[Digestion] Charcoal and biogas

[David]

Alex,

On 11/23/2011 6:09 AM, alexanderb.eaton at gmail.com wrote:
> Do we think that this is related to C:N or the surface area of the 
> carbon matrix or other? Has anyone applied this? It seem that maybe 
> periodic feeding of carbon may work, rather than daily. Thoughts 
> relative to small digesters? 

As it turns out, this publication is available on the web, here 
<http://www.scribd.com/doc/70129379/A-Note-on-Stimulation-of-Biogas-Production-From-Cattle>, 
so you can make your own judgement. The article offers what I would 
say is a speculation:

    The increase in gas production caused by the addition of charcoal
    may be attributed to enhanced microbial activity in the digester
    contributed by growth of bacteria on the surface of the carbon
    particles (Adams, 1976). This is corroborated by the results of
    studies on microbial profiles of the digesters (Table 5) which
    showed that the slurry amended with charcoal had higher microbial
    numbers than the unamended slurry.


The peculiar thing in this report is that charcoal from different 
sources had such different effects, which would tend to indicate that 
whatever is responsible for changes is something that can be strongly 
affected by factors such as (perhaps) the type of wood and the method 
by which it is made into charcoal. Changes in the surface 
characteristics of the charcoal might be expected to have an impact on 
the characteristics of the biofilm which is subsequently supported 
thereon, but as yet, certainly based on this one report, and at least 
as far as what I have seen in the literature if not indeed, it would 
seem that we do not have a reliable answer as to the causes of any 
improvements.


d.
-- 
David William House
"The Complete Biogas Handbook" |www.completebiogas.com|
/Vahid Biogas/, an alternative energy consultancy |www.vahidbiogas.com

|
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"Make no search for water.       But find thirst,
And water from the very ground will burst."
(Rumi, a Persian mystic poet, quoted in /Delight of Hearts/, p. 77)

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