[Digestion] about C/N

Paul Harris harrisfm at aapt.net.au
Thu Jul 24 06:40:33 CDT 2014


G'day All,

As I understand it microbes have a C:N ratio of about 25:1, so if C is 
too much higher they run out of N and methane percentage will fall or if 
N is too high they run out of C and ammonia can become a problem (what 
goes in MUST come out!). Between 20:1 and 30:1 is probably OK but way 
outside this range you may have trouble. There is also a certain need 
for P, K and micro-nutrients but they tend to take care of themselves in 
natural systems - a long time ago I saw an experiment feeding sugar and 
it kept dying.

Hope this helps,
Happy digesting,

HOOROO
Mr Paul Harris

On 23/07/2014 2:16 PM, Anand Karve wrote:
> Dear Herrero,
> the C/N ratio of 25 is a relict of the era when cattle dung was used
> as feedstock. Please note that almost 80 to 90% of the dung consists
> of non-digestible matter, contributed  mostly by lignin from plant
> biomass.  The carbon in lignin is not available for methane
> production.  Counting the carbon in the undigestible part of the
> feedstock is unscientific. Our own biogas plants are made of plastic,
> which is also non-digestible. But we don't count the carbon in the
> plastic while calculating the C/N ratio.
> Yours
> A.D.Karve
>
> On Tue, Jul 22, 2014 at 11:28 PM, Jaime Marti Herrero
> <tallerbiogas at hotmail.com> wrote:
>> hi every body
>> i would like to ask about the parameter C/N that use to be measured and
>> refered in a lot of places. usually it is consider that for a good anaerobic
>> digestion a relation C/N of 20-25 is the optimum, but is this recomendation
>> still used?
>> is the C/N ratio a good parameter to be used in order to know if a substrate
>> is good for anaerobic digestion?
>> i would like to know your opinion
>>
>> keep in touch
>> jaime
>>
>>
>> -----
>> Jaime Martí Herrero, PhD.
>>
>> INER (www.iner.gob.ec). Biomasa
>>
>> CIMNE (www.cimne.com). Building Energy and Environment Group
>>
>> Quito · Ecuador. Tel. (+593)-09 857 03726
>>
>> BIOGAS and Latin America
>> -RedBioLAC:http://redbiolac.org/
>>
>> -Taller Biogas Bolivia:http://tallerbiogas.blogspot.com
>> -Biodigestores familiares: Guía de diseño y manual de instalación:
>> http://grecdh.upc.edu/publicacions/llibres/documents/2008_jmh_guia_biodigestores.pdf
>>
>> -Desarrollo, difusión e implementación de tecnologías
>> apropiadas:Biodigestores en Bolivia:
>> http://grecdh.upc.edu/publicacions/llibres/documents/2014_Biodigestores-Lecciones-Bolivia.pdf
>>
>>
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>
>





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