Contaminants removal by bentonite amended slow sand filter
Earlier studies have indicated that variability in size, surface texture and charge greatly influence the contaminant removal process in granular media. Based on surface characteristics of montmorillonite, it is anticipated that small addition of this clay would increase adhesion sites for bacterial...
Збережено в:
| Опубліковано в: : | Химия и технология воды |
|---|---|
| Дата: | 2013 |
| Автори: | , , , |
| Формат: | Стаття |
| Мова: | Англійська |
| Опубліковано: |
Інститут колоїдної хімії та хімії води ім. А.В. Думанського НАН України
2013
|
| Теми: | |
| Онлайн доступ: | https://nasplib.isofts.kiev.ua/handle/123456789/130749 |
| Теги: |
Додати тег
Немає тегів, Будьте першим, хто поставить тег для цього запису!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Contaminants removal by bentonite amended slow sand filter / Sudhakar M. Rao, R. Malini, A. Lydia, Young Lee // Химия и технология воды. — 2013. — Т. 35, № 1. — С. 43-53. — Бібліогр.: 19 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860098706687131648 |
|---|---|
| author | Sudhakar M. Rao Malini, R. Lydia, A. Young Lee |
| author_facet | Sudhakar M. Rao Malini, R. Lydia, A. Young Lee |
| citation_txt | Contaminants removal by bentonite amended slow sand filter / Sudhakar M. Rao, R. Malini, A. Lydia, Young Lee // Химия и технология воды. — 2013. — Т. 35, № 1. — С. 43-53. — Бібліогр.: 19 назв. — англ. |
| collection | DSpace DC |
| container_title | Химия и технология воды |
| description | Earlier studies have indicated that variability in size, surface texture and charge greatly influence the contaminant removal process in granular media. Based on surface characteristics of montmorillonite, it is anticipated that small addition of this clay would increase adhesion sites for bacterial growth and extracellular polymer production in slow sand filter and thereby enhance its contaminant removal ability. Experiments were performed by permeating groundwater conta-minated with pathogens (total coliform and E. Сoli) and inorganic contaminants through bentonite amended slow sand filter (BASSF). Surprisingly, the BASSF retained inorganic contaminants besides pathogens. Water-leach tests (pH of water leachate ranged from 2 to 9) with spent BASSF specimen indicated that the inorganic contaminants are irreversibly adsorbed to a large extent. It is considered that the combined effects of enhanced - organic matter mediated adhesion sites and increased hydraulic retention time enables the BASSF specimen to retain inorganic contaminants. It is envisaged that BASSF filters could find use in treating contaminated groundwater for potable needs at household and community level.
|
| first_indexed | 2025-12-07T17:28:08Z |
| format | Article |
| fulltext |
ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1 43
SUDHAKAR M. RAO, R. MALINI, A. LYDIA,, YOUNG LEE, 2013
Sudhakar M. Rao1, R. Malini1, A. Lydia1, Young Lee2
CONTAMINANTS REMOVAL BY BENTONITE AMENDED
SLOW SAND FILTER
1Department of Civil Engineering and Chairman Centre for Sustainable
Technologies, Bangalore, India;
2 Enviroment Research Division Institute of Science and Technology,
Seoul, Korea
Earlier studies have indicated that variability in size, surface texture and charge
greatly influence the contaminant removal process in granular media. Based on
surface characteristics of montmorillonite, it is anticipated that small addition of
this clay would increase adhesion sites for bacterial growth and extracellular polymer
production in slow sand filter and thereby enhance its contaminant removal ability.
Experiments were performed by permeating groundwater conta-minated with
pathogens (total coliform and E. Сoli) and inorganic contaminants through bentonite
amended slow sand filter (BASSF). Surprisingly, the BASSF retained inorganic
contaminants besides pathogens. Water-leach tests (pH of water leachate ranged
from 2 to 9) with spent BASSF specimen indicated that the inorganic contaminants
are irreversibly adsorbed to a large extent. It is considered that the combined effects
of enhanced - organic matter mediated adhesion sites and increased hydraulic
retention time enables the BASSF specimen to retain inorganic contaminants. It is
envisaged that BASSF filters could find use in treating contaminated groundwater
for potable needs at household and community level.
Keywords: environment, granular materials, pollution.
Introduction
Slow sand filtration is one of the earliest forms of biological filtration
process [1]. Slow sand filtration reduces bacteria, cloudiness, and organic level.
The effective size of sand (D10) used in slow sand filter lie in the range of
0.15 – 0.35 mm and flow rates range between 0.1 – 0.4 m/h [2]. The contaminant
removal by slow sand filter (SSF) is attributed to straining through the filter
skin (schmutzdecke) developed at the top few mm of sand, together with slow
filtration rate promoted by the fine size of sand [2 – 3].
Stevik et al. [4] had reviewed factors affecting retention of bacteria in
porous media. Besides biological and physical straining, adsorption is also
considered to play an important role in immobilizing pathogens transported
through the porous media. Further, variability in sizes, surface texture and
charge of porous media are considered to greatly influence the contaminant
adhesion process. Smaller particle sizes expose a larger surface area compared
44 ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1
to coarse particles and hence provide greater adhesion sites for bacteria removal
[5 – 6]. Huysman and Verstraete [7] and Fletcher and Loeb [8] have observed
that presence of clay particles in soil media enhances the adhesion of bacteria
due to the charge and surface characteristics of the clay minerals. It has been
indicated that extracellular polymer production often accompanies bacteria
attachment and the polymer mediated interactions can play a role in contaminant
removal [4].
Montmorillonite clay exposes large surface area (800 m2/g), has very small
particle size (< 2 microns) and exposes charged particle surface arising from
isomorphous substitution within the clay lattice and presence of broken bonds
at particle edges [9]. Based on surface characteristics of montmorillonite, it
is anticipated that small addition of this clay would increase adhesion
sites in slow sand filter for bacterial growth and extracellular polymer
production and enhance the filter’s contaminant removal ability.
Experiments were hence performed that involved permeation of
ground water contaminated with pathogens (total coliform and E. coli) and
inorganic contaminants through bentonite amended (bentonite content = 10 %)
slow sand filter. Results of permeating nitrate spiked solutions through SSF and
bentonite amended slow sand filter (BASSF) specimens are also presented.
Experimental
Naturally occurring bentonite from Rajasthan, India and local
river sand (from Karnataka) were used in the construction of BASSF.
Bentonite contains montmorillonite as primary clay mineral [10]. The index
properties of bentonite and sand are provided in Table 1. The bentonite sample
has liquid limit of 184 %, plastic limit of 31 % and contains 48 % clay sized
(particle size < 2 micron) fraction. The sand sample is composed of
71.5 % medium fraction (particle size 2 – 0.425 mm) and 28.5 % fine fraction
(0.425 – 0.075 mm). The D10 for the sand sample is 0.1 mm, which is slightly
smaller than lower range (0.15 mm) of effective particle size recommended for
slow sand filters. To examine the influence of clay addition on the contaminant
retention by slow sand filter, sand-bentonite mix composed of 90 % sand and
10 % bentonite (on dry mass basis) was prepared. Table 2 presents the
composition of the contaminated groundwater sample from Kolar District in
Karnataka that was used to test the efficacy of the BASSF specimen. The
groundwater sample shows pathogen and nitrate contamination and was
obtained from peri-urban community that disposes human waste using pit toilet
system.
ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1 45
Table 1. Index properties of materials
Sample/Property Value
Bentonite
Liquid limit (%) 184
Plastic limit (%) 31
Specific gravity 2.67
% Clay size fraction (< 0.002 mm)
% Silt fraction (0.075 mm – 0.002 mm)
48
52
Sand
% Coarse fraction (4.75 – 2.0 mm) 0
% Medium fraction (2.0 – 0.425 mm) 71.5
% Fine fraction (0.425 – 0.075 mm) 28.5
Specific Gravity 2.7
90 % Sand + 10 % Bentonite
Liquid limit (%) 45
Plastic limit (%) NP (non-plastic)
Specific gravity 2.7
Standard Proctor compaction properties 1.78
Maximum dry density (g/cc) Optimum
moisture content (%) 18
Table 2. Composition of contaminated groundwater sample
Parameter Value
Total coliform (MPN/100 ml) 3200
E. Coli (MPN/100 ml) 600
pH 7.65
Electrical Conductivity (milli-Siemen/cm) 2.17
Total dissolved solids (mg/L) 1409
Calcium (mg/L) 121
Magnesium (mg/L) 52
Potassium (mg/L) 97
Sodium (mg/L) 204
Chloride (mg/L) 388
Nitrate (mg/L) 288
Sulphate (mg/L) 97
Bicarbonate (mg/L) 567
46 ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1
Permeability. Permeability controls the rate of flow of water through
a porous medium. It is known that addition of clay content to coarse
aggregate reduces the permeability of the mix [10]. Therefore a small (10 %)
amount of bentonite was added to sand while preparing the BASSF. Constant
head permeability test was performed with relatively loosely compacted 90 %
sand –10% bentonite specimen as per IS 2720 [11]. The specimens were
statically compacted to dry density of 1.3 g/cc at 22 % water content. The dry
density of the specimen was 0.27 times lower than the Standard Proctor
maximum dry density (MDD) value of the mix (MDD = 1.78 g/cc). Likewise
the compaction water content was 4 % higher than the optimum moisture
content (OMC) value (OMC = 18 %) of the mix. The specimens were
compacted in excess of OMC to ensure saturation of voids. A small hydraulic
gradient (i = 2) was used in the constant head test. Distilled water was used as
the permeating fluid. The sample height and diameter corresponded to 40 mm
and 82 mm respectively. The compacted specimen exhibited equilibrium
coefficient of permeability of 0.0015 m/h. Using Darcy’s equation [12] for
saturated flow in porous media:
v = ki, (1)
where v is the velocity of flow (m/h), k is the coefficient of permeability
(0.0015 m/h) and i is the hydraulic gradient (i = 2) gives flow velocity of
0.003m/h. The flow rate (v) of BASSF is 100-fold smaller than that of slow
sand filter (0.1 to 0.3 m/h).
Contaminant removal by BASSF. The thickness (height) and diameter
of BASSF specimen corresponded to 40 mm and 82 mm respectively. The
BASSF specimen was overlain by 15 mm sand layer to trap any suspended
solids in the water sample. The specimen was permeated with the contaminated
ground water (see Table 2) for 5 – 7 h daily between 10 AM and 7 PM. After
the permeation period, the inletvalve of the constant head reservoir was closed.
Approximately 2 – 3 mm of water layer was allowed to stand above the
specimen during the non-permeation period to prevent drying.
Permeation was resumed next morning. The outflow solution collected daily
(500 – 700 ml over 5 – 7 h) was analysed for calcium, magnesium, sodium,
potassium ions using ICP-OES facility and nitrate, sulphate, chloride ions
by ion chromatograph and bicarbonates by automatic titrator. The
outflow solutions were examined for total coliform and E. coli by multiple
tube method [13 – 15]. Permeation of the contaminated water sample was
terminated when the flow rate reduced from 100 ml/h to 40 ml/h (cumulative
volume permeated = 9850 ml). The reduction in flow rate after passage of the
contaminated water for 16 days is attributed to clogging of pores by organic
matter.
ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1 47
Tests with spent filter specimens. After termination of permeation, the
BASSF specimen was dismantled and thoroughly hand-remolded to obtain
homogenous sample. This spent filter was stored in a desiccator in the moist
state (gravimetric water content = 26 %). Moist samples were used in the
water leach tests, while, oven-dried (dried at 60°C) samples were used in
determination of organic matter. In the water leach tests, the pH of distilled
water was adjusted between 2 and 9 using hydrochloric acid or ammonia solution.
Each pH adjusted water sample (volume = 250 ml) was agitated with 12.6 g of
moist filter sample (corresponding to dry mass of 10 g) for period of 18 h
using mechanical flask shaker. After agitation, the solution was filtered and
the filtrate was analysed for calcium, magnesium, sodium and potassium ions
using ICP-OES, nitrate and sulphate ions using IC and bicarbonate ions using
automatic titrator.
The organic matter (OM) of the spent filter was determined using the
Walkley Black method [16]. Organic matter was also determined for the raw
90 % sand – 10 % bentonite mix to obtain base-line OM value for the filter.
Polarizing microscope (Model Olympus BX 51) images of spent filter (BASSF
and SSF) specimens (magnification = 10 to 20 x) were obtained to examine
any growth of biofilms.
Permeation of SSF and BASSF specimens with nitrate spiked solutions.
To examine the inorganic contaminant retention ability of SSF, an experiment
was performed by intermittently permeating 320 mg/L of nitrate solution
through SSF specimen. The sand sample used in the preparation of
BASSF specimen was used in this experiment. The diameter and
thickness of SSF specimen corresponded to 82 mm of 40 mm respectively. The
moist (water content = 5 %) sand mass was compacted to dry density of
1.3 g/cc. Nitrate solution (concentration = 320 mg/L) was permeated through
the SSF specimen at flow rate of 100 ml/h. The slow, flow rate was achieved
by fixing a capillary nozzle to the reservoir outlet. The nitrate concentration
used in the test is approximately 10 % larger than the nitrate concentration of
the contaminated groundwater sample (nitrate concentration = 288 mg/L).
The experiment was terminated after passage of 10000 ml of nitrate
solution as the experiment with BASSF specimen was terminated after
passage of similar volume (9850 ml) of contaminated ground water sample.
The SSF did not experience any decrease in flow rate after permeation of
10000 ml of nitrate solution.
An experiment was also performed to examine the response of the BASSF
to passage of nitrate spiked solution (initial nitrate concentration = 298 mg/L).
The experiment was terminated after passage of 3660 ml of nitrate solution
as the flow rate decreased from an initial value of 70 ml/h to 28 ml/h. The
differences in flow rates developed by the BASSF specimens on permeation
48 ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1
with nitrate solution (70 ml/h to 28 ml/h) and contaminated groundwater
(100 ml/h to 40 ml/h) are attributed to their differences in dissolved
saltconcentrations. The dissolved salt concentration of nitrate spiked solution
and contaminated groundwater correspond to 409 mg/L and 1409 mg/L
respectively.
The higher dissolved salt concentration of the contaminated ground water
reduces the thickness of diffuse ion layers around the clay particles facilitating
increased void space for water flow thereby rendering the specimen more
pervious with higher flow rate [17].
The outflowing solutions from SSF and BASSF tests were daily analysed
for nitrate concentrations using ion-chromatograph. After permeation with
nitrate spiked solutions was terminated, the SSF and BASSF specimens were
dismantled. The spent specimens were thoroughly hand-remolded, dried at
60°C and used in OM determination by the Walkley Black method [16].
Results and discussion
Fig. 1 illustrates the reduction in total coliform and E. Сoli levels
upon passage of the contaminated groundwater sample through BASSF.
The total coliform (initial value 3200 MPN/100 ml) and E. Coli (initial
value 160 MPN/100 ml) reduce to values ranging from 0 to 50 MPN/100 ml
upon passage through BASSF.
Fig. 1. Total coliform and E. Coli removal by BASSF.
ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1 49
2100 mg of sodium, 1192 mg of calcium, 954 mg of potassium and 510 mg
of magnesium was permeated by the passage of 9850 ml of contaminated
groundwater through BASSF (Table 3). At the end of permeation process, 895 mg
of sodium (43 % retention), 738 mg of calcium (62 % retention), 275 mg of
magnesium ions (54 % retention) and 567 mg of potassium (59 % retention)
were retained by the BASSF (dry mass of BASSF = 275 g). Likewise, 5588 mg
of bicarbonate, 3824 mg of chloride, 2838 mg of nitrate and 951 mg of sulfate
was permeated by the passage of 9850 ml of contaminated groundwater through
the BASSF. At the end of permeation process (see Table 3) 3151 mg of
bicarbonate (56 % retention), 2525 mg of chloride (66 % retention), 1912 mg
of nitrate ions (67 % retention) and 532 mg of sulfate (56 % retention) were
retained by the BASSF (dry mass of BASSF = 275 g).
Table 3. Ion retention by 275 g of BASSF and SSF Specimens
Mass permeated Mass retained
mg
% Retained
Species BASSF Specimen permeated with
contaminated ground water
Sodium
2100 895 43
Calcium 1192 738 62
Magnesium 510 275 54
Potassium 954 567 59
Bicarbonate 5588 3151 56
Nitrate 2838 1912 67
Chloride 3824 2525 66
Sulfate
951 532 56
SSF Specimen permeated with nitrate spiked solution Nitrate 3206 0 0
BASSF Specimen permeated with nitrate spiked
solution
Nitrate 819 384 47
The results in Fig. 1 and Table 3 demonstrate that addition of bentonite to
SSF causes it to retain cationic and anionic contaminants in addition to bacterial
contaminants. Interestingly, the BASSF specimen was able to reduce the nitrate
concentration of the groundwater sample from an initial value of 288 mg/L to
an average value of 92 mg/L and of the nitrate spiked solution from 298 mg/L
to an average value of 145 mg/L. In comparison, the SSF specimen was unable
to remove nitrate even after the passage of 10 liters of nitrate spiked solution
(see Table 3).
50 ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1
After completion of the permeability experiments, dismantling of the spent
BASSF specimens did not reveal growth of green algal mass in as was observed
by Campos et al. [18] in uncovered slow sand filter beds. The spent BASSF filter
specimen (permeated with contaminated groundwater) is characterized by OM
content of 4.2 %. Comparatively, raw (unexposed to contaminated groundwater)
mixture of 90 % sand+10 % bentonite is characterized by organic matter content
of 0.04 %. The spent SSF and BASSF specimens permeated with spiked nitrate
solutions were characterized by OM content of 0.7 % and 3.4 % respectively.
Lack of substantial OM growth in SSF is possibly responsible for its inability
to retain nitrate ions.
Water-leach tests (pH of water leachate ranged from 2 to 9) with spent BASSF
specimen showed that maximum of 5 to 12 % of retained cationic species (at
pH = 2) and 0 to 18 % of anionic species (at pH = 9) is released (Table 4) indicating
that the inorganic contaminants are irreversibly adsorbed by BASSF specimen
to a large extent.
Table 4. Leaching of ions from 100 g of spent BASSF at different pH values
Mass leached (mg) at
different pH
% Retained at different pH
Leachate pH Leachate pH
Species
Mass
retained
(mg)
2
2
4 6 7 9 2 4 6 7 9
Sodium 326 16 13 13 11 13 95 96 96 97 96
Calcium 268 31 7 3 3 5 88 97 99 99 98
Magnesium 100 12 2 0.6 0.9 0.8 88 98 99 99 99
Potassium 206 16 15 16 15 17 92 93 92 93 92
Bicarbonate 1146 29 101 80 95 203 97 91 93 92 82
Nitrate 695 0 0 0 0 0 100 100 100 100 100
Sulfate 193 9 7 4 5 19 95 96 98 97 90
The spent BASSF and SSF specimens show growth of thin films in the
polarizing micrographs (Fig. 2, a, b). Despite growth of biofilms occurring
both in BASSF and SSF specimens, the former alone was capable of retaining
inorganic contaminants. The ability of BASSF to retain inorganic ions is
attributed to the inclusion of bentonite in the filter material. Bentonite
particles increase the adhesion sites for bacterial biofilms leading to
enhanced extracellular polymer production as evidenced by the higher OM
contents of the spent BASSF specimens (3.4 to 4.2 %). It has been suggested
ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1 51
that such films are composed of polysaccharide polymers that can bind
contaminants by hydrogen and Coulombic bonding [ 4,19]. Further, the presence
of micropores in bentonite would increase the hydraulic retention time of
contaminants inside the BASSF specimen. The combined effects of increased
OM mediated adhesion sites and increased hydraulic retention time possibly
enables the BASSF specimen to retain inorganic contaminants besides micro-
organisms. The composition and distribution of the cell biomass developed in
the sand-bentonite mix is under investigation.
a b
Fig. 2. Polarizing microscope photographs of spent filter specimens: BASSF (a),
SSF (b).
Clogging of micropores by accumulation of cell biomass along with other
enzymatic secretions apparently reduced the flow rate during passage of
groundwater and nitrate spiked solution in the BASSF specimens. In order to
minimize clogging of pores by organic growth, the impact of reducing the
bentonite content and dry density of BASSF is being examined. It is envisaged
that BASSF filters could find use in treating contaminated groundwater for
potable needs at household and community level.
Conclusions
Small addition of bentonite to slow sand filter enables it to retain inorganic
contaminants in addition to microbial contaminants as demonstrated by
experiments performed with BASSF specimens permeated with contaminated
52 ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1
groundwater and nitrate spiked solution. The SSF specimen in absence of
bentonite addition was unable to retain nitrate ions on passage of nitrate
spiked solution. The BASSF specimens developed OM contents of 4.2
and 3.4 % respectively on permeation of contaminated groundwater and
spiked nitrate solution. The SSF specimen developed negligible OM content
of 0.04 % on permeation with spiked nitrate solution. It is believed that lack of
substantial OM growth hampered the retention of nitrate ions by SSF
specimen. Comparatively, the combined effects of increased OM
mediated adhesion sites and hydraulic retention period possibly enabled the
BASSF specimen to retain inorganic contaminants besides microbial
contaminants.
Acknowledgements
The authors thank Korean Institute of Science & Technology, South Korea
for supporting the research project "Domestic water treatment technology".
References
[1] El-Taweel G. E., Ali G. H. //Water Air and Soil llution, 2000, vol. 120, P. 21.
[2] Huisman L., Wood W. E. Slow Sand Filtration, Geneva: World Health Organi-
sation, 1974,122 p.
[3] Haarhoff J., Cleasby J. L. Biological and P. hysical mechanisms in slow sand
filtration. In: Slow Sand Filtration, American Society of Civil Engineers, New
York, 1991, P. 19.
[4] Stevik T. K., Aa K., Ausland G., Hanssen J. F. // Water Res., 2004, vol. 38,
P. 1355.
[5] Fontes D. E., Mills A. L., Hornberger G. M., Herman J. S. //Appl. Environ.
Microbiol., 1991, vol. 57, P. 2473.
[6] Tan Y., Bond W. J., Griffen D. M. //Soil Sci. Soc. Amer. J., 1992, vol. 56,
P. 133.
[7] Huysman F., Verstraete W. //Soil Biol. Biochem., 1993, vol. 25, P. 83.
[8] Fletcher M., Loeb G. I.// Appl. Environ. Microbiol., 1996, vol. 37, P. 67.
[9] Van Olphen H. An Introduction to Clay Colloid Chemistry, New York: Wiley,
1963.
[10] Rao S. M., Kachroo T. A., Allam M. M., Joshi M. R., Acharya A. //Proc. of 12th
Int.Conf. of Int. Assoc. for Computer Methods and Advances in Geomechan-
ics, Goa, India, 2008, P. 2106.
[11] IS 2720. Laboratory Determination of Permeability. Part 17, Bureau of Indian
Standards, New Delhi, 2002.
[12] Das B. M. Principles of Geotechnical Engineering, Fifth Edition, Thomson,
Singapore, 2002.
[13] IS 1622. Methods of Sampling and Microbial Examination of Water, Bureau
of Indian Standards, New Delhi, 2003.
ISSN 0204–3556. Химия и технология воды, 2013, т. 35, №1 53
[14] IS 5401. Microbiology; General Guidance for the Enumeration of Coliforms.
Part 2, Most probable Number Technique, Bureau of Indian Standards, New
Delhi, 2002.
[15] APHA. Standard Methods for the Examination of Water and Wastewater: In
Eaton A. D., Clesceri L. S., Rice E. W., Greenberg A. E, Franson M. H. (eds.),
Washington D.C.: American Public Health Association, 2005.
[16] ASTM F1647. Standard Test Methods for Organic Matter Content of P. utting
Green and SP. orts Turf Root Zone Mixes, ASTM, Philadelphia, USA, 2010.
[17] Yong R. N., Warkentin B. P. Soil Properties and Behaviour. New York: Elsevi-
er,1975.
[18] Campos L.C., Su M.F.J., Graham N.J.D., Smith S.R. //Water Res., 2002, vol. 36,
P. 4543.
[19] Lynch J. M., Bragg E. //Adv. in Soil Sci., 1985, vol. 2, P. 133.
Recieved 06.09.2011
.
|
| id | nasplib_isofts_kiev_ua-123456789-130749 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0204-3556 |
| language | English |
| last_indexed | 2025-12-07T17:28:08Z |
| publishDate | 2013 |
| publisher | Інститут колоїдної хімії та хімії води ім. А.В. Думанського НАН України |
| record_format | dspace |
| spelling | Sudhakar M. Rao Malini, R. Lydia, A. Young Lee 2018-02-20T18:17:35Z 2018-02-20T18:17:35Z 2013 Contaminants removal by bentonite amended slow sand filter / Sudhakar M. Rao, R. Malini, A. Lydia, Young Lee // Химия и технология воды. — 2013. — Т. 35, № 1. — С. 43-53. — Бібліогр.: 19 назв. — англ. 0204-3556 https://nasplib.isofts.kiev.ua/handle/123456789/130749 Earlier studies have indicated that variability in size, surface texture and charge greatly influence the contaminant removal process in granular media. Based on surface characteristics of montmorillonite, it is anticipated that small addition of this clay would increase adhesion sites for bacterial growth and extracellular polymer production in slow sand filter and thereby enhance its contaminant removal ability. Experiments were performed by permeating groundwater conta-minated with pathogens (total coliform and E. Сoli) and inorganic contaminants through bentonite amended slow sand filter (BASSF). Surprisingly, the BASSF retained inorganic contaminants besides pathogens. Water-leach tests (pH of water leachate ranged from 2 to 9) with spent BASSF specimen indicated that the inorganic contaminants are irreversibly adsorbed to a large extent. It is considered that the combined effects of enhanced - organic matter mediated adhesion sites and increased hydraulic retention time enables the BASSF specimen to retain inorganic contaminants. It is envisaged that BASSF filters could find use in treating contaminated groundwater for potable needs at household and community level. The authors thank Korean Institute of Science & Technology, South Korea for supporting the research project "Domestic water treatment technology". en Інститут колоїдної хімії та хімії води ім. А.В. Думанського НАН України Химия и технология воды Физическая химия процессов обработки воды Contaminants removal by bentonite amended slow sand filter Article published earlier |
| spellingShingle | Contaminants removal by bentonite amended slow sand filter Sudhakar M. Rao Malini, R. Lydia, A. Young Lee Физическая химия процессов обработки воды |
| title | Contaminants removal by bentonite amended slow sand filter |
| title_full | Contaminants removal by bentonite amended slow sand filter |
| title_fullStr | Contaminants removal by bentonite amended slow sand filter |
| title_full_unstemmed | Contaminants removal by bentonite amended slow sand filter |
| title_short | Contaminants removal by bentonite amended slow sand filter |
| title_sort | contaminants removal by bentonite amended slow sand filter |
| topic | Физическая химия процессов обработки воды |
| topic_facet | Физическая химия процессов обработки воды |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/130749 |
| work_keys_str_mv | AT sudhakarmrao contaminantsremovalbybentoniteamendedslowsandfilter AT malinir contaminantsremovalbybentoniteamendedslowsandfilter AT lydiaa contaminantsremovalbybentoniteamendedslowsandfilter AT younglee contaminantsremovalbybentoniteamendedslowsandfilter |