development of a procedure and apparatus to quantify pathogen
TRANSCRIPT
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Development of a procedure and apparatus to quantify pathogen reduction throughout an
intermittent biosand filter
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Duchity, Haiti
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Duchity, Haiti – Water Quality
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Intermittent biosand filter
Adaptation of a traditional slow sand filter
Designed by Dr. David Manz (1991)
Implemented in more than 70 countries
Appropriate technology
Low cost
Materials availability
Operational simplicity
304 mm
158 mm
543 mm
50 mm
940 mm
222 mm
(5)
(1) Reservoir Zone
(2) Standing water Zone
(3) Biological Zone
(4) Non-Biological Zone
(5) Gravel Zone
50 mm
50 mm
(4)
(3)
(2)
(1)
66 mm
108 mm
(1) CAWST Manual 2009
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Biosand filter operation
Biosand filter mechanisms
Mechanical trapping Adsorption
Lack of oxygen
and nutrients Biological Activity
(1) CAWST Manual 2009
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Technology comparison
Intermittent biosand filter
Traditional slow sand
filter
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Objectives
Evaluate the impact and contribution of microbial activity and
dissolved oxygen concentration in pathogen reduction as
functions of medium depth and time.
Understand the filter mechanisms interaction
Improve filter design
Optimize materials use
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Experimental Apparatus
Table 1. Bench scale dimensions
Diameter [m] 0.10
Total height [m] 1.0
Outlet tube
Inside diameter [mm]
Outside diameter [mm]
Tube height [mm]
9.53
6.35
695
Effective volume [mL] 2,280
Media layers
Sand [mm]
Porosity
Separation Gravel [mm]
Porosity
Drainage Gravel [mm]
Porosity
543
0.44
50
0.50
50
0.55
Diffuser
Perforation diameter [mm]
Distance between perforations [mm]
3.2
12.7
Table 2. Haiti local sand
Particle size [mm] 0.7 - 0.1
Effective size [mm] 0.13
Uniformity Coefficient 2.5
Minerals
Quartz SiO2
Calcite CaCO3
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Sampling Ports
Table 3. Sampling ports dimensions
Ring diameter [mm] 50
Wall distance [mm] 25.4
Tube
Outside diameter [mm]
Inside diameter [mm]
9.53
6.35
Perforations quantity 5
Mesh
Opening size [μm]
105
307 mm
50 mm
543 mm
50 mm
50 mm
1.0 m 148 mm
335 mm
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Methodology
Multi-parameter
PCSTestr 35 Oakton
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Results: Tracer test
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
No
rma
lize
d t
rac
er
co
nce
ntr
ati
on
Time [min]
2.54 cm
17.3 cm
33.5 cm 38.5 cm
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Results: Tracer Test
MDI = 16
MDI = 7
MDI = 4
MDI = 3
Morrill Dispersion Index
Mixture
Plug Flow
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Volumetric flow rate and hydraulic head
y = 101.71e-0.052x
0
20
40
60
80
100
120
0 10 20 30 40 50 60 70
Vo
lum
etr
ic f
low
ra
te [
mL
/min
]
Time [min]
Volumetric flow rate as function of time in a biosand filter
y = 33.143e-0.073x
0
5
10
15
20
25
0 10 20 30 40 50 60 70
Hyd
rau
lic h
ead
[c
m]
Time [min]
Hydraulic head as fuction of time in a biosand filter
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y = 4.2028x + 2.7766 R² = 0.9968
0
20
40
60
80
100
120
0.00 5.00 10.00 15.00 20.00 25.00
Vo
lum
etr
ic f
low
ra
te [
mL
/min
]
Hydraulic head [cm]
Volumetric flow rate as function of the hydraulic head in a biosand filter
Volumetric flow rate and hydraulic head
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Future Work
Develop concentration profiles
as a function of depth and time
Total coliform
Enterococcus spp.
Dissolved oxygen
Evaluate the impact in the
bacteriological quality of the
biosand filter effluent with a
modified zeolite treatment.
Conduct a person-to-person
survey in Duchity, Haiti.
Table 4. Preliminary Results
Sample Treatment
time
E-coli
CFU/100 mL
Total coliform
CFU/100 mL
Source 0 hr 3,100 66,900
Control 1 hr 3,600 56,500
2 hr 3,400 53,700
Non-modified
zeolite
1 hr 400 13,000
2 hr 100 9,700
Modified
zeolite
1 hr 0 0
2 hr 0 0
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Acknowledgements
This material is based upon work supported by the National Science Foundation under Grant No.1033028.
http://greatidea.uprm.edu