Re: DIG-L: Re:'Understanding Anaerobic Treatment' - longishmessage

[doelle <doelle@ozemail.com.au>]

Dear Holger,


>(1) Methanogens are neither bacteria nor archaea bacteria. Methanogens
>are archaea. Bacteria and archaea are two distinct taxonomic domains.

Many thanks for this correction. I should have mentioned it specifically, but I did not know that I had to go into these details.
>
>(2) Interspecies hydrogen transfer (IHT) does not primarily affect the
>redox potential but the concentration of hydrogen in solution.
>

You must admit, however, that the concentration of hydrogen has an effect on the redoxpotential. This is why the redox required is so low. If you have no hydrogen, or less hydrogen, you hardly achieve the redoxpotential required.

>(3) IHT depends on the interaction of two groups of microorganisms, viz.
>methanogens and acetogens. The latter group has to be distinguished from
>the acidogenic bacteria.

If read my outline correctly, I have seprataed clearly acetogens from methanogens. I stated the third group as acetogens and the fourth group of microorganisms as methanogens.
I also mentioned, that acetogens are not absolutely necessary for a good anaerobic digestion and biogas formatoin. They only appear IF you have volatile acids other than acetate in your digester. Since most manure has, of course protein, one automatically has to have acetogens because of the higher volatile fatty acids.
as you can see, I clearly separated acetogens from methanogens. Acetogens, however, can contribute considerably to the hydrogen content.

Thus we have no difference in this aspect. Agreed ?
Best regards
Horst
>


Horst W.Doelle, D.Sc., D.Sc. [h.c.]
Chairman, IOBB
Director, MIRCEN-Biotechnology
FAX: +617-38783230
Email: doelle@ozemail.com.au DIGESTION List Sponsors, Archive and Information http://www.crest.org/renewables/digestion-list-archive http://www.crest.org/renewables/biomass-info/ Beginners Tour of Biogas http://WWW.roseworthy.adelaide.edu.au/~pharris/biogas/beginners