Orpah School excess water with flush toilets

Design, build and install a low cost batch feed composting toilet.

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haitischool
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Joined: Sun May 11, 2008 4:18 pm

Orpah School excess water with flush toilets

Postby haitischool » Tue Sep 02, 2008 9:57 am

I am working with Paul Harris on a design for a school digester in Haiti. I am currently designing an orphan school their. Whats nice about green construction is you can build to suite the need of the digester sewage system.

My questions are:
1. Does any one have a working design that minimizes the amount of flushed water in a US design toilet. I am wanting the minimum water and still clean the toilet. I have thought I would try for 2 liters but I need a high volume to wash the toilet. A European style toilet with the bowl elevated 4 or 5 feet with 2 liters in the bowl might work. Put a plastic jug in the bowl to reduce the water flushing but still allows the toilet bowl system to work normally. I would like to find a working design of any system that reduces the water.

2. Even with 2 liters the digester is huge. I am wanting a continuous feed system to minimize maintenance. Does any one have a design to separate some of the excess water so I can get the 50% mix of water to solid. 50% is what I have read is the target ratio for good gas production.

3. Once the water is separated how do you clean it so it can be released in a stream. Again I need to have a maintenace free system. I have thought about a two lagoon process with a gravel plant mix between the two. I understand the lagoon has to hold the water 100 days. This makes for a huge lake not a lagoon. Any one have a working design.

Currently the school is being designed for 250 kids. However based on others inout in the area it will grow by a factor of 10 or more. 2500 to 3000 kids is just too large a system. Any one else have scools with a digester and flushing toilets with water?

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Bob
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Re: Orpah School excess water with flush toilets

Postby Bob » Thu Sep 04, 2008 8:43 am

Does any one have a working design that minimizes the amount of flushed water in a US design toilet.

I used a Sealand toilet with a small holding tank (a 6" dia x 18" long" PVC pipe) mounted in the floor under the toilet, and pumped out to the composter with a hand pump. See details here. It used less than 1 liter per flush. However, after years of living with it, and experimenting with different variations, I replaced it with something much better -- a urine-separating waterless design. I have come around to the view that having to deal with excess water invariably adds cost and complexity to any system and, rather than continue to struggle with trying to figure out how to deal with it or treat it, it may be easier, simpler and cheaper to just not add it in the first place. But that requires some re-examination of conventional views.

composter1-5.JPG
composter1-5.JPG (46.23 KiB) Viewed 5170 times

Does any one have a design to separate some of the excess water so I can get the 50% mix of water to solid.

I am working on such a (biodigester) system right now, but haven't built and tested a working prototype yet to be able to say how well it will work. (It would also be a bit misleading to say that I am separating excess water. I'm just not adding it in the first place.)


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