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--- michka:research:microbial_fuel_cells:bruxelles2 [2014-09-26 09:43] – created michka
+++ michka:research:microbial_fuel_cells:bruxelles2 [2014-10-09 22:02] (current) – 148.122.12.234
@@ Line 1: / Line 1: @@
 ====Experiment "Bruxelles2"====
-===Salt Bridges===
+{{ :michka:research:microbial_fuel_cells:dscf6353.jpg?300 |}}
-I failed a three batches of salt bridges before managing to have one stable made.
+===Salt Bridges===
-===The right protocol===
+I tried three batches of [[http://www.treehugger.com/slideshows/gadgets/make-microbial-fuel-cell/page/3/#slide-top|salt bridges]] before managing to have a stable one made.
+The right protocol:
    * Mix 200 ml water, 5 g of agar and 75g of salt in a cooking pan.
    * Bring it to a boil while mixing regularly.
@@ Line 16: / Line 17: @@
    * 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
      * This induces a very uneven mix, where salt and agar are not well dissolved
@@ Line 27: / Line 27: @@
 ===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===
+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===
+{{ :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 |}}