recirculation of CO2

Digester design and construction info

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p willis
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recirculation of CO2

Post by p willis » Sat Feb 01, 2003 8:04 am

What does recirculation of CO2 byproducts produced by burning methane, slowly bubbled into the digester, have on overall methane production.

Would not the CO2 become a source of available carbon for further methane generation?

What sort of bacteria (species) are we talking about there?

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Bob
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Post by Bob » Sun Feb 02, 2003 7:43 pm

I've never tried that idea, but I would think that adding CO2 to the digester would have the effect of lowering pH. CO2 is fairly soluble, combining with water to produce carbonic acid. Which would require additional buffer capacity.

Recirculation of biogas, however, is fairly common. In addition to being a simple and effective way to agitate the contents, it also can be used to help strip excess CO2 from the digester, helping the buffering system.

I don't think there's a simple answer to the question of what species of bacteria live in a digester. The microorganisms in the digester make up a complex ecology, including many different species. The populations that eventually come to dominate the soup will be the ones that grow & reproduce the fastest -- which will depend on a variety of different parameters, including substrate composition, loading rate, retention time, temperature, etc. (e.g. if you eat nothing but vegetables, you will harbor a different ecology of intestinal organisms than someone who eats only meat & potatoes.)

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