Biomedical Engineering Reference
In-Depth Information
Chapter 14
D
EACTIVATION AND
R
EJUVENATION
OF
P
HOSPHORUS
A
CCUMULATING
O
RGANISMS
IN THE
P
ARALLEL
AN/AO P
ROCESS
Hong-bo Liu
1,2,*
and Si-qing Xia
2
1
Rhine-Main Water Research Institute, Justus-von-Liebig-Str.10, 64584 Biebesheim am
Rhein, Germany
2
State Key Laboratory of Pollution Control and Resource Reuse, Tongji University,
200092 Shanghai, P. R. China
Abstract
The parallel AN/AO process, first proposed by the authors to efficiently use denitrifying
phosphorus removing bacteria, was briefly introduced in the paper. Deactivation of
phosphorus-accumulating organisms (PAO) occurred in the process when its SRT (Sludge
Retention Time) and HRT (Hydraulic Retention Time) were too long, i.e. SRT and HRT were
30d and 18h respectively. PAO deactivation was observed also in three anaerobic-anoxic SBR
reactors fed with different COD/NO
3
-
-N synthetic wastewater using seed sludge from the
parallel AN/AO process. Possible factors that could cause PAO deactivation such as pH,
temperature, internal/external return ratio, SRT, HRT, DOC (Dissolved Organic Carbon) at
the beginning of anoxic stages and NO
3
-
-N concentration at the beginning of anaerobic stages
were studied. Results showed that SRT and HRT were main factors accounting for PAO
deactivation occurrence in the parallel AN/AO process while DOC concentration at the
beginning of anoxic stages and NO
3
-
-N concentration at the beginning of anaerobic stages
were main factors influencing PAO activity in the anaerobic-anoxic SBR reactors. PAO
rejuvenation occurred in both configurations shortly after main influencing factors were reset
to right values: PAO was rejuvenated by adjusting SRT and HRT to 15d and 9h respectively
for the parallel AN/AO process; by controlling DOC at the beginning of anoxic stages and
NO
3
-
-N concentration at the beginning of anaerobic stages lower than 3 mgL-1 and 2.3 mgL-1
respectively could rejuvenate PAO in anaerobic-anoxic SBR reactors.
Keywords:
Enhanced Biological Phosphorus Removal (EBPR); Parallel AN/AO process;
Phosphorus-accumulating organisms (PAO); PAO inactivation; PAO rejuvenation
*
E-mail address: lhb_7906@163.com Tel: +49(0)6925490-8015 Fax: +49(0)6925490-8009. (Corresponding author)
