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Start-Up of a decentralized pilot plant for the anaerobic treatment of domestic wastewater
Laura Fröba, Marisela Vega, Frauke Groß, Antonio Delgado 16.09.16
Objective of the study
industrial scale
200 m³/ d
2000 PE
pilot scale
2 m³/ d
20 PE
lab scale
0,014 m³/ d
2
- autarc wastewater treatment of small settlements and
megacities
- industrial scale (capacity: 200 m³/ d; PE 2000)
- saving drinking quality water by using service water
(saving potential about 60%)
service
water
domestic
wastewater
decentral easy to use
self-defined limit values
(AbwV 2016, BayBadeGewV 2008)
COD: 75 mg/l
NH4-N: 10 mg/l
TN: 13 mg/l
TP: 1 mg/l
E.coli 900 cfu/ 100 ml
anaerobicdomestic wastewater
COD: 200 mg/l
NH4-N: 40 mg/l
TN: 50 mg/l
TP: 5 mg/l
E.coli: 10^6 cfu/100ml
service
water
R1 R3Buffer
tank
anaerobic digestion Anammox post-treatmentpre-heating
domestic
wastewater R2
Pilot plant for treating domestic wastewater
• three stage biological process
• C-reduction: anaerobic digestion
reactor 1 (R1) and 2 (R2)
• N-reduction: anaerobic Ammonium Oxidation (Anammox)
reactor 3 (R3)
• pre-heating step due to mesophilic conditions (30°C-40°C)
• reactors: R1 + R3: anaerobic sequencing batch reactor
(1300 liters each) R2: fixed bed reactor
buffer tank reactor 1 reactor 2 reactor 3 sand filter activated carbon
5
Pilot plant for treating domestic wastewater
• installation in office container (28 m², H: 2.50 m)
flexible, modular and space efficient (decentral)
caustic
reactor 1
reactor 2
reactor 3post treatment
buffer
electrical
cabinet
5
• reactors were innoculated each with 60 liters of seeding
sludge
• R1+R2: sludge coming from a two-stage anaerobic
digestion plant (Obermichelsbach, GE)
• R3: sludge coming from a Deammonification
(DEMON)-System (Fulda, Gläserzell, GE)
Start-Up of the pilot plant
5
• start-up procedure
reactor 1 reactor 2 reactor 3
adaptation
phase
100% MWW
adaptation phase
100% MWW + organic acids
(acetic acid: propionic acid:
butyric acid in 2:1:1)
adaptation phase
100% SWW
(1000 liters of tab water added
with ammonia sulfate (40mg/l)
and sodium nitrite (50mg/l))stepwise interconnection of R1 and R2
to 33%, 50%, 75% and 100%
100%: no addition of organic acids to R2
stepwise interconnection of anaerobic digestion (outlet of R2) and R3
to 20%, 50%, 80% and 100%
100%: - no addition of ammonia sulfate to R3
- adjsutment of nitrite-nitrogen (NO2-N) to ammonia-nitrogen (NH4-N) ratio
(MWW: municipal wastewater, SWW: synthetic wastewater)
• testing of the three-stage pilot plant for
200 days of operation after start-up
feeding of 100% MWW
additive: sodium nitrite (R3)
Start-Up of the two-stage anaerobic digestion (R1 + R2)
6
(I) adaptation phase (R2) COD removal efficiency increased from 31% to 53%
0
10
20
30
40
50
60
70
80
90
100
075
150225300375450525600675750825900975
1050
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
CO
D r
em
oval
eff
icie
nc
y [
%]
ch
em
ical
oxyg
en
dem
an
d
(CO
D)
[mg
/l]
batch-no.
inlet COD [mg/l]COD [mg/l]outlet COD [mg/l]COD removal efficiency [%]
(II) (III)(I)
(II) Interconnection of R1 to R2 (33%, 50%, 75%,100%)
COD removal efficiency increased to 71%
(III) Testing of the two-stage anaerobic digestion
average COD removal efficiency 62%
Start-up of two-stage anaerobic digestion was
successful
Self-defined service water limit value of 75 mg/ l
could almost be reached
Start-Up of the Anammox-stage (R3)
7
0
20
40
60
80
100
120
0
10
20
30
40
50
60
70
80
90
100
110
120
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
NH
4-N
rem
oval
eff
icie
ncy
[%]
nit
rog
en
co
ncen
trati
on
[m
g/L
]
batch-No.
NH4-N [mg/L]start NO2-N [mg/l]NH4-N Removal efficiency [%]
(I)
(II) (III) (IV)
(V) (VI)
(I): 100% SWW, (II): 20% MWW (III): 50% MWW, (IV): 80% MWW, (Ⅴ): 100% MWW
(I) adaptation phase (R3) NH4-N removal efficiency inbetween 80% to 90%
(I)-(V) interconnection of anaerobic digestion to R3 (20%, 50%, 80%, 100%)
NH4-N removal efficiency decreased from 72% to 48%
(VI) adjustment of substrate to feed ratio (NO2-N/ NH4-N)
NH4-N removal efficiency rised to 92%
start-up of the Anammox-stage was successful
self-defined service water limit value of 10 mg/ l could be
reached
Optimum substrate to feed ratio of the Anammox-stage in pilot
scale: 1.14 mg/ l
Degradation performance after 200 days of operation
8
212
85
3960%
21%
0%
20%
40%
60%
80%
100%
0
50
100
150
200
250
300
rem
oval
eff
icie
ncy
[%
]
CO
D-c
once
ntr
atio
n[m
g/
l]
av. inlet COD of MWW [mg/l]
av. outlet COD after reactor 2 {mg/ l]
av. outlet COD after reactor 3 [mg/ l]
av. COD removal efficiency after reactor 2 [%]
av. COD removal efficiency in reactor 3 [%]
4650
1
96%
0%
20%
40%
60%
80%
100%
0
10
20
30
40
50
60
70
80
rem
oval
eff
icie
ncy
[%
]
NH
4-N
conce
ntr
atio
n[m
g/
l]
av. inlet NH4-N of MWW [mg/l]av. outlet NH4-N after reactor 2 {mg/ l]av. outlet NH4-N after reactor 3 [mg/ l]av. NH4-N removal efficiency in reactor 3 [%]
Self-defined service water
limit values:
COD: 75 mg/ l
NH4-N: 10 mg/ l
further optimization of 2-stage
anaerobic digestion needed
with Anammox-stage limit value is
guaranteed
Conclusion
9
• start-up of the two-stage anaerobic digestion (R1 + R2)
• for a temperature range of 34°C to 38°C
• without automated pH-control
• final average COD removal efficiency: 62%
• start-up of the Anammox-stage (R3)
• for a temperature range of 28°C to 35°C
• optimum NO2-N to NH4-N ratio: 1.14
• final average NH4-N removal efficiency: 92%
• after testing the pilot plant for 200 days of operation
• total COD removal efficiency is 81%
self-defined service water limit value of 75 mg/l could always be
reached with R3 connected in downstream
• total NH4-N removal efficiency is 96%
self-defined service water limit value of 10 mg/l could always
reached only by R3
two-stage anaerobic digestion is limiting process-step, thus further
optimization is needed to increase the plant´s capacity
Thank you for your attention!
10
buffer tank reactor 1 reactor 2 reactor 3 sand filter activated carbon
anaerobic digestion Anammox post-treatmentpre-heating
Acknowledgements:
• Hans Sauer Stiftung
• Klärwerk Erlangen
• Siemens AG
• ZWT Wasser- und Abwassertechnik GmbH
• Maschienenbau Biermann GmbH
• Webfactory GmbH
11
Challenges of the project
guarantee
Process stability
Challenges of
decentral
installation
easy to use
energy- and cost
efficency
domestic
purpose
different wastewater
composition
(place of installation)
Varying
concetrations
(seasonal)
operating parameters
(pH, T)
odourless
noise emission
< 35 dB
space saving
low investment
costs
low operation
costs
automated
low
maintenace
robust
Concept of the pilot plant
R3R2
VB
_1
BV
_R
3
LSH312
LSL311
LSH212
LSL211
LSH112
LSL111
QIRC230
pH
QIRC340
conductivity
QIRC130
pHQIRC
140
NH4
TRC120
TR220
QIRC330
pH
TRC320
VB
_2
influent
Organikabbau
(2. Stufe)
base
R1
LSH001
V_R1_1
V_P_
1
V_N_2
LSL002
Effluent
V_N_5 V_N_6 V_N_7
V_R1_
2
V_R1_5
V_R2_
3
V_R2_2
V_R2_1
V_R3_1
V_R3_2
V_R3_3
V_R3_4
V_R3_5
Biogas
1“ P
VC
Φ1“
PV
C
Φ1“
PV
C
Φ1“
PV
C
Puffer-
tank
Φ 1“ PVC
M 10
M 4
M 1 M 5
M 7
M 2 M 6
V_A_1
buffer-
tankOrganic
digestion
(1. step)
Organic
digestion
(2. step)
Nitrogen
removal
(3. step)
Sandfilte
r
3
Sandfilte
r
2
Sandfilte
r
1
buffer-
tank
Activated
carbon
Conecpt of process control
Basic automation and process
monitoring
State
detection
Fuzzy-Neuro
experts ystem
Ablaufplan
basic automation (PCS7)
analytics R 1 R 2 R 3Online:
Temperature X X X
pH X X X
conductivity X
Offline:
COD X X X
NH4-N X X
TN X
I/O-cuppler[ET 200 M]
[IM 153 -2]
analytic sensors
(Hach-Lange)
FU
Profibus DP
DC-USV
DP/ PA -
Link
Profibus PA
R 1 R 2 R 3
plant bus
ES/OS-Single Station
(Web-Anbindung)
PG-Gerät
temperature sensors
CPU 417-4H[SIMATIC PCS7]
FU
Methods for guaranteeing process stability
Fuzzy Logic (FL)
(expert knowledge) Proportional Integral
Differential (PID) controller
Mathematic models
(differential equations)Artificial Neuronal Nets (ANN)
For pH-control
50 70 90 1103010
Temp. (F°)
Freezing Cool Warm Hot
0
1
for state detection
Protection against overload in anaerobic
digestion (Anaerobic Digestion Model
No. 1)
Process
stability
Estimation of NH4 degradation
0 50 100 150 200 250 300 350 400 4500
500
1000
1500
2000
2500
3000
3500
4000
Time [h]
Concentr
ation [
mg/l]
Input Net: pH, HRT / Otuput Net: Acetic, Butyric & Propionic Acid
pH = 8
pH = 6
AceticNet
ButyricNet
PropionicNet
AceticExp
ButyricExp
PropionicExp
based on ΔpH/ Δt
Ordinary differential equations (ODE) model:
Anaerobic Digestion Model No. 1 (ADM1)*
- Continuous stirred tank reactor configuration
- COD base unit (mg COD/L)
- 24 components: 12 soluble components
(𝑆𝑖|𝑖=1 −12)
12 particulate components
(𝑋𝑖|𝑖=13 −24)
(7 groups of microorganisms)
19 biochemical processes
5 physico-chemical processes
4 inhibition functions
Modeling Two-stage Anaerobic Digestion
Plant specific Modifications:
- Two-stage system
(hydrolysis + acidogenesis → R1
acetogenesis + methanogenesis → R2)
- Batch operation with different reactors (mass balance + initial condition equations)
R
2
Hydrolysis
Acidogenesis
Acetogenesis
Methanogenesis
Xsu, Xaa, Xfa
Batstone, D.J., Keller, J., Angelidaki, I., Kalyuzhnyi, S.V., Pavlostathis, S.G., Rozzi, A., Sanders, W.T.M., Siegrist, H. and Vavilin, V.A. (2002). Anaerobic
digestion model no. 1. Scientific and Technical Report No. 13, IWA Publishing, London.
Xc4, Xpro
Xac, Xh2
Sch4, Sco2
Sbu, Sva, Spro
Sac Sh2,Sco2
Xch, Xpr, Xli
Ssu, Saa, Sfa
R
1
Total inorganic carbon Total ammonia-nitrogen† ‡
COD → *0.5𝑋𝑐ℎ + 0.4𝑋𝑝𝑟 + 0.1𝑋𝑙𝑖
TIC → 𝑆𝐻𝐶𝑂3
TAN → 𝑆𝑁𝐻4
1)
2)
3)
* Schlegel, H.G. and Fuchs, G. (2007). General Microbiology (Allgemeine Mikrobiologie), Eigth Edition. Georg Thieme Verlag, Stuttgart. P. 625.
Transformation method for domestic wastewater
Chemical measurements:
Model
input
Modeling Two-stage Anaerobic Digestion
†
‡
Model
calibration/validation:
Total COD
Model
R2 Model
R1
Easy to use
18
Economic feasability study
Wastewater costs of central wastewater treatment in Germany
Middle Franconia: 2,25 €/ m³ Brandenburg: 3,35 € /m³
20 PE plant 200 PE plant
capacity 730 m³/ a 7.300 m³/ a
useful life 30 Jahre 30 Jahre
required rate of return 7 % 7 %
fixed costs 7.251 €/ a 8.967 €/ a
investment costs 103.185 € 128.300 €
amortisation costs 3.439 €/ a 4.277 €/ a
operating costs 200 €/ a 200 €/ a
average interest 3.611 €/ a 4.491 €/ a
variable costs 6.733 €/ a 24.511 €/ a
total average costs 13.983 €/ a 33.478 €/ a
wastewater costs 19,16 €/ m³ 4,59 €/ m³
19