I.V. Skiadas and H.N. Gavala

Section for Sustainable Biotech., Aalborg University Copenhagen, DK

13-06-2014 Athens 2014 1

The three major pillars of AMMONOX

Optimisation and application of Aqueous Ammonia Soaking as a moderate and sustainable treatment for rendering manure-based biogas plants viable

Application of innovative ammonia recovery technology

Coupling of excess ammonia obtained from manure with the catalytic elimination of NOx emissions from gas engines

13-06-2014 Athens 2014 2

Biogas plants in Denmark

Biogas plants capacity

Manure: 1.750.000 t

Organic residues: 450.000 t

Total: 2.200.000 t

13-06-2014 Athens 2014

22 Centralised biogas plants60 Farm scale biogas plants

3

Biogas potential in Denmark

2011

Biogas production: 4 PJ

Potential for biogas production: 40 PJ

Use of manure: 6%

Use of other organic residues: ~ 100%

Conclusion

Manure could constitute the major biogas source in Denmark

13-06-2014 Athens 2014 4

Organic waste

Transportation liquid manure

Heat and electricity

fertilizer

Increasing prices

Anaerobic digestion

Farms

Costly transportation of large water volume

Manure based biogas plants in DK –current practice

13-06-2014 Athens 2014 5

Solid fractionHigh organic content

Liquid fraction,Low organic content

Heat and electricity

Anaerobic digestion• Minimization of the transported volume.• Elimination of the need of additional organic wastes.

Low methane yield!

Manure based biogas plants in DK –alternative

13-06-2014 Athens 2014 6

Manure based biogas plants in DK – our suggestion

13-06-2014 Athens 2014 7

Pretreatment of manure fibersStudied methods Aqueous Ammonia Soaking

Methods tested so far increase significantly the methane potential but are energy consuming, require advanced equipment and/or consumption of chemicals.

Most of the tested methods originate from the pretreatment of the lignocellulosic biomass for the production of ethanol.

Low temperature (room temperature).

Possibility for ammonia recovery.

No destruction/oxidation of cellulose, hemicellulose and other organic matter

13-06-2014 Athens 2014 8

Lab Scale Process

13-06-2014 Athens 2014

Manure Fibers

AAS-treatment

Ammonia Distillation

Anaerobic Digestion

10 ml reagent (32% w/w in NH3) per 1 g TS3 d at 22°C

9

Batch experiments – ultimate CH4 yield at different TS loadingRaw manure fibers Digested manure fibers

13-06-2014 Athens 2014

0

50

100

150

200

250

300

350

0.16 0.25 0.5 1

Met

ha

ne

yie

ld (

ml

CH

4/

g T

S)

g TS / 10 ml inoculum

control-fibers AAS-fibers

0

50

100

150

200

250

300

350

0.16 0.25 0.5 1

Met

ha

ne

yie

ld (

ml

CH

4/

g T

S)

g TS / 10 ml inoculum

control -fibers AAS-fibers

Jurado et al. 2013, Applied Energy, 109(104-111)

10

Methane yield of digested fibers after AAS with different ammonia concentration

0

50

100

150

200

250

0 10 20 30 40 50 60 70

CH

4 y

ield

, m

l /

g T

S

Time, d

AAS (32%)

AAS (25%)

AAS (20%)

AAS (15%)

AAS (10%)

AAS (5%)

No AAS

13-06-2014 Athens 2014

Mirtsou-Xanthopoulou et al. 2012, 4th International Conference on Engineering for Waste and Biomass Valorisation (WasteEng12), Porto (Portugal), Sept 10-13

11

Continuous experiments and modeling

13-06-2014 Athens 2014

Reactor A: fed with manure – methane yield of manure and fittingof the ADM1 model to manure as feedstock

Reactor B: fed with manure first and subsequently with a mixtureof manure and AAS-digested fibers: validation of ADM1 developed on manure, fitting of ADM1 to the mixture and validation,methane yield of AAS-digested fibers

Reactor C: fed with manure first and subsequently with a mixtureof manure and AAS-raw fibers: fitting of ADM1 to the mixture and validation, methane yield of AAS-raw fibers

Mirtsou-Xanthopoulou et al. 2012, 4th International Symposium on Energyfrom biomass and Waste, San Servolo, Venice (Italy), Nov 12-15

Jurado et al. 2012, 4th International Symposium on Energyfrom biomass and Waste, San Servolo, Venice (Italy), Nov 12-15

Jurado et al. 2012, 4th International Symposium on Energyfrom biomass and Waste, San Servolo, Venice (Italy), Nov 12-15

12

Biochemical processes

13-06-2014 Athens 2014

composites

proteins carbohydrates lipids

inerts

HAc, HPr, HBut, HVa, CO2, NH3,

NH3

microbes

growth

death/decay

H2HAc

CO2

CH4

Physicochemical processes

amino acids

mono saccharides

LCFA

gas H2O

Ac-, Pr-, But-, Va-, HCO3-, NH4

+, LCFA-

HCO3-

NH4+

1st order

Monod accounting for inhibition of pH, NH3 and Η2

Ion balanceEquilibrium equations for weak acid/base dissociation

Dynamic transfer from liquid to gas phase

X

13

Reactor A: manure as influent

13-06-2014 Athens 2014 14

Reactor B: manure and a mixture of manure and AAS-digested fibers as influent

0

0,001

0,002

0,003

0,004

0,005

0,006

0,007

0,008

40 90 140 190 240

Gas

flo

w (

m3/

d)

Time, d

Model Experimental

2nd Phase 3rd

Phase4th Phase

13-06-2014 Athens 2014

1st phase

15

Kinetic parameters Kinetic Parameters Units Manure Manure +

AAS- fibers

Carbohydrates hydrolysis constant,

khydr_ch

d-1 << 6.8x10-2

Proteins hydrolysis constant, khydr_pr d-1 2.8x10-4 7.0x10-3

Lipids hydrolysis constant, khydr_li d-1 3x10-3 3x10-3

Maximum uptake rate of long chain

fatty acids, km_fa

kg COD fa/kg COD

x_fa/d

0.93 0.93

Maximum uptake rate of butyric acid,

km_c4

kg COD c4/kg COD

x_c4/d

13.1 13.1

Maximum uptake rate of propionic

acid, km_pro

kg COD pro/kg COD

x_pro/d

6.56 6.56

Maximum uptake rate of acetic acid,

km_ac

kg COD ac/kg COD

x_ac/d

45.02 45.02

13-06-2014 Athens 2014 16

Methane yield in batch assays and continuous reactors

0

50

100

150

200

250

300

350

Batch Continuous

Me

tha

ne

yie

ld,

L k

g-1

TS

AAS-raw

AAS-digested

200%

13-06-2014 Athens 2014

90%

Increase compared to non-treated fibers

17

Swine manure,

4% TS

~ 11.3 m3 CH4/ t

Non -profitable without subsidies

In practice

13-06-2014 Athens 2014 18

Swine manure,

+ AAS- fibers, 12% TS

> 30 m3 CH4/ t

Profitable without subsidies

In practice – implementing oursuggestion

13-06-2014 Athens 2014 19

Ammonox: a sustainable and holisticapproach for manure based biogas plants

13-06-2014 Athens 2014 20

Chemistry of RETROMAX processPrecipitation Regeneration

13-06-2014 Athens 2014 21

• Optimisation of Aqueous Ammonia Soaking for CH4 enhancement from:

• Manure fibers

• Lignocellulosic agricultural residues

• Coupling AAS to RETROMAX in lab-scale

• Proof-of-concept in continuous digesters

• Cost analysis of the AMMONOX concept

Important issues withinAMMONOX

13-06-2014 Athens 2014 22

Acknowledgements to:EUDP, DK ENERGINET, DK

RETROGAS (2009-2013)

Demonstration of cost effective production of biogas from manure only comprising new pre-separation technology and enzyme liquefaction

AMMONOX (2013-2017)

Ammonia for enhancing biogas yield & reducing NOx

13-06-2014 Athens 2014 23

Other co-workers are:Research

Esperanza Jurado, PhD student

Anna Lymperatou, PhD student

Chrysoula Mirtsou-Xanthopoulou, Master student

Siddhartha Bhakta Bhandari, Master Student

13-06-2014 Athens 2014 24

Industry

N.B.K. Rasmussen, Danish Gas Technology Center

P. Thostrup, Nordic Bioenergy

K. Paamand, Gascon.dk

13-06-2014 Athens 2014 25