[Digestion] Re Digestate as fertilizer

Thu Nov 18 18:48:38 CST 2010

Dear Paul,
I would like to give an example of what you are saying. We have developed a
domestic biogas plant having a digester of 1000 litre capacity, which
accepts daily 10 kg macerated green leaves as feedstock. The biogas plant
produces daily about 800 litres biogas, which is enough for a family of 4 or
5 persons to cook their daily food with. One requires a plot of only about
50 square meters (7mX7m) to obtain the daily quantum of 10 kg leaves.
Depending upon the season, it requires daily from 250 to 400 litres water,
which can be the wash- and bath water generated by the household. The
effluent from the biogas plant goes back into the plot. So one is harvesting
the sunlight in this plot of land and delivering it in the form of methane
into the kitchen.
Yours
A.D.Karve

On Fri, Nov 19, 2010 at 7:58 AM, Paul Harris <paul.harris at adelaide.edu.au>wrote:

>  G’day All,
>
>
>
> As a generalisation Westerners tend to have “tunnel vision”, so only
> concentrate on one thing (I know this does not apply to all members of this
> group!). This is from my observations and I don’t have too much experience
> in other cultures for comparison. I think it really results from our
> “reductionist” approach, or maybe the approach is a result of this
> limitation.
>
>
>
> As a result some people see AD as “biogas”, some as “Carbon”, some as
> “waste disposal”, some as “pathogen reduction” and some as “fertiliser”.
> What we really need to do is see anaerobic digestion as all of the above and
> as part of a larger system. This involves a move away from the typical
> Western “linear” approach (of extract, use, discard) to a more cyclic
> approach (we have a Reuse, Recycle, Reduce slogan going around, sometimes
> with a 4th R that I can’t remember). I know some areas have been doing
> this for centuries, and even Westerners used to be better at it (before coal
> and oil!).
>
>
>
> Happy digesting,
>
> HOOROO
>
>
>
> Mr. Paul Harris, Room S116b, Waite Main Building Faculty of Sciences, The
> University of Adelaide, Waite Campus, PMB 1, Glen Osmond SA 5064 Ph    : +61
> 8 8303 7880      Fax   : +61 8 8303 4386
> mailto:paul.harris at adelaide.edu.au <paul.harris at adelaide.edu.au>
> http://www.adelaide.edu.au/directory/paul.harris
>
>
>
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> *From:* digestion-bounces at lists.bioenergylists.org [mailto:
> digestion-bounces at lists.bioenergylists.org] *On Behalf Of *P M Allison
> *Sent:* Thursday, 18 November 2010 6:06 PM
> *To:* digestion
> *Subject:* [Digestion] Re Digestate as fertilizer
>
>
>
> The use of digestate for crop fertilizers, is to me the very best option.
>
> The material contains all the nutrients required by plant-life as it is
> made up of the very same ingredients.
>
> Laboratory analysis of the spent material confirms this.
>
> A very similar substance is derived from vermiculture.
>
> The main problem with spent digestate is the fiber content. This will
> create nozzle lock-up on any spray delivery system. Fiber is not digested by
> anaerobes or worms.
>
> If the digestate is splayed too thick it will smother soil and emerging
> plants.
>
> The simple solution is to vibro filter the fiber and undigested material
> from the slurry. The solid matter is ideal for pelletizing and broadcast
> delivery.
>
> The resultant liquid component is a colloidal nutrient complex containing
> the same ingredients as the original material but in plant ready form.
>
> This liquid does contain particulate matter which can clog nozzles. My
> solution to this is to centrifuge the liquid and trap out the sedimentary
> material leaving a purely colloidal substance. This can be used as a foliar
> fertilizer when diluted with water as the substance is too rich to be used
> neat.
>
> The trapped debris is a rich nutrient mud, primordial ooze so to speak.
> This is also rich in nutrient and the finest of carbon flocs. An ideal
> binder for pelletizing the solid matter  initially extracted.
>
> By the way, the carbon flocs are the same as those used carbon-fiber
> production.
>
> Biogas is a wonderful bonus to the system, but should not be the be-all and
> end-all of the process. The spent material is the sort of substance which
> will make sustainable agriculture a much better option than what chemical
> farming will ever do. The crop improves, the soil improves, the soil biology
> improves, soil moisture holding capacity improves, soil carbon increases.
> Remember, it's the dark matter  which differentiates soil from being just
> lifeless dirt.
>
> Regards,
>
> Peter.
>
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> for more information about digestion, see
> Beginner's Guide to Biogas
> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
>
>
>

-- 
***
Dr. A.D. Karve
President, Appropriate Rural Technology Institute (ARTI)

*Please change my email address in your records to: adkarve at gmail.com *
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