Degradation Profile of Phenol in Sequential
Batch Reactor
Farah Khan, Mohammad Zain Khan and Suhail Sabir* Environmental Research Laboratory, Department of Chemistry,
Aligarh Muslim University, Aligarh-202002, India
E-mail: [email protected]
Tel/Fax: 0915712703515
Abstract
Compact well settling granules were cultivated for degrading 3.9 kg m-3
d-1
of phenols. Formed granules were studied qualitatively using SEM and it was found
that a large number of bacterial types including bacterial rod, cocci, diatoms are
dispersed in the extracellular polymeric substance (EPS). Degradation studies show
that initially the removal rate of phenol was fast but later on it becomes slow. Low
concentration of 50 mg l-1
, 100 mg l-1
, 200 mg l-1
phenol comes down below detection
limit in about 170 min of the SBR cycle but high concentration of 400 mg l-1
, 650 mg
l-1
took around 240 min for complete removal. This study demonstrates the utilization
of aerobic granulation for treating high concentration of phenol and other xenobiotics.
Keywords: Granules, Degradation, Sequential batch reactor, Aerobic sludge.
Introduction
Various industries such as oil refineries, petrochemical plants, coke
conversion, pharmaceuticals and resin industries produces many toxic substances as
their effluent, phenol being one of it. Phenol is also most frequently found pollutant in
rivers and land fill runoff water (Prasad and Ellis, 1978). Phenol concentration of up
to10 000 mg l-1
has been reported in much industrial waste water (Fedorak and
Hrudey, 1988).
Phenol is toxic at relatively low concentrations and is listed as priority
pollutants by the United States Environment Protection Agency (Ghisalba, 1983). The
toxicity of phenol often results in the reduction of wastewater biotreatment even at
relatively low concentration (Hinteregger et al., 1992).
A wide range of adverse effects have been reported following well
documented human exposure to phenol by dermal, oral or intravenous routes. Phenols
are also toxic to some aquatic species at low concentration as low as 1 mg l-1
(Brown
Environment & We
An International
Journal of Science
& Technology
Available online at www.ewijst.org
ISSN: 0975-7112 (Print)
ISSN: 0975-7120 (Online)
Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
124
et al., 1967) and far lower concentration caused taste and odor problem in drinking
water (Rittmann and McCarty, 2001). Hence the removing phenol is significant.
For the removal of aromatic compounds from the ground water various
physical, chemical and biological methods are used (Strier et al., 1980; Atlas et al.,
1981; Kobayashi et al., 1982; National Academy of Sciences 1983; Gills et al., 1986).
Biological methods have advantage over physical and chemical methods. In chemical
and physical methods the intermediate formed are even more toxic than the original
compounds (Strier et al., 1980 and Gils et al., 1986). In the case of phenol the use of
non biological methods like solvent extraction, mineralization etc. suffers from high
cost and formation of hazardous by-products (Loh et al., 2000). Because of lower cost
and possibility of complete mineralization and complete oxidation to carbon di oxide
and water, biological methods are most commonly used. Phenolic wastewater is
treated in activated sludge process. This system is sensitive to high phenol loading
rates and to fluctuations in phenol loadings (Kibret et al., 2000 and Watanabe et al.,
1999). These difficulties arise because of substrate inhibition, whereby growth (and
consequently phenol degradation) is inhibited because of phenol toxicity.
The inhibition difficulties associated with high strength phenolic wastewater
can be overcome by strategies such as bioagumentation (Watanabe et al., 2002) and
the other one is cell immobilization (Keweloh et al., 1989). Aerobic granulation
technology (a cell immobilization technique) has been developed for treating a wide
variety of wastewaters (Peng et al., 1999; Moy et al., 2002; Lin et al., 2003; Yang et
al., 2003). This technology is also been extensively investigated (Morgenroth et al.,
1997; Beun et al., 1999; Tay et al., 2001; Liu and Tay 2004). Most studies have either
focused on granule cultivation through various substrates or treating efficiency of
various granule processes (Arrojo et al., 2004; Kim et al., 2004; McSwain et al., 2004;
Wang et al., 2004; Hu et al., 2005).
Aerobic granulation represents a cell immobilization technology that has
attracted recent research attention (Tay et al., 2001, 2002). Without the inert support
for biofilm attachment aerobic granules that are microbial aggregate are cultivated in
SBR. The compact microbial structure can confer on aerobic granules the good
settleability and the high biodegradation capacity for toxic and recalcitrant
compounds (Jiang et al., 2002; Tay et al., 2005a; Yi et al., 2006). Flocculated
activated sludge fed with phenol as sole carbon source aerobic granules has been
successfully cultivated (Jiang et al., 2002). With the kinetic data it is indicated that
phenol degrading aerobic granule have potential to treat wastewater with high phenol
loading and also possess highly active compact structure and good settleability.
The main object of this work is to study the aerobic degradation profile of
phenol through an aerobic granulation technology by a sequential batch reactor
(SBR).
Materials and Methods
Reactor set up and operation
A column type sequential aerobic sludge blanket reactor (5 cm diameter and
150 cm high) made of transparent perfex glass with total volume of 1.5 l (working
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
125
volume 1.4 l) was used. The reactor was housed in a thermostat at about 30±20C. The
reactor was fed with phenol as a sole carbon source and was left open for the growth
of natural mixed population. At the bottom of column fine bubble aerator was fitted
for supplying air at superficial air velocity of 2.67 cm s-1
. Reactor was operated
sequentially in 4 hrs cycle (2 min of influent filling, 205-230 min of aeration, 2-30
min of settling and 5 min of effluent withdrawal). To avoid excess loss of sludge, the
reactor was initially operated at high settling time of 30 min. Later the settling time
was reduced to 10 min and finally to 2 min. At the initial stage, feeding time was kept
high which was decreased gradually as the operation proceeds. The reactor set-up
included two sampling port, arranged along the height of column type reactor, one at a
distance of 70 cm and, other at 30 cm from the bottom of the reactor. The effluent was
withdrawn through 70 cm port at a volumetric exchange ratio of 50% giving a
hydraulic retention time (HRT) of 8 hrs. The HRT of 8 hrs was kept constant during
the analysis. Port at 30 cm height was used for the collecting samples for
MLSS/MLVSS determinstion and periodical sludge wasting. The operation proceeded
with abiotic losses of phenol which were negligible under identical operation
condition.
Seed sludge and wastewater
The source of aerobic digested sludge with mixed liquor suspended solid
(MLSS) and mixed liquor volatile suspended solid (MLVSS) content of 3.5 gm l-1
and
0.43 gm l-1
respectively was taken from secondary clarifier of Star Paper Mills
Saharanpur, India. For the period of first 15 days, it was conditioned in an aeration
tank where the content was fed with phenol as an only source of carbon along with
nutrient (Jiang et al., 2002) and micronutrient (Moy et al., 2002). The acclimatization
towards phenol was done in a high precision water bath at a temperature of 30±20C.
After the period of acclimatization, the aeration tank was fed in sequential batch
reactor and started with 50 mg l-1
phenol in mineral salt medium which was gradually
increased to 650 mg l-1
in a stepwise process.
Wastewater feed
A stock solution of phenol was prepared having concentration of 10 gm l-1
(10000 mg l-1
). The desired concentrations of phenol for experiments were obtained
by proportionate dilution with double distilled water and fed into SBR along with
nutrients solution) with following composition (Moy et al., 2002) Table 1. Stock
solution of micronutrients was prepared at 1 000 times concentration (Table 1). For
optimal growth 1 ml of this solution was added to the feed solution. SBR was
operated at a constant temperature of 30±20C and the pH was maintained at around
7.5-7.7 throughout the study.
Microbial granulation depends upon factors such as pH and temperature. A
slight alkaline pH (around 7.5) is also necessary for proper aerobic granulation and
granulation cease to occur at pH> 8.5 as reported by (Hailei et al., 2006). Yang et al.,
(2008) reported that a slight low pH favors fungi dominating granules where as a
slight alkaline pH favors bacterial granules. Temperature change also affects the
reactor performance upto a certain degree. Song et al., (2009) reported that 300C is
optimum temperature for matured granule cultivation.
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
126
Table 1 Nutrients composition as given by Moy et al., 2002.
Nutrients Amount required (gm l-1
)
Macro Nutrients
KH2PO4 1.35
K2HPO4 1.65
MgSO4.7H2O 0.13
NH4Cl 0.20
Micro Nutrients
H3BO3 0.05
ZnCl2 0.05
CuCl2 0.03
MnSO4.H2O 0.05
Mo7O24.4H2O 0.05
AlCl3 0.05
CoCl2.6H2O 0.05
NiCl 0.05
Analytical Methods
Measurement of pH, suspended solids, mixed liquor suspended solids
(MLSS), mixed liquor volatile suspended solids (MLVSS), chemical oxygen demand
(COD) were conducted in accordance with the Standard Methods (APHA, 1998). The
phenol concentrations were determined spectrophotometrically using the absorbance
values at 500 nm λmax with a UV/VIS spectrophotometer (GENESYS 20,
Thermospectronic) according to APHA 1995.
Optical density (O.D.600) was calculated using UV/VIS spectrophotometer at
600 nm as specified by Ziagova et al., 2007. O.D. 600 gives density of the microbes
present in the SBR. All the experiments were performed in duplicate.
Morphology and surface structure of granules were observed qualitatively
with a scanning electron microscope (STEREO SCAN 360). Granules were prepared
for SEM image by washing with a phosphate buffer and fixing with 2%
glutaraldehyde overnight at 40C. Fixed granules were washed with 0.10 M sodium
cacodylate buffer, dehydrated by successive passages through 25, 50, 75, 80, 90, 95
and 100% ethanol and dried with a CO2 Critical Point Dryer.
Result and Discussion
Phenols are most common compounds, distributed in waste discharge of pulp
and paper industries. The microorganisms are already acclimatized for phenol and its
derivatives through natural selection. In our experiment conditioning period was
reduced due to already acclimatized sludge. This is the reason for choosing the
aerobic sludge from Star Paper Mills Saharanpur, India. However, for getting more
specific microbes, the sludge was initially acclimatized for about 15 days to allow
biomass to adopt phenol. The SBR cycle was performed 45 days.
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
127
Microbial density in SBR system (O.D.600)
Optical density (O.D. 600) gives the density of microbes present in the SBR.
Figure 2 shows the O.D.600 of the acclimatized sludge is around 0.63 which increases
after inoculating in to SBR. This acclimatized sludge shows two sharp decreases on
day 13 and day 23 due to reduction settling time from 30 to 10 min and from 10 to 2
min. From first day to day 12, when the settling time was 30 min, O.D.600 increases
from 0.63 to 0.82, but on day 13 when the settling time was reduced to 10 min the
O.D.600 of SBR decreases to 0.69 and then increases gradually up to day 22 with same
settling time. There is again a decrease in the in the value of O.D.600 to 0.98 on day 23
due to reduction in settling time to 2 min and then the value of O.D.600 increases for
rest of the cycle till day 38 and then stabilized at 1.65.
Figure 1 Sequencing batch reactor (SBR) design principle.
Shape and Size of Microbial Granule
In SBR stable granule were obtained. Stable granules were compact and strong
but not much spherical. However, high degradation efficiency of granules is due to
their compact structure (Khan et al., 2009) and not effected by their shape. It has also
been proved earlier that granules have a high resistant to toxic xenobiotic due to their
compact structure (Glancer et al., 1994; Jiang et al., 2002, Tay et al., 2005b, Bergsma-
vlami et al., 2005) The diameter of formed granules is about 1-2 mm. Figure 3 shows
close packed structures with evenly distributed channels which facilitates movement
of waste water inside the granules.
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
128
0 5 10 15 20 25 30 35 40 45
0.6
0.8
1.0
1.2
1.4
1.6
1.8
SB
R O
.D. 6
00
Days
Figure 2 O.D.600 of SBR during degradation of Phenol.
Effluent and Influent concentration
Figure 4 shows concentration graph of effluent and influent with respect to
number of days. According to the graph, initially the concentration of effluent is high
27.56 mg l-1
due to the absence of compact granules although the concentration of
influent added was quite low 52 mg l-1
. The concentration of effluent did not
decreases remarkably in the first few days of the SBR cycle but decreases gradually
for the rest of the cycle inspite of being increase in the influent concentration from 52
to 656 mg l-1
.
Effluent and Influent COD (mg l-1
)
Figure 5 shows COD graph of effluent and influent Vs days. This graph
shows that initially, the COD of effluent was high 215 mg l-1
even though the COD of
influent was 516 mg l-1
, because the lack of stability in aerobic granules. After few
days of operation, compact granules were formed and the COD of influent was very
much high but the effluent COD was low. At the end of cycle, influent and effluent
COD were 7418 and 263.31 mg l-1
respectively.
Phenol Removal Profile
The degradation profile shows that initially the degradation of phenol was
high later on degradation rate decreases till the end of cycle (Figure 6). This is due to
the fact that initially microorganism has large amount phenol available, which is food
for them, so they degrade it faster in the beginning. During the first 60 min of 240 min
cycle (with 50% volumetric exchange giving 8 hrs HRT) sufficient amount of phenol
was removed but in next 180 min its concentration reduces to as low as 2 mg l-1
.
Figure 4 also shows that concentration of 50, 100 mg l-1
of phenol decreases to below
detection limit in just 150 min but high concentration of phenol (200, 400, 650 mg l-1
)
took around 220-230 min for complete removal. Just after addition of influent, a sharp
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
129
decrease in phenol concentration was observed (as shown in Figure 6 first 20 min),
this is due to dilution.
Figure 3. SEM image of mature granule at 15000 magnifications.
0 10 20 30 40 50
0
100
200
300
400
500
600
700
Co
nce
ntr
ati
on
(m
g l
-1)
Days
Influent
Effluent
Figure 4 Concentration of Effluent and Influent VS time.
COD Removal Profile
Similarly the removal rate of COD was high in the beginning but later on it
goes on decreasing. Just after addition of influent in the SBR there is sharp decrease
in COD which is attributed to dilution but this value of COD further increases to give
COD concentration below 50 mg l-1
by microbial action (Figure 7).
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
130
0 10 20 30 40 50
0
1000
2000
3000
4000
5000
6000
7000
8000
CO
D (
mg
l-1
)
Days
Influent
Effluent
Figure 5 COD of Effluent and Influent Vs Time.
COD Removal Efficiency with Phenol Concentration
Figure 8 illustrates that COD removal efficiency increases with phenol
concentration and attains maxima (94.54%) at 600 mg l-1
. This is because at high
concentration of phenol, influent COD was itself very high hence high removal
efficiencies were achieved by using the following formula
% COD removal = [(Influent COD - Effluent COD) / Influent COD] * 100
However, at very high concentration of phenol, removal efficiency decreases
owing to microbial inhibition caused by high substrate concentration.
Biomass Concentration (MLSS and MLVSS)
The initial sludge has MLSS concentration of 3.5 gm l-1
and MLVSS of 0.43
gm l-1
. After conditioning period, MLSS increases 5.2 gm l-1
and MLVSS to 0.82 gm
l-1
. Then the sludge was inoculated in to SBR for the cultivation of aerobic granules.
Aerobic granules developed along with amorphous flocs were first observed after 10
days of inoculation. However the biomass concentration of MLSS and MLVSS
reduces to 3.5 gm l-1
and 0.94 gm l-1
due to reduced settling time from 30 min to 10
min. The biomass with small settling velocity had been washed out of the reactor.
Small granules grew rapidly in subsequent week, while more floc like sludge washed
out from reactor gradually. The MLSS and MLVSS concentrations increases till 5.6
gm l-1
and 2.1 gm l-1
and again shows a sharp decrease, due to decrease in settling
time from 10 to 2 min on day 23. The granules become dominant form of biomass as
evident from gradual increase in biomass concentration beyond day 24. MLSS and
MLVSS concentration finally shows an upward trend and stabilizes at 7.3 gm l-1
and
4.1 gm l-1
(Figure 9).
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
131
0 50 100 150 200 250
0
100
200
300
400
500
600
700
50 mg l-1
100 mg l-1
200 mg l-1
400 mg l-1
650 mg l-1
Time (min)
Ph
eno
l R
emo
va
l (m
g l
-1)
Figure 6 Concentration profile of phenol during single cycle.
0 50 100 150 200 250
0
1000
2000
3000
4000
5000
CO
D (
mg
l-1
)
Time (min)
50 mg l-1
100 mg l-1
200 mg l-1
400 mg l-1
650 mg l-1
Figure 7 COD removal profile of phenol during single cycle.
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
132
0 100 200 300 400 500 600 700
78
80
82
84
86
88
90
92
94
96
Per
cen
t C
OD
rem
ov
al
Phenol Concentration (mg l-1
)
Figure 8 COD removal efficiency VS phenol concentration.
0 5 10 15 20 25 30 35 40 45
0
1
2
3
4
5
6
7
8
Bio
ma
ss C
on
cen
tra
tio
n (
gm
l-1
)
Days
MLSS
MLVSS
Figure 9 Variation of MLSS and MLVSS concentration of Phenol during its
degradation
Conclusion
This study illustrate that compact aerobic granule cultivated in SBR can
tolerate fluctuation in COD load of 1000 mg l-1
and higher COD load of 7500 mg l-1
.
Optical density (O.D. 600) of SBR system was stabilized at 1.65 which shows
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
133
maximum retention of biomass. The concentration and COD of influent and effluent
shows that after the formation of compact granule phenol degradation was more
efficient. The COD removal efficiency was above 94%. Degradation profile illustrates
that during first hour of cycle removal rate of phenol and COD were very fast but later
on becomes slow. MLSS and MLVSS stabilized at 7.3 gm l-1
and 4.1 gm l-1
. The
process appears very useful for treating waste water containing phenols and other
toxic xenobiotics. This technology is advantageous as the same biomass can be used
over a long period. This technology can withstand high organic load as well as
fluctuation in organic load so it can be exploited for treating high strength municipal
and industrial waste both.
Acknowledgments
Authors wish to thank Prof. (Mrs.) A. Lal, Chairperson, Department of
Chemistry for providing necessary research facilities. F.K. and M.Z.K. thank UGC for
providing fellowship.
Authors' contributions: Farah Khan performed experiment, wrote the manuscript and peformed
calculations; and Mohammad Zain Khan performed a portion of experiment and helped in the
calculations and Dr. Suhail Sabir (Associate Professor), contributed in experiment design and final
editing of the manuscript;
References
APHA, 1995. Standard methods for the examination of water and wastewater. 19th
edition, American Public Health Association: Washington, D.C.
APHA, 1998. Standard methods for the examination of water and wastewater. 20th
edition, American Public Health Association: Washington, D.C.
Arrojo, B., Mosquera Corral, A., Garrido, J. M., Mendez, R, 2004. Aerobic
granulation with industrial wastewater in sequencing batch reactors. Water
Research, 38, 3389-3399.
Atlas, R. M. 1981. Microbial degradation of petroleum hydrocarbons: an
environmental perspective. Biotechnology Bioengineering, 36, 539-545.
Beun, J. J., Hendriks, A., Van Loosdrecht, M. C. M., Morgenroth, E., Wilderer, P. A.,
Heijnen, J. J., 1999. Aerobic granulation in a sequencing batch reactor. Water
Research 33, 2283–2290.
Brown, V. M., Jordan, D. H. M., Tiller, B. A., 1967. The effect of temperature on
acute toxicity of phenol to rainbow trout in hard water. Water Research, 1,
587-589.
Fedorak P. M., Hrudey S. E, 1988. Anaerobic degradation of phenolic compounds
with application to treatment of industrial waste waters In: Wise DL (ed)
Biotreatment systems, vol 1.CRC, Boca Raton, pp 170-212.
Ghisalba, O, 1983. Microbial degradation of chemical waste, an alternative to
physical methods of waste disposal. Experientia 39, 1247-1257.
Gills, G. V., Pirbazari, M., 1986. Development of a combined ultrafiltration and
carbon adsorption system for industrial wastewater reuse and priority pollutant
removal. Environmental Programs, 5, 167-170.
Hailei, W., Guangli Y., Guosheng L., Feng P., 2006. A new way to cultivate aerobic
granules in the process of papermaking wastewater treatment, Biochemical
Engineering Journal 28, 99-103.
Hinteregger, C., Leitner, R., Loidl, M., Fersh, A., Streichsbir, F., 1992. Degradation
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
134
of phenol and phenolic coMSMounds by pseudomonas putida EKI. Applied
Environmental Microbiology, 37, 252-259.
Hu, L., Wang, J., Wen, X., Qian, Y., 2005. The formation and characteristics of
aerobic granules in sequencing batch reactor (SBR) by seeding anaerobic
granules. Process Biochemistry, 40, 5-11.
Jiang, H. L., Tay, S. T. L., 2002. Aggregation of immobilized activated sludge cells
into aerobically grown microbial granules for the aerobic biodegradation of
phenol. Letter in Applied Microbiology, 35, 439-445.
Keweloh, H., Heipieper, H. J., Rehm, H. J., 1989. Protection of bacteria against
toxicity of phenol by immobilization in calcium alginate. Applied
Microbiology and Biotechnology, 31, 383–389.
Khan F., Khan M. Z., Shams Q. S., Sabir Suhail. (2009). Biodegradation of phenol by
aerobic granulation technology. Water Science and Technology, 59 (2), 273-
278.
Kibret, M., Somitsch, W., Robra, K. H., 2000. Characterization of a phenol degrading
mixed population by enzyme assay. Water Research, 34, 1127–1134.
Kim, S. H., Choi, H. C., Kim, I. S., 2004. Enhanced aerobic floc-like granulation and
nitrogen removal in a sequencing batch reactor by selection of settling
velocity. Water Science and Technology, 50, 157-162.
Kobayashi, H., Rittman, B. E., 1982. Microbial removal of hazardous organic
compounds. Environmental Science and Technology, 14, 28-31.
Leahy, J. G., Colwell, R. R., 1990. Micobial degradation of hydrocarbons in the
environment. Microbiology Review, 54, 305-315.
Lin, Y. M., Liu, Y., Tay, J. H., 2003. Development and characteristics of phosphorous
accumulating microbial granules in sequencing batch reactors. Applied
Microbiology and Biotechnology, 62, 430-435.
Liu, Y. Q, Liu, Y, Tay, J. H., 2004b. The effects of extracellular polymeric substances
on the formation and stability of biogranules. Applied Microbiology and
Biotechnology, 65, 143-148.
Loh, K. C, Chung, T. S, Ang, W. F., 2000. Immobilized-cell membrane bioreactor for
high-strength phenol wastewater. Journal of Environmental Engineering, 126,
75–79.
McSwain, B. S, Irvine, R. L., Wilder, P. A., 2004. The influence of settling time on
the formation of aerobic granules. Water Science and Technology, 50, 195-
202.
Morgenroth, E., Sherden, T., van Loosdrecht, M. C. M., Heijnen, J. J., Wilderer, P.A.,
1997. Aerobic granuler sludge in a sequencing batch reacter. Water Research
31, 3191-3194.
Moy, B. Y. P., Tay, J. H., Toh S. K., Liu, Y., Tay, S. T. L., 2002. High organic
loading influence the physical characteristics of aerobic granules. Letter in
Applied Microbiology, 34, 407–412.
National Academy of Sciences, 1983. Polycyclic aromatic hydrocarbons: evaluation
of sources and effects. National Academy Press, Washington, DC.
Peng D, Bernet N, Delgenes J. P., Moletta R., 1999. Aerobic granular sludge- a case
report. Water Research, 33, 890-3.
Prasad, S., Ellis, E., 1978. In vivo characterization of catechol ring cleavage in cell
cultures of Glycine max. Phytochemistry 17, 187-190.
Rittmann B. E., McCarty P. L., 2001. Environmental Biotechnology: Principles and
Applications, New York: McGraw-Hill.
Song, Z., Ren, N., Zhang, K., Tong, L. J., 2009. Influence of temperature on the
Khan et al. / Environ. We Int. J. Sci. Tech. 5 (2010) 123-135
135
characteristics of aerobic granulation in sequencing batch airlift reactors.
Journal of Environmental Science China, 21, 273-278.
Strier, M. P., 1980. Pollution treatability: a molecular engineering approach.
Environmental Science and Technology, 14, 28-31.
Tay, J. H., Liu, Q. S., Liu, Y., 2001. The effect of shear force on the formation,
structure and metabolism of organic granules. Applied Microbiology and
Biotechnology, 57, 227-233.
Tay, J. H., Liu, Q. S., Liu, Y., 2001. The effect of upflow air velocity on the structure
of aerobic granules cultivated in sequential batch reactor. Water Science and
Techonology, 49, 35-40.
Tay, J. H, Jvanov, V, Yi, S, Zhuang W. Q., Tay J. H, 2002. Presence of anaerobic
Bacteroides in aerobically grown microbial granules. Microbiology Ecology,
44, 278-285.
Tay, S. T. L., Zhuang, W. Q. Tay J. H., 2005a. Start –up, microbial community
analysis and formation of aerobic granules in a tert-butyl alcohol degrading
sequencing batch reactor. Environmental Science and Technology, 39, 5774-
5780.
Wang, Q. Du, G, Chen J., 2004. Aerobic granular sludge cultivated under the
selective pressure as a driving force. Process Biochemistry, 39, 557-563.
Watanabe, K., Teramoto, M., Harayama, S., 1999. An outbreak of nonflocculation
catabolic populations caused the breakdown of a phenol-digesting activated
sludge process. Applied and Environmental Microbiology, 65, 2813-2819.
Watanabe, K., Teramoto, M., Harayama, S., 2002. Stable augmentation of activated
sludge with foreign catabolic genes harboured by an indigenous dominant
bacterium. Environmental Microbiology, 4, 577-583.
Yang, S. F., Tay, J. H., Liu, Y., 2003. A novel granular sludge sequencing batch
reactor for removal of organic and nitrogen from waste water. Journal of
Biotechnology, 106, 77-86.
Yang, S.F., X.Y. Li, H.Q., Yu, 2008. Formation and characterization of fungal and
bacterial granules under different feeding alkalinity and pH conditions,
Process Biochemistry, 43, 8–14.
Yi, S., Zhuang, W.Q, Wu, B., Tay, S. T. L., Tay, J. H., 2006. Biodegradation of p-
nitro phenol by aerobic granules in a sequencing batch reactor. Environmental
Science and Technology, 40, 2396-2401.
Ziagova, M. and Liakopoulou-Kyriakides, M. 2007. Kinetics of 2,4-dichlorophenol
and 4-Cl-m-cresol degradation by Pseudomonas sp. cultures in the presence of
glucose. Chemosphere, 68, 21-927.
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