Pee Power using microbial fuel cell measuring output

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SciB
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Re: Pee Power using microbial fuel cell measuring output

Post by SciB »

Don't add more urine now. If the mud surface where the cathode makes contact is not moist, add some distilled water. I think it's an electrical problem and not a bacterial one. What do you think?
kbmcgill
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Project Question: Pee Power using Microbial Fuel Cell
Project Due Date: January 18, 2016
Project Status: I am conducting my experiment

Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Today's peak power was 14.143 using 4670 ohms down from 16.484 (2190 ohms).

Should we add more urine?

Kerry
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Re: Pee Power using microbial fuel cell measuring output

Post by SciB »

It's your call. What I would do is remove the cathode and add some distilled water to the surface. How moist is the soil? When you replace the cathode onto the mud, press it gently to make sure it is in good contact.

Another possible cause of loss of power is that the wire to the cathode is no longer making good contact. You could pull it out, scrape it off if it looks a bit corroded and reinsert it.

Also make sure that all the wires in the hacker board are tight and making good contact.

Once you rule out all the possible electrical failures then the conclusion you are left with is that the urine is inhibiting the bacteria. 14 to 16 uW is still in the readable range, but it is way lower than what you were getting before you added the urine. If you add more and the power drops again then it means the urine is somehow preventing the MFC from working.

You really need to repeat this experiment with at least two cells and take readings more often.

Sybee
kbmcgill
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Project Question: Pee Power using Microbial Fuel Cell
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Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Sybee:

I added 2ml distilled water on 1/13/16. By 1/14/16 the peak power had increased from 14.143 on 1/12/16 to 61.504 on 1/14/16.

It is still nowhere near the peak power output of 155.

What do you think we should do now?

Kerry
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Re: Pee Power using microbial fuel cell measuring output

Post by SciB »

Add 10 ml of DW!

Maybe the urine you added contained an unusually high amount of sodium chloride and the ions interrupted the flow of electrons from the anode to the cathode. You still did not tell me yet whether the soil at the surface next to the cathode was moist. If it dries out then the cathode will not make good contact with the soil and the power may drop because of that.

You can't be certain that the power would not have increased anyway without the addition of DW but if you can get the power up to a higher and stable level then you can try adding another shot of urine. When you do that be sure you have time afterwards to take hourly readings after the addition so you can see how quickly the power was interrupted.

You could even do an additional test by adding a solution of sodium chloride to the mud and see if it has the same effect as adding urine. If it does then you can be pretty confident that it is the ions that are causing the power drop and not an effect of the urine on the bacteria.

Thanks for keeping us posted on your progress!

Sybee
kbmcgill
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Project Question: Pee Power using Microbial Fuel Cell
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Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Latest peak powers

1/15 86.436
1/16 114.92
1/17 122.50
1/18 152.83
1/19 175.61

i added the distilled water and seemed to do the trick. our peak power numbers have now exceeded the pre urine peak power numbers. urine was added on 1/10.

Any thoughts?

thank you for all of your help.

kerry
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Re: Pee Power using microbial fuel cell measuring output

Post by SciB »

Very interesting! Thanks for posting the data. This will make a good poster for the science fair. You have some really good bacteria there! Maybe the nutrients in the urine were finally washed down to the bacteria and that is why the power is higher.

Obviously the urine did something at first to interrupt the power, but what? My guess is that the salts in the urine alter the physical connection between the anode and the cathode and not that the urine inhibits the bacteria. I think you could test this by waiting till your power stabilizes--at least as much as it was before--then adding another 2 mL of urine and immediately measuring the power. If it drops instantly then you can be sure that the drop is due to something physical rather than biological. Then you can repeat the same experiment with the DW and hopefully see the reversal of the inhibition again.

I think you have really made some interesting findings with this project. Congratulations!

Sybee
kbmcgill
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Project Question: Pee Power using Microbial Fuel Cell
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Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

thanks so much. i will keep you posted. i'm not sure what we've done but i'm glad the mfc is still producing power.

kerry
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Project Question: Pee Power using Microbial Fuel Cell
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Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Sybee:

The project continues... I have attached the peak power graph. The red dots represent the measurement the day after urine was added. Let me know if you have any thoughts. Thank you.

Kerry
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Project Question: Pee Power using Microbial Fuel Cell
Project Due Date: January 18, 2016
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Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Date Peak Resistor
Power
Day 1 9.078 2190
Day 2 22.707 2190
Day 3 34.780 2190
Day 4 34.530 2190
Day 5 35.790 2190
Day 6 26.520 2190
Day 7 132.980 470
Day 8 76.730 1000
Day 9 70.750 1000
Day 10 67.680 2190
Day 11 75.076 1000
Day 12 81.790 1000
Day 13 77.840 1000
Day 14 96.620 2190
Day 15 112.250 1000
Day 16 118.330 1000
Day 17 114.240 1000
Day 18 132.496 1000
Day 19 144.930 470
Day 20 155.106 470
Day 21 16.484 2190 Day after 1 ml urine added
Day 22 14.143 4670
Day 23 50.939 2190
Day 24 61.504 1000
Day 25 86.436 1000
Day 26 114.920 1000
Day 27 130.850 1000
Day 28 152.830 470
Day 29 175.560 1000
Day 30 216.220 1000
Day 31 187.680 470
Day 32 147.170 470
Day 33 187.680 470
Day 34 157.420 470
Day 35 68.640 1000
Day 36 69.700 1000
Day 37 59.050 1000
Day 38 42.850 1000
Day 39 37.610 2190
Day 40 40.280 2190
Day 41 102.400 1000 Day after 2 ml urine added
Day 42 97.430 470
Day 43 88.210 1000
Day 44 77.840 1000
Day 45 95.480 1000
Day 46 67.600 1000
Day 47 9.530 4670
Day 48 96.530 4670 Day after 3 ml urine added
Day 49 122.550 470
Day 50 147.170 470
Day 51 115.500 470
Day 52 48.841 1000
Day 53 62.500 1000
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Re: Pee Power using microbial fuel cell measuring output

Post by SciB »

Hi Kerry,

Thanks for posting your latest data. I have one question--are the power measurements from a new MFC or the one you used before? Why I asked was that the last power reading you showed from Jan. 19 was 175 uW and on this series Day 1 power is 9.1 uW. On what day did you take the 'Day 1' reading? Did it drop from 175 to 9?

I really don't know what to make of your data. It is risky to base a conclusion on one experiment. If you had set up three MFCs and got similar power readings in each of them, your results would be much more believable. You would still have a challenge to explain the urine-induced changes but at least you could be statistically certain that they were accurate. I suspect that the measurements on day 7 and 47 are not correct just because they differ so much from the values before and after them.

What are your ideas about the way the power fluctuates after the various urine additions? I suggested a long time ago that you take V readings right after you add the urine to establish whether the salts or other chemicals in it affected the electrode directly. Did you ever try that? You could also test it by making a sodium chloride solution and adding 1 ml of that to the cell and immediately measuring the V. That would tell you if there is an effect on the electrode separate from the effect of the nutrients on the bacteria. The increase in V upon addition of distilled water after the urine would argue that this is true.

Post again with answers to my questions and your conclusions. I would like to know the explanation for these results.

Sybee
kbmcgill
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Project Question: Pee Power using Microbial Fuel Cell
Project Due Date: January 18, 2016
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Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

This is all the data from the MFC we have been using. We just changed the dates to day 1, day 2 etc. I know we should have set up multiple MFCs so that will be our recommendation for future experiments. I agree that day 7 does not appear correct and is more of an outlier. Day 21 saw a significant decline in power. I believe your speculation was that sodium in the urine may have adversely affected the power output. When we subsequently added 2 ml of distilled water we saw a significant increase in power output. Days 40 and 41 saw increases after 2 ml urine added then a decline. After adding 3 ml of urine we saw another increase. I would assume that after almost 2 months the bacteria in the soil must have declined significantly so although we do see power output increases after adding urine they are short lived.

Understanding the limitations of using only one MFC, do you think we can make a conclusion that adding urine increases the power output? We are neophytes at this but it has been very interesting. Thanks for helping us with this.. Do you think we should trying adding 1 ml of sodium chloride solution. I was thinking maybe adding 4 ml of urine and see what happens.

Day 1 9.078
Day 2 22.707
Day 3 34.780
Day 4 34.530
Day 5 35.790
Day 6 26.520
Day 7 132.980
Day 8 76.730
Day 9 70.750
Day 10 67.680
Day 11 75.076
Day 12 81.790
Day 13 77.840
Day 14 96.620
Day 15 112.250
Day 16 118.330
Day 17 114.240
Day 18 132.496
Day 19 144.930
Day 20 155.106
Day 21 16.484 First measurement after 1 ml urine added no distilled water added.
Day 22 14.143
Day 23 50.939 First measurement after adding 2 ml distilled water
Day 24 61.504
Day 25 86.436
Day 26 114.920
Day 27 130.850
Day 28 152.830
Day 29 175.560
Day 30 216.220
Day 31 187.680
Day 32 147.170
Day 33 187.680
Day 34 157.420
Day 35 68.640
Day 36 69.700
Day 37 59.050
Day 38 42.850
Day 39 37.610
Day 40 40.280 First measurement after adding 2 ml urine 2 ml distilled water
Day 41 102.400
Day 42 97.430
Day 43 88.210
Day 44 77.840
Day 45 95.480
Day 46 67.600
Day 47 9.530
Day 48 96.530 first measurement after adding 3 ml urine 2 ml distilled water
Day 49 122.550
Day 50 147.170
Day 51 115.500
Day 52 48.841
Day 53 62.500
Day 54 22.911
SciB
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Re: Pee Power using microbial fuel cell measuring output

Post by SciB »

Hi Kerry,

Congratulations on generating a really interesting set of data! Yes, it would have been better to have multiple MFCs so you could do statistics, but having daily readings allows you to be pretty confident that the patterns you saw were true. What do they mean?--that is the question.

So, does Day 1 correspond to Jan. 20? When you plot the data you can just use numbers for the days rather than dates but be sure they are consecutive or else indicate where there was a break in measurement.

I am still wondering about the timing. Did you add the 1 ml of urine on Day 20 and then measure the V on Day 21? How many hours after you added the urine did you do the measurement? How many hours after you added the DW did you do the measurement?

My suggestion is to add 1 ml of saline at an early enough time so you can make hourly V measurements for say 6 hours. What I want to see is if there is an IMMEDIATE effect of salt on the V and to answer that question you need to take a reading at 30 mins after adding the salt and then at hourly intervals. After the V has stabilized again by addition of DW, you could add 1 ml of urine and do the same set of measurements. If you see the same pattern as with the salt you can be pretty certain that the initial effect is electrical and not bacterial. The urine will provide nutrients to the bacteria and that makes them grow and divide but this effect would take several days, not one hour.

If you could construct a MFC such that nutrients were continuously added to the bacterial layer and waste products withdrawn from the bottom then it should produce power constantly. The bacteria would be continuously fed and could remain healthy as long any waste products were eliminated. It wouldn't be enough to power a water heater or even a TV, but maybe it could light some LEDs for the bathroom!

Congratulations again and if you have any questions about writing the report and presenting the data let us know.

Sybee
kbmcgill
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Project Question: Pee Power using Microbial Fuel Cell
Project Due Date: January 18, 2016
Project Status: I am conducting my experiment

Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Day 1 is from the beginning of our experiment. Dec 22. Day 54
Is February 13th. (Yesterday)
kbmcgill
Posts: 46
Joined: Sat Jan 02, 2016 11:11 am
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Project Question: Pee Power using Microbial Fuel Cell
Project Due Date: January 18, 2016
Project Status: I am conducting my experiment

Re: Pee Power using microbial fuel cell measuring output

Post by kbmcgill »

Yes added 1 ml of urine on day 20 and measured day 21

Added 2 ml urine day 39 measured day 40

Added 3 ml urine day 47 measured day 48.

Added 1ml if urine alone. Saw significant decline then added 2 ml
Water then saw increase.

Added 2 ml urine. 2 ml water

Added 3 ml urine and 2 ml water.
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