[Digestion] Dry fermentation in developing countries
renertech at xtra.co.nz
Fri Oct 29 00:47:44 PDT 2010
Yvonne Hi! When you say developing countries, what sort of construction materials are you thinking of? Would old 20 tonne shipping containers be available?
Are cement materias and tradesmen skilled in cement plaster work readily available? What about PVC tarpaulin cloth? Are there trucks on the roads that have waterproof covers that can be strapped down over a load? What is the local soil and terrain? Is it possible to dig say 2-3 metres deep in the soil and get a smooth surface, or is the terrain too soft and sandy to hold to the shape of a cistern or trench dug in the soil? Is it too rocky to allow any sort of digging at all? If you can home in a little more on the country side and local skills available I can make several different suggestions. Sincerely, Ken Calvert. www.coffee.20m.com
----- Original Message -----
From: Voegeli, Yvonne
To: digestion at lists.bioenergylists.org
Sent: Thursday, October 28, 2010 9:53 PM
Subject: [Digestion] Dry fermentation in developing countries
I like to start a new discussion on a different topic, namely the dry-fermentation process (discontinuous) similar to the digesters developed by the companies Bekon or Bioferm in Germany. The organic waste is filled batch-wise into simple garage-like digesters for about 30-40 days.
Experts report that this process has a high potential for application in developing countries as it has the simplest design and the solid waste digesters are the least expensive ones. Also, substrates that lead to operating problems during wet fermentation due to their structure or the proportion of impurities they contain can still be processed using dry fermentation methods. However, up to date, there is no experience with this technology in developing countries. Therefore, our idea is to develop a dry-fermentation biogas plant adapted to the situation in developing countries using locally available material.
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 anybody of you familiar with discontinuous dry-fermentation systems and has an idea how the security can be assured in a developing country context? Is it possible to install a simpler venting system?
- Likewise, when removing the drum from a floating-drum digester for emptying, how is ensured that at no time an explosive gas-air-mixture occurs?
Thanks for your ideas,
Eawag / Sandec
P.O. Box 611
Phone: +41 (0)44 823 54 20
Fax: +41 (0)44 823 53 99
yvonne.voegeli at eawag.ch
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