[Digestion] Biogas plant at Zoo

[Paul Harris]

G'day All,

Good to see some discussion again - well done (but be sure to be nice to 
each other!).

Some people see a biogas plant as an energy machine, some as a waste 
treatment process and some as a way of making nutrients more plant 
friendly. Can I nicely say that the smartest people (anyone working in 
biogas MUST be smart!) see it as all three. I admit that in some 
applications external factors may dictate some decisions. For example Dr 
Karve has focused his work on urban users who have limited space and 
limited access to manure, so his compact units using food waste (which 
they do have!) are ideal in this situation. I worked with a nursery 
owner who was interested in the nutrients, so for him the energy was a 
bonus. Early digesters were often "waste treatment" units (part of a 
treatment plant), the nutrients were just a nuisance to be disposed of 
and the gas may have been just flared off to get rid of it

If you dry and burn dung (which will work, cow dung is widely used in 
India I believe) it is a bit smelly during drying, messy and time 
consuming. You get rid of the waste and pathogens (except for the 
workers being exposed to infection) and generate energy but you lose all 
the nutrients and organic carbon (important for crop production) and the 
combustion process is not very efficient and generates smoke (causing 
eye and throat problems, like with burning wood, I expect).

As an aside (I am not being critical here) one of my favourite quotes is 
"Minds are like parachutes, they only work when open!" (Lord Thomas 
Dewar) and a while back I realised both are usually used in emergencies.

Happy digesting,
HOOROO

On 28/06/2013 6:21 AM, paul perrin wrote:
> What I have read does say that human waste is pretty useless for 
> biogas (I saw a figure of 1 cubic foot per day from one humans waste) 
> - but I understand that animal like elephants have massively 
> inefficient digestion systems (much food passing through almost 
> entirely undigested) so their dung will be entirely different and 
> contain much more raw ingredients for biogas generation (would dried 
> elephant dung even burn?). There is a calculation to be done, and it 
> can't be based on 'averages' across species.
>
>
> On 27 June 2013 20:28, Anand Karve <adkarve at gmail.com 
> <mailto:adkarve at gmail.com>> wrote:
>
>     Dear Rabin,
>     all animals, including humans, function as live biogas plants. The
>     fecal matter represents slurry coming out of a biogas plant. Using
>     animal dung as feedstock in a biogas plant is a highly inefficient
>     way of producing biogas. You get about 800 litres biogas from just
>     1 kg starch. To get the same amount of biogas from cattle dung,
>     you need 40 kg of it. One gets much more energy from dung if it
>     can be dehydrated and burned directly
>     Yours
>     A.D.Karve
>     On Wed, Jun 26, 2013 at 11:35 AM, Rabin Shrestha
>     <rshrestha at winrock.org.np <mailto:rshrestha at winrock.org.np>> wrote:
>
>         Hello,
>
>         Will it be a good idea to install biogas plant at zoo to
>         manage and generate energy from the animal waste in the zoo???
>
>         Regards,
>
>         Rabin
>
>
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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. A.D. Karve
>     Trustee & Founder President, Appropriate Rural Technology
>     Institute (ARTI)
>
>
>     _______________________________________________
>     Digestion mailing list
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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/
>
>
>
>
>
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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/
>

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