Is there a future
for enzymatic
application in the
waste sector?
Dr Raffaella Villa
September 2016
www.cranfield.ac.uk
What are enzymes?
Biological catalysts
• Reduce activation energy of
reactions
• Specific
• Stable and work in mild conditions
2
Share of enzymes use in the industrial sector
Animal
feed
Food and
Beverages
Biofuel
Paper and
textile
Household
care
Medicine
and
Biotech
http://www.kyrobio.eu/index.html
3
Advantages of enzymes
Energy Saving – mild conditions
Cost Saving – less chemicals
Time Saving – ?
Eco-friendly – biodegradable
High Specificity
4
In anaerobic digestion: enzyme addition
How can we use them?
Direct addition
Pre-treatment
5
Cellulases: not all the same
9000
800
Increase in sCOD (mg/l)
8000
7000
600
6000
5000
4000
300
100
3000
3000
2000
1000
9000
18000
1500
9000
18000
3000
0
1
2
3
Enzyme dose (U/g TS)
6
4
Solubility
sCOD released
•
•
How do they translate
into biogas?
Celluclast 1.5L (800 U/g of TS) = 54.67 %
Cellulase CEL30 (18000 U/g of TS) = 36.93 %
Price of enzyme
Commercial
name
Enzyme
type
Minimal
Activity
(U/g)
Price
Celluclast 1.5L
Cellulase
700
2.00*10-3 £/U
Cellulase CEL 200
Cellulase
2,000,000
6.08*10-9 £/U
Cellulase CEL 30
Cellulase
300,000
4.33*10-8 £/U
7
BMP test
Anaerobic digestion: batch test
Pre-treatment at 37°C
Pre-treatment at 37°C
with enzyme
Pre-treatment at 50°C
Pre-treatment at 50°C
with enzyme
Blank
0
200
400
600
800
Total Methane Production (ml/g of VSadded)
Total Biogas Production (ml/g of VSadded)
8
1000
Anaerobic digestion:
batch test
Direct addition
Blank
0
200
400
600
Total Methane Production (ml/g of VSadded)
9
Total Biogas Production
(ml/g of VSadded)
800
Biogas
Pre-treatment at 37°C
Pre-treatment at 37°C with
enzyme
Pre-treatment at 50°C
Pre-treatment at 50°C with
enzyme
Direct addition
Blank
0
500
1000
1500
Total Methane Production (ml/g of VSremoved)
Total Biogas Production (ml/g of VSremoved)
Enzymes for improved biogas production, Čermáková, A., Bajón Fernández,Y.
10 and Villa, R. in preparation
2000
Different pre-treatments = release of different
compounds
What is this
sCOD
composed of?
Proteins
Sugars
11
…and what about biogas?
12
Enzymes and landfill biogas
Waste
Waste +
leachate
Waste +
Leachate
+ enzyme
15 million U
tonne-1
waste
García, J., Davies, S., Villa, R., Gomes, D.M., Coulon, F., Wagland, S.T. Compositional analysis of excavated landfill samples and the determination of
residual biogas potential of the organic fraction (2016) Waste Management, . Article in Press. DOI: 10.1016/j.wasman.2016.06.003
13
Batch landfill reactors
8
Biogas (L kg-1 waste)
7
6
5
4
3
2
1
0
0
20
40
Time (days)
Leachate
Leachate + Enzyme
60
80
Control
R.R. Frank, S. Cipullo, J. Garcia, S. Davies, S.T. Wagland, R. Villa, C. Trois, F. Coulon, Compositional and physicochemical changes in waste
materials and biogas production across 7 landfill sites in UK, Waste Management, Available online 28 August 2016, ISSN 0956-053X,
http://dx.doi.org/10.1016/j.wasman.2016.08.026
14
Semi-continuous reactors
0.70
Biogas (L kg-1 waste))
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0
20
40
60
80
Time (days)
Leachate
Leachate + Enzyme
100
120
Control
R.R. Frank, S. Davies, S.T. Wagland, R. Villa, C. Trois, F. Coulon, Evaluating leachate recirculation with cellulase addition to enhance waste
biostabilisation and landfill gas production, Waste Management, Volume 55, September 2016, Pages 61-70, ISSN 0956-053X,
http://dx.doi.org/10.1016/j.wasman.2016.06.038.
15
140
Energy recovery from the algal waste
- Strong resistance to bacteria degradation
- Limited biogas production
- Residual intact cell after digestion (40d)
RESIDUAL
CELL
Biogas potential
ENZYMES
Pre-treatments
to improve
biogas
production
16
Commercial
enzymes
50°C, 24h
Enzymatic pre-treatments
1000
600
400
Mixture
Esterase
Pectinase
Esterase + Protease
0
Alpha amylase
200
Cellulase +
Endogalactour.
sCOD (mg/gVS)
800
Ometto, F., Quiroga, G., Pšenička, P., Whitton, R., Jefferson, B., Villa, R. Impacts of microalgae pretreatments for improved anaerobic digestion: Thermal treatment, thermal hydrolysis, ultrasound and
17
enzymatic hydrolysis (2014) Water Research, 65, pp. 350-361.
What is the action of the pre-treatments
do to the beads?
Enzymes
Thermal
18
Do the systems compare?
1.2
Biogas sample
(ml/gVS)/Cellulose
Biogas (ml/gVS)
1.2
1.0
1.0
0.8
1.0
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
1.2
Untreated cells
Pre-treated cells
0.0
Digested sludge control (S)
S. Obliquus (cells)
Digested sludge Thermally
control (S)
treated cells
E1 Depol 40
E 2 Lipomod
957
E1+E2 MIX
Untreated beads
Pre-treated beads
0.6
0.4
0.2
0.0
Digested Blank Beads Clean Algae 6 days Used 10 days Algal Sludge Digested Blank Beads Clean Algae 6 days Used 10 days 6 days Used
Sludge
(BB) E1 Beads (CA) Algae Beads Used Algae Algae Beads
Sludge
(BB)
Beads (CA) Algae Beads Used Algae Residue
Control
(S)
E1
(6-UA) E1 Beads (10- (6-UA) E2
Control (S)
(6-UA)
Beads (10(AS)
UA) E1
19
UA)
With gratitude…
20
www.cranfield.ac.uk
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