Chemical Process of Alcohol Fermentation

[SenoraRaton]

I will preface this with the fact that I am no chemist. I am currently working on a project to design low cost alternatives to gasoline/diesel for local farms. My primary area of focus at the moment is in ethanol production from "waste" products already being produced on the farm. I have my still designed and built (Yes I'm applying for a small scale ethanol producers permit). The question that I get from every farmer I talk to about implementing the system is first of all inputs, both labor and materials, and the second is whether or not there is a loss of fertility from the process. The things that they would be fermenting are often produce that either didn't sell at market, or were unsaleable. Traditionally these would be put into the compost pile and "recycled" to fertilize crops at a later date.

 

I understand the basic chemical process of alcohol fermentation, my question is what happens to the micro nutrients and more importantly the Carbon/Nitrogen ratio of the byproducts of the fermentation/distillation process? Are there more complex reactions in the fermentation process besides just glucose->alcohol + co2 because of the presence of complex inputs? I know that brewers often source their grain to animal producers as feed which would lead me to believe that there are viable nutrients remaining. Ultimately does the "fertility" of the byproducts of distillation(mash) decrease substantially, or are there minor/no fertility losses?

Edited November 20, 2012 by SenoraRaton

[John Cuthber]

In principle, the distillation process only removes alcohol and water so that's carbon, hydrogen and oxygen. That will increase the ratio of nitrogen to carbon.

All the other elements are left behind.

Part of the problem of recycling some of the nutrients would be that they are in solution and so you would need to carry a lot of water about to transport the nutrients from the still to the field. That's less of a problem if you are on the farm and would irrigate the crops anyway.

 

There are other more complex reactions- the obvious reason is that they yeast makes more yeast.

 

As an aside, if you put fruit on the compost heap some of the sugars will be fermented by wild yeasts and the alcohol will be partly lost by evaporation.

So, what you are proposing happens naturally anyway to some degree.

Recovering some of the energy value as ethanol won't stop you being able to compost the residual stuff, and the compost should still contain Nitrogen phosphorus etc, but it will mean you have to deal with a lot of water.