|Composting toilet setup aboard Floating Empire.|
Monday, August 10, 2015
Composting Toilets: a Q and A
We've had so very much interest in our composting toilet setup lately, both here at the marina and from other websites, that I thought I would post some of the questions that we've been getting. The system has worked wonderfully for us over the year: a simple bucket and sawdust composting toilet rig with no moving parts, things to pump out, chemicals to use, or smell. The setup we use, its construction and operation is detailed on an earlier blog here.
Here we go:
1) Are there different kinds of composting toilets? What kind do I need?
Yes, there are several. First there are the continuous process toilets like the Clivus Multrum. These continually turn the waste into dirt, generally through a gravity fed process. They work great and with little or no attention, but are huge and far more suited to a home or business.
Then there are the "self contained" composting toilets like Envirolet, Nature's Head and others. These store the waste in a barrel or drum which is agitated to aerate the mass. They often also include a urine separator. They work well on vessels and cut down on the frequency of your having to empty them, but they're pricy, often running near $1000 for the toilet setup.
Batch digesters are the simplest. These can range from a drum that is changed out and allowed to ferment when full to a simple bucket and sawdust toilet that gets dumped into a compost pile or into the trash. They are extremely inexpensive and work well. It's what we have and what I recommend. We use the "luggable loo" snap on toilet seat from Reliance on top (there are others) which cost us all of about $16 US. (Please note: there is also a wooden seat and bucket toilet available called the "Loveable Loo". Nice system as well, but somewhat more expensive).
2) What kind of biomass can you use in the toilets? Can I use cat litter?
Any dry, absorbent material will work. Classically, dry sawdust is used, but any number of things can be used: Dry leaves, coir (coconut husk fiber), shredded cellulose. . . .anything that will lock up the moisture and allow air to circulate to the rest of the waste. Remember, you want to create a situation for aerobic (oxygen containing, which smells like dirt) decomposition as opposed to wet, anaerobic (which smells like. . . well. . .sewage) decomposition. Aboard Floating Empire, we mostly use wood stove pellets, which are made of compressed hardwood or softwood sawdust. We find it compact, cheap, and easy to handle. While pine based cat litters (look at it. Its mostly wood stove pellets. . . no kidding), will work fine, clay based (clumping or not clumping) cat litters will not. They keep air away from the waste, and that's not what you want.
3) Will these meet Coast Guard regulations?
Yes. They are largely considered type III non discharge waste treatment systems. Simple bucket systems are generally considered 'waste containment' systems, not waste treatment ones, and are not regulated.
4) How often do you have to empty it?
Hard to answer accurately. It depends, of course, on it's use. Using a simple bucket system with no urine separation, the two of us wind up emptying the toilet about every week in winter (when we're on the boat most of the time and not hanging out on shore). Urine separation will extend your time and cut down on the biomass you need to add to keep the waste mass dry, but do note that you'll have to find somewhere to dump the urine. Parenthetically, most of smell from pretty much all toilet systems is from urine, not solid waste.
We recommend, if you're using a bucket system, having two buckets available for the head. There will be times when it's getting full and you won't wish to or won't be able to get ashore to dump it, so just switch out the buckets, snap a lid on the full one, snap the seat on the empty one, and dump them when convenient.
5) Can I use toilet paper?
Yes. We recommend single layer stuff, which breaks down more easily.
6) Should I put in disinfectants, antiodorants, or other stuff?
No. They'll just interfere with the composting process and may result in MORE smell. As it is, with enough biomass, the toilet should smell like damp dirt--which it is--even if you stick your nose in it. . . .which we don't necessarily recommend.
7) Can I put in tampons, sanitary napkins, disposable diapers, dental floss, etc etc etc.
Not recommended. Most of the above products have things in them that either won't break down or do so very slowly. We recommend a separate trash container for this stuff.
8) Doesn't it look gross?
It looks like wet oatmeal.
9) Would you consider going back to a wet, blackwater marine head?
Not on your freaking life. I've never met one that didn't reek, they jam, they overflow, you have to have them pumped out.. . . .no thanks.
10) Are there other sources for information on this?
The bible on this sort of thing is a work called "The Humanure Handbook" by Joseph Jenkins, available on Amazon here and through humanurehandbook.com. I recommend it highly.
11 to infinity) Doesn't it smell?