Development of a peristaltic flexible transfer system for transporting feces under microgravity: Construction and validation of transport models

In this study, we propose a peristaltic flexible transfer system for transferring feces in a free piping route. Currently, human feces is incinerated and disposed in space, such as on the International Space Station. As feces contain a large amount of reusable organic matter and water, the ability to recycle feces will improve the performance of manned space technology. However, existing space toilets are not designed to reuse feces, and the transportation of feces from the toilet bowl to the collection area is a technical challenge. A method for transporting intermittent supplies such as feces with less energy and water consumption is required. In a previous study, a peristaltic transfer system was developed based on the peristalsis of the intestinal tract of living organisms. In this method, multiple pump units driven by low air pressure generate peristaltic motion, which enables horizontal, vertical, and curved transfer of simulated feces. However, because the frame of each unit is rigid, the transport path cannot be changed flexibly, and the design must be adapted to the installation location. Therefore, the frame must be flexible.We propose a peristaltic flexible transfer system for transferring feces in a free piping route. First, we construct a simple model of content transfer using the peristaltic flexible transfer system and calculate the transfer rate based on data obtained from basic characteristic experiments of a single unit. Then, we conduct an actual content transfer experiment using the transfer system and compare the results with the simplified model results.