[Digestion] Effect of Surface Area

[Murali Krishna]

Good day All,

If ideal conditions are maintained in a biogas digester the biogas yield
will increase by 20 to 25% than the conventional digesters.   When the
percentage of TS of a substrate is less than  3 to 4%, the tendency is that
a fair amount of microorganisms flush out through outlet along with
digestate.  The growth rate of methanogenesis fermentative bacteria is slow
unlike acidogenic bacteria.  If a bio media is provided in the digester
bacteria they cling on to media and develop colonies.  As there is optimum
load is maintained in the digester, effective fermentation takes place.
Hence, the overall efficiency of fermentation and biodegradation impvoes,
so is biogas yield.

Depending upon the substrate, the digesters are designed and the design
should ensure best ideal conditions, such as temperature, microbial load
and pressure. For certain substrates with high SRT/HRT and especiaqlly when
the TS percentage is on higher side, you may not require these bio media
rings.

If there is a flood, water flows at a faster rate and carrys with it a
fairly large amount of branches, and other matter and sometimes even
people.  When it happens, we disperately look for something to hang on and
survive and work again.  For tiny microorganims even your one inch flow is
also a flood.  So you need to ensure sufficient  workers to cook the food
in the digester.

A good number of bio media chips, rings and tubes (in different shapes) are
available on the market.  You need to choose the right ones keeping in mind
your needs (if at all you need them). To conclude, Yes, if the bio media is
rightly selected and placed, it will certainly help in enhancing the
overall performance of the digester and yields.

Krishna.


On T thehu, Nov 1, 2012 at 10:26 PM, David <david at h4c.org> wrote:

>
>
> Paul,e
>
>
> On 11/1/2012 1:32 AM, Paul Muthui wrote:
>
> Good Day All,
>
>  I read in an article that increasing the surface area inside the biogas
> digester  (e.g. by introducing vertical structures), increases the
> population bacteria population and consequently more gas production.  By
> what percentage does this increase gas production? And what's the most
> effective way to do it?
>
>
> Methanogens are part of a complex ecology that likes to sustain itself by
> forming biofilms on any available surface. However, for most kinds of
> digestion-- that is, at any percentage of solids that one might "choose,"
> rather than having it *imposed* by the high water content of the
> substrate-- there is plenty of surface for the biofilms to form.
>
> Adding surface to the inside of a digester, then, is almost exclusively
> done where the dilution of the incoming substrate is considerable (1%-2% or
> less). What happens where such substrates are digested with sufficient HRT
> is that floating consortia of microbes develop. These a bit like sponges,
> and are often referred to as "flocs".
>
> You may be able to learn more by searching for [biogas dilute flocs] and
> adding any reference to the substrate you have in mind.
>
>
>
> d.
> --
> David William House
>  "The Complete Biogas Handbook" www.completebiogas.com
> *Vahid Biogas*, an alternative energy consultancy www.vahidbiogas.com
>
>  "Make no search for water.       But find thirst,
> And water from the very ground will burst."
> (Rumi, a Persian mystic poet, quoted in *Delight of Hearts*, p. 77)
>
> http://bahai.us/
>
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> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
>
>
>


-- 
Regards.

Murali Krishna
Chairman
Hyderabad, Andhra Pradesh, India.
Ph:+91-40-24339999, 24333333,243355555, 24333555
www.villagevisionindia.com
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