Building a composting toilet in a bus

The International Compost Sanitation Forum and Message Board: General Composting Issues: Building a composting toilet in a bus
Author: Joe (Joe)
Tuesday, March 19, 2013 - 10:39 pm
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Here's a post from the Humanure Facebook Page (http://www.facebook.com/HumanureCompost):

We live and travel full-time in our RV, and we've been using a composting toilet for three years. Hopefully you don't mind me sharing a post I made about it:

http://www.thegoodluckduck.com/2012/10/composting-toilets-for-rvs-and-simple.html

Author: Knothead (Knothead)
Thursday, March 14, 2013 - 10:49 am
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Arbor, One drawback to locating the buckets/containers under the floor that I can think of it that it will be more difficult to cover the deposits correctly. I don't know if you've used a system like this before, but one thing that happens is what is called the pyramid effect. (use your imagination).
I find it neccesary to flatten out the deposits while covering leaving a nice flat surface that is completely covered and odorless. I use a stainless steel perforated ladle type of thing that I bent into the right shape. I sprinkle enough cover material to completly cover the deposit and then gently flatten while making sure that everything remains covered.
Trying to cover a pyramid that is never flattened is a little troublesome. What happens eventually is that the pyramid tumbles over messing up the side of the bucket and exposing uncovered poop.
I can see this happening a lot with a moving, bouncing vehicle mounted arrangement. And I can't envision you wanting to reach down into the toilet to reach the container located under the floor. You would need a long handled tool and then where would you stow it?
Trust me, carrying out the bucket is no big deal. And you will most likely have a lid on it anyway.

Just something to think about.

Steve

Author: Arbor (Arbor)
Thursday, March 14, 2013 - 12:17 am
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Thanks Knothead. I think I will go that route with it, but have a more built-in setup. I'll divert the urine to the gray water and have the buckets (or similar type of container) under the floor so I don't have to carry shitbuckets through the bus.

I'm just a young up and comer, so no wife yet. Maybe I'll meet one along the way, so I'm planning my bus for 1 or 2 people.

I'll check out the bio-char.

Thanks,
Arbor

Author: Knothead (Knothead)
Wednesday, March 13, 2013 - 1:11 pm
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Arbor, You might try what I did on my boat. Being that boats and RV's are somewhat similar in that they can't really carry a proper compost pile.
I made a simple system that uses a urine separating seat called a "Privy Kit" that I bought.
http://www.ecovita.net/privy.html
It takes me, as I pointed out in another thread a full two weeks of daily use before my bucket needs to be emptied. Because it's mostly dry, it is very light. I would think that in your RV you might find a place to store a few buckets and just carry the full ones around until you come across a good place to dispose of the contents.
Assuming that two people are using the system, you should be able to use one bucket a week so that if you carry three spare buckets, you can cruise for a month without having to worry about it.
As far as disposal, I think that people worry way too much about that. Burying the immature compost in a wooded area away from water sources can't be a problem and has to be a lot better than what goes on everyday with people throwing diapers and uncomposted poop in the dumpsters. This happens a lot near marinas because they have no other place for cruising boaters to empty their stuff.
Sure it's better to be able to have a proper compost pile that heats up to the proper temp. But as the "book" also mentions, given enough time, even cold composting will achieve the same end result.

So, bottom line. KISS. :-)
Make a pretty (so the wife likes it), little box that holds your bucket and jug. Pour the pee out at every rest stop and carry around the filled buckets until you find a good place to get rid of it.
Use that nice space under the bus for an extra water tank or something.

I am sort of "Persona non Grata" around here because I separate the urine. There are some who can't or won't accept that, in some situations, separating works best.

I also strongly suggest that if you care about such things, you consider adding bio-char to your sawdust. I am utterly convinced that it really helps eliminate odors. Plus it is a good soil additive. Google bio-char, Terra Preta.
I know that if I were RVing, I would be sure to pack along my collection of TLUD stoves for camp cooking and just for fun.

Good luck.
Steve

Author: Arbor (Arbor)
Wednesday, March 13, 2013 - 1:51 am
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This is the FAQ page for the Separett (copy the whole thing if you want to look, not just the part it turned into a link) http://www.separett-usa.com/index.php?option=com_content&view=article&catid=24&id=59

Author: Arbor (Arbor)
Wednesday, March 13, 2013 - 1:48 am
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Thanks for the suggestions. I appreciate the advice, even though it's not really what I wanted to hear. I'll try to answer the questions you have.

Basically my plan is to live in the bus when I finish it and travel here and there, maybe park it for a year/month/week/day/etc. So you are right that most of the time, I would have no place for a real compost pile. I want to poop in my own bathroom, especially since I often won't be around town. Even if I'm carrying around a few hundred pounds of waste, it won't be enough for the bus to even feel it, so that's not a problem. I am ok with digging a hole in the woods to empty it - though it would obviously be easier to just drop it on the ground - I don't expect to have it composted to the point where it is safe to do that. I will do whatever I need to for safe disposal.

I have read a lot of conflicting advice about diverting the urine...It seems that the HH and folks here say that the urine must be composted with the feces, but other people say that if you mix them, there will be too much liquid for it to compost properly. Maybe if you're composting in a bin without a drain, the urine will make it too wet, but if you're composting on a pile it's fine? That's just a guess, trying to connect different things I've read. Is it possible that in my case just some urine should be diverted, or does the compost need all the nitrogen from it? The main reason I was planning to divert the urine was to keep the volume of compost smaller, meaning it could be in there longer to compost better and I could go longer between dumping it. I am not hung up on that, just trying to do the best thing.

The box under the bus would be insulated with at least 2" of rigid foam (R-12), and I could heat it some if necessary (though I would prefer not to). I can also run a small fan to move air across the containers. Is this just too small of a space for composting to happen?

I have researched some of the store-bought "composting toilets" such as the Separett...the Separett is a urine-diverting model that pretty much dries out the solid waste. They say it takes 3-6 weeks for 4 people using it every day to fill up the bucket. After it is full, you put a few shovels of soil in the bucket and set it outside for 6 months, at which point they claim the soil bacteria have rendered the fecal pathogens harmless. Then it's buried or put on a proper compost pile. Is this legit, does it really work like they say? Maybe I should be designing my system to act more like this? I don't expect to pull out a bucket of nice black dirt from the side of my bus to put on Mom's roses...I just don't want to be dumping shit on the ground, or using the normal RV system of wasting water to make my shit bigger and then having to go somewhere and pay to dump it.

Thanks a lot for your help.

Arbor

Author: Test2 (Test2)
Tuesday, March 12, 2013 - 7:59 pm
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Arbor - Dah on me. Please provide more info. Are you driving around - is that why you cant have a pile - that must mean you will lugging all those pails around with you. That would be somewhat wasteful - you would be better off just using a stores bathroom. When one is not avaialble just poop in a bucket, and dump at the next gas station.

Author: Test2 (Test2)
Tuesday, March 12, 2013 - 7:53 pm
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Arbor - another option is bury a concrete or some other water proof container under the bus - figure about 4'x4'x4'. Poop directly into it. Every so often throw in some soil (likely has worm eggs) or wait till its full and throw in some worms. After its full wait one year before use. But if you are not adding urine it may not heat up - that would not be good.

If you can the best way to "go" is per the book.

Author: Test2 (Test2)
Tuesday, March 12, 2013 - 7:46 pm
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Arbor - your post is not fully clear. I suggest reading the whole book carefully. I am glad you are trying to learn more about it.

18" high boxs that fit in a 2'by 7' by 18" box are not compost containers.

You say "Inside the box, I would have a few separate rectangular composting containers, so that one of them would always be under the toilet. Then when the one under the toilet filled up, I would dump the oldest one, slide the containers over, and put the empty one under the toilet." Dump it where ? That stuff you are dumping can be toxic. It's not compost. Of course you could dump it into a real compost pile.

Even the whole 2' x 7' x18" high pile may not heat up to create real compost. Also without the Urine it will likely be short of Nitrogen and moisture to, another reason why it will not heat.

I assume you have no place to have a real compost pile. Some people have tried using 55 gall drums - that may be an option. Search this site. Another option that is not really compost but may work for you is seeding the containers with certain kinds of worms and or beetles. Maybe their action would make the product safe enough if buried.

Author: Arbor (Arbor)
Tuesday, March 12, 2013 - 10:47 am
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Hi,

I am converting a school bus into my home, and I want to build a composting toilet in it. I have done a lot of research and read most of the Humanure Handbook, but I'm still not sure if my idea will work the way I want it to. Here's my plan so far:

The toilet will be just behind the rear wheels on the left side. There is a space underneath the floor of the bus where the composting will take place. The space is about 2' wide and 7' long, and I can use at least 18" vertically before running into ground clearance issues. Inside the bus, there will basically be a toilet seat on top of a 12" PVC pipe that drops straight down through the floor above the 2'x7' space. I'll have a lid that seals tight when I'm not using it. I'll make a urine diverter that sends the urine to the grey water tank. I have that part all thought through and I think it will work well.

I have a rough idea for the composting chamber underneath the floor, but this is where I need some help from someone who has actually composted human waste before. I would build an enclosed box in that 2'x7' space, with a door on the side so I could access it. Inside the box, I would have a few separate rectangular composting containers, so that one of them would always be under the toilet. Then when the one under the toilet filled up, I would dump the oldest one, slide the containers over, and put the empty one under the toilet.

Goals:
Full-time use for 1 or 2 people
Preferably don't have to empty more than once a month (though opening the door and turning the compost every week wouldn't be a big deal)
Not stinky inside or outside the bus
When finished composting, have a product that's not feces - basically I plan to bury it, trash it, or put it on a compost pile, depending on where I am

Questions:
Is my idea sound? If so,
How much of the 2'x7' space should I use for the outer box? All of it?
How big should each of the composting trays be? How deep?
How many separate composting trays should I have? 2, 3, 4?
How much waste does one person make per week (including cover material)? I've read that people fill a 5 gallon bucket in a week, but that includes urine...I'm planning on using a urine diverter

I'm trying to do this right, and taking the time to build a very nice home in this bus, so I want to think this toilet thing through all the way. I'm a very capable guy and I have a large array of tools to use, so I think I can do whatever it takes to build a good system. I really appreciate any insight you guys have to offer.

Thanks,
Arbor

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