Science Buddies: "Ask an Expert"

I am investigating the amount of biogas generated by cow manure, human biosolids, and food waste in 1-liter bottles with balloons on the mouths of the bottles to capture the biogas. Each type of biomass is contained in its own bottle. (Science Buddies project: https://www.sciencebuddies.org/science- ... Q&from=TSW). After 10 days of fermentation the manure and biosolids are each generating some biogas and inflating the balloons, but the food waste is sucking the balloon inside the bottle. Why is the food waste doing this? Why isn't it generating biogas?

Charlie Hull

Hello,

I was able to find a topic similar to your problem posted earlier this year. You might want to take a look at what the expert had to say.

Here is the link: https://www.sciencebuddies.org/mentorin ... =31&t=8864

Best of luck.

Thank you for the research and possible explanation. All my bottles were filled to the top with distilled water to make them anaerobic. I also have a side experiment going on where I put the same amount of biomass in bottles without adding water (slightly aerobic?). Again, the manure and biosolids are creating biogas and the food waste is sucking the balloon inside the bottle. I think I'll ask the lab where I got my food waste slurry if they have a theory.