|
Journal of Applied Sciences and Environmental Management
World Bank assisted National Agricultural Research Project (NARP) - University of Port Harcourt
ISSN: 1119-8362
Vol. 10, Num. 1, 2006, pp. 73-77
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Journal of Applied Sciences & Environmental Management,
Vol. 10, No. 1, March, 2006, pp. 73-77
Sand
Intermittent Filtration Technology for safer Domestic Sewage Treatment
*1Prasad, G; 1Rajeev Rajput; 2Chopra,
A K
1Department of Zoology and
Environmental Science. Gurukula Kangri University, Haridwar, INDIA
*2Department of Botany
and Microbiology, Gurukula Kangri University, Haridwar, INDIA
Code Number: ja06012
ABSTRACT: The present investigation was undertaken to find out
pollution reduction potential of Sand intermittent filtration bed in term of
physico-chemical and microbiological characteristics of domestic sewage. The
domestic sewage was filtered through Sand intermittent filtration beds of
mixture of sand and soil at different ratio i.e. 1:1; 1:3; 3:1 and one set of
100% of each sand and soil were also taken. Results revealed that there was a
significant pollution reduction in various physico-chemical and microbiological
parameters of domestic sewage in sand soil mixture. In general sand and soil
beds have shown better performance than only sand or soil bed for sewage
treatment. Albeit Sand soil bed of 2 feet depth has been found better in term
of pollution reduction ability than other depths used in the present study, but
variation of pollution reduction potential has been recorded for different
parameters in sand and soil bed of the same ratio. Mixture of Sand soil bed at
ratio 3:1 has yielded better results in general than all other used ratio but
for certain parameters stands equal with 1:1 ratio. Maximum percentage of
reduction in pH i.e. 16.7% and in Temperature 27.9% was found at 2 feet depth
in mixed sand and soil bed of 1:1 ratio. Maximum pollution reduction potential
of intermittent filtration bed was recorded at 2 feet depth of sand and soil
mixture at ratio of 3:1. Percentage of pollution reducing potential was found
in CO2 83.4%, BOD 72.5%, COD 69.9%, Total alkalinity 37.9%, Total
solids 88.5%, Total dissolved solids 86.1%, Total suspended solids 91.2%, MPN
82.4% and SPC 78.4%. Minimum reduction ability was found in 100% sand and soil
bed without mixture. @JASEM
Water pollution is a current global burning problem as
a large quantity of water of earth planet i.e. 97% is stored in sea. Marine
water is not suitable for domestic use due to high salinity. Remaining 3% water
is found in form of ice caps, surface water and underground water. Since a very
small quantity of available water is being used in different way i.e.
agriculture, industry and domestic purposes. Various types of pollutants such
as industrial, domestic waste (solid and liquid) are reaching in surface water
through different means. Most of the cities in India are situated on the banks
of different rivers. These rivers are receiving both industrial and domestic
sewage, which has high percentage of untreated sewage because most of the
cities do not have an adequate sewage treatment system.
In India it is estimated that more than 8642X106m3 of wastewater is generated per annum from 212 class I cities and 241 class II
towns. Only 23% of wastewater is being treated mostly at primary level prior to
disposal and 77% untreated water is discharged on land (Rajeswaramma and Gupta,
2002). Indiscriminate discharge of domestic and industrial effluent in the
rivers has generated alarming water pollution as maximum water supply for
domestic use is being obtained from these rivers. Efforts have been made by the
government of India force to setup the treatment plants in different parts of
country for the proper and efficient treatment of domestic sewage. But these
treatment plants consume lots of energy and require more money for its
maintenance. Economy of developing country like India is not so good to afford
such types of expensive treatment plants. Besides these irregular power supply
and labours problem has affected the working and efficiency of the treatment
plants. Sand filtration is one of the earliest forms of potable water treatment
and remains an important process for water purification throughout the world
(Campos et al., 2002). Simplicity and low cost capital and operating
cost are principal advantages of sand filtration compared with more sophisticated
methods of water treatment. Keeping in view of the facts present investigation
was undertaken to find out the treatment of domestic sewage. Some important
contribution in this area has been made by some workers and important can be
quoted here (Huisman and Wood, 1974; Zibell et al., 1975; Bellamy et
al., 1985; Sarkar et al., 1994; Setvik et al., 1999;
WeberShirk, 2002; Rooklidge and Ketchum, 2002; Ausland et al., 2002).
But in India very little work (Rao et al., 2003) has been done on sand
intermittent filtration. In present study efforts have been made to develop a
cost effective and low maintenance model of sand intermittent filtration for
the treatment of wastewater with a special reference to domestic sewage.
MATERIAL AND
METHODS
Experimental design of sand intermittent filtration
tank: A septic metal tank
of 35cm radius with 5 feet height with strong stand and a sieve of 0.5 mm
fitted 1 feet above from base was constructed. A device was also made at the
base of the tank to take out treated water for analysis of physico-chemical and
bacteriological characteristics.
Filter media: Different
mixture of sand and soil were used for the filtration of domestic sewage. Sand
Intermittent Filtration tank was filled by different mixtures of sand and soil
i.e. 100% sand, 100% soil, sand and soil 1:1, 3:1, 1:3. Different depth i.e. 1
feet, 1.5 feet and 2 feet of each kind of sand and soil mixture was used as
sand intermittent filtration for filtration of domestic sewage.
Sampling site and sample collection: Sewage pumping station, located at the right bank of Ganga Canal at Ramnager opposite Swami Shraddhanand Chowk, Haridwar (Uttaranchal) was
selected for the collection of domestic sewage. To obtain a composite sample of
domestic sewage, the site was selected as pumping station contains a mixture
of domestic sewage of different locality of Haridwar. Sampling was done 4
times in the morning between 7.30 to 11.00 am and a time composite sample was
collected in plastic container and brought to the laboratory for analysis.
Analysis of domestic sewage and filtered domestic
sewage: Domestic sewage
and filtered domestic sewage through different Sand intermittent filter were
analyzed for their various physicochemical and bacteriological characteristics
by standard methods (APHA, 1998).
RESULTS
AND DISCUSSION
The values of different parameters of
domestic sewage viz. Temperature, Turbidity, Total solids (TS), Total dissolved
solids (TDS), Total suspended solids (TSS), pH, Total alkalinity, Free carbon
dioxide (CO2), Chemical oxygen demand (COD), Dissolved oxygen (DO),
Biochemical oxygen demand (BOD), Standard plate count (SPC) and Most probable
number (MPN) before filtration are given in Table 1 and values of these
parameters of domestic sewage after filtration with Sand intermittent
filtration are given in Table 2. Temperature of domestic sewage was recorded
25.98 OC. Maximum percentage of temperature reduction is 27.9% was
observed after treatment with Sand intermittent filtration of ratio 1:1 at
depth of 2 feet. Decrease in temperature may be due to the climatic conditions
as the sewage was stored in a steel tank for filtration. Maximum fall in the
temperature at 2 feetdepth may
be perhaps due to taking more time and long distance travelled by wastewater
during filtration. Temperature reduction has positive co-relation with
retention time factor in the bed as evident by minimum temperature reduction in
the sand at 1feet depth. Turbidity of domestic sewage was found 85.0 mg/l
before filtration. Complete reduction of turbidity was found in domestic sewage
at 2 feetdepth in all the
combinations of the filtration bed. Turbidity decreases due to decrease in
suspended solids and dissolved solids. Ojeda (1989) was found that turbidity
was removed by 90% using slow sand filters. El-Taweel (2000) reported that 92%
of turbidity was removed when slow sand filter was used for wastewater
treatment. Slight variation of these findings, from Ojeda (1990) and El-Taweel
(2000) may be due to variation of sand granules and soil particles size as well
as the depth of the bed. Total solids of domestic sewage was recorded 2740.0
mg/l. Total suspended solids of domestic sewage was found 1300 mg/l. Total
solids and Total suspended solids shows maximum reduction i.e. 88.5% and 91.2%
respectively at 2 feet depth in 3:1 ratio while minimum reduction of Total
solids was found i.e. 19.7% in soil only at 1 feet and minimum reduction of
Total suspended solids was found i.e. 35.8% in sand only at 1 feet. These
findings are in accordance to the findings of Ellis (1987). He has reported 90
% reduction of suspended solid when it was filtered through 3.5 feet sand
filtration. Total dissolved solids of domestic sewage were recorded 1440 mg/l.
Total dissolved solids shows maximum reduction i.e. 86.1% at 2 feet depth in
3:1 ratio while minimum was found i.e. 2.7% at 1 feet depth in soil only.
Solids reduced after sand intermittent filtration because mixture of soil and
sand works as a sieve. These results are in accordance with the findings of
Kumar et al. (2003). Also due to retention time of sewage into Sand
intermittent filter reduces total solids, total dissolved solids and total
suspended solids
Table
1: Physico-chemical
and microbiological parameters of Domestic Sewage before filtration (Values are
mean ± Standard Deviation of six observations).
Parameters |
Before Filtration |
|
|
Temperature (oC) |
25.98 ± 0.06 |
|
Turbidity (JTU) |
85.0 ± 0.0 |
|
Total Solids
(mg/l) |
2740 ± 276.8 |
|
Total Dissolved
Solids (mg/l) |
1440 ± 185.90 |
|
Total Suspended
Solids (mg/l) |
1300 ± 293.66 |
|
pH |
8.68 ± 0.03 |
|
Total Alkalinity
(mg/l) |
423.33 ± 3.72 |
|
Carbondioxide
(mg/l) |
143.73 ± 1.03 |
|
Dissolved Oxygen
(mg/l) |
0.6 ± 0.0 |
|
Biochemical
Oxygen Demand (mg/l) |
183.83 ± 8.16 |
|
Chemical Oxygen
Demand (mg/l) |
314.66 ± 4.13 |
|
Most Probable
Number (MPN/100ml) |
50833.33 ± 7756.71 |
|
Standard Plate
Count (Bacteria/ml) |
254.22 X103 ± 11.51X103 |
|
pH of domestic sewage was recorded 8.68. Maximum
decrease of 16.7% was recorded after treatment with Sand intermittent
filtration in the mixture of sand and soil having ratio 1:1 and depth of 2 feet
while minimum was found i.e. 0.57% in sand only at 1 feet depth. Total
alkalinity of domestic sewage was recorded 423.33 mg/l. Maximum reduction of
Total alkalinity i.e. 37.9% was found at 2 feet depth in 3:1 ratio while
minimum was found i.e. 0.19% in sand only at 1 feet depth. Carbon dioxide of
domestic sewage was recorded 143.73 mg/l before filtration. Maximum decline of
CO2 i.e. 83.4% was found at 2 feet depth in 3:1 ratio while minimum
reduction was found i.e. 0.7% in 1:1 ratio of sand and soil at 1 feet depth.
Since temperature decreases after Sand Intermittent Filtration, the growth of
microorganisms along with decomposition of organic substances as well as the
respiratory activity also slows down, this reduces the carbondioxide level in
the effluent.
Dissolved oxygen of domestic sewage was found 0.6 mg/l
before filtration. Low oxygen concentration is associated with heavy
contamination by organic matter (Trivedy and Goel, 1995). Maximum increase in
oxygen concentration from 0.6 to 3.91 mg/l was recorded after treatment with
Sand intermittent filtration at 2 feet depth of ratio 3:1. Enhancement of
dissolved oxygen in the sewage after treatment may be due to the minimization
of organic pollution load and bacterial population due to their retention
(organic pollutants and microbial population) in bed and simultaneously mixing
of atmospheric oxygen. . Biochemical oxygen demand (BOD) of domestic sewage
was recorded 183.83 mg/l. Maximum percentage of BOD reduction i.e. 72.5% was
recorded at 2 feet depth in 3:1 ratio of sand and soil mixture while minimum
was found i.e. 0.9% in sand only at 1 feet depth. 0.9% reduction was found in
100% sand at 1 feet depth but at the same time enhanced value was found at 2
feet depth of 100% soil i.e. 12.6%. It appears that depth of filtration bed was
great impact on purification of wastewater as it is evident by table 2. Our
conclusions are supported by Ellis (1987). He reported more than 65% reduction
in BOD, when effluent was allowed to filter from 3.5 feet depth of sand
filtration containing sand only of 0.3mm and then later 0.6mm in size. The
variation from our findings may be due to variation in the component of
filtration as in our case both sand and soil has been used in proportion of the
filter. Maximum percentage of BOD reduction may be due to lowering of
temperature, which minimizes the multiplication of microbial (bacterial)
population by generating unfavorable temperature resulted lowered uptake of
oxygen and due to their retention in the bed. Chemical oxygen demand (COD) of
domestic sewage was recorded 314.66 mg/l. Maximum reduction of COD i.e. 69.9%
was found at 2 feet depth in 3:1 ratio while minimum was found i.e. 0.42% in
100% sand only at 1 feet depth. Reduction of COD may be due to the fact that
most of the organic wastes were oxidized. Van Buuren et al. (1986)
reported 76-82% removal of COD in wastewater by using intermittent slow sand
filtration. Similar trends i.e. decrease in Chemical oxygen demand was also
recorded by Rao et al. (2003) when wastewater was filtered throughslow sand filter. The SPC found in domestic
sewage was 254.6X103 bacteria/ml.
TABLE 2:Pollution
Reduction Potential of Sand-Soil bed at different ratios and depth of Sand
Intermittent Filtration.
Parameters |
Sand/Soil=1:1 |
Sand/Soil=1:3 |
Sand/Soil=3:1 |
Sand 100% |
Soil 100% |
1' |
1.5' |
2' |
1' |
1.5' |
2' |
1' |
1.5' |
2' |
1' |
1.5' |
2' |
1' |
1.5' |
2' |
Temperature (oC) |
18.88
±0.04
(-27.3) |
18.85
±0.05
(-27.4) |
18.73
±0.04
(-27.9) |
22.23
±0.05
(-14.4) |
21.98
±0.07
(-15.3) |
21.45
±0.08
(-17.4) |
24.5
±0.0
(-5.6) |
24.43
±0.09
(-5.6) |
21.95
±0.05
(-15.5) |
25.65
±0.05
(-1.27) |
25.51
±0.13
(-1.80) |
25.0
±0.08
(-3.77) |
20
±0.06
(-23.0) |
19.98
±0.07
(-23.0) |
19.0
±0.16
(-26.8) |
Turbidity (JTU) |
30
±0.0
(-64.7) |
NIL |
NIL |
79.16
±2.04
(-7.8) |
NIL |
NIL |
25±0.0 |
NIL |
NIL |
27.5
±0.0
(-67.6) |
25
±0.0
(-70.5) |
NIL |
85
±0.0 |
NIL |
NIL |
TS
(mg/l) |
1600
±326.5
(-41.6) |
1193.33
±27.48
(-56.4) |
480
±73.02
(-82.4) |
1613.33
±32.65
(-41.1) |
1093.33
±20.65
(-60.0) |
966.66
±30.11
(-64.7) |
1066.66
±188.56
(-61.0) |
380
±20.0
(-86.1) |
313.33
±27.48
(-88.5) |
1833.33
±179.5
(-33.0) |
1133.33
±94.28
(-58.6) |
800
±0.0
(-70.8) |
2200
±219.08
(-19.7) |
1066.66
±206.5
(-61) |
1016.66
±93.09
(-62.8) |
TDS
(mg/l) |
960
±51.63
(-33.3) |
680
±40.0
(-52.7) |
280
±51.63
(-80.5) |
1186.33
±32.65
(-17.5) |
780
±21.9
(-45.8) |
706.66
±20.65
(-50.9) |
800
±56.56
(-44.4) |
206.66
±14.9
(-85.6) |
200
±0.0
(-86.1) |
1000
±305.5
(-30.5) |
640
±172.81
(-57.1) |
620
±44.72
(-56.9) |
1400
±219.08
(-2.7) |
720
±155.7
(-50) |
700
±48.98
(-51.3) |
TSS
(mg/l) |
640
±278.0
(-50.7) |
513.33
±14.90
(-60.5) |
200
±23.09
(-84.6) |
426.66
±60.22
(-67.1) |
313.33
±30.11
(-75.8) |
260
±33.46
(-80) |
266.66
±131.99
(-79.48) |
173.33
±29.31
(-86.66) |
113.33
±27.48
(-91.2) |
833.33
±242.67
(-35.8) |
493.33
±82.19
(-62.05) |
180
±44.72
(-86.15) |
800
±0.0
(-38.46) |
346.66
±54.65
(-73.3) |
316.66
±47.6
(-75.6) |
pH |
8.61
±0.27
(-0.80) |
7.48
±0.04
(-13.8) |
7.23
±0.04
(-16.7) |
8.6
±0.08
(-0.92) |
7.86
±0.05
(-9.4) |
7.58
±0.04
(-12.6) |
8.55
±0.05
(-1.49) |
8.08
±0.08
(-6.9) |
8.01
±0.13
(-7.7) |
8.63
±0.05
(-0.57) |
8.25
±0.05
(-4.9) |
7.98
±0.06
(-8.0) |
8.58
±0.11
(-1.15) |
7.85
±0.05
(-9.5) |
8.58
±0.11
(-1.15) |
TA
(mg/l) |
417.5
±2.73
(-1.37) |
328.33
±4.71
(22.4) |
310
±2.88
(-26.7) |
419.16
±2.04
(-19.8) |
313.33
±2.58
(-25.9) |
298.33
±2.58
(-29.5) |
416.66
±5.16
(-1.57) |
283.33
±2.35
(-33.0) |
262.5
±2.5
(-37.9) |
422.5
±2.73
(-0.19) |
271.66
±2.35
(-35.8) |
265
±4.08
(-37.4) |
418.33
±6.05
(-1.18) |
360
±5.16
(-14.95) |
320
±3.16
(-24.4) |
CO2
(mg/l) |
142.63
±1.51
(-0.7) |
37.4
±1.27
(-73.9) |
24.2
±1.96
(-83.1) |
96.8
±1.96
(-32.6) |
33.73
±1.13
(-76.5) |
29.7
±1.20
(-79.3) |
86.9
±1.1
(-39.5) |
29.7
±2.76
(-79.3) |
23.83
±2.66
(-83.4) |
81.4
±2.54
(-43.36) |
32.63
±2.34
(-77.2) |
24.2
±3.81
(-83.1) |
93.13
±1.13
(-35.2) |
37.03
±2.16
(-74.23) |
28.6
±1.39
(-80.10) |
DO
(mg/l) |
0.94
±0.52
(+56.66) |
2.0
±0.0
(+233.33) |
2.49
±0.10
(+315) |
0.84
±0.39
(+40.0) |
3. 0
±0.08
(+400) |
3.07
±0.0
(+411.6) |
1.14
±0.52
(+90.0) |
2.9
±0.27
(+383.3) |
3.91
±0.16
(+551.6) |
0.63
±0.08
(+5.0) |
1.11
±0.10
(+85) |
1.48
±0.16
(+146.6) |
1.14
±0.52
(+90.0) |
2.97
±0.10
(+395) |
3.03
±0.12
(+405) |
BOD
(mg/l) |
175.5
±10.48
(-4.5) |
165.5
±8.36
(-9.9) |
132.16
±11.69
(-28.1) |
180.5
±8.94
(-1.81) |
107.16
±10.32
(-41.7) |
95.5
±13.78
(-48.0) |
170.5
±12.64
(-7.2) |
105.5
±10.48
(-42.6) |
50.5
±12.64
(-72.5) |
182.16
±4.08
(-0.90) |
172.16
±7.52
(-6.3) |
160.5
±6.32
(-12.6) |
178.83
±7.52
(-2.7) |
153.83
±5.16
(-16.3) |
120.5
±8.94
(-34.4) |
COD
(mg/l) |
312.66
±3.93
(-0.6) |
232.66
±4.67
(-26.0) |
182.66
±4.84
(-41.9) |
311.33
±5.88
(-1.05) |
170.66
±3.26
(-45.7) |
134.0
±5.51
(-57.4) |
307.33
±3.01
(-2.3) |
129.33
±4.84
(-58.8) |
94.66
±3.26
(-69.9) |
313.33
±4.84
(-0.42) |
298.66
±3.26
(-5.08) |
258.33
±4.13
(-9.3) |
309.33
±3.26
(-1.6) |
201.33
±2.06
(-36) |
151.33
±8.16
(-51.9) |
MPN
(MPN
/100ml) |
33166.6
±4490.7
(-34.7) |
26000
±3098.3
(-48.8) |
18000
±2000
(-64.5) |
25333.3
±2065.5
(-50.1) |
21000
±2449.4
(-58.6) |
17500
±547.72
(-65.5) |
13666.6
±2581.8
(-73.1) |
13166.6
±408.2
(-74.0) |
8900
±774.5
(-82.4) |
47666.6
±9811.5
(-6.2) |
35833.3
±9537.6
(-29.5) |
33833.3
±2857.7
(-33.4) |
28166.6
±4119
(-44.5) |
24666.6
±1632.9
(-51.4) |
11500
±1224.7
(-77.3) |
SPC (X103 Bacteria/ml) |
124.3
±4.4
(-51.1) |
119
±12.0
(-53.2) |
109.8
±12.2
(-56.8) |
136
±38.8
(-46.5) |
127
±22
(-50.1) |
104.5
±20.5
(-58.9) |
106.8
±10.2
(-58.0) |
82.3
±10.7
(-67.6) |
54.8
±10.2
(-78.4) |
135
±10.2
(-46.9) |
129.3
±8.3
(-49.2) |
114.5
±8.6
(-55.03) |
132
±10.1
(-48.1) |
123.3
±15.3
(-51.5) |
107.5
±11.9
(-57.7) |
± = Standard
Deviation, % Increase and Decrease given in parentheses
' = Feet
Reduction of 82.4% was observed in the ratio 3:1
having a depth of 2 feet while minimum was found i.e. 6.2% in sand only at 1
feet depth. Bacterial population decreases due to depletion of organic
components, which serve as nutritive substances and due to fall in temperature,
which does not support bacterial multiplication. Bomo et al. (2003) were
found that Sand filters removed 99.9% of bacteria. Since a significant
reduction in most of the parameters related with pollution load of sewage has
been recorded after passing through Sand Intermittent Filtration, therefore it
is desirable to investigate its ability under different conditions in order to
make a program to treat the sewage on overhead stabilization pond to protect
under ground water reservoir and inland surface water.
Acknowledgement: Thanks are due to the Head, Department of Zoology
and Environmental Sciences, Gurukula Kangri University, Haridwar (UA), INDIA
for providing necessary facilities for this research work.
REFRENCES
- APHA. (1998). Standard
Methods for the examination of water and wastewater. 14th Ed.
Washington DC.
- Ausland,G; Stevik,T.K;
Hanssen,J.F; Kohler,J.C; Jenssen,P.D. (2002) Intermittent filtration of
wastewater-removal of fecal coliforms and fecal Streptococci. Wat. Res. 36,
3507-3516.
- Bellamy,W.D; Hendricks,D.W;
Logsdon, G.S (1985). Slow sand filtration: influences of selected process
variables. J. Am. Water Well Assoc. 12, 62-66.
- Bomo, A.M; Husby, A; Stevik,
T.K; Hanissen, J.F (2003). Removal of fish pathogenic bacteria in biological
sand filters. Wat. Res. 37, 2618-2626.
- Campos, L. Cl; Su, M.F.J;
Graham, N.J.D; Smith, S.R (2002) Biomass development in slow sand filters. Wat.
Res. 36, 4543-4551.
- El-Taweel, G.E; Ali, G.H
(2000). Evaluation of roughing and slow sand filters for water treatment. Water
Air Soil Pollu. 120(1-2), 21-28.
- Ellis,K.V (1987). Slow sand
filtration as a technique for the tertiary treatment of municipal sewages. Wat.
Res. 21(4), 403-410.
- Huisman,L; Wood,W.E (1974).
Slow sand filtration. Geneva: World health Organization. 20-46.
- Kumar,A; Singhal,V;
Joshi,B.D; Rai,J.P.N. (2003). Lysimetric approach for ground water pollution
control from pulp and paper mill effluent using different soil textures. Ind.
J. Sci. Ind. Res. 63, 429-438.
- Ojeda,P (1990). Treatment of
turbid surface water for small community supplies. Dissertation Abstracts
International. 51(3), 1471-B.
- Rajeswaramma,C; Kapil,Gupta
(2002). Hydraulic design of a constructed wetland for an urban area. J. Wat.
Works. Asso. 149-152.
- Rao,R.Ravinder; Reddy,R.C;
Rama Rao, K.G; Kelkar,P.S (2003). Assessment of slow sand filtration system for
rural water supply schemes-A case study. Indian J. Environ. Hlth. 45(1),
59-64.
-
- Rooklidge,S.J; Ketchum,Jr L.H
(2002). Corrosion control enhancement from a dolomite-amended slow sand filter.
Wat. Res. 36, 2689-2694.
- Sarkar,A.K; Georgiou, G;
Sharma,M.M (1994). Transport of bacteria in porous media. I. An experiment
investigation. Biotechnol. Bioeng. 44, 489-497.
- Stevik,T.K; Ausland,G;
Jenssen,P.D; Siegrist,R.L (1999). Removal of E. coli during intermittent
filtration of wastewater effluent as affected by dosing rate and media type.
Wat. Res. 33, 2088-2098.
- Trivedy,R.K; Goel,P.K (1995).
Chemical and biological methods for water pollution analysis studies. Environ.
Publications, Post box no. 60 Karad. 1-247.
- Van Buuren,J.C.L; Willers,H;
Luyten,L; Van Manen, M (1986). The pathogen removal from UASB-effluent by
intermittent slow sand filtration. In: Anaerobic treatment a grown-up
technology, conference papers. Aquatech. 86, 707-709.
- WeberShirk,M.L (2002).
Enhancing slow sand filter performance with an acid-soluble seston extract.
Wat. Res. 36, 4753-4756.
- Zibell,W.A; Anderson,J.L;
Bouma,J; McCoy,E (1975). Fecal Bacteria: Removal from sewage by soil. Winter
meeting, ASAE publication, Chicago, IL, paper no. 75-2579.
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