comparison of single-stage and temperature-phased...

Comparison of single-stage and temperature-phased anaerobic digestion of

sugar beet by-products

Kaoutar Aboudi*, Xiomara Gómez Quiroga, Carlos José Álvarez Gallego and Luis Isidoro Romero García

Chemical Engineering and Food Technology Department, University of Cádiz, Campus Río San Pedro, 11510 Puerto Real, Spain

*kaoutar.aboudi@uca.es

22 June 2017

5th International Conference on Sustainable Solid Waste Management-ATHENS201724-27 June, 2017

Contents BACKGROUND

EXPERIMENTAL STRATEGY

RESULTS AND DISCUSSION

CONCLUSIONS

5th International Conference on Sustainable Solid Waste Management-ATHENS201724-27 June, 2017

Lignocellulosic biomass

20 Mt of dry SBP

1 tonne of Sugar beet processed 70 kg of exhausted dried pulp ≈ 250 kg of exhausted pressed pulp Total global production in 2014

267 Mt

Animal feedstock supplement

Background Experimental strategy          Results & Discussion         Conclusions

Lignocellulosic biomass

Background Experimental strategy          Results & Discussion         Conclusions

Bioenergy = Anaerobic digestion technology

METHANOGENESIS

CH4CO2

ACIDOGENESIS

Volatile fatty acidsAlcohols

ACETOGENESIS

H2CO2

Aceticacid

Complexbiopolymers

CarbohydratesProteinsFat/oil

Simple monomers

HIDROLYSIS

SugarsAminoacids

Background Experimental strategy          Results & Discussion         Conclusions

ANAEROBIC DIGESTION = BIOLOGICAL PROCESS

METHANOGENESIS

CH4CO2

ACIDOGENESIS

Volatile fatty acidsAlcohols

ACETOGENESIS

H2CO2

Aceticacid

Complexbiopolymers

CarbohydratesProteinsFat/oil

Simple monomers

HIDROLYSIS

SugarsAminoacids

Background Experimental strategy          Results & Discussion         Conclusions

SINGLE STAGE ANAEROBIC DIGESTION PROCESS

METHANOGENESIS

CH4CO2

ACIDOGENESIS

Volatile fatty acids

ACETOGENESIS

H2CO2

Aceticacid

Complexbiopolymers

CarbohydratesProteinsFat/oil

Simple monomers

HIDROLYSIS

SugarsAminoacids

H2CO2

DARK FERMENTATION METHANOGENESIS

Background Experimental strategy          Results & Discussion         Conclusions

TWO PHASED ANAEROBIC DIGESTION PROCESS

METHANOGENESIS

CH4CO2

ACIDOGENESIS

Volatile fatty acids

ACETOGENESIS

H2CO2

Aceticacid

Complexbiopolymers

CarbohydratesProteinsFat/oil

HIDROLYSIS

Simple monomers

SugarsAminoacids

H2CO2

Background Experimental strategy          Results & Discussion         Conclusions

TWO PHASED ANAEROBIC DIGESTION PROCESS

DARK FERMENTATION METHANOGENESIS

Background Experimental strategy Results & Discussion         Conclusions

OBJETIVESINGLE STAGE VS TWO-PHASED

ANAEROBIC DIGESTION OF SUGAR BEET BY-PRODUCTS

Experimental design

Run ISingle stage

Run IITPAD

Background Experimental strategy Results & Discussion         Conclusions

Acidogenic Methanogenic

HRT = 10 daysOLR = 6.6 ± 0.4 (gVS/Lr*d)

HRT = 20 daysOLR = 2.5 ± 0.2 (gVS/Lr*d)

35°C55°C

HRT = 20 daysOLR = 3.4 ± 0.2 (gVS/Lr*d)35°C 55°C

65°C 35°C

Experimental design

Run ISingle stage

Run IITPAD

Background Experimental strategy Results & Discussion         Conclusions

Acidogenic Methanogenic

HRT = 10 daysOLR = 6.6 ± 0.4 (gVS/Lr*d)

HRT = 20 daysOLR = 2.5 ± 0.2 (gVS/Lr*d)

35°C55°C

HRT = 20 daysOLR = 3.4 ± 0.2 (gVS/Lr*d)35°C 55°C

65°C 35°C

Background Experimental strategy Results & Discussion         Conclusions

Semi‐continuous stirred tank digesters

2 L

Biogas collection

Mixing system

Temperature monitoring

Feeding/Effluent

Heater plate

0

100

200

300

0 50 100 150 200 250

Accumulated

methane

(L)

Time (Days)

Mesophilic Thermophilic

45 %

Background Experimental procedure Results & Discussion         Conclusions

Single stage anaerobic digestion assays

MPR = 0.55 LCH4/Lr*d

MPR = 0.30 LCH4/Lr*d

Background Experimental procedure Results & Discussion         Conclusions

Single stage anaerobic digestion assays

pH = 7 ‐ 7.8VS removal (%) = 83 %

pH = 7.5 ‐ 8VS removal (%) = 66%

Background Experimental procedure Results & Discussion         Conclusions

Two‐phased anaerobic digestion assays

Combination 1: Thermophilic acidogenic ‐mesophilic methanogenic

HPR= 0.45 (LH2/Lr*d) MPR= 0.19 LCH4/Lr*d

pH = 5.5 ‐ 6VS removal (%) = 46 %

pH = 7.5 ‐ 8VS removal (%) = 70 %

Background Experimental procedure Results & Discussion         Conclusions

Combination 1: Thermophilic acidogenic ‐mesophilic methanogenic

Two‐phased anaerobic digestion assays

Acidogenic digester Methanogenic digester

pH = 5.5 ‐ 6VS removal (%) = 46 %

pH = 7.5 ‐ 8VS removal (%) = 70 %

Background Experimental procedure Results & Discussion         Conclusions

Combination 1: Thermophilic acidogenic ‐mesophilic methanogenic

Two‐phased anaerobic digestion assays

Acetoclasticmethanogensinhibition

Acidogenic digester Methanogenic digester

Two‐phased anaerobic digestion assays

Combination 2: Hyperthermophilic acidogenic ‐mesophilic methanogenic

Background Experimental procedure Results & Discussion         Conclusions

HPR= 0.11 LH2/Lr*d MPR= 0.09 LCH4/Lr*d

Two‐phased anaerobic digestion assays

Combination 2: Hyperthermophilic acidogenic ‐mesophilic methanogenic

Background Experimental procedure Results & Discussion         Conclusions

pH = 5.5 ‐ 6.5VS removal (%) = 23 %

pH = 7.5 ‐ 8.5VS removal (%) = 72 %

Acidogenic digester Methanogenic digester

Two‐phased anaerobic digestion assays

Combination 2: Hyperthermophilic acidogenic ‐mesophilic methanogenic

Background Experimental procedure Results & Discussion         Conclusions

pH = 5.5 ‐ 6.5VS removal (%) = 23 %

pH = 7.5 ‐ 8.5VS removal (%) = 72 %

Acetoclasticmethanogensinhibition

Acidogenic digester Methanogenic digester

Two‐phased anaerobic digestion assays

Background Experimental procedure Results & Discussion         Conclusions

Two‐phased anaerobic digestion assays

Background Experimental procedure Results & Discussion         Conclusions

Palmitate

Lignocerate

Background Experimental procedure Results & Discussion         Conclusions

Co‐digestion:Including a livestock co‐substrate in the TPAD assays (pig slurry and 

cow manure)

Next step 

Single stage

Is the TPAD suitable for sugar beet by-products??

Thank you for your attention