DIG-L: Fwd: Re: Biodigestion

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

> Date: Sat, 12 Aug 2000 07:59:18 +1000
> To: "Kermit Schlansker" <kssustain@provide.net>
> From: doelle <doelle@ozemail.com.au>
> Subject: Re: Biodigestion
>
> To Kermit,
>
> Many thanks for your information in regards to peat. Yes, the ratio C/N
> can be up to 30/1. It all depends how much biogas you want to produce. If
> you want at least 1m3 gas per m3 volume, you have to watch the C/N ratio
> very closely.
> In regard to your manure, transporting the manure in wagons was very much
> a custom in Germany during and after WW2.  However, since then we
> introduced
> a) extensive antibiotic treatment and feeding in eg chicken
> factories
> b) hormone feeding to get more meat
> These changes in raising animals endangers the use of manure direct for
> fertilisation. It has been shown that antibiotic resistant salmonellas
> were found attached to seeds and plants and thus could cause havoc.
> This is one of the reasons why I have warned many times before that we
> cannot organic farm in the old way. The microbes are too resistant and
> much more dangerous to what they used to be - in relative terms. 
> Before applying human and/or animal manure to the fields as fertiliser,
> they HAVE TO BE either anaerobically digested or composted in order to
> avoid spreading the diseases.
> You may realise that 90% of all infecticious diseases still occur in
> developing countries, because of the contact with waste and manure and
> lack of sanitation or application of manure on the fields and in ponds
> for fish feeding.
> Why would you apply manure directly onto the field, when anaerobic
> digestion gives you cheap cooking etc energy and the residue - free of
> pathogens - is still a magnificent fertiliser, particularly after
> vermiculture. In Vietnam and Cambodia, Philippines it has been shown that
> you can build anaerobic digesters of 6-10 m3 for around US$ 100.
> Polyethylene digesters nowadays are so cheap, that farmers can easily
> afford it. What I cannot understand is, why farmers in the developing
> world are prepared to do it, yet our farmers in the developed world, who
> have much more money, are not.
> Best regards
> Horst
> At 10:14  11/08/00 -0400, you wrote:
> > To Kevin,
> >  
> >          Your
> > remarks about the piggery remind me of the German farmer just after WW2.
> > They transported their urine and manure in a tank wagon pulled
> > usually  by cows. They mixed this mixture with straw on a platform
> > just outside their houses before putting it on the fields. The stench was
> > horrible. I suspect that all third world countries are living with this
> > odor because it takes money to buy fertilizer.  Maybe some of this
> > material could be piped or brought in on tank wagon.
> >          You know more about the
> > chemistry than I do. However one reference states that paper and straw
> > can be biodigested. From that I assume that sawdust could be also. This
> > brings us to the question of how much energy would be left in the solids
> > after biodigestion. If peat is more carbon than cellulose than it
> > probably would not digest. The 50% efficiency of course related to the
> > fact that about 50% of the total energy comes out as waste heat at the
> > fermentation temperature. This heat could possibly be used to heat
> > buildings in Winter, heat water, or distill water.
> >         One of the problems is that we
> > are talking about some large expensive tanks. On the other hand storage
> > of large amounts of water may help in heating and cooling and water
> > recycling. 
> >         
> >   To Horst,
> >  
> >           
> > My reference stated that the ratio of carbon to nitrogen  should be
> > about 30/1. They used manure to get the nitrogen and computed the ratio
> > fairly closely, presumably because they wanted to maximize the carbon
> > content. They experimented with several types of materials.
> >  
> >   To Johannes,
> >  
> >          I hope your
> > project succeeds because biomass and total energy projects will become
> > crucial as fossil fuels are depleted. One way to minimize odors is to use
> > more carbon and less nitrogen. In fact the human sewage itself might
> > furnish sufficient nitrogen.  If the btus /acre yield were high
> > enough then clover might be the best crop for the biodigester because it
> > would furnish its own nitrogen and make energy and fertilizer. Crop
> > residues could also feed the digester. Wood ashes from a wood fired
> > Combined heat and Power system also would make fertilizer.
> >  
> >                                                           
> > Kermit Schlansker 
> >  
> >  

Horst W.Doelle, D.Sc., D.Sc. [h.c.] 
Chairman, IOBB 
Director, MIRCEN-Biotechnology 
FAX: +617-38783230 
Email: doelle@ozemail.com.au