I had a chance to visit with the staff at De Nora during OTC 2019. Here is a video that is a bit dated, 2 years old. However, I find the Omnipure system for treating human waste intriguing.
The reason why I find this so interesting is because the staff at De Nora told me that at present the IMO requires human wastewater to be treated before being dumped into the ocean. This is shocking due to the fact that, during the time of this video being created and I think to the present date, ships are allowed to dump sulfate into the ocean.
My understanding is that sulfate forms sulfuric acid when mixed with water. Thus, an interesting dilemma; and I think De Nora provides an interesting solution. Please enjoy their video.