co-digestion of used cotton clothingbiogas.ifas.ufl.edu/internships/2012/files/kelly.pdf · sell 8%...
TRANSCRIPT
Co-digestion of Used Cotton Clothing
Allison Kelly 2012 BioEnergy and Sustainability School
August 7, 2012
Summary of Problem
• Used cotton clothing commonly sent to landfill
• Wasted energy source
- ~90% cellulose
• Possibility of anaerobically digesting discarded clothing
Donate clothing 43%
Landfill 9%
Give to others 25%
Repurpose 15%
Sell 8%
Survey on the Disposal of Used
Clothing
N=130
Composition of Cotton
cellulose-94%
protein-1.3%
pectic substance-.95%
wax-0.6%
mineral matters-1.3%
acid-0.8%
sugar-0.3%
Cellulose
• Cellulose
-Hard to break down
-Hydrolysis limited
• Need for pretreatment!
Objectives
• Assess biodegradability of cotton fabric by using cellulase enzyme
• Test if cotton fabric can produce biogas using co-digestion in a Biomethane Potential Assay
Assessment of Cotton Fabric Biodegradability
-
• Test biodegradability
-Factory enzyme Kerry Biocellulase
• Compare biodegradability
-Filter Paper (control)
-Cotton T-shirt
-Biocellulase (blank)
Methods • Microscopic examination of
sample before and after
• Chemical Oxygen Demand (CODT)= indirectly measures organic material
- measured liquid portion
• Soluble Chemical Oxygen Demand (CODs)= measures dissolved organic material
Effect of Treatment with Cellulase
Before After
Total Chemical Oxygen Demand (CODT)
0
20000
40000
60000
80000
100000
120000
140000
160000
Cellulase Cellulase+ CotonFabric
Water + CottonFabric
Cellulase +FilterPaper
Water+ Filterpaper
CO
D m
g/L
Soluble Chemical Oxygen Demand (CODS)
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
Cellulase+Water
Cellulase+Cotton Fabric
Water + CottonFabric
Cellulase +FilterPaper
Water + FilterPaper
CO
D m
g/L
Downside of Factory Cellulases
• Very expensive!
• Need a lot to be fully effective
• Possible Solutions: natural enzymes
- Food waste
Possible Solution: Co-digestion with Food Waste
• Food waste is an efficient feedstock
• Food waste has low C: high N quickly acidifies inhibition
• Cotton has high C: low N longer to produce methane
• Both feedstocks balance each other out
Possible need for Different Temperatures
• Different enzymes have different optimal temperatures
• Kerry Biocellulase= 55 °C
• Food Waste BMP= 35 °C
• 35, 45, 55 °C
Measurement
• Tested by measuring Biochemical Methane Potential (BMP)
-100% Cotton T-Shirt (TS)
-100% Food Waste (FW)
-50% Cotton TS, 50% FW
-25% Cotton TS, 75% FW
-Blank
Results-BMP 35 °C
0
50
100
150
200
250
300
350
400
450
500
0 5 10 15 20
Cu
mu
lati
ve C
H4 m
L/g
of
VS
Days of incubation
100% cotton
100% foodwaste
50/50 %
25/75 %
Results-BMP 45 °C
0
50
100
150
200
250
300
350
0 5 10 15 20
Cu
mu
lati
ve C
H4
mL/
g o
f V
S
Days of incubation
100% cotton
100% foodwaste
50/50%
25/75%
Results-BMP 55 °C
0
50
100
150
200
250
300
350
400
450
0 5 10 15 20
Cu
mu
lati
ve C
H4
mL/
g o
f V
S
Days of incubation
100% Cotton
100% food waste
50/50
25/75
Comparing Temperatures
0
50
100
150
200
250
300
350
400
450
500
100% cotton 100% Food waste 50/50 25/75
Cu
mu
lati
ve C
H4
mL
/g o
f V
S
35° C
45° C
55° C
Conclusion
• Cotton clothing can be a feedstock for anaerobic digestion
• Food waste aids clothing in methane production and vice versa
• 35°C is most efficient temperature with the tested inoculum
Future Studies • Test for any other
possible natural pretreatments
-septic system treatment
-natural digestion enzymes
• Create digester with food waste and used clothing
• Test if effluent is efficient fertilizer
• Test effects of dyes and detergents
Thank you!
Questions or Comments?