These look similar to flushing toilets but the urine is directed down a second set of pipes to a holding tank, which farmers empty at regular periods, using the urine as fertilizer.
Mitchell said the recycling systems have side benefits for the environment because the toilets use less water and less energy is needed at the treatment stage.
But uptake of the technology has been limited.
A Queensland trial, run by Department of Natural Resources and Waterresearcher Cara Beal, is now under way with 10 toilets being installed in the Currumbin Valley, near the Gold Coast of Australia.
Mitchell said the impending phosphorus supply crisis should be the catalyst for rethinking attitudes toward the use of fecal matter.
But urine-separating toilet systems have to overcome the same public inhibitions that make recycling sewage for drinking water unpalatable to some.
"There is a poo taboo that happens and happens differently in different cultures," she said.
In Sweden where the urine-separating toilet technology is being embraced, there is a history of residents collecting urine and transporting it to nearby farming areas to use as fertilizer.
But Mitchell is in no doubt the "revolution" will happen
"It has to for the simple reason that we are going to run out of other concentrated forms of phosphorus in about 50 years," she said.
"We are going to need sources of fertilizer ... and the most concentrated, readily accessible source of phosphorus is us."
