[Digestion] Hi

[Anand Karve]

Dear Paul,
I had not realised the theoretical possibility of too short a retention
period. I agree that there would be a washout if one completely replaced
the water in the digester in a matter of 2 or 3 days.
Yours
A.D.Karve

***
Dr. A.D. Karve

Chairman, Samuchit Enviro Tech Pvt Ltd (www.samuchit.com)

Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)

On Wed, Jun 8, 2016 at 11:45 AM, Paul Harris <harrisfm at aapt.net.au> wrote:

> 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"
> (OC) (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)
>
> Abstract: In spite of new knowledge gained since the advent of the 21st
> 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 ( <http://www.samuchit.com>
> 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> wrote:
>
>> Guys do u have any information about biogas?
>>
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>> 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 Biogashttp://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
>
>
>
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> for more information about digestion, see the Biogas Wiki
> http://biogas.wikispaces.com/
>
>
>
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