Transcript Appropriate Household Water Treatment for Floating Villages in

BioSand Filters: Appropriate Household Water Treatment for Floating Villages in Cambodia
Curry,
1:
Background and Overview
1
K.D. ,
M.
Moat Khla is a floating village in Siem Reap Province , where all 189
families use the natural lake/ river for their water source which by
WHO standards is deemed unsafe.
*10 BSF’s installed January 2010; village members requested more.
•WfC evaluated BSF’s in December 2010 and February 2011
comparing 40 families using BSF’s and 40 families not using BSF’s.
• Turbidity in lake source water decreased in December, and mean
bacterial levels increased from 550 CFU’s to over 1100 in February.
• >90 % of both households types were using high risk lake source
water (>100 CFU’s of E. coli bacteria per 100 ml) using WHO standard.
• 5 % of BSF and 40% of Non-BSF household storage water had
bacteria levels in the high risk range (> 100 E.coli per 100ml) indicating
some source of recontamination .
•Non-BSF households untreated storage water showed significant
reduction in mean Log10 E.coli levels compared to the lake source
water.
•Surveys revealed Non-BSF families use a wide range of treated and
untreated sources for their drinking water showing wide variation in
bacteria levels and the occurrence of diarrhea.
•Recontamination occurred no matter the source or treatment.
•Demand for BSF’s increased to over 80 by February 2011 even though
a floating U.V. filtration system was available.
2
Peang ,
S. H.
S.
2
Seang
Bridgewater State University, Bridgewater, MA, USA 02325
2. Water for Cambodia, Siem Reap, Cambodia.
Number (percent) of 40 BSF and 40 Non-BSF homes
Moat
Study
February
2011: Number
of 40by
households
inKla
Moat
Khla
in February
2011(percent)
assessed
WHO
drinking water from BSF assessed by WHO Microbial Risk
microbialCategories
risk categories
for E. colifor E. coli
Recent work done in Cambodia by Brown et al. (2007) and Liang et al.
(2010) have documented ceramic water filters and biosand filters as
cost effective point of use (POU) treatment systems capable of
removing over 95% E. coli bacteria when properly used and
maintained.
Water for Cambodia (WfC) constructs, installs and tests BSF’s in Siem
Reap Province as part of their WASH outreach program and explored
using BioSand filters (BSF) to provide microbiologically safe drinking
water for people in the Moat Khla floating village community on the
Tonle Sap Great Lake.
2
Morgan ,
WHO
Microbial
Risk
Range of
E.coli (CFU/
100 ml)
Low
Intermediate
<1
1 - 10
11 - 100
0
0
3 (7.5)
E. coli levels in lake source water
increased downstream in
sample zones closer to the
mouth of Moat Khla
High
101 1000
>1000
BSF
households
Location of
Moat Khla Village
Lake Water
23 (57.5) 14 (35)
Directly from
BSF
19 (47.5) 15 (37.5)
5 (12.5)
1 (2.5)
0
BSF Treated
and stored 17 (42.5) 15 (37.5)
6 (15)
0
2 (5)
Moat Kla Study February 2011: Number (percent) of 40 NON BSF
households drinking water from BSF assessed by WHO Microbial
Risk Categories
WHO
Microbial
Risk
Lake Source E. coli and Turbidity Increase as Lake
Level Drops from December to February
Lake
December
Lake
Range of
E.coli (CFU/
100 ml)
February
•Removal effectiveness of BSF’s ranged 2.2 to 2.4 Log Reduction
however recontamination of treated water illustrates that WASH
education is essential no matter what water treatment and storage
method is used for remote floating villages in Cambodia.
Lake
1 - 10
11 - 100
High
101 1000
>1000
0 (0)
1 (2.5)
3 (7.5)
21
(52.5) 15 (37.5)
8 (20)
6 (15)
10 (25)
8 (20)
More BSF homes
Moved from
High Risk to
Low Risk than
Non-BSF homes
BSF
Lake
Water
BSF
Filter
Water
BSF
Confirm the removal efficiency of BSF’s where source water quality varies
between the wet and dry season
SW
BSF
Compare E. coli levels in lake source water used by participating
households between geographic zones in a 1 to 1.5 km area of Moat Khla
Methods
Samples of source water, filtered water, and household storage water for
BSF and Non-BSF households obtained during user surveys in December
2010 and February 2011
Processed E. coli samples by membrane filtration and incubation at 44.5
°C on modified m-Tech media for 22-24 hours using a HACH portable
incubator on site.
Turbidity levels evaluated using a HACH 2100P Turbidimeter.
Means compared using independent t-tests or Mann-Whitney U
depending on Kolmogorov-Smirnof test of normality within SPSS.
E. coli
n
Log10
E. coli
E. coli
CFU/100ml CFU/100ml E. coli
Mean and Mean and
(SD)
(SD)
LRV
CFU
%
Red.
Dec. 2010
Lake Water
28
550.0
(604.8)
BSF filtered
BSF filtered
and stored
28
3.2 (8.0)
2.56 (0.42)
0.30 (0.44)
2.26
> 99%
30
4.9 (13.4)
0.36 (0.52)
2.2
>99%
39
39
1147.8
(1173.0)
4.8 (9.9)
2.84 (0.53)
0.41 (0.51)
2.43
>99%
38
8.2 (20.8)
0.48 (0.57)
2.36
>99%
Feb. 2011
Lake Water
BSF filtered
BSF filtered
and stored
Both BSF and Non-BSF homes
had large variation in E.coli
levels in their stored drinking
water = Recontamination
Mean E.
coli per
100 ml
N
Std.
Dev.
Min
Max
RDB UV water system
369.2
13
827.2
0
3000
BSF water from neighbor
550.0
2
678.8
70
1030
Buy water
720.0
1
.
720
720
Ceramic filter
13.0
2
18.4
0
26
Korea filter
70.0
1
.
70
70
River sometime RDB UV water
13.0
1
.
13
13
River water
781.5
13
951.1
5
2920
River water with boiling
339.7
6
823.2
0
2020
2.0
1
.
2
2
473.2
40
808.5
0
3000
SW
BSF’s provide
Low Risk
Drinking Water
≥ 2.2 Log Reduction of E. coli by BSF in both periods
Moat Khla
BSF
Households
Stored
Water
Moat Khla Non BSF Families:
Number of Ecoli / 100ml in
Stored Water Feb 2011
Evaluate BSF’s as an effective treatment system to provide
microbiologically safe drinking water for floating village communities on
the Tonle Sap Great Lake.
Compare bacteria levels in lake source and household storage water for
families with and without BSF’s as a treatment for their drinking water.
Lake
Water
Stored
Water
February
December
Lake
NonBSF
8 (20)
Which water do you use for your
drinking water( dry season)
Objectives
E. coli levels were significantly
greater in lake water for homes
in Zone 1 than Zone 4
SW
BSF
SW
<1
Intermediate
NON-BSF
households
Lake Water
NO BSF
NON-BSF
stored
BSF
Low
Zones of Floating Houses in Moat Khla
BSF
Lake
BSF
FW
BSF
HS
River water with alum
Non
BSF
Lake
&
other
Total
non
BSF
HS
Non BSF Households used many
types of source water for
drinking all of which showed
wide variability in E.coli levels
even UV treated and filtered
water , Boiled water, and filtered
water = Recontamination
Non BSF Households suffered
diarrhea even when water was
boiled or filtered = Recontamination
Acknowledgements
This study was made possible by the
generous support of
Bridgewater State University
and the
Middletown Rhode Island Rotary
Club but most of all the tireless
commitment of all the staff at
Water for Cambodia.