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