Microcogen.info/***/SOMRAD Forums
Welcome, Guest. Please login or register.
July 25, 2014, 06:39:18 AM

Login with username, password and session length
Search:     Advanced search
32041 Posts in 2509 Topics by 1079 Members
Latest Member: ukboater
* Home Help Search Login Register
+  Microcogen.info/***/SOMRAD Forums
|-+  Fuels/alternatives
| |-+  Methane, Producer Gas, Propane, etc. (Moderator: SteveU.)
| | |-+  methane digester for septic systems?
« previous next »
Pages: [1] Print
Author Topic: methane digester for septic systems?  (Read 4727 times)
cschuerm
SOMRAD
Full Member
******
Posts: 122


View Profile
« on: December 26, 2010, 09:22:41 AM »

I've not been able to find a single reference to methane production from sanitary septic systems.  Has anyone done any research in this area?  I assume that it must not be worthwhile but I know very little on the topic.  Just curious and this seems like a good place to ask.
thanks
chris
Logged
SteveU.
Moderator
Sr. Member
*****
Posts: 318


View Profile
« Reply #1 on: December 26, 2010, 09:35:05 AM »

Hi Chris
On a Russian language forum member AleseyA once put up pictures and text to a current day Vietnamese govenment sponsored rural inititive to devepope and build 100's of thousands of individual below ground beehive shaped sewage digesters. Program was to clean up and preserve ground water contamination in their wet environment and supply domestic individual cooking gas.
Try google searching from this direction.
Regards
Steve Unruh
Logged

"Use it up. Wear it out. Make do. Or do without."
"Trees are the Answer" to habitat, water, climate moderation, food, shelter, power, heat and light. Plant, grow, and harvest more trees. Then repeat. Trees the ultimate "no till crop". Trees THE BEST solar batteries. Now that is True sustainability.
cschuerm
SOMRAD
Full Member
******
Posts: 122


View Profile
« Reply #2 on: December 26, 2010, 05:55:50 PM »

Thanks for the tip Steve.  Did find some interesting info, but not a lot of detail.   Ran across a number of articles about feedlot sized systems, but really nothing much smaller.  I've been thinking about all the bio waste generated by a typical residence (not only sewage but food, grass clippings, leaves, etc) and wondered about the viability of a small digester system.  From what I've read, the process is simple, but the mechanics of something useful appear to get fairly complex (read: expensive) so I suspect that's why there's not been much work done at a small scale.
cheers,
chris
Logged
LowGear
Hero Member
*****
Posts: 1287


If it ain't diesel - I ain't buyin!


View Profile
« Reply #3 on: December 26, 2010, 06:05:20 PM »

I think I've seen a couple of public TV stories relating to this focused on India and Africa. 

Casey
Logged
cschuerm
SOMRAD
Full Member
******
Posts: 122


View Profile
« Reply #4 on: December 27, 2010, 12:56:00 PM »

I've found some useful engineering texts and articles on the topic of waste water based production.  To distill the math down, the short answer is that you can get slightly less than 1 cubic foot of methane per day per person.  A candle would be more useful.   I'm trying to work out how much waste plant biomass might be necessary to get a reasonable quantity of fuel gas now.  Appears that different "bugs" are involved, but gas production can be much higher since much of the energy has already been removed from waste water (biologically speaking).  Between tree leaves and grass clippings, I could supply quite a bit of plant material....
still have much to learn, but an interesting topic!

chris
Logged
Tim
Newbie
*
Posts: 13


View Profile
« Reply #5 on: December 27, 2010, 01:06:08 PM »

Cschuerm,

This sure is possible. It's my daily job, but then with 50% cow manure and 50% dairy/food/industrial organic waste.

Thing is that with a little sewage from your household, you wont get much biogas. With other organic waste you can put up your gas production. Simple trick to predict the succes is look at how fast it normally decomposes. The faster it composes, the faster it will digest. Oak leafs for example, don't go away very fast. Wood takes ages. This is not suitable for digestion. Drying them and burning would work better.

But leftovers, like patatos, vegetables, meat: Grind it up, feed the digester and it will have a feast.

Then also problems like cleaning detergents, medicine and too much salts can destroy your biology. If its not good for you, the digester will not like it too.

Antoher problem with sewage is the dry matter. You flush 100gram, if your a real man, 200gram of shit away with 6-9 liters of water. The pile contains about 10-20% dry matter, and I'm guessing that dry matter contains about 80% organic matter. This would work, but with the 6-9 liters of water you also flush out your bacteria from the digester. Separating would give better results.

The easiest way to use the biogas is in your stove. Buffer it in a old inner truck tyre, stones on top for pressure. Make sure all water can drain out before use. Condensate has to be run down to the digester. Untreated biogas is corrosive. Your stove will not care, but a motor, central heating will corrode due to H2S, NH3 and condensate.

If you have question ask, I'll have the same plans for a while, but no time.

Regards,
Tim

Logged

Kubota KND3 Genset
jimmason
Newbie
*
Posts: 33


View Profile
« Reply #6 on: December 28, 2010, 03:44:36 AM »

Cschuerm,

search also on gobar gas in india.  there  has been lots of work done there on small systems.  not sure exactly which org was the umph. 

the main person i see working on diy systems is paul harris at the univ of adelaide.  he is the moderator of the bioenergylists digesetion list.  see here:
http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org

from here you will find some knowledge collections in case you have not already found them.

and yes, the usual problem for the diyer is to get enough gas for anything more than a stove.  one needs a highly concentrated production situation, like a feed lot or dairy, to get a feedstock volume to do much.  the payback is the tech is much more simple than thermal conversion of dry material.

all these alt energy solutions are very context specific.  none are general case silver bullets.

j

Logged
Pages: [1] Print 
« previous next »
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.13 | SMF © 2006-2011, Simple Machines LLC Valid XHTML 1.0! Valid CSS!