Journal of Water Resource and Protection, 2012, 4, 831-837
http://dx.doi.org/10.4236/jwarp.2012.410095 Published Online October 2012 (http://www.SciRP.org/journal/jwarp)
Pr ocess W indow Determination for Biofiltration by the
Taguchi Method
Man Chung Law1, Hong Chua1, Ka Po Cheng2*, Chi Wai Kan3
1Department of Civil and Structure Engineering, The Hong Kong Polytechnic University, Hong Kong, China
2Department of Industrial Centre, The Hong Kong Polytechnic University, Hong Kong, China
3Department of Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong, China
Received August 2, 2012; revised September 3, 2012; accepted October 1, 2012
ABSTRACT
Raw water from the Yantian Reservoir in Southern China was used for this study. Several process parameters of biofil-
tration, temperature, media, empty bed contact time, ozone dosage and concentration of geosmin and MIB, were
adopted in order to determine their effects. Experiments were conducted using the Taguchi method and 9 experiments
were needed to obtain the best process parameter settings and parameter effects. The results of these experiments indi-
cate the use of biological filtration as a method of geosmin and MIB removal, to be satisfactory. In addition, the results
show that temperature impacts the removal rate of both geosmin and MIB. Useful insights into the effects of the filter
media on such as, empty bed contact time, ozone dosage and concentration of geosmin and MIB were also obtained.
Keywords: Taste and Odor; Water Quality; Design of Experiment; Taguchi Method
1. Introduction
Yantian reservoir, established in 1976, is situated in
Dongguan (Figure 1). It is used mainly as a source of
drinking water for the Dongguan area—Fenggang. The
area and storage capacity of the Yantian reservoir are
equal to approximately 256,000 m2 and 8,990,000 m3 re-
spectively.
From October 2010 to October 2011, the geosmin and
MIB concentration of Yantain reservoir are around 3 ng
to 168 ng/L and 4 ng to 139 n g/L respect ively (Figure 2).
Several factors may significantly influence geosmin
and MIB removal in biofilters. These factors include
such asseasonal water temperature variations, filter me
dia (GAC, EC, or sand), empty bed contact time. Some
Figure 1. Location of the China’s Yantian reservoir.
*Corresponding a uthor.
C
opyright © 2012 SciRes. JWARP

M. C. LAW ET AL. 832
Figure 2. Concentration of geosmin & MIB for Yantian surface water over a year.
investigations demonstrated that temperature and media
are the most important factors affecting drinking water
biofiltration processes [1] and may influence the removal
of compound s such as geo smin and MIB. In addition , the
geosmin and MIB concentrations are important factors
affecting their removal in biofilms [2]. In view of the
lack of recorded systematic approaches, the best possible
outcome is usually achieved by “trial-and-error” or by
changing one control variable at a time while holding the
rest constant.
The use of DOE enables an increase in the information
available and reduces the number of tests required for a
given number of factors and levels. If the experiments
are designed correctly, a large amount of information can
be collected with a minimum of experimental effort. A
number of successful DOE applications for improving
process performance have been reported over the last 15
years [3-5]. In the case study conducted in this research
study, the major factors thought to affect geosmin and
MIB removal in biological degradation are examined.
These factors include 1) initial concentration; 2) empty
bed contact time; 3) ozone dosage; and 4) media.
2. Methods
2.1. Design of Experiment
Given that a range of values is suggested, experiments
should be setup in order to determine the most appropri-
ate. In the case, each of the parameters has a three value
level standby, and the maximu m possible cond ition is 81.
This means 81 experiments/columns should be setup to
examine the effects of these parameters and the potential
interactions among them regarding geosmin and MIB
removal. In order to determine/obtain the best process
parameter settings, with the least number of experiments,
the Taguchi method was selected. Only 9 experiments/
columns were needed to quantify the effects and interac-
tions of 3 or more parameters/factors. As temperature
affects the removal rate of geosmin and MIB, two levels
of temperature were selected as the noise factor. The
high, medium and low levels of control factors selected
for the experiments are shown in Table 1. The levels
were assigned on the basis of values found in the litera-
ture for the different param eters.
2.2. Isolation of Bacteria
Due to limited resources, the bacteria source was from
the sludge in the aeration tank of Tai Po waste water treat-
ment plant in Hong Kong and the target bacteria used for
the development of the biofilter was Bacillus cereus and
Pseudomonas-aeruginosa. Bacillus cereus and Pseudo-
monas-aeruginosa were chosen for the removal of geos-
min and MIB as they had been proven to provide effec-
tive geosmin and MIB removal [6,7] and their presence
in the sludge from the aeration tank of Tai Po waste wa-
ter treatment plant had been confirmed [8].
200 mL of the sludge was put into 3 L of synthetic wa-
ter with an internal air pump which supplied oxygen to the
bacteria, and aluminum foil was used to cover the buck-
et to prevent the entry of pollutants. The specimen was
kept in the Water and Wastewater Laboratory of the Hong
Kong Polytechnic University at a tem perature of 18˚C.

M. C. LAW ET AL.833
Table 1. The high, medium and low levels of each c o ntr o l fac tor & noise fac tor.
Control Factors
A B C D Noise Factor
Level Media Empty Bed C ontact Time (EBCT)Concentration Ozone Dosage Temperature
1 GAC 4 mins 100 ng/L 1 mg/L 10˚C
2 EC 8 mins 25 ng/L 2 mg/L 20˚C
3 Sand 12 mins 50 ng/L 3 mg/L
A typical empirical formula for a bacterial cell,
C55H77O22N11P2 [9], indicates a C:N:P ratio of 21:5:1
(w/w/w). Some Researcher [10] chose a C:N:P ratio of
15:5:1 (w/w/w) to guarantee that the organic carbon was
the limiting nutrient. As the sludge contained a variety of
bacteria, a specific C:N:P ratio adapted for Bacillus cer-
eus and Pseudomon as-aerugi nosa was applied to the mix-
ture aiming at removing other bacteria and accelerating
the growth of bacillus cereus and Pseudomonasaerugi-
nosa. The same C:N:P ratio as [10] was used in this
study. Glucose (C6H12O6), ammonia sulfate ((NH4)2·SO4)
and potassium phosphate (K2HPO4) were used as the
sources of carbon, nitrogen and phosphor respectively.
The target carbon source (C12H22O) of concentration
100 mg/L was chosen, since this concentration is the
usual concentration of nutrients adapted by the bacteria
in sludge. The calculated nutrient mass was fed every
day for 3 weeks.
In order to monitor the condition of the bacteria, the
pH of the mixture was measured every day by a CD510
pH meter (CD510, WPA) during these 3 weeks. Since a
pH value between 6.5 and 7.2 is the most suitable for the
growth of Bacillus cereus [11], the pH of the mixture
was measured to ensure that the condition of the mixture
was suitable for the growth of Bacillus cereus a nd Pseu-
domonas-aeruginosa. If the pH of the mixture became
out of range, an alkaline solution produced by 1M NaOH
was added to the mixture to adjust its pH.
The total organic carbon (TOC) of the mixture was
measured by a total organic carbon analyzer (TOC-5000
A, Shimadzu). On the first day after the addition of nu-
trients, the TOC of the mixture was measured and there-
after every day before and after the addition of nutrien ts.
The growth of the microorganisms can be shown by the
decrease in the TOC content. Therefore, by having the
TOC measurement, the growth of the bacteria was re-
vealed.
Before putting the mixture into the TOC Analyzer, it
was filtered to ensure that there were no solids in the
liquid that would damage the analyzer. The growth of
bacteria could be demonstrated from the TOC measure-
ments, as the decrease of the TOC concentration indi-
cated the growth of bacteria.
The prepared Bacillus cereus was inoculated into the
nine columns, three of which were filled with the ex-
hausted GAC, another three were filled with sand and the
final three were filled with the prepared EC. Each was
connected to one of nine individual water pumps. The
flow rate for the mixture into the columns was 3.5 cm3/
minute and the inoculation process was carried out for
the duration of two weeks. The comparably low flow rate
was intended to allow time for the bacteria to attach to
the surface of the media.
The delay in the biological degradation occurrence is
regarded as the lag period and lag periods from days to
months before complete degradation of organic com-
pounds have been recorded in the literature [12]. The
bacteria was fed with glucose as the carbon source
originally, thus it may not obtain the carbon nutrient
from geosmin or MIB in the water during the biofiltra-
tion and hence lead to the lag period. An attempt was
made to decrease the lag period prior to degradation of
geosmin or MIB occurred in the column. This was con-
ducted by introducing a series of geosmin or MIB spik-
ing trials over a period of two week.
During the two weeks of inoculating the bacteria into
the nine columns, nine filter columns were spiked with
geosmin and MIB on day 1 of the inoculation. Target
concentrations of 100 ng/L for both geosmin and MIB
were introduced into each of the filter influents. These
concentrations were in the higher range of what is typi-
cally seen in nature and represent the worst case scenario
[13]. Finally, a rest period of 3 days was provided before
the biodegradation experiments began.
2.3. Experimental Arrangement
The experiments were conducted in the Water and
Wastewater Laboratory of the Hong Kong Polytechnic
University. Nine sets of 25 mm internal diameter glass
columns with a total length of 43 cm of filter bed were
used. Stock solutions of geosmin and MIB (20 ng/L)
were prepared by diluting geosmin standard solution
(G5908—2 mg/mL in methanol, SIGMA) and MIB stan-
dard solution (G5908—2 mg/mL in methanol, SIGMA)
in synthetic water. Each set of columns consisted of dif-
ferent media (GAC, EC or Sand), different empty bed

M. C. LAW ET AL. 834
contact time (4 mins, 8 mins or 12 mins) and different
concentrations (25 ng/L, 50 ng/L or 100 ng/L) to filter
the deionized water with different ozone dosage (1, 2 or
3 mg/L) under different temperatures (10˚C or 20˚C). For
example, column 1 was filled with GAC (Filtrasorb 300
with an effective size of 0.8 to 1.0 mm) in order to filter
the synthetic water with a concentration of 100 ng/L
geosmin and MIB and 1 mg/L ozone dosage with an
empty bed contact time of 4 mins. Column 4 was filled
with EC (Filtralite MC with an effective size of 2.45 to
2.75 mm) in order to filter the synthetic water with a
concentration of 50 ng/L Geosmin and MIB and 3 mg/L
ozone dosage with empty bed contact time of 4 mins.
Column 7 was filled with Sand (effective size of 0.5 mm)
in order to filter the synthetic water with a concentration
of 25 ng/L Geosmin and MIB and 2 mg/L ozone dosage
with an empty bed contact time of 4 mins. The removal
rates of geosmin and MIB were identified at two tem-
perature conditions, 10˚C and 20˚C for all 9 columns.
The setup condition for the rest of the columns is
shown in Table 2. Each column was connected to an in-
dividual water pump. 9 water pumps were connected, in
parallel, to pump the water samples, which were stored
in individual glass boxes. The air pumps acted as the
influent and provided oxygen for the biofilm in each
column by the up-flow method.
Based on the L9 layout, the experiments on the 9
columns for the determination of the geosmin and MIB
removal rate were run twice at the two temperature con-
ditions of 10˚C and 20˚C.
2.4. Solid Phase Microextraction-Gas
Chromatography-Mass Spectrometry
Analysis
Solid phase microextraction (SPME) and gas chroma-
tography/mass spectroscopy (GC/MS) were employed to
determine the levels of the geosmin and MIB of different
process settings. The procedure for the analysis of 2-MIB
and geosmin was the same as that prescribed by the
standard method 6040D. The method was based on the
Solid Phase Micro-Extraction (SPME) concentration. A
commercially available SPME fiber (NO. 57328-U Su-
peloc, US) was selected to concentrate the MIB and
geosmin. The fiber was comprised of a composite mate-
rial with Divinylbenzene, carboxen, and polydimethylsi-
loxane.
GC-MS analysis was carried out with a Varian Model
CP3380 gas chromatograph-mass spectrometer in conjunc-
tion with a GCMS Model 12 00 L Qu adrupo le MS/MS. A
5% phenyl-methyl column VF—5 ms (Varian, Lake For-
est, CA, USA: 30 mm (L) × 0.25 mm (ID) × 0.39 mm
(OD) and 0.25 µm fil m thickn ess) wa s u sed.
According to Ligor and Buszewski (2005), the GC
operating conditions should be as follows: injection and
detector temperatures, 280˚C; column temperature, held
at 190˚C for 2 min, incr eased to 270˚C at 10˚C/min; inlet
helium carrier gas flow rate, 1.43 mL/min maintained by
an electronic pressure controller; split ratio, 5:1. The
electron impact (EI)-MS conditions were as follo ws: ion-
source temperature, 200˚C; ionizing voltage, 70 eV. Full
scan mass spectra were obtained at an m/z range of 80 -
200 u. Selected ion monitoring (SIM) mode detections
for MIB and GSM were obtained as m/z = 112 (GSM)
and m/z = 95 (MIB). The peak height was measured to
construct the calibration cu rve and to determine the MIB
and GSM concentrations in the samples.
2.5. Statistical Analysis Method
The removal rate was recorded, enabling the signal-to-
noise ratio to be calculated, to determine the variation of
each parameter in the removal rate of geosmin and MIB,
and also the interaction between the factors. With the aid
of ANOVA, the effect of each parameter on the removal
rate of geosmin and MI B was calculated.
Table 2. The layout of L9 (34) by taguchi method.
No Media Empty Bed C ontact Time (EBCT) Concentration Ozone Dosage
1 GAC 4 mins 100 ng/L 1 mg/L
2 GAC 8 mins 25 ng/L 2 mg/L
3 GAC 12 mins 50 ng/L 3 mg/L
4 EC 4 mins 50 ng/L 3 mg/L
5 EC 8 mins 100 ng/L 1 mg/L
6 EC 12 mins 25 ng/L 2 mg/L
7 Sand 4 mins 25 ng/L 2 mg/L
8 Sand 8 mins 50 ng/L 3 mg/L
9 Sand 12 mins 100 ng/L 1 mg/L

M. C. LAW ET AL.835
3. Results and Discussion
3.1. Best Process Window for the Removal of
Geosmin & MIB
The optimum condition for Geosmin was shown in ex-
periment no 1 (media: GAC; EBCT: 4 mins; concentra-
tion: 100 ng/L; ozone dosage: 1 mg/L) while the opti-
mum condition for MIB was experiment no 1 (media:
GAC; EBCT: 4 mins; concentration: 100 ng/L; ozone
dosage: 1 mg/L). From the experimental results (Table 3
and Figure 3), it is seen that the removal rates of both
Geosmin and MIB are better when the working tempera
ture is 20˚C.
3.2. Effect and Interactions of Process Parameters
Since the removal rate of geosmin and MIB has a larger-
the-better characteristic, the S/N ratio for a larger-the-
better characteristic is used for the calculation of th e total
variation. Table 4 shows the S/N ratio for exper imen t No .
1 to 9 and Table 5 shows the square of the S/N ratio for
experiment No. 1 to 9.
The correction term (CF) of Geosmin
= (–86.57)2/9 = 832.71
The correction term (CF) of MIB
= (–116.33)2/9 = 1503.63
The total variation of the experiment for geosmin:
ST = 881.79 – CF = 881.79 – 832.71 = 49.08
The total variation of the experiment for MIB:
ST = 1550.32 – CF = 155 0. 3 2 – 15 0 3. 63 = 46.6 9
For the variation of factors in the removal rate of
geosmin, the level totals for the S/N ratio of geosmin is
calculated and shown in Table 6.
Table 3. The geosmin & MIB removal rate of each column at two temperature conditions.
Control Factors Removal Rate of Geosmin Removal Rate of MIB
No Media Empty Bed Contact Tim (EBCT) ConcentrationOzone Dosage10˚C (R1)20˚C (R2) 10˚C (r1) 20˚C (R2)
1 GAC 4 mins 100 ng/L 1 mg/L 38% 89% 24% 88%
2 GAC 8 mins 25 ng/L 2 mg/L 32% 81% 20% 76%
3 GAC 12 mins 50 ng/L 3 mg/L 33% 86% 21% 80%
4 EC 4 mins 50 ng/L 3 mg/L 21% 32% 13% 28%
5 EC 8 mins 100 ng/L 1 mg/L 28% 40% 19% 33%
6 EC 12 mins 25 ng/L 2 mg/L 19% 34% 11% 22%
7 Sand 4 mins 25 ng/L 2 mg/L 20% 28% 16% 23%
8 Sand 8 mins 50 ng/L 3 mg/L 24% 56% 18% 35%
9 Sand 12 mins 100 ng/L 1 mg/L 30% 62% 20% 48%
Figure 3. Comparison of geosmin & MIB removal rate at two temperature conditions (Columns 1 to 9).

M. C. LAW ET AL. 836
Table 4. List of S/N ratio for the removal rate of geosmin & MIB.
Removal Rate of Geosmin Removal Rate of MIB S/N Ratio of Geosmin (db) S/N Ratio of MI B (db)
No 10˚C (R1) 20˚C (R 2) 10˚C (r1) 20˚C (r2) 10
log2
11
11 1
2RR
2





 


 10 22
11
11 1
2rr



 


log
1 0.38 0.89 0.24 0.88 –6.12 –9.70
2 0.32 0.81 0.20 0.76 –7.52 –11.26
3 0.33 0.86 0.21 0.80 –7.22 –10.83
4 0.21 0.32 0.13 0.28 –12.10 –15.56
5 0.28 0.40 0.19 0.33 –9.78 –12.66
6 0.19 0.34 0.11 0.22 –12.59 –17.13
7 0.20 0.28 0.16 0.23 –12.76 –14.62
8 0.24 0.56 0.18 0.35 –10.12 –12.90
9 0.30 0.62 0.20 0.48 –8.36 –11.66
Total –86.57 –116.33
Table 5. Square of S/N ratio for experiment no 1 to 9.
No S/N Ratio of Geosmin (db) (S/N Ratio of Geosmin)2 S/N Ratio of MIB (db) (S/N Ratio of MIB)2
1 –6.12 37.47 –9.70 94.03
2 –7.52 56.50 –11.26 126.79
3 –7.22 52.07 –10.83 117.39
4 –12.10 146.43 –15.56 242.07
5 –9.78 95.62 –12.66 160.23
6 –12.59 158.63 –17.13 293.47
7 –12.76 162.82 –14.62 213.79
8 –10.12 102.37 –12.90 166.50
9 –8.36 69.90 –11.66 136.07
Total 881.79 Total 1550.32
The sum of the squares caused by control factor A is
called variation SA
SA = {[(–20.85)2 + (–34.47)2 + (–31.24)2]/3} – CF =
33.57
The sum of squares caused by control factor B is
called variation SB
SB = {[(–30.98)2 + (–27.41)2 + (–28.17)2]/3} – CF =
2.16
The sum of squares caused by control factor C is
called variation SC
SC = {[(–32.87)2 + (–29.44)2 + (–24.26)2]/3} – CF =
12.52
The sum of squares caused by control factor D is
called variation SD
SD = {[(–24.26)2 + (–32.87)2 + (–29.44)2]/3} – CF =
12.52
The total of SA, SB, SC and SD is calculated:
SA + SB + SC + SD = 33.57 + 2.16 + 12.52 + 12.52 =
60.77
The variation err or = 49.0 8 – 60 .7 7 = –1 1. 69
The difference between the total variation and factor
variations is found in the interaction between the factors.
After the interaction is calculated, the ANOVA table for
the removal rate of geosmin and MIB is constructed as
shown in Table 7. The removal rates of geosmin and
MIB, were most affected by the media.
The same steps are applied for MIB and the level to-
tals for the S/N ratio of MIB were calculated and are
shown in Table 8.
Table 6. Level totals for S/N ratio of geosmin.
Control Factors
Level A B C D
1 –20.85 –30.98 –32.87 –24.26
2 –34.47 –27.41 –29.44 –32.87
3 –31.24 –28.17 –24.26 –29.44
Total –86.56 –86.56 –86.56 –86.56
Table 7. ANOVA table for the removal rate of geosmin.
Factor Degree of Freedom Variation (S) Variance (V)
Media 2 33.76 16.88
Empty Bed Contact
Time (EBCT) 2 2.36 1.18
Concentration 2 12.52 6.26
Ozone Dosage 2 12.52 6.26
Table 8. Level totals for S/N ratio of MIB.
Control Factors
LevelA B C D
1 –31.79 –39.88 –43.01 –34.02
2 –45.35 –36.82 –39.30 –43.01
3 –39.19 –39.63 –34.02 –39.29
Total–116.33 –116.33 –116.33 –116.33

M. C. LAW ET AL. 837
The sum of squares caused by control factor A is
called variation SA
SA = {[(–31.79)2 + (–45.35)2 + (–39.19)2]/3} – CF =
30.73
The sum of squares caused by control factor B is
called variation SB
SB = {[(–39.88)2 + (–36.82)2 + (–39.63)2]/3} – CF =
1.92
The sum of squares caused by control factor C is
called variation SC
SC = {[(–43.01)2 + (–39.30)2 + (–34.02)2]/3} – CF =
13.61
The sum of squares caused by control factor D is
called variation SD
SD = {[(–34.02)2 + (–43.01)2 + (–39.29)2]/3} – CF =
13.34
The total of SA, SB, SC and SD is calculated:
SA + SB + SC + SD = 30.71 + 1.92 + 13.61 + 13.34 =
59.58
The variation err or = 46.6 9 – 59 .5 8 = –1 2. 89
The difference between the total variation and varia-
tion of factors is the interaction between the factors. Af-
ter the interaction was calculated, the ANOVA table was
constructed as shown in Table 9. The removal rates of
geosmin and MIB, were most affected by the media.
4. Conclusion
As stated in the introduction, the use of the Taguchi
method can help the water reservoir operation in the
identification of the critical process parameters. The
coding of independent variables (influent concentration,
Ozone dosage, temperature, media and EBCT) for the
Taguchi Analysis is shown in the Table 1, where it can
be confirmed that temperature is shown to increase the
biodegradability of geosmin and MIB, often leading to
enhanced removal of geosmin and MIB across the biofil-
ter. The removal rates of geosmin and MIB, were most
affected by the media and were substantially larger than
their interactions. The EBCT valu e had the least effect on
removal rates in this study. This result could help the
water reservoir to identify of the critical process parame-
ters for biofiltration on site.
Table 9. ANOVA table for the removal rate of MIB.
Factor Degree of Freedom Variation (S) Variance (V)
Media 2 30.71 15.36
Empty Bed Contact
Time (EBCT) 2 1.92 0.96
Concentration 2 13.61 6.81
Ozone Dosage 2 13.61 6.81
5. Acknowledgements
This work was funded by Yantian reservoir in China and
the Hong Kong Polytechnic University. I would like to
thank the Water and Waste Water Laboratory for sup-
porting this project.
REFERENCES
[1] D. Urfer, “Effects of Oxidants on Drinking Water Biofil-
te rs,” Ph.D. Thesis, Department o f Civil Engineering, Uni-
versity of Waterloo, Waterloo, 1988.
[2] E. Namkung and B. E. Rittmann, “Removal of Taste- and
Odor-Causing Compounds by Biofilms Grown on Humic
Substances,” Journal of the American Water Works Asso-
ciation, Vol. 79, No. 7, 1987, pp. 107-112.
[3] J. Antony, “Improving the Wire Bonding Process Quality
Using Statistically Designed Experiments,” Microelec-
tronics Journal, Vol. 30, No. 2, 1999, pp. 161-168.
doi:10.1016/S0026-2692(98)00104-9
[4] R. G. Bullington, et al., “Improvement of an Industrial
Thermostat Using Designed Experiments,” Journal of
Quality Technology, Vol. 25, No. 4, 1993, pp. 262-271.
[5] M. Hamada, “Using Statistically Designed Experiments
to Improve Reliability and to Achieve Robust Reliability,”
IEEE Transactions on Reliability, Vol. 44, No. 2, 1995,
pp. 206-215. doi:10.1109/24.387372
[6] M. Yagi, S. Nakashima and S. Muramoto, “Bi ological De-
gradation of Musty Odorcompounds, 2-Methylisoborneol
and Geosmin, in a Bio-Activated Carbon Filter,” Water
Science & Technology, Vol. 20, No. 8-9, 1988, pp. 255-260.
[7] D. G. Bourne, G. J. Jones, R. L. Blakeley, A. Jones, A. P.
Negri and P. Riddles, “Enzymatic Pathway for the Bacte-
rial Degradation of the Cyanobacterial Cyclic Peptide
Toxin Microcystin LR,” Applied & Environmental Mi-
crobiology, Vol. 62, No. 11, 1996, pp. 4086-4094.
[8] Y. F. Tsang, “A Novel Bi ofiltration Technology for Odour
Treatment,” PhD Thesis, Department of Civil and Struc-
tur e E ngineering, The Hong Kon g Polytec hni c Uni ve rsi ty,
Hong Kong, 2009.
[9] G. Tchobanoglous and F. L. Burton, “Wastewater Engi-
neering: Treatment, Disposal, and Reuse,” Metcalf and
Eddy, McGraw-Hill, New York, 1991.
[10] D. Urfer, P. M. Huck, S. D. J. Booth and B. M. Coffey,
“Biological Filtration for BOM and Particule Removal: A
Critical Review,” Journal of American Water Works As-
sociation, Vol. 89, No. 12, 1997, pp. 83-98.
[11] M. Bridget, H. Daniel, N. Gayle, P. Christopher and H.
Lionel, “Enhancing the Biofiltration of Geosmin by Seed-
ing Sand Filter Columns with a Consortium of Geosmin-
Degrading Bacteria,” Water Research, Vol. 43, 2009, pp.
433-440. doi:10.1016/j.watres.2008.10.044
[12] S. W. H. Lionel, “The Removal of Cyanobacterial Me-
tabolites from Drinking Water Using Ozone and Granular
Activated Carbon,” University of South Australia, Ade-
laide, 2004.
[13] S. L. N. Elhadi, et al., “Removal of Geosmin and 2-Me-
thylisoborneol,” Biological Filtration Water Science &
Technology, Vol. 49, No. 9, 2004, pp. 273-280.