62
Tecnología y Ciencias del Agua
, vol. VIII, núm. 2, marzo-abril de 2017, pp. 61-70
Chen
et al.
,
Reactivation of hypersaline aerobic granular sludge after low temperature storage
•
ISSN 2007-2422
2013). Therefore, it has been widely applied to
the treatment of industrial wastewater
(Adav,
Lee, Show, & Tay, 2008; Moussavi, Barikbin, &
Mahmoudi, 2010; Taheria, Khiadani, Amina,
Nikaeen, & Hassanzadeh, 2012; Rosman,
Anuar, Chelliapan, Md Din, & Ujang, 2014).
However, during the reactor operating, there
is idle frequently in aerobic granular sludge
system because of accidents or other causes,
and then granules will lose activity easily dur-
ing long-term idle process. Thus it has a great
significance to study the storage and activity
recovery of aerobic granular sludge in its en-
gineering application. In particular, the success
development of storing aerobic granular sludge
can extend application of aerobic granules as
inoculums for rapid startup, and as microbial
supplement to enhance treatment of bioreactor
systems. There are reports on the reactivation
of aerobic granular sludge and results have
showed that aerobic granular sludge has a good
stability and resiliency after the thawed gran-
ules have to be recovered successfully, and the
activity of revived sludge can even return to the
level of original state (Adav, Lee, & Tay, 2007;
Lee, Chen, Show, Whiteley, & Tay, 2010; Gao,
Yuan, & Liang, 2012; Lv
et al
., 2013). However,
to the authors’ knowledge, there are no reports
concerning the reactivation of aerobic granules
after thawing under high salt stress.
In order to solve the problem mentioned
above, high salt aerobic granules, which were
cultivated successfully in laboratory scale
column-type sequencing batch reactor (SBR)
operating with synthesis saline wastewater
(the NaCl content of 3%, calculated as weight
to volume) in previous study, was took out
to be washed by distilled water several times
to remove the substrate on the surface of the
granules, and then transferred into the polypro-
pylene plastic bottles and kept in storage at 4 °C.
After six-week storage in low temperature, the
thawed aerobic granules were re-cultivated by
controlling the organic loading to investigate the
reactivation process of granules in this study.
The aim of this study was expected to provide
theoretical support for aerobic granular sludge
as a novel technique for the biological treatment
of saline wastewater in practical engineering.
Materials and methods
Reactor set-up
The column-type SBR reactor used in this
study was made of Plexiglas (internal diameter
of 4.8 cm, high of 105 cm and H/D ratio was
22) giving an operation volume of 1.9 L. Bot-
tom aeration of the reactor was supplied by air
pump, and the aeration rate was controlled to
meet different level of dissolved oxygen (DO)
in different experimental period. The reactor
was operating for 12 h per cycle at a volumetric
exchange ratio of 50%, included 2 min influent
(via the reactor top), 3 min discharge, aeration
and sedimentation for the remaining time, in
which, the time of aeration and sedimentation
should be adjusted to operating condition.
The reactor controlled the temperature
needed in different reactivation of aerobic
granular sludge by a heater, and a program-
mable logic controller was used to actuate and
control the pump, heater, and the operating
cycle. Inoculated sludge was provided from
hypersaline aerobic granules (Chen, Yang, & Yu,
2013) in previous study, which were formatted
from flocculent sludge in SBR reactors after
more than two-month culture under high salt
content of 3%. Detailed information about the
characteristics of aerobic granules in this study
is shown in table 1.
Synthetic substrate
In this test, each column was dosed with simu-
lated wastewater, the compositions of which
fed to the reactor were as follows: 3% of salt
content, 849-4245 mg of glucose (900-4500 mg
l
-1
as chemical oxygen demand (COD) basis),
21.9-109.6 mg of KH
2
PO
4
(5-25 mg l
-1
as PO
4
3-
-P
basis), 171.7-858.8 mg of NH
4
Cl (45-225 mg l
-1
as
NH
4
+
-N basis), 266.7-1333.3 mg of MgSO
4
·7H
2
O
(26-130 mg l
-1
as Mg basis), 55.4-277 mg of CaCl
2
