Anaerobic digestion of Jatropha curcas oil cake

Marcin Łukaszewicz, Sławomir Jabłoński

Tadeusz BeutelMaciej Sygit

Biodiesel from Jatropha curcas

• Oil seeds producing shrub belonging to Euphabioaceae family.

• Seed oil content 30-40% (by weight).• Seed yield 1-6 ton/ha.

2Figure sources: http://cambia.pe/la-planta-jatropha-curcas-una-solucion-natural-para-mitigar-el-cambio-climatico/

What to do with oil cake?

• Oil cake is toxic due to the presence of phorbol esters.

• It also contains atinutrients: saponins, phyticacid, trypsin inhibitors.

3Figure sources: http://hilo.hawaii.edu/sustainability/PlantOil.php

Anaerobic digestionBenefits:

• Detoxification

• Recovery of the energy

• Recovery of nutrients: ammonium and phosphates

• Reduction of uncontrolled green house gases release

4Figure sources: http://sites.duke.edu/environ398_10_f2010_ct95/?page_id=46

Why should we recover nitrogen?

Haber process:• N2 + 3 H2 → 2 NH3 (ΔH = −92 kJ/mol)• CH4 + H2O → CO + 3 H2 (ΔH= 206 kJ/mol)• CO + 1/2 O2 → CO2 (ΔH=-283 kJ/mol)

• To produce 1 ton of ammonia about 1000 m3 of methane is required.

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How much can we get?Composition of J. curcas oil cake:

• Volatile solids - 87.4%• Protein - 19.9%• Phytate - 10.5%

Maximal theoretical gain:Biogas - 616 m3∙t-1

Ammonium nitrogen - 31.8 kg∙t-1

Phosphate - 89.2 kg∙t-1

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Obstacle 1: Low biogas yield

Brasica napusTBY: 711 m3∙t-1BY: 507 m3∙t-1Efficiency: 71.3%

Linum usitatissimum TBY: 792 m3∙t-1BY: 545 m3∙t-1Efficiency: 78.8%

Jatropha curcasTBY: 616 m3∙t-1BY: 281 m3∙t-1Efficiency: 45.6%

7Figure sources:http://www.transgen.de/datenbank/pflanzen/63.raps.html, http://www.uprawyekologiczne.pl/634_len.html, http://cambia.pe/la-planta-jatropha-curcas-una-solucion-natural-para-mitigar-el-cambio-climatico/

http://www.uprawyekologiczne.pl/634_len.html

Possible causes

• Protease inhibitors may reduce protein digestability.• Phytate may reduce microorganisms activity by

helating metal ions.

BPTI

8Figure sources: https://pl.wikipedia.org/

Solution: pretreatment

• Oilcake samples were incubated at different temperatures with NaCl solution orhydrochloric acid solution.

9Figure sources:hdimagegallery.net,

Pretreatment result

• The activity of trypsin inhibitor was reduced after incubation at 115 °C.

10

0

20

40

60

80

100

120

140

Water Jatropha extract

20°C 70°C 100°C 115°C

Trip

sine

act

ivity

[U/m

l]

NaCl

HCl

• Concentration of phytate was also reduced even afterincubation at 70°C.

Pretreatment result

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0,0

2,0

4,0

6,0

8,0

10,0

12,0

20°C 70°C 100°C 115°C

Phyt

ate

conc

entr

atio

n[%

]NaClHCl

Production rate

0,0

5,0

10,0

15,0

20,0

25,0

30,0

0 5 10 15 20 25

Daily

bio

gas

prod

uctio

n ra

te [c

m3 /

day]

Time [days]

A)

NaCl 20°C

NaCl 70°C

NaCl 100°C

NaCl 115°C

Digestion rate for samples with salt addition incubated at 20 °C and 115 °C was similar, for other samples it was lower.

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Biogas production efficiency

• Total biogas production level was not affected by preptreatment.

0%

20%

40%

60%

80%

100%

120%

NaCl 20°C HCl 20°C NaCl 70°C HCl 70°C NaCl 100°C HCl 100°C NaCl 115°C HCl 115°C

Rela

tive

biog

aspr

oduc

tion

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Alternative solution: percolation system

• Hydrolysis step is performed in micro aerobic conditions allowing digestion of lignin and cellulose.

• Water demand is reduced.14Figure sources:http://www.herhof.com/en/products/biogas-system.html

Obstacle 2: Nitrogen accumulation

• Digestion of proteins produces ammonia• At high concentration ammonia is toxic to microorganisms

Proteins – 19% of J. curcas oilcake

Up to 32 kg∙t -1of oilcake

15Figure sources: www.caslab.com, http://www.helsinki.fi/~pjojala/Hemoglobin.htm

http://www.caslab.com/

Solution: struvite formation

• Ammonium ions may be removed from the solution by the precipitation with phosphate and magnesium.

• Nitrogen removal efficiency reached 53%.

(NH4)MgPO4∙6(H2O)

16Figure sources:https://pl.wikipedia.org/wiki/Struwit

pH4,8

InCO2CH4

Modular bioreactor construction (allowing separation of individual steps in anaerobic digestion)

17

pH6,0

Out

CH4CO2

pH7,0

Flow meter

Other possible improvements

CH4CO2

Metanogens databasewww.metanogen.biotech.uni.wroc.pl

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Metanogens growth in pH

19

pH4,8

InCO2CH4

Modular bioreactor construction (allowing separation of individual steps in anaerobic digestion)

20

pH6,0

Out

CH4CO2

pH7,0

Flow meter

Other possible improvements

CH4CO2CH4CO2

CH4CO2

CH4CO2

CO2 CO2

CO2 CO2

CO2

CO2

CO2

P

pH4,8

InCO2CH4

Electrobiochemical reduction of CO2 (production of methane from electrical current)

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pH6,0

Out

CO2CH4

CH4CO2

pH7,0

Flow meter

Other possible improvements

Electrode

H2H2

H2

H2

H2

H2

O2

O2

CH4CO2

CH4CO2

+-

ElectrodeElectrode

And how does it look like in reality?

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Conclusions• Pretreatment of J. curcas oil cake does not

improve biogas yield

• Continuous fermentation of J. curcas oil cake may result in process collapse due to ammonia formation

• Excessive nitrogen may be removed by struviteprecipitation.

• Additional benefits such as reduction of CO2concentration may be achieved in modular bioreactor

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Faculty of Biotechnologywww.biotech.uni.wroc.pl

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Thank you for your attention.

Anaerobic digestion of Jatropha curcas oil cakeBiodiesel from Jatropha curcasWhat to do with oil cake?Anaerobic digestionWhy should we recover nitrogen?How much can we get?Obstacle 1: Low biogas yieldPossible causesSolution: pretreatmentPretreatment resultPretreatment resultProduction rateBiogas production efficiencyAlternative solution: percolation system Obstacle 2: Nitrogen accumulationSolution: struvite formationModular bioreactor construction (allowing separation of individual steps in anaerobic digestion)�Metanogens database �www.metanogen.biotech.uni.wroc.plMetanogens growth in pHModular bioreactor construction (allowing separation of individual steps in anaerobic digestion)�Electrobiochemical reduction of CO2 (production of methane from electrical current)And how does it look like in reality?ConclusionsSlide Number 24