evaluation of the removal of heavy metals using the biosand filter lesly j. mamani paco laboratorios...

CAWST Learning Exchange - June 2011 1

Evaluation of the removal of heavy metals using the Biosand Filter

Lesly J. Mamani Paco

Laboratorios Analíticos del Sur, Peru


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

http://www.cawst.org/


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)


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 · LMPWhere 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)


Chromium (Cr)

6

Results: Percentage removal of Cr

80

85

90

95

100

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 - - - -

500 500 750 750 1000 1000 - - - -

% d

e re

moc

ión

Filtro

Carbón Activado (g)

Gránulos Cu-Zn (g)

Promedio porcentaje de remoción del Cromo

C. Baja E. 0,0206 ppm

C. Intermedia E. 0,1922 ppm

C. Alta E. 2,530 ppm

Chromium average removal (final concentration / initial concentration) in percent

Ci (low): 20.6 µg/L

Ci (intermediate): 192.2 µg/L

Ci (high). 2,530 µg/L

Filter

Activated carbon (g)

Cu-Zn granules (g)

Rem

oval

%


Results: Percent removal with and without accessory

95

96

97

98

99

100

F01 F02 F03 F04 F05 F06

% d

e re

moc

ión

Filtros

Porcentaje de Remoción del Cromo(Concentración inicial alta)

PROMEDIO C/ACC. C. E. 2,530 ppm

PROMEDIO S/ACC. C. E. 1,545 ppm

Chromium removal percentage - High initial conc. (Ci)(final concentration/ initial concentration) in percent

Rem

oval

%

Removal WITH accessory Ci = 2,530 µg/LRemoval WITHOUT accessory Ci = 1,545 µg/L

Filter


Results for ChromiumRemoval 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


Cadmium (Cd)


Results : Percentage removal of Cadmium

80

85

90

95

100

F 11 F 12 F 13 F 14 F 15 F 16 F 17 F 18 F 19 F 20

200 400 300 300 200 400 - - - -

500 500 750 750 1000 1000 - - - -

% d

e re

moc

ión

Filtro


Gránulos Cu-Zn (g)

Promedio porcentaje de remoción del Cadmio




Ci (low): 4.1 µg/L

Ci (intermediate): 31µg/L

Ci (high). 280.2 µg/L

Rem

oval

%

Filter


Cu-Zn granules (g)

Cadmium average removal (final concentration / initial concentration) in percent


Results: Cadmium removal with and without accessory

95

96

97

98

99

100

F11 F12 F13 F14 F15 F16

% d

e re

moc

ión

Filtros

Porcentaje de Remoción del Cadmio(Concentración inicial alta)



Cadmium removal percentage (High Ci)(final concentration/ initial concentration) in percent

Rem

oval

%

Filter

AVERAGE WITH accessory Ci = 280 µg/L

AVERAGE WITHOUT accessory Ci = 253 µg/L


Results for CadmiumRemoval 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


Lead (Pb)


Results: Percent Removal of Lead

0

10

20

30

40

50

60

70

80

90

100

F 21 F 22 F 23 F 24 F 25 F 26 F 27 F 28 F 29 F 30

300 200 400 100 300 300 500 200 400 300

250 500 500 750 750 750 750 1000 1000 1250

% d

e re

moc

ión

Filtro


Gránulos Cu-Zn (g)

Promedio porcentaje de remoción del plomo




Lead average removal

Rem

oval

%

Ci (low): 21.5 µg/L

Ci (intermediate): 101.4 µg/L

Ci (high). 890.2 µg/L

Filter


Cu-Zn granules (g)


Results: Lead removal with and without accessory

95

96

97

98

99

100

F21 F22 F23 F24 F25 F26 F27 F28 F29 F30

% d

e re

moc

ión

Filtros

Porcentaje de Remoción del Plomo(Concentración inicial alta)



Lead removal percentage (High Ci)(final concentration/ initial concentration) in percent

Rem

oval

% AVERAGE WITH accessory

Ci = 890 µg/L

AVERAGE WITHOUT accessory Ci = 879 µg/L

Filter


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


Iron (Fe)


Results: Average % of Iron removal

70

75

80

85

90

95

100

F 31 F 32 F 33 F 34 F 35 F 36 F 37 F 38 F 39 F 40

200 400 300 300 200 400 - - - -

500 500 750 750 1000 1000 - - - -

% d

e re

moc

ión

Filtro


Gránulos Cu-Zn (g)

Promedio porcentaje de remoción del hierro




Iron removal; average percentage

Rem

oval

% Ci (low) =

315.3 µg/L

Ci (intermediate) =553.1 µg/L

Ci (high) =3146 µg/L

Filter


Cu-Zn granules (g)


Results: Iron removal with and without accessory

95

96

97

98

99

100

1 2 3 4 5 6

% d

e re

moc

ión

Filtros

Porcentaje de Remoción del Hierro(Concentración inicial alta)


PROMEDIO S/ACC. C.E. 3,712 ppm

Iron removal percentage (High Ci)(final concentration/ initial concentration) in percent

Rem

oval

% AVERAGE WITH accessory

Ci = 3,146 µg/L

AVERAGE WITHOUT accessory Ci = 3,712 µg/L

Filter


Results for IronRemoval 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


Conclusions (Laboratory)• Based on the results from these experiments, the biosand filter demonstrated

good removal effectiveness with and without the use of Cu-Zn 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.


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.

evaluation of the removal of heavy metals using the biosand filter lesly j. mamani paco laboratorios...

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