[Digestion] Attachment to previous Article - More scientific based research and questions

[David Fulford]

  Hello Alex and Listers,

The best independent papers on the ARTI system are by EAWAG 
(www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_swm/ 
<http://www.eawag.ch/organisation/abteilungen/sandec/publikationen/publications_swm/index_EN#owm>) 
who have also looked at the digestion of food residues from markets in 
Kerala, South India. While food residues have an average TS of 50% or 
less, Dr Karve bases his results on starch residues (e.g. flour dropped 
on the floor from milling). Suich residues have a TS of almost 100%. 
This means that we need to consider his gas production results as per kg 
total solids, rather than per kg of wet material.

As the assessor from Ashden Awards who visited ARTI in 2006 (see 
www.ashdenawards.org/winners/arti06 
<http://www.ashdenawards.org/winners/arti06>), I had to evaluate Dr 
Karve's statements.and his technology. The biogas plant uses simple 
cylindrical drums, so there is nothing special about the design. The 
major difference is the use of food residues rather than dung as the 
feed material. Since an animal has used as much of the input energy in 
the food as it can before it evacuates the rest, the gas production from 
undigested food is likely to be much higher than that from dung. 
Processed food (flour, sugar and cooked food) is likely to have a higher 
gas output than raw food, as much more of the material is accessible to 
the microbes. There are several other biogas projects in India using 
food residues as feed material, that started at about the same time as 
the ARTI one. I have visited the first Biotech Ltd project in Kerala 
(www.ashdenawards.org/winners/biotech 
<http://www.ashdenawards.org/winners/biotech>) about which the EAWAG 
report was written and another in Mumbai called the Nisargruna system 
developed by BARC (see www.green-ensys.org/site/Biogas_Plant.html 
<http://www.green-ensys.org/site/Biogas_Plant.html>), which uses a 
two-stage digestor design.

Looking at the basic thermodynamics of the process, it seems quite 
feasible to generate 1 kWh of electrical energy from 1 kg of starch, as 
Dr Karve suggests, although it does suggest a very high efficiency for 
the conversion of starch to biogas. However, in practice, a 1 cu.m ARTI 
biogas plant is too small to run an ic engine, as small ic engines are 
not very efficient.

Regards,

David Fulford

On 07/10/2010 01:39, Alexander Eaton wrote:
> Dr Karve,
>
> Your innovation and work in the field is quite appreciated, and your 
> system really opens doors for us who are also not technically focused 
> in the biology of biogas, but rather its application to families and 
> communities.  That is why it seems your use of food waste and loading 
> rates based on gas production for a family really widens the 
> populations we may be able to work with globally.  Do you have a paper 
> or document that has this data and other user data available?
>
> Best,
>
> Alex
>
> On Wed, Oct 6, 2010 at 5:40 PM, Anand Karve <adkarve at gmail.com 
> <mailto:adkarve at gmail.com>> wrote:
>
>     Dear Alexnder,
>     to be quite frank, I do not call myself an expert in biogas
>     technology. I developed my system as a layman. Being a biologist,
>     I argued that since all industrial fermentation systems used
>     sugar, why not try it in a biogas plant. Because sugar was costly,
>     I used only 1 kg sugar in a biogas plant that consumed daily 40 kg
>     cattle dung. To my surprise I found that I got about 700 to 800
>     litres of biogas, just 24 hours later. Since sugar was costly, I
>     shifted to using flour of cereal grains, which also gave similar
>     results. Then we tested spoilt milk, oilcakes of various edible
>     and non-edible oilseeds and peels of fruits like banana, mango and
>     papaya, and got similar results. We then constructed biogas plants
>     geared to using food waste as feedstock. It was by trial and
>     error, that we arrived at our present configuration which is just
>     a conventional moving dome biogas plant. The rule of thumb is to
>     use 1 g (dry weight) of food waste per litre of digester capacity.
>      When I started talking about our system in conferences on biogas,
>     I used to be hooted out by the experts. Once they found out that I
>     had no theoretical knowledge of the biogas plants, they would
>     embarass me by asking questions like C:N ratio, volatile solids %
>     etc. It was only after our system received the Ashden Award in
>     London (2006), that the world started believing in me.
>     Yours
>     A.D.Karve
>     On Thu, Oct 7, 2010 at 7:00 AM, Alexander Eaton
>     <alex at sistemabiobolsa.com <mailto:alex at sistemabiobolsa.com>> wrote:
>
>         Hi Dr. Karve,
>
>         I recently had the pleasure of meeting your associate and
>         representative for Tanzania at a conference in Sweden.  He
>         explained much of the same thing about the ARTI system.  When
>         you describe your system as primarily a biogas generation
>         system (as opposed to waste treatment), do you mean that you
>         optimize HRT and loading rates for biogas production, rather
>         than balancing biogas production with the reduction of organic
>         load (TOC or COD?).  Reviewing the plans of your systems, it
>         does not seem as though the vessel itself holds massive
>         differences with any other AD reactor, so can we assume that
>         this is a management practice, versus technology comparison?
>
>         Best,
>
>         Alex
>
>         On Wed, Oct 6, 2010 at 4:45 PM, Anand Karve <adkarve at gmail.com
>         <mailto:adkarve at gmail.com>> wrote:
>
>             Dear Alexander,
>             thanks for the correction. In our system, 1 kg (dry) food
>             waste provides 1 kW electricity for 1 hour. I am
>             absolutely sure of these figures, because we are daily
>             generating electricity on our own campus by using food
>             waste from our own hostel. If your calculations show our
>             system to be 3 times as efficient as the one reported in
>             the article, then it must be so. All I can claim is that
>             our biogas production system is currently the cheapest and
>             the most efficient biogas system in the world. Scientists
>             of a prestigeous Institute of the Government of India
>             had come to us to have a look at our biogas system,
>             because using the same amount of waste, our system
>             produced 10 times as much biogas as the two phase
>             system developed by them. The report submitted by them to
>             their bosses explained the difference in the performance
>             of the two systems being due to the fact that their system
>             was primarily a waste disposal system, whereas ours was
>             primarily a biogas generating system. So far, we have
>             installed about 5000 such biogas plants all over India and
>             also about 50 on the African continent.
>             Yours
>             A.D.Karve
>
-- 

********************************************************************
Dr David Fulford CEnv MEI, 15, Brandon Ave, Woodley, Reading RG5 4PU
d.j.fulford at btinternet.com <mailto:d.j.fulford at btinternet.com>, Tel: 
+44(0)118 326 9779 Mob: +44(0)7746 806401
Kingdom Bioenergy Ltd, www.kingdombio.com <http://www.kingdombio.com>, 
davidf at kindombio.com <mailto:davidf at kindombio.com>

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