The idea,Chris, is that the fecal matter has an enzyme added to it to break it down into fertilizer while the chamber sits unused for six months. Urine is (by and large) diverted away from the chamber and run to the outside so that only solid waste goes into the chamber. I have other pictures but they were not high resolution and the paper could not use them. Shame, because it would make it more clear. It is not the easiest thing to conceptualize. I think the paper did an admiral job with what they had.  Hope the explanation helped. 

Doc