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michka:research:microbial_fuel_cells:bruxelles2 [2014-09-26 09:44] – michka | michka:research:microbial_fuel_cells:bruxelles2 [2014-10-08 14:33] – michka | ||
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====Experiment " | ====Experiment " | ||
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+ | {{ : | ||
===Salt Bridges=== | ===Salt Bridges=== | ||
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I failed a three batches of [[http:// | I failed a three batches of [[http:// | ||
- | ===The right protocol=== | + | The right protocol: |
* Mix 200 ml water, 5 g of agar and 75g of salt in a cooking pan. | * Mix 200 ml water, 5 g of agar and 75g of salt in a cooking pan. | ||
* Bring it to a boil while mixing regularly. | * Bring it to a boil while mixing regularly. | ||
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* Place them in the fridge for a few hours | * Place them in the fridge for a few hours | ||
- | ===What not to do=== | + | What not to do: |
* Use hot water from a kettle and mix everything in a cold pot | * Use hot water from a kettle and mix everything in a cold pot | ||
* This induces a very uneven mix, where salt and agar are not well dissolved | * This induces a very uneven mix, where salt and agar are not well dissolved | ||
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===Mud, Tall=== | ===Mud, Tall=== | ||
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+ | {{ : | ||
+ | Mud samping location - Sint-Jans-Molenbeek, | ||
+ | |||
+ | |||
+ | Design details: | ||
+ | * The mud sample was taken from the waterland at the bottom of Scheutbos Park in Sint-Jans-Molenbeek. | ||
+ | * Its approximate volume is 50 cl. | ||
+ | * On top is a highly concentrated Petri-dish-sized salt bridge. | ||
+ | * On top is filtered water. | ||
+ | * Electrodes are made of copper from dead batteries. They have an approximate surface area of 100cm2 each. | ||
+ | * Crocodile clips are clipped on the electrodes and brought out of the pot for measurement. | ||
+ | |||
+ | Results: | ||
+ | * Tension is unsensitive to oxygen presence, and is in the 300mV range. | ||
+ | * Current is in the 1-2mA range. | ||
+ | * Power is therefore in the mW range. | ||
===Mud, Small=== | ===Mud, Small=== | ||
+ | |||
+ | Design details: | ||
+ | * The mud sample was taken from the waterland at the bottom of Scheutbos Park in Sint-Jans-Molenbeek. | ||
+ | * Its approximate volume is 3 cl. | ||
+ | * On top is a salt bridge the size of the jar. | ||
+ | * On top is filtered water. | ||
+ | * Electrodes are made of copper from dead batteries. They have an approximate surface area of 10-20cm2 each. | ||
+ | * Crocodile clips are clipped on the electrodes and brought out of the pot for measurement. | ||
+ | |||
+ | Results: | ||
+ | * Tension is sensitive to oxygen presence, and is in the 100mV range when activated, 30 mV at rest. | ||
+ | * Current is sensitive to oxygen presence, and is very low - about 0.3 mV when activated, dropping to 0.1 mV at rest. | ||
+ | * Power is therefore in the microW range. | ||
===Vegetable Waste & Compost Tea=== | ===Vegetable Waste & Compost Tea=== | ||
+ | |||
+ | {{ : | ||
+ | |||
+ | Design details: | ||
+ | * The substrate is made of vegetable scraps (potatoes, carrotes, zucchinis) covered with compost tea (from FoAM's vermicompost production), | ||
+ | * Its approximate volume is 7 cl. | ||
+ | * On top is a salt bridge the size of the jar (broken during the manipulations). | ||
+ | * On top is filtered water, which was quickly populated by compost tea from below the salt bridge. | ||
+ | * Electrodes are made of copper from dead batteries. They have an approximate surface area of 10-20cm2 each. | ||
+ | * Crocodile clips are clipped on the electrodes and brought out of the pot for measurement. | ||
+ | |||
+ | Results: | ||
+ | * Tension is sensitive to oxygen presence, and is in the 200mV range when activated, 80 mV at rest. | ||
+ | * Current is sensitive to oxygen presence, and is very low - about 0.4 mV when activated, dropping to 0.1 mV at rest. | ||
+ | * Power is therefore in the microW range. | ||
+ | |||
+ | ===Conclusion=== | ||
+ | |||
+ | * Electrode surface area seems an important feature. | ||
+ | * Most of the mud in the Tall-Mud design has been sitting here for a week, which may have an influence on community development. | ||
+ | |||
+ | ===Further Designs=== | ||
+ | * Scale-up the vegetable+compost tea design. | ||
+ | * Look for carbon electrodes, which seem more appropriate | ||
+ | * Replace salt bridge with paper | ||
+ | |||
+ | {{ : |