It's nice to see how simple things can be. The loo in my van is a cassette thing, and normally you put some chemical in the cassette to eliminate the smell and help the contents to break down. It's basically a seat with a hole into a container with a lid on it. You can also get one of these, http://www.outdoorbits.com/system-kits- ... -p-26.html
, to do without the chemical. It's an extractor fan and filter that starts up when you open the flap. It's not really practical to chuck sawdust down the hole, as you'd have trouble emptying it. It uses water for flushing, but only to clear the bowl, and the 15 litres of water in the tank lasts for ages. You can control exactly how much, if any, water you use for each flush. All very simple ideas, in this case using lots of plastic and complex components, but it doesn't need to if it's not in a vehicle, where you need to stop the end product splashing about.
I don't know the best way to make use of the contents of the cassette, as it ends up as a liquid, so would be difficult to contain in a compost bin. I wouldn't like to pour it straight on the land. I guess this is something I might have to deal with if I get some land, and have to live in the van while I'm building or renovating a house.
Disposal on camp sites unfortunately goes the same way as conventional loos, but it's great fun emptying a full cassette of brown yucky liquid
. I did have an offer of having a hole made by a digger to empty it in last weekend.