[Stoves] papaya as feedstock for biogas

Sat May 5 07:02:32 CDT 2007

Dear Dr. Karve

If one put a high sugar feedstock into an anaerobic environment, 
wouldn't it ferment to Ethanol?

Is it perhaps a case that if sugar is put into an environment with some 
oxygen initially, to enable development of a strong yeast colony, then 
it will be fermented to alcohol, BUT, if it is put into an anaerobic 
environment where the methanogenic bacteria were already established, 
then the result will be biogas rather than alcohol?

Asked in another way, how does the sugar in the feed know if it should 
turn into ethanol or methane?

Is there any ethanol in the effluent from an anaerobic digestor?

Thanks!!

Kevin

adkarve wrote:
> Dear Peter,
>  5 kg papaya pulp would give you about 1 cubic meter biogas. The weight of
> the biogas would be 1 kg but the methane in this biogas would weigh only
> about 250 g.  It would have about 12500 kilojoul energy.
> Any high energy feedstock containing sugar or starch would give you more
> biogas than dung and that too in a much shorter time. So don't dilute the
> high calorie feedstock with dung. Your biogas output would be reduced.
> As to water for irrigation, how much is your rainfall and how is it
> distributed over the year? It might be cheaper to build a small tank and
> harvest the rainwater. Reverse osmosis is costly because it requires a lot
> of pressure. RO would be all right for drinking water but not for irrigation
> water.Gravity can be used if your for RO if your saline water source is at a
> high elevation. I read some time ago, that if the Israelis built a pipeline
> from the mediterranean sea to the dead sea and used the level difference to
> conduct reverse osmosis of the mediterranean sea water, they would be able
> to get sweet water.
> Yours
> A.D.Karve
> Yours
> A.D.Karve
> ----- Original Message -----
> From: Peter Singfield <snkm at btl.net>
> To: <stoves at listserv.repp.org>
> Sent: Saturday, May 05, 2007 7:59 AM
> Subject: Re: [Stoves] papaya as feedstock for biogas
> 
> 
>> At 06:09 AM 5/5/2007 +0530, adkarve wrote:
>>> Dear Peter,
>>> you wanted to know if overipe papaya could be used as a source of
> methane.
>>  Please remember, that if you are going to use only fruit pulp as the
>> feedstock, and no dung, restrict yourself to only 1 kg dry weight of fruit
>> pulp to 1 cubic meter of the digester capacity. Assuming about 80% water
> in
>> papaya, the maximum amount of pulp that you can feed into the biogas plant
>> would be 5 kg per cubic meter of digester capacity. You would get about
> one
>> cubic meter of biogas from this much papaya pulp.
>>> Yours
>>> A.D.Karve
>>
>> Dear AD;
>>
>> That is extremely vital information you supply and will have saved me much
>> trial and error. Thanks so much!!
>>
>> While we are on this topic -- how much energy is in one meter of
> bio-methane??
>> And -- I assume those figures are for a 24 hour period?
>>
>> And last -- there will be much dung available -- but mostly from chicken
>> and or pig.
>>
>> Would addition of dung (how much??) mean greater production of bio methane
>> from the same volume of digester tank?
>>
>> I made an interesting discovery a few years back on how to make small
>> holding ponds that do not leak for hand style irrigation.
>>
>> The plan would be to use these for bio methane production --
>>
>> Our soil in this area is and average thickness of one foot of  Terra Preta
>> over soft marl substrate.
>>
>> We simply dig holes of the required size down into the white marl -- then
>> with a little cement added to some screened white marl -- make a
> plastering
>> paste that is very endurable -- and stays water tight.
>>
>> We position such a "well" of around 1000 liters capacity about one per
>> hundred feet in a square grid.
>>
>> One central pumping station supplies water to many of these -- keeping
> them
>> filled.
>>
>> Growers dip 20 liter buckets into these and then go plant to plant --
>> applying .5 liters or .25 -- to the base of each and every plant. Once in
>> the early morning -- and once in the late evening.
>>
>> Water supply to refill these small ponds is accomplished using a small 3
> HP
>> diesel powering a 1.5 KW generator -- which is sufficient to run a
> small --
>> 1/2 HP -- submersible pump.
>>
>> Very little diesel is consumed per week to accomplish this feat. And --
>> these small diesel engines are multi fuel capable -- and as such -- run
>> well on plant oils of any kind.
>>
>> Unfortunately for this experiment -- the deep well turned alkaline after
>> one years use -- and the small project had to be abandoned -- well -- most
>> of it.
>>
>> I still maintain some growth during dry season (right now!!) by hauling
>> 3000 liters per trip on the diesel mule. At present -- a 25 mile trip.
>>
>> We have just discovered an ancient Mayan well but 5.5 miles away -- that
>> indeed does have good water -- have yet to know how much flow/water can be
>> pumped.
>>
>> Hope to cut a road through the jungle to it in the next week.
>>
>> Has anyone one this list experience with reverse Osmosis purification of
>> water??
>>
>> The new line of plunger/displacement pumps can operate to 500 PSI --
>>
>> But I have heard the membranes are terribly expensive. And this is a
> costly
>> way to make potable water.
>>
>> They have an ancient saying here -- in Spanish:
>>
>> Agua est Vida.
>>
>> (Water is life)
>>
>> And water conditions are ever changing these days.
>>
>> My small farm is situated 12.5 miles from my village residence -- but here
>> at the house -- I have an excellent deep aquifer -- that never runs out --
>> and is always excellent water.
>>
>> Thanks ever so much again AD -- Peter / Belize
>>
>>
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> 
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