Proces imbalance in biogas plants.

Proces imbalance in biogas plants.

Henrik Bangsø NielsenBiogasforum, seminar, 14/6-2006

Strategies for preventing breakdown and recoveryof the biogas process

Outline

Project strategy

Resume of last presentation (29-11-05)

Follow up on last presentationDigestion of blood (Lemvig biogas plant)

Ongoing experiments:Process recovery following ammonia and lipid inhibition

Comments from the audience ?

Visits at biogasplants

Data collection

Experiments and resultsthat can be 1) directly related and used by specific plants and 2) can

be published

A B

C

Overall project strategy

Main conclusions:

“No problems”

Pre-storage tanks are not useful

Substrate composition is unknown

Substrate degradation characteristics is unknown

Inadequate surveillance, especially with regard to VFA

A: Visits at biogas plants

B: Data collection

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

29-08-2002

28-10-2002

27-12-2002

25-02-2003

26-04-2003

25-06-2003

24-08-2003

23-10-2003

22-12-2003

20-02-2004

20-04-2004

19-06-2004

18-08-2004

17-10-2004

16-12-2004

14-02-2005

15-04-2005

date

met

han

e (m

3/m

3 re

acto

r vo

l.)

daily

10 per. Mov. Avg. (daily)

20 per. Mov. Avg. (daily)

Foaming starts april 2003 Foaming ends march 2005

C: Experiments and results

Pre-storage tanks are not useful: Plant constructors

Substrate composition is unknown and substrate degradation characeristics is unknown: E and R: Screening of various wastes with regard toxicity and biogas potential. Establishment of waste index.

Inadequate surveillance, especially with regard to VFA E and R: VFA surveillance and development of VFA sensors

Follow up on last presentation

Digestion of blood at Lemvig biogas plant

0

1

2

3

4

06-okt-05

13-okt-05

20-okt-05

27-okt-05

03-nov-05

10-nov-05

17-nov-05

24-nov-05

m3/

(m3

reac

tor v

ol.)

0

20

40

60

80

09-nov-05 14-nov-05 19-nov-05 24-nov-05

mM

Acetat Propionate Isobut. Butyrate Isoval. Valerate

Biogas production VFA concentration

Blood from pigs added from 1. of September 2005

Slow inhibition of biogas production observed in the beginning of October

Biogas production constituted only 40% of normal production at the 8. of november

Inhibition a combination of increasing pH and ammonia

Related experiments

Substrate characterization in batch

37 Degree

0

2

4

6

8

10

12

14

0 10 20 30 40 50

time (days)

pro

du

ctio

n (

ml

CH

4/m

l sa

mp

le)

0,5 g/l

1 g/l

5 g/l

10 g/l

55 Degree

0

2

4

6

8

10

12

14

0 10 20 30 40 50

time (days)

pro

du

ctio

n (

ml

CH

4/m

l sa

mp

le)

0,5 g/l

1 g/l

5 g/l

10 g/l

Degradation more effective at 37oC than at 55oC

Inhibition level at 37oC: between 0.5 and 1.0 g/l

Inhibition level at 55oC: < 0.5 g/l

Digestion at different temperatures in lab-scale reactors

Related experiments

37oC 55oC

0

50

100

150

t i me (days )

VFA

(m

M)

Total VFA

acetic

propionic

isobutyric

butyric

isovaleric

valeric

0

100

200

300

CH

4 yi

eld

(ml

CH

4/g

VS

)

0

10

20

30

40

biog

as p

rod.

(m

l /m

l fee

d)

7

7,2

7,4

7,6

7,8

8

8,2

pH

0,0

0,2

0,4

0,6

0,8

1,0

0 10 20 30 40 50 60 70 80 90 100 110

time (days)

free

am

mo

nia

(gN

/l)

0

50

100

150

200

250

300

CH

4 yi

eld

(ml C

H4/

g V

S)

0

10

20

30

40

bio

gas

pro

d.

(ml/

ml

feed

)

7

7,5

8

8,5

pH

0

50

100

150

VF

A (

mM

)

acetic

isobutyric

butyric

isovaleric

valeric

propionic

0,0

0,2

0,4

0,6

0,8

1,0

0 10 20 30 40 50 60 70 80 90 100

time (days)

free

am

mo

nia

(g

-N

/l)

Conclusions:Work at mesophilictemperatures or measureVFA frequently

Threshold value for the Thermophilic reactor was3.8 gN/l and 0.7-0.9 g freeAmmonia-N/l.

At mesophilic conditions itWas possible to work at an Ammonia concentration of 4.7 gN/l with a yield of 130Ml methane/g VS

VFA surveillance of the plant

0

10

20

30

40

50

60

70

80

90

1.8.05 20.9.05 9.11.05 29.12.05 17.2.06 8.4.06 28.5.06

dato

Ace

tat/

pro

pio

nat

(m

M)

0

1

2

3

4

5

6

7

8

To

tal

syre

(g

/l)

acetat Propionat Total syre Total syre

++++-+

Minkfedt+-

Related experiments

Related experiments

R1 biogas production

0

1000

2000

3000

4000

5000

0 20 40 60 80 100

mlbiogasR2 biogas production

0

1000

2000

3000

4000

5000

0 20 40 60 80 100

ml biogas

Reactor experiment with lipids

Day 60: 5% lipid (W/W) were added = 50% VS = no inhibitionDay 87: 25% lipid (w/w) were added = 85 VS = inhibition

Conclusion: plant added more lipid than allowed (25% TS)

Ongoing experiments

0,0

0,5

1,0

1,5

2,0

2,5

16-10-2001

15-12-2001

13-02-2002

14-04-2002

13-06-2002

12-08-2002

11-10-2002

10-12-2002

08-02-2003

09-04-2003

08-06-2003

07-08-2003

06-10-2003

05-12-2003

03-02-2004

03-04-2004

02-06-2004

01-08-2004

30-09-2004

29-11-2004

28-01-2005

29-03-2005

date

me

tha

ne

(m

3/m

3 r

ea

cto

r v

ol.

)

What now?

Recovery of the process following process imbalances

Recovery strategies

Stop feeding (the process recovers automatically).

Continued feeding with manure (addition of fresh substrate to keep up the biogas production)

Continued feeding with substrate adaptation will occur)

Re-inoculation with effluent (addition of new microorganisms)

Dilution with water (inhibiting compound is diluted)

Recovery of the biogas process

Set-up

Mixture

1: Inoculum

2: Manure

3: LCFA or ammonia at steady biogas production


Long chain fatty acids inhibition

Identification of oleate inhibition level

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70days

CH

4 (

mL

/gV

S)

control

oleate 3gVS/L

oleate 5gVS/L

oleate 7gVS/L

inoculum and oleate 3gVS/L

mixture + BA media + oleate 3gV/L

Oleateaddition

10

100

1000

Day 4 Day 7bef. Inhib

Inhib + 3Bef. Recov

Inhib + 7Recov + 4

Inhib + 13Recov + 10



ml C

H4/

gV

S in

itial

no inhib.

inhib no recov.

recov water dilution

recov.inoc dilution

recov manure dilution

1180



Test of strategies



Inhibition 5gVS oleate/L with different inoculum/manure ratio

0

100

200

300

400

500

600

4 7 10 14 20 28 38

ml C

H4/

gV

S

inoc 25/ man 15

inoc 11/ man 29

Inhibition

days

R1 TS/VS = 2.9/2.1%

0

100

200

300

400

500

100 110 120 130 140 150 160 170 180 190

met

hane

ml/g

VS

R2 TS/VS = 5.4/4.1%

0

100

200

300

400

500

100 110 120 130 140 150 160

met

hane

ml/g

VS

0.5 g/l 0.5 g/l1.0 g/l 1.0 g/l2.0 g/l 2.0 g/l

2.0 g/l

0

15

30

45

60

75

90

100 110 120 130 140 150 160

acet

ate

mM

0

5

10

15

20

25

30

prop

iona

te m

M

time (days)

0

15

3045

60

75

90

100 110 120 130 140 150 160 170 180 190

acet

ate

mM

0

5

1015

20

25

30

prop

iona

te m

M

time (days)

Pulses with oleate

Effect of TS/VS



Conclusions:

Using one of the strategies could stimulate the recovery of the process

Following inhibition with LCFA, the recovery proceeded fastest whenthe biomass was diluted with manure.

The fast recovery with manure could be due to a higher concentration ofTS/VS (fibers)

However, what about reactor experiments!!!


Ammonia inhibition

10

100

1000

Day 5 Day 9bef. Inhib

inhib+3 /bef. Recov

inhib+6 /recov+3

inhib+16 /recov+13

inhib+29 /recov+26

inhib+41 /recov+38

ml C

H4

/gV

S in

itia

l

no inhib. TN=3.0g/L

inhib. TN=7.0g/L

inhib+water dilution TN=3.5g/L

inhib+inoc dilution TN=5.2g/L

inhib+manure dil. TN=4.6g/L

inhib+pH decrease TN=7.0g/L

932Test of strategies

Prodution rates day 9 to 12Control: + 50 mlInhibition: + 26 ml


Ammonia inhibition

Utilization of biogas potential

0

100

200

300

400

500

600

700

no inhibition inhibition norecov.

recov w ater recov inoc recov manure

ml C

H4

theorical level

experimental level

Effienciency as a function of N-content

70

75

80

85

90

95

100

105

110

2,5 3,5 4,5 5,5 6,5 7,5N content (gN/L)

effic

ien

cy %

w ater dil.manure dil.

inoculum dil.

no recovery

no inhibition

No inhibition

No recovery

Water dilution

Inoculum dilution

Manure dilution

% of theoretical level 96 74 92 77 99

Final N-content 3 7 3,5 5,2 4,6


Ammonia inhibition

Conclusions:

The recovery of the biogas process following sn smmonis inhibition was strongly related to the ammonia concentration.

Addition of fresh manure gave the best recovery (lower ammonia concentration, fresh substrate)

However, what about reactor experiments!!!

Acknowledgements

Thanks to Sonia Guldener, Henar Meer de Soto and Elena Pueyo Abad forsharing their results.Thanks to Hector Garcia and Prasad L. Kaparaju for their technical assistanceThe work is supported by Energistyrelsens Energiforsknings-program (EFP-2005)

Thank you for your attention!!!!

Waste type Temperature Inhibition level

g VS/l = kg VS/tBlood from pigs 37oC 0,5-1,0

Blood from pigs 55oC <0,5

Shrimp sludge 37oC 1,0-5,0

Shrimp sludge 55oC 0,5-1,0

Meat and Bone meal 37oC 1,0-5,0

Meat and Bone meal 55oC 0,5-2,0

100% Fat, DAO 55oC <1,0

Flotations fedt, pigs 55oC 0,5-1,0

Bakery (mainly fat) 55oC 5,0-10,0

Flotationsfedt, pigs 55oC 5,0-10,0

Flotationsfedt, pigs 55oC 5,0-10,0

Limfedt (fat) 55oC 5,0-10,0

Food waste (fat) 55oC >10,0

Flotationsfedt, chickens

55oC >10,0

Waste index

Proces imbalance in biogas plants.

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