[Digestion] Dung burning vs. anaerobic digestion
Paul Harris
paul.harris at adelaide.edu.au
Thu Nov 15 21:38:13 CST 2012
G'day Krishna,
When replying to a series of messages like this can you please delete
all except the latest Reply so the e-mail is shortened.
Thanks for your inputs,
HOOROO
Mr Paul Harris BEng (Ag) (Melbourne)
Visitor at The University of Adelaide
On 15/11/2012 2:57 PM, Murali Krishna wrote:
> Good day Dr. Karve,
>
> While agreeing with you that some Indian villagers are making cow
> dung/bufalloe dung cakes for thermal application, a majority of the
> villagers have stopped making cow dung flakes. Labour is becoming
> precarious day by day and the daiary industry is finding it extremely
> difficult to organize their routine activities ....forget about making
> cow dung cakes and selling them. The amount of methane left into the
> atmosphere should also be taken into consideration. Everyone will
> agree that green or dry grass/leaves contain more amount of methane
> but why should they run around to fetch these. These units can simply
> recycle the avaialble dung, extract methane (other wise a menace in
> rainy season), generate power and the cake from the digestate can be
> bunt if they wish so or it is a rich manure. The grasses and green
> leaves matter can be fed to animals.
>
> Undoubtedly recycling of cow dung/buffaloe dung via anerobic digestion
> is the best way. It serves more than one purpose.
>
> Regards,
>
> Krishna
> India.
>
>
> On Thu, Nov 15, 2012 at 6:13 AM, Anand Karve <adkarve at gmail.com
> <mailto:adkarve at gmail.com>> wrote:
>
> Dear Mr. Ward,
> Thanks a lot for making us aware of the situation in Denmark. I
> agree with you that situations differ from country to country and
> that one should do what is best suited to one's needs and also
> what the environment allows. Please remember that the posting that
> I reacted to refered specifically to cow dung and its
> author complained about extremely low biogas yield. My experience
> is mainly from India. In my posting I specifically refered to dung
> of ruminents, i.e. bovine cattle and water buffalo. In
> India, these animals mainly graze and they eat mainly grass, which
> is dry except for the rainy season. The dung of such animals has
> very little digestible matter in it. Excreta of poultry and pigs
> have much more digestible matter than those of ruminents. In
> India, dung cakes are made only from dung of cattle. They are
> sun-dried. You must be aware of the fact that except for Muslims
> and Cristians, dead bodies are cremated in India. There is a big
> market in India for dung cakes as fuel for creamtion of dead
> bodies. Compressing agricultural waste into fuel briquettes (as
> boiler fuel) has emerged as a big Industry in India. Dung can also
> serve as boiler fuel. People are even looking at filter presses,
> which would squeeze the water out of dung, so the solids can be
> coverted into burnable briquettes.
> Yours
> A.D.Karve
> On Wed, Nov 14, 2012 at 2:35 PM, Alastair James Ward
> <Alastair.Ward at agrsci.dk <mailto:Alastair.Ward at agrsci.dk>> wrote:
>
> Dear A.D. Karve,
>
> I disagree that manure only consists of lignin, mucus and
> microorganisms. There is a lot of digestible but undigested
> protein, fat and carbohydrate in manure, not to mention a high
> concentration of fatty acids which are just one or two steps
> in the biological pathway away from methane production. It is
> not disputed that plant material usually produces more biogas
> than manure, but I think that you have to stand back and
> consider what factors are most important to the very varied
> users of this list. I live in northern Europe in a country
> with a high animal density. It has been calculated that if we
> could collect all manure produced, all organic wastes
> available and use all non-food producing land for energy crop
> production and put it all into biogas plants, we would still
> not make a very large impact on the national energy
> requirement (sorry but I forget the exact figures). However,
> we view anaerobic digestion as a method of treating wastes,
> with the recycling of nitrogen and phosphorous being of great
> importance. The fact that we can produce energy is a nice
> bonus that (hopefully) makes the whole process financially
> feasible. Burning manure is not a realistic option here. As an
> example, we produce in excess of 20 million fattening pigs
> every year, in a country of less than 6 million people. As a
> result, we have a lot of wet manure to deal with and anaerobic
> digestion is widely viewed as the best available technology to
> do so. Pig manure has a low dry matter content so the energy
> input necessary for drying, not to mention space to do so and
> any other issues regarding odour emissions etc makes the
> drying and burning of wet manures impractical. We also want to
> keep the N to put back into the soil and thus reduce the need
> for artificial fertiliser and the non-degradable carbohydrates
> in digestate are useful in maintaining soil carbon levels.
>
> As I understand, the original post was not from a northern
> European country but there are still many advantages to
> anaerobically digesting manure in warmer climates. Biogas is
> certainly a cleaner and more flexible fuel than dry material
> for burning, the fact that one can quite easily run lights and
> a small generator on biogas being major advantages. I came
> across a paper a couple of years ago that suggested the
> increased use of AD in preference to burning of organic
> material could be linked to an improvement in the health of
> people in rural Indian communities, specifically eye problems
> due to smoke as I remember.
>
> Please, consider the motives of the people posting on this
> list before you tell us that we are wasting our time digesting
> manure. If Kyle has manure available I suggest he continues to
> use it in his digester, the low yield can be compensated for
> by having a large supply that is easily available. If he has
> any plant wastes available then certainly put these in as well
> to boost yield, but I would not recommend actively collecting
> large amounts of biomass from the surrounding area, the time
> and energy used to do so may negate the gain.
>
> Med venlig hilsen
>
> *Alastair James Ward*
> Post doc.
>
>
>
> *Inst. for Ingeniørvidenskab
> *Aarhus Universitet
> Blichers Allé 20, Postboks 50
> 8830 Tjele
>
> Tlf.: 8715 7645
> Mobil: 4112 2494
> Email: Alastair.Ward at agrsci.dk <mailto:Alastair.Ward at agrsci.dk>
>
>
>
>
> Tlf.: 8715 6000
> Web: www.agrsci.au.dk <http://www.agrsci.dk/>
>
> Description: Logo
>
>
>
> --
> ***
> Dr. A.D. Karve
> Trustee & Founder President, Appropriate Rural Technology
> Institute (ARTI)
>
>
>
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>
>
>
>
>
> --
> Regards.
>
> Murali Krishna
> Chairman
> Hyderabad, Andhra Pradesh, India.
> Ph:+91-40-24339999, 24333333,243355555, 24333555
> www.villagevisionindia.com <http://www.villagevisionindia.com>
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> and the Biogas Wiki http://biogas.wikispaces.com/
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