DIG-L: Re: [IBS-GEN] methane digesters from clay and mud

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

The type of digesters described by Brent are the old type of anaerobic digesters, called Gobar plants, which originated in India. I learned in China that they had a lot of problems with them as they eventually started to leak.
Nowadays, anaerobic digesters are not biult in the ground anymore and bricks have been replaced with concrete or even the cheaper material polyethylene. Whereas the former can easily be above ground, the latter needs to be in a ditch.
Above ground digesters require a jacket to keep the temperature with biogas heated water. This is one of the reasons why mesophilic digestion is much more preferable and more economical than thermophilic digestion.
Thermophili digestion kills more pathogens and has far lower BOD in its effluent, whereas mesophilic digester effluent is still rich in nutrient for aquaculture. Mesophilic digester effluent has a strongly reduced pathogen level, and is thus save to work with or being used for further product formation.
Horst Doelle
At 12:34  13/02/00 +0100, you wrote:
>-----Original Message-----(edited)
>From:   Brent  G. Bingham [bingham@zekes.com]
>
>The article I first saw was a comparison of the clay ovens built near in
>the southwest USA to digesters they were using in India. The entire
>structure is built from hand made clay bricks heated with very hot wood
>fire to vitrify the clay into a glass like inert material like clay sewer
>pipe. The bricks are laid in a circle in a pit in the ground. The bricks
>are laid up to the surface in a circle. At the surface the circle is
>gradually decreased to form a dome with a manhole on top to form a lid. The
>inside of the structure is plastered with clay. After it dries the interior
>is vitrified by fire to make it waterproof.  I saw later articles where
>they used plastic sheeting to make a gas dome.
>
>I do not know who sent me the information. It has been almost 7 years ago.
>Perhaps others saw the information. I will look through my boxes of old
>information to see if I copied it.
>
>Brent G. Bingham
>
>
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