Bio-mass to bio-gas experiment

[tjneer]

My daughter is conducting an experiment where you put biomass in a 2 liter bottle, fill it to the top with distilled water then attach a baloon to see what type of bio-mass does the best. She is using Cow Manure, bananas, eggs. She had filled up a bottle with 80g of bio-mass (say manure), then added the water. I went to some sites that had this experiment and it says to use 10g of bio-mass. What will be the impact of her experiment since she used so much? 80g of bananas is about 1/2 cup mashed. Do we need to redo her experiment using 10g instead of 80g? She just started this experiment last night.

[sunmoonstars]

Hi,

This is a great project. I wouldn't worry about the differences in how you did it, for two reasons. First, since you said 80g of banana is about 1/2 cup mashed, I imagine it doesn't look like much in the bottom of a two liter bottle full of water. It should still produce gas, but maybe you will find the balloons get fuller faster because more gas is being generated. I would watch for that, so maybe measure the balloons 2x (say 8am and 8 pm) so you have alot of data points even if the balloon blow up faster than expected.

Second, science is about trial and error. The experiment is a chance to work through the process of the scientific method, even if your experiment didn't work exactly as planned. Have fun!

[tjneer]

Thank-you! We will take your suggestion to monitor more often. Thanks

[donnahardy2]

Hi,

This is a great experiment and the production of gas is dependent on the growth of anaerobic bacteria from the cow manure growing on the food and producing methane gas. Sunmoonstars was right that it won't matter for your experiment; you should have used the same quantity of ingredients for your control and experimental containers so you will be able to compare results. However since you used a lot more than suggested, you should expect to see more gas produced. I hope you are using really big balloons. It will take a while, up to several days, for the fermentation to begin because you introduced some oxygen when you mixed the sample together. However, once anaerobic conditions are reestablished, the bacteria will grow and produce lots of gas.

What temperature are you using? The cow manure bacteria have an optimum temperature of about 37 degrees Centigrade and will grow more slowly if you are using a lower temperature.

Donna Hardy