[Digestion] Dry fermentation in developing countries

Hoysall Chanakya chanakya at astra.iisc.ernet.in
Thu Oct 28 09:28:35 PDT 2010


Dear All,
At IISc Bangalore there has been sustained work on small scale dry
digestion carried out over the last 20 years (termed as solid state
stratified bed reactor) in principle very similar to Bekon.  There is
quite some data on how the process works and how much gas can be obtained
from various feedstocks.

I could send 4 research papers bearing this information to whoever is
interested.  Please send me a mail directly.  Tommorrow I will make a
small gist of this work and post it to the server.
with best wishes
chanakya




> In a developing world context, it would also make sense to utilize the as
> much of the gas production as possible, meaning that maybe a two-chamber
> system would make the most sense so that you could allow the HRT to be
> 100+
> days in each chamber.  Then, if there was a flexible portion of each
> chamber
> that could be compressed while venting you would be able to essentially
> eliminate any risk of an explosive mixture inside the system.  My point it
> that it would make sense to push the gas through to the end-use, then open
> the chamber while it was empty.  Under that scenario I see very little
> risk.  I may also be talking at a small scale, as I am imagining chamber
> of
> maybe 50 m3 and smaller.  Dry digestion for us would be a huge step, as we
> have a water limitation that keeps us from installing digesters in many
> areas of Mexico and Latin America.
>
> I am returning from the UN Genus waste to energy meeting in Costa Rica,
> where I did have a really interesting discussion about a multi-chambered
> dry
> digester system for food waste and solid waste collected at a larger level
> and installed at landfills.  In that scenario, I also envision some sort
> of
> flexible cover that could be vacuum pumped empty before the cover was
> opened.  We were also talking about cells with 2+ year HRTs.
>
> Does anyone have some good info on dry digestion, appropriate substrates,
> HRTs and gas production rates?
>
> A
>
> On Thu, Oct 28, 2010 at 10:22 AM, David <david at h4c.org> wrote:
>
>>
>> Yvonne,
>>
>> On 10/28/2010 1:53 AM, Voegeli, Yvonne wrote:
>>
>> After visiting a Bekon biogas plant in Switzerland, I’m especially
>> concerned regarding the opening of the digester for emptying and
>> refilling.
>> Before opening the door, the digester has to be vented in order to avoid
>> a
>> gas-air-mixture which is explosive. This installation seems to me rather
>> complicated....
>>
>>  ...Is it possible to install a simpler venting system?
>>
>>
>> I would venture a guess that where the inlet air is being forced in by
>> bubbling through water, and the outlet air likewise is allowed to escape
>> by
>> bubbling through water, then the only place in the system where there
>> would
>> be both a potentially explosive gas mixture and the potential of a spark
>> would be at the evacuation point of the exiting gas mixture. Where
>> sufficient air is blown over the water through which the evacuating air
>> is
>> exiting, then the risk of any explosion would, I would think, be very
>> close
>> to zero.
>>
>>
>>
>> d.
>> --
>> David William House
>>  "The Complete Biogas Handbook" www.completebiogas.com
>> *Vahid Biogas*, an alternative energy consultancy www.vahidbiogas.com
>>
>>  "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)
>>
>> http://bahai.us/
>>
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>> for more information about digestion, see
>> Beginner's Guide to Biogas
>> http://www.adelaide.edu.au/biogas/
>> and the Biogas Wiki http://biogas.wikispaces.com/
>>
>>
>>
>
>
> --
> Alexander Eaton
> Sistema Biobolsa
> IRRI-Mexico
>
> Mex cel: (55) 11522786
> US cel: 970 275 4505
>
> alex at sistemabiobolsa.com
> alexanderb.eaton at gmail.com
> sistemabiobolsa.com
> www.irrimexico.org
>
> --
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>
> for more information about digestion, see
> Beginner's Guide to Biogas
> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
>
>


-- 
Dr. Hoysall Chanakya
Centre for Sustainable Technologies
(Assoc. Faculty at Centre for Infrastructure, Sustainable Transport and
Urban Planning (CiSTUP) and Centre for Contemporary Studies)
Indian Institute of Science, Bangalore 560 012
ph 91-80-2293 3046; fax-91 80 2360 0683


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