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creating biogas from familly waste

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Melodie de l'Epine

Jan 1, 1970
0
I have found a lot of information about communities and farmers
(especially in Vietnam and China) creating biogas (for cooking/heating)
from their toilet , kitchen and farm wastes.

But I can't find anything about small scale setups. Is it
practicable/possible to create biogas when you only have 1 family's
wastes (from dry toilets and kitchen scraps)?

I have already tried Google with little success.

Thanks,
Melodie
 
B

Ben Simons

Jan 1, 1970
0
Am Thu, 15 Apr 2004 09:16:00 +0200 hat Melodie de l'Epine
I have found a lot of information about communities and farmers
(especially in Vietnam and China) creating biogas (for cooking/heating)
from their toilet , kitchen and farm wastes.

But I can't find anything about small scale setups. Is it
practicable/possible to create biogas when you only have 1 family's
wastes (from dry toilets and kitchen scraps)?

I have already tried Google with little success.

Thanks,
Melodie

From the Bool "biogas from water hyacinths":

.......A family size plant (for cooking purposes) requires approximately
100kg input every day. In case of fermenting cowdung, about half of this
quantity is water that needs to be added.

-> a lot to shit (sorry for that one) and to pump.

But you can stuff any organic material in a biogas plant like grass or
water plants.

Best regards
 
S

Steve Spence

Jan 1, 1970
0
You need more than just your crap and kitchen scraps. You'll need quite a
few farm animals, a large garden, and a large family. Check out
www.methane-gas.com

"The size of digester tank a person may want is determined by the amount of
available material to put into the digester on a daily basis. So the
principal number to consider in the specs that follow is the daily input
figure. If the animal manure being used to "feed" the digester is somewhat
dry, it needs to be mixed with enough water - which is free of chlorine
treatment - to make an easily pourable liquid. The consistency needs to be
about the same as the thickness of cement coming from a cement mixer as it
is being poured. "

"In a spirit of compromise for determining how long the slurry should be in
the digester, we suggest a holding time of 40 days. This is a more or less
"happy medium" between quick and abundant gas production and effluent that
is as devoid of odor and pathogens as possible.

To determine the holding time we look to a simple volume-to-volume ratio.
This ratio is determined by the volume of the daily input in relation to the
holding capacity of the volume of the slurry tank. In other words, if daily
input is 1/40th of the volume of the slurry tank, it will require 40 days
for a given amount of material to migrate from the fill pipe to the exit
pipe. This is why on the schedule for various tank sizes, the suggested
daily input is always 1/40th of the overall holding capacity of the tank."

"To illustrate, the present digester of Al Rutan is capable of producing 3
to 4 cubic feet of gas for each cubic foot of fermenting slurry in a 24 hour
period. But with any heat loss whatsoever during a cool period, it may
require more than 4 cubic feet of gas to keep each cubic foot of working
slurry at optimum temperature for a 24 hour period. Proper design is
critical to reaping the benefits of the process. "

--
Steve Spence
Renewable energy and sustainable living
http://www.green-trust.org
Discuss vegetable oil and biodiesel
powered diesels at
http://www.veggievan.org/discuss/
 
A

Anthony Matonak

Jan 1, 1970
0
Melodie said:
But I can't find anything about small scale setups. Is it
practicable/possible to create biogas when you only have 1 family's
wastes (from dry toilets and kitchen scraps)?

If the gas is for cooking or heating then you may want to explore
using solar for these purposes. Solar cookers have been designed
which can store the heat for cooking at night if that is your
concern.

Anthony
 
M

Melodie de l'Epine

Jan 1, 1970
0
I am not really looking for an energy source, but more a way to exploit
the energy contained in the waste from dry toilets, maybe in a
semi-urban environment.

(Apart from composting, which means gardens etc...).

thanks
Melodie

Anthony Matonak a écrit :
 
Melodie de l'Epine said:
I have found a lot of information about communities and farmers
(especially in Vietnam and China) creating biogas (for cooking/heating)
from their toilet , kitchen and farm wastes.

I saw slides of an interesting South American "manure sausage" at the
Sustainable Resources conf in Boulder, CO last October. A polyethylene
film circular greenhouse ventilation air duct was laid on the ground and
partially filled with water. Each end was raised, and fermentables dumped
into one end and scooped out of the other, after they traveled the length
of the duct in the water. The duct might have been 30 feet (9 m) long and
30 inches (75 cm) in diameter, about 4 feet (1,2m) wide when laid flat.

The gas was trapped in the upper part of the duct by two horizontal boards
about a foot above the ground and perpendicular to the duct a few feet from
each end. This requires a lot less labor and material than an underground
masonry Chinese pit digester :) The duct costs about 25 cents per foot
(1 Euro per meter) in rolls. It's treated for UV sun protection, and it
should last at least 4 years unless punctured with pitchforks. In a cold
northern climate, it might run east-west to collect sun, with a reflective
wall on the north side. It might be covered with shadecloth in summertime
to lower the temperature and make the poly film last longer.
Is it practicable/possible to create biogas when you only have 1 family's
wastes (from dry toilets and kitchen scraps)?

The Phoenixville, PA sewage treatment plant has two 70' diameter x 28' high
anaerobic digesters with floating covers that move up and down 7', which
are kept at 100 F by boilers burning their own methane. Metcalf and Eddy's
Wastewater Engineering book says secondary sewage treatment plants produce
about one cubic foot of biogas per capita per day. Not much...

The NRAES-20 On-Farm Biogas Production Manual says one "sow unit" (an
average animal weight of 1300 pounds of pigs and sow producing an average
of 16 pigs per year) makes 1.75 ft^3 of manure per day, yielding 56 ft^3
of biogas (55-70% methane, plus CO2) over a retention time of about 15 days.
Manure from one cow produces about the same.

The Chinese Biogas Manual (trans. Michael Crook, Int'l Tech Pubs, 1979,
ISBN 0 903031 65 5) says a metric tonne of dried "general stable manure"
makes 270 m^3 of biogas, dried pig manure makes 561, horse manure, 250,
fresh grass, 630, straw, 342, leaves, 250, and sludge, 640. They also give
C:N ratios to help in making an optimum 25:1 mix. "Fresh human manure" is
about 3:1, horse and cow manure are about 25:1, leaves are 40:1; dry straw
is about 90:1. Know anyone with a horse and straw bedding?

They say a family of 5 in the countryside needs about 1 m^3/day of biogas
for cooking and lighting, and each m^3 of pit digester produces about 0.2
m^3/day in summer and 0.1 in winter (each 10 C increase in temperature
doubles the gas production rate.) Making 18 ft^3 (0,5 m^3) of biogas per day
might require a 3 m^3 digester fed with one person's manure and something
like an average of 5 pounds (2 kg) of dry leaves per day. Using 10 pounds
of leaves or 5 pounds of straw might make 1 m^3/day with a better C:N ratio.

So it looks like this could work on a small scale, with a source of leaves
or straw or grass clippings. A meter of fully-inflated 30 inch round poly
duct has a volume of 0.456 m^3...

Bonne chance,

Nick
 
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