Human Solid Waste Water Recovery for NASA
At the conclusion of my freshman year at university, I returned home to work at Ultrasonic Technology Solutions (UTS) designing and manufacturing an advanced prototype which utilized piezoelectric elements to mechanically separate water from human solid waste for recovery. For more details on the technology and project outline, view NASA’s TechPort project. When I started, the team at UTS had verified the technology for the application and provided a rough outline of what the overall drying system would look like. I was provided the constraints of an overall system weight of < 5kg, dimensions such that the entire system could fit inside Blue Origin’s standard single locker, and was given basically completely free reign over the design. I came up with, sketched out, and proposed an alternative design than the one outlined in the initial report to NASA that would be significantly simpler and lighter. After a few rounds of prototypes and design iterations, my design proved to be effective and a “final” prototype was completed on time, well within budget, and met all the above constraints.
My design pivoted around the “bag belt” mechanism. This mechanism enabled the efficient handling, sealing, and alignment of the semi-permeable bag within the system. I utilized Carbon fiber pultrusions and SLS printed nylon to minimize size, weight, reduce part count and complexity, maintain vacuum safety, and create convenient surfaces where sealed panels could be bolted to create an air-tight enclosure. High temperature, dry self-lubricating bushings and materials were used for all bearing surfaces to further reduce weight and reduce the need for maintenance and messy lubricants.
A single spring loaded pivot with a simple winch actuated arm were used to apply force to and squish the material in the bag, increasing the surface area with the piezo plate. Although many other solutions were considered, I chose this mechanism primarily for its simplicity and reliability.