Stovers,
The pH of dung is dependent on the C/N (available C/ available N)
ratio. A lot of dung has a very high pH. If you smell ammonia you know
you have high pH dung. Bacteria need available carbon and available
nitrogen. One or the other will likely be the limiting factor, so if
nitrogen is limiting (high C/N ratio above ~15) the excess carbon will
form organic acids. and a low pH results. If carbon is limiting the
nitrogen forms ammonia and the pH goes up releasing the ammonia into the
air (smells). Finally enough goes off (lost nitrogen from the ag
system), pH drops.
In the end it all comes out about the same. Excess carbon is a slow
system as the nitrogen needs to recycle between dead and living
bacteria. Carbon is lowered as CO2 goes off until a C/N ratio ends up
~10. With excess nitrogen the nitrogen is lowers as it is lost as
ammonia until the system ends up ~10 C/N. Acid conditions due to organic
acids build up and high pH due to ammonium build up both slow down the
system until pH is finally at a level optimum for the microbes.
Wood chips and other non-available carbon forms will results in high C/N
ratios meaning the C/N ratio is really not very usable numbers because
the only ones that count are the C and N in available forms when
predicting proper mixes. Not easy to do.
The above is how I think of it today.
Frank
Anand Karve wrote:
Dear Richard,
the acidification of dung is only due to organic acids. It may change
the pH but should not have any effect on the organic substances like
cellulose, lignin or even mucus in the dung.
Yours
A.D.Karve
On Wed, Dec 8, 2010 at 7:36 AM, Richard Stanley
<[email protected] <mailto:[email protected]>> wrote:
Good questions Kevin,
I am embarrassed to say that I have never pursued the issue, an
admission made worse by the fact of having extolled Biogas tech
widely in Tanzania through most of the 70's . Question is if the
bath is acid as Crispin implies through his description of the
mentioned peace corpsman, what effect would that have on the
fiber content of the dung so essential for wet process
briquetting ? We would need the fibers intact.
As also related to Crispin's story about the use of the decanted
liquid for solidifying clay: I'm just wondering Crispin; did you
get any idea of the thermal properties of the resulting
clay-cement ? Would it in other words be good for stove insulation
and/or structure ?
Richard
On Dec 7, 2010, at 7:58 AM, Kevin wrote:
> Dear Rajan
> ----- Original Message ----- From: <[email protected]
<mailto:[email protected]>>
> To: "Kevin" <[email protected]
<mailto:[email protected]>>; "Discussion of biomass cooking
stoves" <>>>
>>
>> Dear Kevin,
>>
>> Well, we also use biogas plants where animal dung is a major
feedstock.
>>
>> Here the energy part comes out as methane ( which is used as
fuel ) and the slurry from the plant contains all the nutrients (
without any loss ).
>
> I have no experience with biogas plants run on animal manure. Is
the slurry from a biogas plant filterable? If so, would it
potentially make a fuel equivalent or superior to dung that was
burned directly, with no washing?
>
> As I understand it, Richard Stanley uses a retting process on
biomass, to develop binding characteristics for his holey
briquette feed. Would the drained solids from a biodigester
perhaps have better "binder characteristics than freshly washed
dung? Perhaps Righard has already explored this avenue?
>
> Best wishes,
>
> Kevin
>
>
>>
>> Best Regards,
>>
>>
>> Rajan
>>
>>
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com <http://www.avg.com/>
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12/07/10
>
>
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