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Thermophilic Humanure Tank Build  RSS feed

 
Brendan Edwards
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Location: Hiroshima-shi, Japan
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I've run successful humanure bins for a few years and never had any trouble with them. I am now preparing to build a more solid tank system that can work for people more accustomed to standard plumbing. I saw the Humanure book and have read parts of that.. Wondering if anyone has some specifics on tank dimensions, management, tips, additives (paper, sawdust, straw)? I'm used to the outdoor system, but I imagine there are some different challenges with a tank system and would love some thoughts on it? I am looking for a thermophilic compost using a non-flushing system. I will build a slightly larger system to deal with visitors to our place, I'll figure 10 people will use it so size it that way. I'll hit the Manure book as well. Thanks!
 
William Bronson
Posts: 1451
Location: Cincinnati, Ohio,Price Hill 45205
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I will follow this with interest. I have never done humanure composting, but a tanked system might work for our urban setting.
I imagine some way to control the amount of moisture in the tank would be nessisary.
There are some nice designers for flush toilets that lead to vermicomposting tanks. They drain leachate into a growbed.
With a waterless system there is nothing to move the waste away. So unless you are dumping buckets, you are right over the tank, so I think redirecting the stink would be the real challenge.
A solar powered fan and/or a solar(black painted) chiminey might help
 
Brendan Edwards
Posts: 40
Location: Hiroshima-shi, Japan
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I'm pretty sure I've solved most of the problems already via some research and an email reply from a Permaculture Master/friend. I'm building a 2 tank system. I'm already not worried about stink, I've dealt with that previous, charcoal dust/grains and carbon (shredded paper, straw, leaves, sawdust etc) added at bottom in large amounts and then on top of each poo in small bits will stop the stink and ensure good composting. Make sure you have a top exhaust pipe. The dimensions of his recent tank are 9' H x 4 x 6.. I'm looking at something similar.. so you need a second floor or basement to locate tanks/toilet. his was a 2 chamber concrete. He needed a physical structure to put the toilets on. I don't require that, so the effort and expense of concrete isn't necessary, though my final design may make it useful.SO, big box, 2 poo-holes on top, use one till sufficiently filled, shut it and switch. Let tank 1 sit for a year while you fill the other. After a year you've got food grade compost as long as you had enough carbon/air to offset liquids (prevent anaerobic/waterlogging) This size tank will serve small commercial size usage. You need a certain critical mass to get good thermophilic action. For 4-6 people you could probably just use those big plastic cubes... like 1.5 meter cubed... 2 of them... though I can't be certain without checking further into it.
 
Brendan Edwards
Posts: 40
Location: Hiroshima-shi, Japan
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If anyone has built a wood frame tank and used PVC lining or similar on a project like this, I'd love to know.
 
Brendan Edwards
Posts: 40
Location: Hiroshima-shi, Japan
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I'm in Japan and I had plans to build a tank for a humanure system. I need to include a Washlet or bidet system which uses perhaps 1/8 gallon or less of water... My guess right now is that I can make this work with a larger tank and more dry goods added at the beginning. I'd love knowledgeable commentary on this. should I install an overflow? like a pvc pipe portion with holes sticking above the floor of the tank and exiting somewhere none too dangerous? or is this likely to be taken care of by evaporation overtime? Thanks!
 
Rose Pinder
Posts: 410
Location: Otago, New Zealand
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can you describe your situation more? Is it for lots of people or a single household? The immediate solution to having half a litre of water with each use* is to have some people pee somewhere else some of the time (or use urine separation). Or, just use more bedding at the start and more cover material as you go. It doesn't seem like a lot of extra liquid to me (I've done pee only/sawdust buckets as well as humanure), but I think amount of use, size of tank etc are important in terms of design.

*is that each poo, or each pee as well?

Are you intending to compost in the bin? How will you manage that?

btw, here's Milkwood's integrated wheelie bin system, which might have some ideas about how to manage the tank. This is a starting link but there is more on their website.

http://www.milkwood.net/2011/04/18/compost-toilet-specifics-the-bins/
 
Rebecca Norman
gardener
Posts: 1273
Location: Ladakh, Indian Himalayas at 10,500 feet, zone 5
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Brendan, I'm not sure I understand how you're planning to prevent liquid from pooling in the tank. I have experience: if liquid pools in the tank, even if the tank has plenty of nice carbon materials, you will get a terrible anaerobic methaney smell. I've tried making a pee barrel twice, once full of dry autumn leaves and once full of wood shavings, and they both eventually gave off an aggressive methane stink. And with our dry composting toilets, sometimes but not often, when we empty them the bottom two feet or so have gone anaerobic and give off a powerful stink while emptying, which can linger in the area for a day or two. This is sometimes true even though the bottom is usually started with a foot or two of dry autumn leaves or wood shavings. We have several theories about what causes this to happen in only one out of ten or so of our toilets: certainly it happened after we used crumbled cow manure for cover material for a year; there is some suspicion that our Indian volunteers taking a water bottle in with them causes it; or maybe it's just when the manure chamber pile gets too high, like 6 feet, and squishes all the air out of the bottom.
 
Brendan Edwards
Posts: 40
Location: Hiroshima-shi, Japan
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Yea, Becka, your notes are my concern. I've done a lot of composting... but tanks... different.. and I figure there's a tipping point with water content. I know pee/poo mix is fine.. but there is a very limited amount of water beyond that that can be accepted by a closed tank system. I don't know what that amount is. I've seen notes on putting whole straw bales in the bottom. I would use saw dust, not chips... and some charcoal dust to prepare the stuff and control smell... but liquid has a limit... and putting a drain in has its own challenges.. I could put the wash system in and run that through a graywater system from a seperate throne.. which doesn't frighten me due to the small amounts of butt....juice? sorry... involved.. If I can I will run one system (seating position) that does everything... I wonder if putting a low depth liquid run-off that went to a subsurface graywater system might work? Thanks for your notes. Straw bales do have a greater suck than leaves which don't absorb nearly as much.. I think I've gotten better results with straw than saw dust as well as far as bases.. then sawdust in the layering and in my buckets.... I've seen some notes on massive drygoods inputs... like 3 -4 feet high in larger tanks. I'm building a large double tank. maybe 6 -7 feet high... I could probably load the tank extremely with dry carbon and lose some time on usage via the extra mass... and test the wash system... then close it down if it gets weird.. how long were you letting tanks sit? If it was too wet I could add dry material and switch tanks.. then re-mediate during the fill time of the new tank... I guess I'm thinking that there is some amount of dry material that will offset the added liquid.. if the tank is large enough.. what dimensions are your tanks? My tanks will compost for a year after shut.. Best!
 
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