As John Laumer noted earlier, there is a lot of useful stuff in pee, but we dilute it with gallons of water, send it down big pipes mixed with everything else, and suddenly we have monstrous networks of waste piping, sewage treatment plants and water shortages feeding it all. Yet as Carol Steinfeld wrote in Liquid Gold, urine can be used "to grow food and landscapes, while protecting the environment, saving its users the cost of fertilizer, and reconnecting people to the land and the nutrient cycles that sustain them."
That's why we were so intrigued by the Swedish Separett Composting toilet that we saw at the Cottage Life Show. It separates out the urine, which can be put to use in the garden or drained to a leaching pit, and the poop, which is kept within the toilet for composting. Because the urine is removed, the volume is much smaller, and the mixture does not ferment, creating that familiar smell of overused outhouses.
Sitting on the seat activates a trap door and rotates the container below so that it fills evenly, and electric fans exhaust any smells to the outdoors, and aids in drying of the poop. (12V solar powered version available).
After three to six weeks, one opens the lid and removes the container, adds some soil, carries it out to the back forty and lets it sit for six months, in order to inactivate all human pathogens. Then it can be used as compost. (so you are going to need about six containers, or use the compostable waste bag as a liner)
We were a bit suspicious of that last aspect of it, lining up containers in the garden, but they have been doing this in Sweden since 1976 and have sold over 200,000 units. It has UL and CSA approvals, so it has been tested and deemed safe. However we think that perhaps this might not be the best unit for urban use of composting toilets, unless you have a very big backyard or balcony.
An optional 50 litre ejektortank can be used to gather the urine and dilute it 8-1 with water; connect a hose and spray it around the garden. Now available in Canada via ::Separett.ca and in the States, from ::Ecovita.