As removal (%)
-.803**
.005
1
.
discarded Adarsha filter and Passive Sedimentation from
the list of viable removal technologies. The same criteria
were followed in the present investigation to evaluate Safi
filter and Home-based filters to ensure the comparability of
the findings with that of the remaining seven technologies.
Comparative study revealed that performance was not the
sole determinant of acceptability; design, size, installation,
reagents used, maintenance etc are also taken into
consideration by the users in their evaluation of the
technologies (Table III). We have found that both Safi and
Home-based filters were preferred by the users on these
grounds and similar preferences were observed for DPHE /
Danida, Sono and Stevens filters but not for high
performance Buet and Garnet filters.
Table IV shows the results of the additional queries
made along with the set criterions for this specific study.
None of the two filters cause physical problem to the users.
Though the taste of the filtered water was different from the
un-filtered water according to 80% of the users but the
odour was not un-pleasant. Safi filter is a commercial
product and as such users were ignorant about the adsorbing
materials. Home-based filters are made up locally from
available materials and all the users had fair idea about the
adsorbing ingredients. After the use, if people start dumping
the As-laden candle of the Safi filter or ingredients of
Home-based filter without any precaution, it may create
another health hazard as none of the users were found aware
of it.
Only 30% of the Safi filter users followed the
recommended washing schedule of fifteen days and 40% of
them cleaned it up once a week while 10% almost everyday
(Fig. 3). Washing more or less frequently than the
recommended intervals may hamper the efficiency of the
filters. As per recommendation, Home based filters must be
subjected to thorough washing after every 7-10 days and
after washing it should be dried in the sunlight. Only 20% of
the users followed it while 70% washed their unit once in a
month and the rest didn’t even wash the unit for nearly 2
months (Fig. 3). The observed removal efficiency of Homebased filters can not be sustained with such erratic
maintenance and the users must be made aware of it.
Acknowledgments. We appreciate the assistance of Dhaka
Community Hospital (DCH) staffs of DCH Bera Branch,
Pabna during the field survey. Thanks to the Chemistry
Division of Bangladesh Council of Scientific and Industrial
Research (BCSIR) Laboratories of Chittagong for their
support in sample measurement.
Fig. 3. Maintenance graph for Safi filter and Homebased filters, as stated by the users
70
P ercen ta g es of u sers
60
Once a week
Twice a week
Almost everyday
No comment
Once in a month
After every 7-10 days
Not washed till 2 month
50
40
30
20
10
0
Safi Filter
Home-based filters
Initial As conc.
As removal (%)
1
-.806**
.
.005
-.806**
1
.005
.
Home based filter
363
RAHMAN et al. / J. Agri. Soc. Sci., Vol. 1, No. 4, 2005
Table III. Comparison between seven candidate technologies with Safi filter (SF) and Home-based filters (HBF) [*
candidate technologies]
Questions
ALCAN*
Does the technology Yes
reduce As to below the (100%
Bangladesh Guideline samples)
Standard (0.05mg L-1)?
Does the technology No
create any problems
regarding major water
chemistry parameters?
Is
the
technology Yes
acceptable to users?
(a) Major user defined High cost
problems
BUET*
DPHE/
DANIDA*
Yes
Yes
(99.5%)
(but only
below
groundwater
As<0.12
mg/L)
No
Yes – Mn
and Al
exceeds
Bangladesh
Standards
No
Fairly
acceptable
Too tall and Bothersome
unstable,
use
difficult
(reagents),
use.
waiting times.
(b) Are the reasons for problems
easy
to
address?
Redesign
required.
What are the volumes of >3600
water produced in 12 litres
hours?
Enough
for >100
families
50 litres
(Enough
for 1.5
families)
GARNET*
SONO*
STEVENS* TETRA*
SF
HBF
Yes
(if operated
according to
instructions
75% & If not
43% samples
No
Yes
(99%
samples)
Yes
(>90%
samples)
Yes
(>80%
samples)
Yes
(86 to 100%
depending
on
initial
conc.)
Yes
(73 to 82%
depending
on
initial
conc.)
No
No
No
No
No
No
Yes
Fairly
acceptable
Test and odour
were
objectionable,
Cost was high
Fairly
acceptable
Decrease of
flow
with
time,
Too
heavy
Fairly
acceptable
Fixed set up
in
open
place,
Difficulty in
use during
rainy season
Portable
version
is
needed
Slow
flow
rates
(not
enough As
free water),
heavy.
Maybe
reconsider
reagents.
Further
Research on
materials/
design.
43 litres
13 litres
(Enough for 1 (Not enough
family)
for 1family)
Fairly
acceptable
Difficult to High cleaning
move and frequency,
slow flow Bad taste
rates.
-
Need
for additional
reagents.
Redesign
required.
13 litres
(Not
enough
for
1family)
169 litres
(Enough
for 5
families)
55 litres
38 litres
(Enough for (Enough for
1.5
1
family)
family)
624
Enough
for >20
families
Table IV. Findings of additional query about the acceptability of Safi filter and Home-based filters to the users
Is filtered water causing any physical problem?
Is the taste of filtered water different from unfiltered water?
Whether the filtered water has any odour?
Whether the users know the name of chemicals used in this unit?
After being out of order, where the adsorbent will be dumped?
Yes
0
80
0
0
0
No
80
20
80
100
0
Safi filter
No Comment
20
0
20
0
100
Yes
0
60
0
100
0
Home-based filter
No
No Comment
90
10
40
0
80
20
0
0
0
100
86: 79–90
Crisp, P.T. and A.H. Chowdhury, 2001. Design of a low-cost purification
system for the removal of arsenic from tube-well water in
Bangladesh and India. In: BUET-UNU International Workshop on
Technologies for Arsenic Removal from Drinking Water, Dhaka,
Bangladesh, May 5–7
Dhar, R.K., B.K. Biswas, G. Samanta, B.K. Mandal, D. Chakrabarti, S.
Roy, A. Jafar, A. Islam, G. Ara, S. Kabir, A.W. Khan, S.A. Ahmed
and A.S. Hadi, 1997. Ground-water arsenic Calamity in Bangladesh.
Curr. Sci., 73: 48–59
Hering, J.G., P.Y. Chen, J.A. Wilkie and M. Elimelech, 1997. Arsenic
removal from drinking water during coagulation. J. Enviorn. Eng.,
ASCE. 123: 800–7
Hering, J.G., P.Y. Chen, J.A. Wilkie, M. Elimelech and S. Liang, 1996.
Arsenic removal by ferric chloride. J. American Water Works Assoc.,
88: 155–67
Hug, S.J., L. Canonica, M. Wegelin, D. Gechter and U. Von Gunten, 2001.
Solar oxidation and removal of arsenic at circumneutral pH in iron
containing waters. Environ. Sci. Technol., 35: 2114–21
Jekel, M.R., 1994. Removal of arsenic in drinking water treatment. In:
Nriagu, J.O. (Ed.) Arsenic in the Environment, Part 1: Cycling and
Characterization, John Wiley & Sons, Inc., New York
Joshi, A. and M. Chaudhury, 1996. Removal of arsenic from ground-water
by iron-oxide-coated sand. J. Enviorn. Eng., ASCE. 122: 769–71
REFERENCES
Ahmed, M.F., 2001. An overview of arsenic removal technologies in
Bangladesh and India. In: BUET-UNU International Workshop on
Technologies for Arsenic Removal from Drinking Water, Dhaka
Bangladesh, May 5–7
Alam, M.G., G. Allinson, F. Stagnitti, A. Tanaka and M. Westbrooke, 2002.
Arsenic contamination in Bangladesh ground-water: a major
environmental and social disaster. Int. J. Environ. Health Res,. 12:
235–53
Anonymous, 1974. Analytical Methods Manual, Water Quality Branch,
Inland Waters Directorate Ottawa, Ontario, Canada
Bhattacharya, P., G. Jacks, K.M. Ahmed, J. Routh and A.A. Khan, 2002.
Arsenic in ground-water of the Bengal delta plain aquifers in
Bangladesh. Bull. Environ. Contam. Toxicol., 69: 538–45
Bhattacharyya, R., D. Chatterjee, G. Jacks, S.S. De Dalal, 2002. Technique
for arsenic removal from ground-water utilizing geological optionsan innovative low cost remediation, 275: 391–6. IAHS-AISH
Publications
Chatterjee, A., D. Das, D. Chakraborti, 1993. A study of ground-water
contamination by arsenic in the residential area of Behala, Calcutta
due to industrial pollution. Environ. Pollut., 80: 57–65
Cheng, C.R., S. Liang, H.C. Wang and M.D. Beuhler, 1994. Enhanced
coagulation for arsenic removal. J. American Water Works Assoc.,
364
APPRAISAL OF TWO ARSENIC REMOVAL TECHNIQUES UNDER FIELD CONDITIONS / J. Agri. Soc. Sci., Vol. 1, No. 4, 2005
Kartinen, E.O. and C.J. Martin, 1995. An overview of arsenic removal
processes. J. Desalination, 103: 79–88
Khan, A.H., S.B. Rasul, A.K.M. Munir, M. Alauddin, M. Habibuddowla
and A. Hussam, 2000b. On two simple arsenic removal methods for
ground-water of Bangladesh. In: Bangladesh Environment-2000,
Ahmed, M.F. (Ed.). Bangladesh Poribesh Andolon, pp 151–73
Khan, A.H., S.B. Rasul, A.K.M. Munir, M. Habibuddowla, M. Alauddin,
S.S. Newaz and A. Hussam, 2000a. Appraisal of a simple arsenic
removal method for ground-water of Bangladesh. J. Environ. Sci.
and Health, A35: 1021–41
Khan, M.M., F. Sakauchi, T. Sonoda, M. Washio and M. Mori, 2003.
Magnitude of arsenic toxicity in tube-well drinking water in
Bangladesh and its adverse effects on human health including
cancer: evidence from a review of the literature. Asian Pacific J.
Cancer Prev., 4: 7–14
Meng, X., G.P. Korfiatis, C. Christodoulatos and S. Bang, 2001. Treatment
of arsenic in Bangladesh well water using a household coprecipitation and filtration system. Water Res., 35: 2805–10
Munir, A.K.M., S.B., Rasul, M. Habibuddowla, M. Alauddin, A. Hussam
and A.H. Khan, 2001. Evaluation of performance of Sono 3-Kolsi
Filter for arsenic removal from ground-water using zero valent iron
through laboratory and field studies. In: BUET-UNU International
Workshop on Technologies for Arsenic Removal from Drinking
Water, Dhaka Bangladesh, May 5–7
Neku, A. and N. Tandukar, 2003. An overview of arsenic contamination in
ground-water of Nepal and its removal at household level. J. De
Physique., IV: JP. 107: 941–4
Petrusevski, B., S.K. Sharma, F. Kruis, P. Omeruglu, J.C. Schippers, 2002.
Family filter with iron-coated sand: Solution for arsenic removal in
rural areas. Water Sci. Tech. Water Supply, 2: 127–33
Rahman, I.M.M., M.A. Majid, M. Nazimuddin and A.S.M.S. Huda, 2003.
Status of arsenic in ground-water of some selected areas of
Chittagong district. Chittagong University J. Sci., 27: 7–12
Rahman, M.M., U.K. Chowdhury, S.C. Mukherjee, B.K. Mondal, K. Paul,
D. Lodh, B.K. Biswas, C.R. Chanda, G.K. Basu, K.C. Saha, S. Roy,
R. Das, S.K. Palit, Q. Quamruzzaman, and D. Chakraborti, 2001.
Chronic arsenic toxicity in Bangladesh and West Bengal, India-a
review and commentary. J. Toxicol. Clin. Toxicol., 39: 683–700
Safiullah, S., A. Kabir and S. Tareq, 2000. Removal of Arsenic by
composite Porous and Mesoporous Materials Based on Oxides and
Hydroxides of Fe, Mn and Al. In: International Conference in
Dhaka, Bangladesh, January 14–5
Sarkar, S., A. Gupta, R.K. Biswas, A.K. Deb, J.E. Greenleaf, A.K.
SenGupta, 2005. Well-head arsenic removal units in remote villages
of Indian sub-continent: Field results and performance evaluation.
Water Res., 39: 2196–206
Smith, A.H., E.O. Lingas and M. Rahman, 2000. Contamination of
drinking-water by arsenic in Bangladesh: a public health emergency.
Bull. World Health Organ., 78: 1093–103
Sutherland, D., M.O. Kabir and N.A. Chowdhury, 2001. Rapid Assessment
of Technologies for Arsenic Removal at the Household Level. In:
BUET-UNU International Workshop on Technologies for Arsenic
Removal from Drinking Water, Dhaka, Bangladesh, May 5–7
Sutherland, D., P.M. Swash, A.C. Macqueen, L.E. Mcwilliam, D.J. Ross
and S.C. Wood, 2002. A field based evaluation of household arsenic
removal technologies for the treatment of drinking water. Environ.
Technol., 23: 1385–403
Tahura, S., S.M. Shaidullah, T. Rahman and A.H. Milton, 2001. Evaluation
of an arsenic removal household device: Bucket Treatment Unit
(BTU). In: BUET-UNU International Workshop on Technologies
for Arsenic Removal from Drinking Water, Dhaka, Bangladesh, May
5–7
Zaw, M. and M.T. Emett, 2002. Arsenic removal from water using
advanced oxidation processes. Toxicol. Lett., 133: 113–8
(Received 10 April 2005; Accepted 22 September 2005)
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