Poop and pee are valuable stuff; that's why people used to collect it and even pay for it. That's why our current toilet system is so awful, just mixing them with lots of water and flushing them away, and why the Caltech Toilet that got all the coverage in the Gates Foundation Reinvent the Toilet program was so problematic, it was really just a fancy flush.
In fact human byproducts (don't call it waste) have real value is a world of peak fertilizer and peak phosphorus; it provides both. That's what's so interesting about the Blue Diversion toilet developed by Eawag, the Swiss Federal Institute of Aquatic Science and Technology. It is a mix of high and low tech that does a whole lot more than just flush and forget.
Water is for washing
The basic principle is that of a dry urine-separating toilet, which keeps the poop and pee in separate containers for easier processing. However, the designers note that these have not been hugely popular, particularly in cultures where people wash instead of wipe. So, independent of the poop and pee collection and transport, they add water for personal hygiene and for cleaning the bowl.
This water, which is far less contaminated than regular toilet output would be, is treated and then recirculated.
The water is biologically treated in situ, and pathogens are removed by the gravity-driven passage of the water through a membrane. The production of chlorine by solar-powered electrolysis prevents the re-growth of undesirable bacteria in the recycled water.
There is a real business model
But wait, there's more. Since the poop and pee is collected and separate, it can be processed into fertilizer and phosphorus, creating a real business model.
The business model covers all activities along the sanitation value chain. Upstream in the sanitation chain, it structures the marketing, sales, operation and maintenance of the Blue Diversion Toilet. Downstream in the sanitation chain, the business model highlights the collection of urine and faeces, their transport to the off-site resource recovery plants, and the production and sale of marketable fertilizer end products.
There is still some pretty high tech stuff going on here to recirculate that water; it is put through a bioreactor, a membrane, using new tech developed by Eawag, treated by electrolysis and then chlorinated. But it isn't a huge amount of water, it isn't essential to the use of the toilet and it can always be topped off with a bucket or two. The important thing is that it is not the medium for moving the stuff, it's just for washing.
Forget the banana stand, there is money in human byproducts. Sanergy has been saying that for years, and is working with the Blue Diversion people on this project. Because doing your business can build a good business.