Since I've got three kids and I'm planning to do a year in Europe and would like to avoid hookups whenever possible, I'd be interested in any opinions for this kind of high-use situation. So far it seems like a large tank and dumping every couple of days can't really be avoided. I like the idea of cassettes, but the capacity seems too small - same for composting. I haven't really looked at incinerating toilets yet.
Jay, with the Eco Roamer vehicle, used one of these waste seperating toilets, and travels with a wife and kids. I seem to recall he did something like run the urine line to the exhaust somehow to burn off the liquid.
No idea how he handles the solid waste. Probably just tosses a bag of it in a handy dumpster.
Incinerating toilets have been discussed here - there is a thread somewhere I think.
Basically, they come in electric, propane or diesel fired.
The electric ones use about a kilowatt per cycle. Good luck powering that sucker without running a generator.
The propane unit I've seen is designed for full-time use for a family of 4, and costs I think around 3 grand.
The diesel fired...there is one that is for installation in a trucker's sleeping berth - it has a 1/2 gallon chamber and takes 40 minutes for an incineration cycle - and then another half-hour to cool down from 1200 degrees F before you can sit on it again. [EDIT: Now that I think about it...that one might be 24v electric...probably is...oh, lament the failing memory...]
The only other diesel fired I've seen, is designed to handle a job site crew of 20, weighs 200 lbs. and costs around 5 grand.
Both the propane fired and the larger diesel fired come from the same company, and they can both have an optional catalytic converter (with forced flow fan) fitted into the 8" chimney to trap the odor of incinerating waste. That option I think runs another grand or so. (But the neighbors will thank you. Or at least not kill you, which they would do if they had to deal with the smell.)
And then, there was the Thermasan system installed as an option on the old GMC motorhomes. It used a single grey/black water tank, and used a pump to inject the waste into the exhaust pipe just aft of the engine, where it would get incinerated by the heat of the engine exhaust.
It used both speed and vacuum sensors, so the pump wouldn't come on unless the vehicle was moving at 35 mph or more AND the exhaust gas was over 900 degrees.
Developed with the co-operation of the EPA, it was fully approved for use in the U.S. Too bad they don't make it anymore...
http://www.gmcgreatlakers.org/GMCGr.../Thermasan-System/Pages795-800 from X7425.pdf