Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
Last revisionBoth sides next revision
michka:research:microbial_fuel_cells:bruxelles2 [2014-09-26 09:44] michkamichka:research:microbial_fuel_cells:bruxelles2 [2014-10-09 16:09] michka
Line 1: Line 1:
 ====Experiment "Bruxelles2"==== ====Experiment "Bruxelles2"====
 +
 +{{ :michka:research:microbial_fuel_cells:dscf6353.jpg?300 |}}
  
 ===Salt Bridges=== ===Salt Bridges===
Line 5: Line 7:
 I failed a three batches of [[http://www.treehugger.com/slideshows/gadgets/make-microbial-fuel-cell/page/3/#slide-top|salt bridges]] before managing to have one stable made. I failed a three batches of [[http://www.treehugger.com/slideshows/gadgets/make-microbial-fuel-cell/page/3/#slide-top|salt bridges]] before managing to have one stable made.
  
-===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.
Line 16: Line 17:
    * 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
Line 27: Line 27:
  
 ===Mud, Tall=== ===Mud, Tall===
 +
 +{{ :michka:research:microbial_fuel_cells:dscf6283.jpg?300 |}}
 +//Mud samping location - Sint-Jans-Molenbeek, Belgium//
 +
 +
 +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.
 +
 +Longer-term results (12 days & more):
 +   * Tension is stable at 110  mV, but drops when measuring current (and rises up afterwards).
 +   * Current is stable at 107 microA, but drops after measuring tension (and rises up afterwards).
 +   * Overall power is therefore around 11 mW.
  
 ===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.
 +
 +Longer-term results (12 days & more):
 +   * Tension is stable at 20 mV.
 +   * Current is stable at 1 microA.
 +   * Overall power is therefore around 20 microW.
  
 ===Vegetable Waste & Compost Tea=== ===Vegetable Waste & Compost Tea===
 +
 +{{ :michka:research:microbial_fuel_cells:dscf6352.jpg?300 |}}
 +
 +Design details:
 +   * The substrate is made of vegetable scraps (potatoes, carrotes, zucchinis) covered with compost tea (from FoAM's vermicompost production), and inoculated with a tea spoon of mud from Scheutbos Park.
 +   * 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.
 +
 +Longer-term results (12 days & more):
 +   * Tension is stable at 120 mV.
 +   * Current is stable at 135 microA.
 +   * Overall power is therefore around 16 mW.
 +
 +===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.
 +   * Considering electrode area and overall volume, the compost tea design seems very productive.
 +
 +===Further Designs===
 +   * Scale-up the vegetable+compost tea design.
 +   * Look for carbon electrodes, which seem more appropriate
 +   * Replace salt bridge with paper
 +
 +{{ :michka:research:microbial_fuel_cells:dscf6357.jpg?300 |}}
  • michka/research/microbial_fuel_cells/bruxelles2.txt
  • Last modified: 2014-10-09 22:02
  • by 148.122.12.234