[Digestion] Hi

Wed Jun 8 01:15:24 CDT 2016

G'day All,

While I am happy to agree to differ on some of Dr A,D.Karve's ideas I 
disagree with points 6) and 7) below (if taken at face value).

6) There should be a C:N ratio of approximately 20-30:1. The exact value 
is not critical, but microbes need both these nutrients (and other 
elements) to survive. Too much N will result in ammonia and too much C 
probably reduces the biogas quality.

7) Retention Time (RT) is reasonably important! Too short a RT results 
in "washout", which stops digestion. The actual "washout" RT depends on 
operating temperature, as this influences microbial growth rate. Best 
use of digester volume occurs at a RT about twice the "washout" time, 
but longer RTs result in more biogas per unit influent and more robust 
operation.

	Retention Time
Temp. 	Gwth Rte 	Washout 	"Optimum"
(^O C) 	(days^-1 ) 	(days) 	(days)
5 	0.020 	49.0 	97.9
10 	0.034 	29.4 	58.9
15 	0.056 	17.7 	35.5
20 	0.093 	10.8 	21.6
25 	0.150 	6.7 	13.3
30 	0.233 	4.3 	8.6
35 	0.336 	3.0 	6.0
40 	0.434 	2.3 	4.6
45 	0.502 	2.0 	4.0

I hope this is some help,

HOOROO
Mr Paul Harris

On 06-Jun-16 1:30 PM, Anand Karve wrote:
>
> *Biogas technology revisited*
>
> Dr.A.D.Karve
>
> Samuchit Enviro Tech P. Ltd. Law College Road, Ekata Park Co-Op. 
> Housing Society, Behind Nirmitee Showroom, Erandawane, Pune 411 004 
> (adkarve at gmail.com <mailto:adkarve at gmail.com>)
>
> Abstract: In spite of new knowledge gained since the advent of the 
> 21^st century the biogas researchers still use some of the older 
> concepts.  The new concepts pointed out in this article are 1) Because 
> the biogas producing microbes reside in the intestines of animals, 
> they eat what the animals eat. 2) Breeding super-methanogens can be 
> achieved, but their use in a biogas plant would not be practical, as 
> it would be impossible to maintain them. 3) All animals represent 
> living biogas plants, and therefore the fecal matter of animals is the 
> effluent slurry of a biogas plant. The biogas producing microbes are 
> found universally in the fecal matter of animals because they exit the 
> animal body along with dung.  4)Even the anaerobic microbes need 
> oxygen for their metabolism. They extract the chemically bound oxygen 
> from their feedstock.  Therefore, feedstock of a biogas plant must 
> have oxygen in its chemical make up. The same is also true of food 
> eaten by animals. 5)The value called % volatile solids actually 
> represents the % digestibility of the concerned substance. 6)There is 
> no justification for laying emphasis on the C/N ratio of a feedstock. 
> 7) There is no justification for laying emphasis on the hydraulic 
> retention time of a biogas plant. It is a useless concept. 8) In a 
> biphasic system, the feedstock is first treated aerobically and then 
> subjected to anaerobic conditions. This is wrong, because most of the 
> organic carbon, which would have yielded methane in the anaerobic 
> phase, gets oxidized in the aerobic phase itself, leading to drastic 
> reduction in the methane yield.
>
>
> ***
> Dr. A.D. Karve
>
> Chairman, Samuchit Enviro Tech Pvt Ltd (www.samuchit.com 
> <http://www.samuchit.com>)
>
> Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)
>
> On Mon, Jun 6, 2016 at 6:44 AM, Kelvin masule <kmasule97 at gmail.com 
> <mailto:kmasule97 at gmail.com>> wrote:
>
>     Guys do u have any information about biogas?
>
>
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>
>
>
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> for more information about digestion, see
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> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
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