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Day 0 Day 63 Day 120 Day 185
0.00
0.05
0.10
0.15
0.20
0.25
10 15 20 25 30 35
NO
B a
ctiv
ity (
g N
/(g
VSS d
))
Temperature (ºC)
Total
Flocculent fraction
Granular fraction
0.00
0.01
0.02
0.03
0.04
0.05
0
20
40
60
80
100
0 50 100 150 200
NO
R (
g N
/(L d
))
Tota
l N
itro
gen
Rem
oval
(%
)
Time (d)
TN removal
NOR
AOB
NOB
Anammox
Secondary settlerAerobic SRT: 2 d
Anaerobic digester
Digested Sludge
Biogas
Annammox based processes unit
Annammox based processes unit
Reject Water
Modifications of a conventional WWTP
with the inclusion of ELAN® process
Primary settler Mainstream
T 15º C80% of total N
NH4
+ 50 mg N/L
Sidestream
T 30º C20% of total N
NH4
+ 1000 mg N/L
AOBNOBAnammox
NOB activity suppression in the anammox based process ELAN® applied to the water line of a WWTP
Acknowledgments:
This work is enclosed in the ITACA project which is funded by the Spanish Ministry of Economy
throught the DCTI INNPRONTA program. The authors belong to the Galician Competitive Group
GRC 2013-12
Referents:
[1] Volcke et al. (2010), Enviromental Technology, 31(11), 1271-1280
[2] Vázquez-Padín et al. (2014), Wter Sciencie and Technology, 69 (6), 1151-1158
Introduction and Objective
Materials and Methods
Results
A. Val del RíoJ.L. CamposA. Mosquera-Corral
R. Méndez
Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain. e-mail: [email protected], Tel.: +34 881816739
involves the reduction of the aeration costs, diminishes the sludge production [1]
and reduces the need of organic carbon for denitrification.
sludge anaerobic digesters that normally accounts for 20% of the total nitrogen in
a WWTP.
is applied to the mainstream line of a WWTP: the low a mmonia concentration and
the low temperatures of municipal wastewater.
Objective: the present work is focused on the study of the feasibility of the ELAN®
(“ELiminación Autótrofa de Nitrógeno”) process applied to the main stream of a
WWTP. The ELAN® process consists of a one-stage autotrophic nitrogen removal
process based on granular biomass.ELAN®: Partial nitrification + anammox in a single stage with granular biomass
REACTOR: A laboratory scale sequencing batch reactor (SBR)
with a useful volume of 4 L was operated in cycles of 3 hours
comprising: 150 min of feeding+aeration+stirring, 28 min of
settling and 2 min of withdrawal.
FEEDING: Supernatant from an anaerobic sludge digester diluted
to simulate an urban wastewater, which COD was previously
removed. The average ammonia inlet concentration was 50 mg
NH4+-N/L.
The applied nitrogen loading rate (NLR) was of 0.10 g NH4+-N/L·d
and the hydraulic retention time (HRT) of 0.5 days.
INOCULUM: 9 g VSS/L of granular biomass from an ELAN® pilot
plant [2] treating reject water from a anaerobic digester of a
municipal WWTP.
N. Morales J.R. Vázquez-Padín R. Fernández-González
Aqualia (FCC Group), Guillarei WWTP, Camino de la Veiga s/n, E-36720 Tui, Spain
Parameter Stage I Stage II Stage III
Days 0 – 40 41 – 170 171 – 220
Settling velocity imposed (m/h) 0.13 0.13 0.36
VSSreactor
(g/L) 10.4 ± 2.4 10.5 ± 1.8 11.7 ± 1.7
Average granules diameter (mm) 2.4 ± 0.1 2.4 ± 0.2* -
NOB activity mainly present on the flocculent fraction
Biomass evolution through the operational period (size bar 2 mm).
During the first 40 operational days with the granular
sludge the nitrogen removal efficiency achieved was
around 80%.
Nitrite oxidizing bacteria (NOB) were present in the
inoculum in a low proportion (2 – 3%), but with a
negligible activity at macroscopic scale.
The structure of the granular biomass was progressively
damaged and the detachment of biomass from the granule
surface occurred. The increase of the surface for oxygen
liquid-solid transfer promoted the access of NOB to the
substrates, and an increase of the nitrite oxidation rate
(NOR) was observed.
Biomass activity assays showed that NOB were more active
in the flocculent fraction than in the granular one.
An increase of the imposed settling velocity in the SBR
removed most of the NOB, which were mainly present in
the flocculent biomass. This action favored the recovery
of the nitrogen removal efficiency (from values of 20% to
60%).
An ELAN® reactor at pilot plant scale treating primary
settled wastewater is being operated in a municipal WWTP
in order to further assess the performance of the process.
Discussion and Conclusions
3
Thermostatic system
Air pump
Effluent
Feeding
11
9
8
2
1
5
4
6
7
Photograph of the laboratory
SBR and scheme of the
experimental set-up:
1.- Effluent pump.
2.- Influent pump.
3.- Dissolved oxygen indicator.
4.- Thermostatic bath.
5.- Gas diffuser.
6.- Air pump.
7.- Effluent port.
8.- Dissolved oxygen probe.
9.- Influent port.
10.- Recycled air port.
11.- Mechanical stirring
system.
S-I S-II S-III
Stage III: increase on the settling velocity imposed to remove the flocculent fraction characterized by a high NOB activity