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Evaluation of tomato waste feedstocks for microbial fuel cells
Ryan Dowdy, Jonathan Weeks and Christopher W. Simmons
Department of Food Science & Technology
University of California, Davis
INTRODUCTION
VOLTAGE PRODUCTION WITHOUT BUFFER
• Voltage measured over time at 50% loading rate without added buffer
• Gas production and high variability observed
Tomato
Processing
Waste
Voltage Production over Time
Microbial
Fuel Cell
Average Voltage Production
60
70
Channel
Control 1
Channel
4
Dicing waste
Channel
7
Flume waste
50
Electrical
Energy
Channel
3
Dicing waste
Channel
6
Flume waste
60
50
30
20
External Resistor
• 1000 Ohm Rating
• Provides External Resistance
Before
After
12000
10000
8000
6000
4000
2000
0
40
Voltage (mV)
MICROBIAL FUEL CELL DESIGN
Channel
2
Dicing waste
Channel
5
Flume waste
Chemical Oxygen Demand (mg
O2/L)
14000
Voltage (mV)
• Microbial Fuel Cells (MFCs) are selfcontained devices that use bacteria to
convert organic compounds directly into
electrical energy.
• The purpose of this research was to
determine if an MFC could be used to
generate electricity from different tomato
processing waste streams.
• Research question: How do different
tomato waste streams affect power
production in microbial fuel cells?
Change in Chemical Oxygen Demand
Control
40
30
Dicing Juice
Flume Water
CONCLUSIONS
20
10
• Tomato wastes can be used in MFCs, but exoelectrogens may be inhibited
10
• Voltage production is variable
0
0
0
5000
10000
Time (minutes)
Control
15000
Dicing Juice
Flume Water
• Phosphate buffer may enhance longevity of system
• COD may not the best predictor of voltage output
VOLTAGE PRODUCTION WITH PHOSPHATE BUFFER
Air Cathode
• Platinum Catalyzed
• Coated with PTFE
• Drives Electron Flow
• Optimization of operating parameters is necessary
• Voltage measured over time at 10% loading rate with PBS buffer
• No gas production and lower variability
Voltage Production over Time
Carbon Brush Anode
• Electrically Conductive
• Allows growth of biofilm
Control
Channel 1
Dicing
waste
Channel
4
Flume
waste
Channel
7
50
EXPERIMENTAL SETUP
Dicing waste
Channel
2
Flume waste
Channel
5
No Buffer Solution
Voltage (mV)
Voltage (mV)
• Optimize COD of feedstock
50
40
30
• Optimize buffer for pH and buffering capacity
40
• Centrifuge inoculant to remove excess COD
30
• Slow the enrichment time for better bioconversion capabilities
20
10
CONTACT INFORMATION
10
0
0
5000
10000
Time (minutes)
15000
Control
Dicing Juice
Flume Water
CHANGES IN CHEMICAL OXYGEN DEMAND
Chemical Oxygen Demand (COD)
Dicing Juice
(Ch. 2-4)
• Measures overall oxidizable materials (feedstock strength)
• Changes in chemical oxygen demand should correlate with voltage output
• Calculations of COD made both before and after for each group
Flume Water
(Ch. 5-7)
• Identify inhibitory compounds in tomato waste streams
• Develop alleviation strategies
60
0
Control
(Ch. 1)
70
Dicing waste
Channel
3
Flume waste
Channel
6
20
Phosphate Buffer
(pH 7)
FUTURE DIRECTIONS
Average Voltage Production
60
• MFCs fed with tomato dicing juice, flume water, or deionized water
• Voltage datalogger measured the voltage output over time
• Negative Control MFC fed with deionized water
• Power production may rely on other factors besides pH
• Similar change in COD observed for each experimental group
• Differing voltage outputs indicate differing unit efficiencies
• Fermentation is occurring, but decreased exoelectrogenic activity
Ryan Dowdy
University of California, Davis
Department of Food Science & Technology
Davis, CA
Phone: 334-524-5999
E-mail: [email protected]
ACKNOWLEGEMENTS
This project would not have been possible without the help and support of:
• UCD Department of Food Science & Technology
• Joshua Claypool
• Qingqing Jiang
• UCD College of Agricultural and Environmental Sciences
• UCOP Global Food Initiative