Evaluation of the removal of heavy
metals using the Biosand Filter
Lesly J. Mamani Paco
Laboratorios Analíticos del Sur, Peru
CAWST Learning Exchange - June 2011
1
Reason & Purpose for Study
 The drinking water sources for the peri-urban
communities surrounding Lima, Peru are
contaminated with heavy metals from closed
mines that had not been abandoned properly.
 This study was undertaken to evaluate if the
biosand filter*, with and without amendment,
could remove these heavy metal contaminants
from the drinking water.
* A sand filter sized for a household’s water needs www.cawst.org
CAWST Learning Exchange - June 2011
2
Objective
• To evaluate the removal of heavy metals*
from drinking water; using the Biosand
filter (BSF) amended with copper-zinc
granules and activated carbon.
* chromium (Cr), cadmium (Cd), lead (Pb) and iron (Fe)
CAWST Learning Exchange - June 2011
3
Experimental procedure
• 10 biosand filters for each metal studied (40 in total)
• For 3 metals; Chromium (Cr), Cadmium (Cd) and Iron (Fe):
6 filters were amended with differing amounts of Cu-Zn
and activated carbon (accessory) and 4 were not
amended.
• In the experiments for Lead (Pb); all 10 filters were
amended.
• Targeted 3 initial concentrations (Ci) of each metal:
Ci ≈ LMP; Ci ≈ 10 · LMP; Ci ≈ 100 · LMP
Where LMP is maximum allowable limit for drinking water; Cr = 50
µg/L; Cd = 3 µg/L; Pb = 10 µg/L; Fe = 300 µg/L (Peruvian Legislation)
CAWST Learning Exchange - June 2011
4
Chromium (Cr)
CAWST Learning Exchange - June 2011
5
Results: Percentage removal of Cr
100
Chromium average
removal
Promedio
porcentaje
de
remoción
del Cromo
(final concentration / initial concentration) in percent
% de remoción
%
Removal
95
90
(low):
20.6 µg/L
C.CiBaja
E. 0,0206
ppm
C.CiIntermedia
E. 0,1922
(intermediate):
192.2ppm
µg/L
C. Alta E. 2,530 ppm
Ci (high). 2,530 µg/L
85
80
Filtro
Filter
F 01
F 02
F 03
F 04
F 05
F 06
F 07
F 08
F 09
F 10
200
400
300
300
200
400
-
-
-
-
Carbóncarbon
Activado(g)
(g)
Activated
500
500
750
750
1000
1000
-
-
-
-
Cu-Zn
granules
(g)(g)
Gránulos
Cu-Zn
6
Results: Percent removal with and without
accessory
Porcentaje
de Remoción
del Cromo
Chromium
removal
percentage
- High initial conc. (Ci)
(Concentración initial
inicial concentration)
alta)
(final concentration/
in percent
100
% de remoción
Removal %
99
Removal WITH accessory
98
Ci = 2,530
µg/L
PROMEDIO
C/ACC.
C. E. 2,530 ppm
Removal S/ACC.
WITHOUT
PROMEDIO
C. E. accessory
1,545 ppm
Ci = 1,545 µg/L
97
96
95
F01
F02
F03
F04
Filter
Filtros
F05
CAWST Learning Exchange - June 2011
F06
7
Results for Chromium
Removal Effectiveness:
• In all tests, with and without accessory, Cr concentrations
were reduced by 85% - 99.9%
– Higher removals were found for higher initial concentrations
– Improvement in removal WITH accessory versus WITHOUT
accessory ranged from 1 -5% depending on initial concentration
– Little benefit apparent from greater amounts of Cu-Zn granules
Output Concentration of Chromium:
– No result exceeded the maximum allowed limit: 50 µg/L
pH Influence:
– In general, initial pH has no influence in chromium removal
CAWST Learning Exchange - June 2011
8
Cadmium (Cd)
CAWST Learning Exchange - June 2011
9
Results : Percentage removal of Cadmium
del Cadmio
remoción
deaverage
Promedio porcentaje
Cadmium
removal
(final concentration / initial concentration) in percent
100
% de remoción
%
Removal
95
90
(low):
µg/L ppm
0,0041
E. 4.1
C.CiBaja
E. 0,0310
C.CiIntermedia
(intermediate):
31µg/Lppm
C. Alta E. 0,2802 ppm
Ci (high). 280.2 µg/L
85
80
F 11
F 12
F 13
F 14
F 15
F 16
F 17
F 18
F 19
F 20
Filter
Filtro
200
400
300
300
200
400
-
-
-
-
Carbón Activado
Activated
carbon(g)
(g)
500
500
750
750
1000
1000
-
-
-
-
Gránulos Cu-Zn (g)
Cu-Zn
granules (g)
CAWST Learning Exchange - June 2011
10
Results: Cadmium removal with and
without accessory
Cadmiumde
removal
percentage
(High Ci)
Porcentaje
Remoción
del Cadmio
(Concentración
inicial
alta)
(final concentration/
initial
concentration)
in percent
100
% de remoción
%
Removal
99
98
AVERAGE WITH accessory
PROMEDIO
C/ACC. C. E. 0,280 ppm
Ci = 280 µg/L
97
AVERAGE WITHOUT
PROMEDIO
S/ACC. C. accessory
E. 0,253 ppm
Ci = 253 µg/L
96
95
F11
F12
F13
F14
F15
F16
Filter
Filtros
CAWST Learning Exchange - June 2011
11
Results for Cadmium
Removal Effectiveness:
• In all tests, with and without accessory, Cd concentrations
were reduced by 88% - 99.9%
– Higher removals were found for higher Ci
– No improvement in removal WITH accessory versus WITHOUT
accessory is apparent at any initial concentrations
– No benefit from any amount of Cu-Zn or activated carbon
Output Concentration of Cadmium:
– No result exceeded the maximum allowed limit: 3 µg/L
pH Influence:
– In general, initial pH has no influence in chromium removal
CAWST Learning Exchange - June 2011
12
Lead (Pb)
CAWST Learning Exchange - June 2011
13
Results: Percent Removal of Lead
Promedio porcentaje
de removal
remoción del plomo
Lead average
100
90
80
%
Removal
% de remoción
70
60
50
(low): 21.5 µg/L
C.CiBaja
E. 0,0215 ppm
40
(intermediate):
101.4 ppm
µg/L
C.CiIntermedia
E. 0,1014
30
C.CiAlta
E. 0,8902
ppm
(high).
890.2 µg/L
20
10
0
F 21
F 22
F 23
F 24
F 25
F 26
F 27
F 28
F 29
F 30
Filtro
Filter
300
200
400
100
300
300
500
200
400
300
Carbón Activado
(g)
Activated
carbon (g)
250
500
500
750
750
750
750
1000
1000
1250
Gránulos
Cu-Zn(g)
(g)
Cu-Zn
granules
CAWST Learning Exchange - June 2011
14
Results: Lead removal with and
without accessory
Lead
removal del
percentage
(High Ci)
Plomo
de Remoción
Porcentaje
(final concentration/
initial
alta)concentration) in percent
inicial
(Concentración
100
Removal %
% de remoción
99
AVERAGE WITH accessory
Ci = 890 µg/L
C/ACC. C. E. 0,890 ppm
PROMEDIO
98
AVERAGE S/ACC.
WITHOUT
0,879 ppm
C. E.accessory
PROMEDIO
97
Ci = 879 µg/L
96
95
F21
F22
F23
F24
F25
F26
Filter
F27
F28
F29
F30
Filtros
CAWST Learning Exchange - June 2011
15
Results for Lead
Removal Effectiveness:
•
•
•
•
20 – 40% removal for Low Ci (21.5 µg/L)
70 – 90% for Intermediate Ci (104.5 µg/L)
97 – 99% for High Ci (890.2 µg/L)
No apparent change from differing amounts of Cu-Zn or
activated carbon
Output Concentration of Lead:
– Some results exceeded the maximum allowed limit of 10 µg/L
especially at the higher Ci
pH Influence:
– In general, initial pH has no influence in lead removal
CAWST Learning Exchange - June 2011
16
Iron (Fe)
CAWST Learning Exchange - June 2011
17
Results: Average % of Iron removal
Promedio
porcentaje
de remoción
del hierro
Iron removal;
average
percentage
100
95
%
Removal
% de remoción
90
Ci (low) =
315.3 µg/L
C. Baja E. 0,3153 ppm
(intermediate)
= ppm
C.CiIntermedia
E. 0,5531
553.1 µg/L
C. Alta E. 3,146 ppm
Ci (high) =
3146 µg/L
85
80
75
70
F 31
F 32
F 33
F 34
F 35
F 36
F 37
F 38
F 39
F 40
Filter
Filtro
200
400
300
300
200
400
-
-
-
-
Carbón Activado
Activated
carbon (g)
(g)
500
500
750
750
1000
1000
-
-
-
-
Gránulos Cu-Zn (g)
Cu-Zn
granules (g)
CAWST Learning Exchange - June 2011
18
Results: Iron removal with and without
accessory
Ironde
removal
percentage
Porcentaje
Remoción
del Hierro(High Ci)
(final (Concentración
concentration/ initial
in percent
inicial concentration)
alta)
100
% de remoción
%
Removal
99
AVERAGE WITH accessory
98
PROMEDIO
Ci = 3,146 C/ACC.
µg/L C. E. 3,146 ppm
PROMEDIO S/ACC. C.E. 3,712 ppm
AVERAGE WITHOUT accessory
Ci = 3,712 µg/L
97
96
95
1
2
3
4
5
6
Filtros
Filter
CAWST Learning Exchange - June 2011
19
Results for Iron
Removal Effectiveness:
• 75 – 90% removal for Low Ci (315 µg/L)
• 90 – 97% for Intermediate Ci (553 µg/L)
• 98 – 99% for High Ci (3146 µg/L)
• No improvement in removal WITH accessory versus WITHOUT
accessory is apparent at any initial concentrations
• No apparent change from differing amounts of Cu-Zn or activated
carbon
Output Concentration of Lead:
• No results exceeded the maximum allowed limit of 300 µg/L
pH Influence:
• In general, initial pH has no influence in iron removal
CAWST Learning Exchange - June 2011
20
Conclusions (Laboratory)
• Based on the results from these experiments, the biosand filter
demonstrated good removal effectiveness with and without the use of CuZn granules and activated carbon.
• Removal effectiveness increased with higher initial concentrations for all
metals.
• No influence of the accessory, Cu-Zn granules and activated carbon, was
observed in the cadmium and iron removal. For the case of chromium,
the presence of the accessory improved removal a maximum of 5%.
• pH input had no influence in the removal effectiveness. pH increased in
the effluent in all cases as a result of the water contacting the calcium
carbonate in the concrete body of the filter.
• For all the metals (except the lead) all the output samples were under the
guidelines determined by WHO.
CAWST Learning Exchange - June 2011
21
Research Issues
• This study was short-term (approx. 2 months) with limited repeated
sampling. Additional long-term testing is needed to determine if
the removal effectiveness decreases with time.
• Detailed information regarding the filters (sand size, ripening time,
daily throughput) was not available.
• The source water chemistry was not characterized. Further testing
with different water sources is necessary to determine if the results
are applicable generally.
The biosand filter did remarkably well in removing
these heavy metal contaminants. Further research of
this topic is recommended to validate the results and
address the research issues.
CAWST Learning Exchange - June 2011
22