[Digestion] mixed waste AD

[Deepak D. G.]

Dear Anandji...

I just understood that it is called byphasic. Yes, the first tank is for 
stirring purpose and for simplification of mixing all types of input.

Thanks for the idea. I will feed the food waste directly.
I will use as small as possible of water tank (may be max 25 liter) for 
the fecal matter.

Namaste,
Deepak

> Message: 2
> Date: Sun, 20 May 2012 21:26:02 +0800
> From: Anand Karve<adkarve at gmail.com>
> To: ghindwani at gmail.com, For Discussion of Anaerobic Digestion
> 	<digestion at lists.bioenergylists.org>
> Subject: Re: [Digestion] mixed waste AD
> Message-ID:
> 	<CACPy7SetgTOPqeNC3P_BNfdapYt-Vu_i-DGGGTS4u-BEa0b5Xw at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Dear Deepak,
> If I have understood you correctly, what you are planning to do is to have
> a biphasic digestion system, in which the first tank would be for stirring
> the material with water in an open tank, exposed to air, and to allow the
> overflow from this tank to enter into the anaerobic digester. The quantity
> of biogas generated by anaerobic digestion is directly proportional to the
> digestibility of the feedstock. Human food consisting of sugar, starch,
> protein and fats has high digestibility, so that 1 kg (dry weight) of any
> of the above substances would yield about 1 kg biogas, if it is introduced
> directly into an anaerobic digester. In the case of green leaves, the
> midribs and veins, consisting of lignin, cannot be digested by the
> methanogens, so that the digestible matter constitutes only about half the
> dry weight. You would therefore have to introduce about 2 kg (dry weight)
> of leaves into the anaerobic digester to produce 1 kg biogas.  In
> comparison to the anaerobic microbes, the aerobic micro-organisms are much
> more efficient in breaking down biomass. Therefore, stirring the biomass
> with water in an open tank would oxidise the easy-to-digest material into
> carbon dioxide and water. If you spent too much time on stirring, only the
> difficult-to-digest material would enter the anaerobic digester and your
> biogas yield would be rather low. My advice would be to introduce food
> waste and kitchen waste directly into the anaerobic digester and subject
> only the fecal matter to mixing under aerobic conditions.
> Yours
> A.D.Karve
>
>
>