Science Buddies: "Ask an Expert"

My daughter is working on the trash to Biogas experiment. We made it our own by putting different species's manure in each bottle (cow, horse, & sheep). No veggie scraps, just manure. We weighed equal amounts of each manure and mixed with same amounts of water. We are on day 9 of 12. The balloons on the sheep manure have sucked into the bottle, 1 of them completely sucked in! Not sure why this is happening... Sample A of the horse manure has a very small amount of air in it. All other samples of horse and cow are completely flat. Did we do something wrong? Should we start again? The room that the samples are in is about 63 degrees and remains the same. I greatly appreciate any guidance you can offer! Thank you

Hi Kaschuessler!

I found an earlier Ask an Expert post that may explain why the samples with sheep and horse manure are not working (link: viewtopic.php?t=17043).

As for the cow samples that are flat, it says in the experiment instructions that an environment at warmer temperatures produces better results than one at colder temperatures so that could be an influence on your results. It also said that if there is an accumulation of biomass/manure at the top of the bottle, it can prevent biogas from going into the balloon and inflating it. If this has happened to your samples, tilt your bottle horizontally by about 45 degrees until the biomass is dislodged. Make sure to do this to all the bottles because they all need to be treated the same. Finally, make sure to check that your balloons do not have holes in them and your bottles do not have leaks.

I recommend also checking out the troubleshooting section of the experiment instructions because it offers more extensive info on why your balloons might not have inflated (link: https://www.sciencebuddies.org/science- ... #procedure).

Hope this helps, and let us know if you have any more questions!
Neha

NehaK6 wrote:Hi Kaschuessler!

I found an earlier Ask an Expert post that may explain why the samples with sheep and horse manure are not working (link: viewtopic.php?t=17043).

As for the cow samples that are flat, it says in the experiment instructions that an environment at warmer temperatures produces better results than one at colder temperatures so that could be an influence on your results. It also said that if there is an accumulation of biomass/manure at the top of the bottle, it can prevent biogas from going into the balloon and inflating it. If this has happened to your samples, tilt your bottle horizontally by about 45 degrees until the biomass is dislodged. Make sure to do this to all the bottles because they all need to be treated the same. Finally, make sure to check that your balloons do not have holes in them and your bottles do not have leaks.

I recommend also checking out the troubleshooting section of the experiment instructions because it offers more extensive info on why your balloons might not have inflated (link: https://www.sciencebuddies.org/science- ... #procedure).

Hope this helps, and let us know if you have any more questions!
Neha

Thank you for this pinned thread. My son is doing the same project and I needed some knowledge to guide him through. Fortunately found it here!

No problem, glad I could help!