68
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
decreased a little, which can be explained by
the fact that sufficient substrate concentration
promoted microbial energy metabolism process
to recover growth activity of heterotrophs with
the increase of organic loading. It should be
indicated in particular that filamentous gradu-
ally become dominant bacteria during recovery,
resulting in growth of nitrifiers restrained
eventually. Meanwhile, nitrifying bacteria were
washed out of the system with broken granules
because of the deterioration of granules settling
performance, and then resulted in the decrease
of NH
4
+
-N removal rate gradually. The removal
efficiency of NH
4
+
-N decreased to the lowest,
only 62.58%, when influent ammonia nitrogen
concentration was 75 mg l
-1
. With filamentous
bacteria effectively controlled, particle size of
aerobic granules increased and compacted
gradually with nitrifiers constantly fixing in
all parts of the granule interior, and finally re-
sulted in presenting different metabolic function
of aerobic granules and forming a distinctive
structural features. Thereafter, removal effi-
ciency of NH
4
+
-N increased constantly with the
continued increase of influent organic and am-
monia nitrogen loading. On cycle 64, removal
rate of NH
4
+
-N reached to 84.35%, and this time
aerobic granules in SBR had reached the treat-
ing loading before storage. The final ammonia
removal rate was stable at about 85% at 225 mg
l
-1
of influent concentration. Result demonstrates
that nitrifying property of hypersaline aerobic
granules has been recovered.
Conclusions
The apparent structure of granules basically
remained an initial shape after storage, while
the colors had turn to gray white or light yel-
low and structure had translated to loose. The
stored aerobic granules experienced a process
of particle disintegration, fragmentary particles,
filamentous bacteria-like particles, and dense
granules during more than one month recov-
ery, and finally developed smooth and compact
granules during reactivation. Meanwhile, set-
tling performance of granules experienced a
process of expansion and recovery. Some effec-
tive strategies had been adopted in this study,
such as properly adding influent water alkalin-
ity, increasing aeration rate, shortening settling
time and others, and then decentralized growth
pattern of granules was availably controlled in
the following operation phase, resulting in the
recovery of settling property of granules. SVI
was finally stable at 34 mg l
-1
and MSV was high
to 3.83 m h
-1
. Experiencing more than one-month
re-cultivated, activity of hypersaline aerobic
granules were completely recovered. DHA of
stored granules was relatively low and only 1/8
of initial level, while nitrifying characteristic can
resume in a short time. After one-week opera-
tion, DHA gradually improved to the maximum
of 48.9 ugTF g
-1
SS h
-1
with the dispersive growth
of granules, whereas nitrifying bacteria were
continuously washed out from the system due
to sludge bulking, resulting in a gradual drop
of nitrification performance. When filamentous
was controlled effectively during the following
re-cultivated, nitrifying bacteria bred to strength
the nitrification characteristic to a certain extent,
and removal rate of NH
4
+
-N was finally stable
at about 85%. At the same time, DHA declined
a little and maintained around 38 ugTF g
-1
SS h
-1
.
Acknowledgment
The research was supported by Scientifical & Technologi-
cal Research Project of Chongqing Education Commission
(No. KJ110403), Research Plan of National Engineering
Research Center for Inland Waterway Regulation (No.
NERC2014B06) and Chinese Scholarship Council (CSC)
(Grant No. 201508505098).
References
Adav, S. S., Lee, D. J., & Tay, J. H. (2007). Activity and
structure of stored aerobic granules.
Environ
.
Technol
., 28,
1227-1235.
Adav, S. S., Lee, D. J., Show, K. Y., & Tay, J. H. (2008). Aerobic
granular sludge: Recent advances.
Biotech
.
Adv
.,
26
(5),
411-423.
APHA (2005).
Standard methods for the examination of water
and wastewater
(21st ed.). Washington, DC: American
Public Health Association.
