The Pre-Treatment Solution for Water Recovery was developed by NASA Johnson to increase the amount of potable water recovered from the International Space Station’s urine processor assembly system. Turning wastewater, urine, or seawater into potable water requires three important steps: 1) pre-treatment, 2) distillation or membrane filtration, and 3) transport and storage of potable water and brine. This solution is added during the first step, consequently improving the next steps in the process primarily by reducing the formation of solid precipitates.
The solution reduces the amount of precipitates caused by urinary calcium, sulfate ions, and sulfuric acid, creating less acidic brines. By reducing these precipitates, less surface scaling and clogging occurs in the distillation systems and more potable water can be recovered. Also, the solution contains a biocide to prevent the growth of bacteria, thereby increasing storage time and the amount of water recovered.
The solution increased the water recovery rate in the ISS distiller from 75 to 90 percent, doubled the volume of feed processed per cycle, reduced the volume of brine in half, and eliminated the formation of precipitate up to 90% water recovery. The benefits extend to other steps in the process; for example, less precipitate has the potential to reduce the frequency of changing the filters and the number of filters used per gallon filtered during the distillation stage. Furthermore, this pre-treatment solution prevents bacterial and fungal growth during storage.
Although the solution was developed for the ISS distiller, the technology can potentially be used on Earth to pretreat contaminated water that is usually treated with a chemical solution to recover water from organic-laden, high-salinity wastewaters. The technology is a simple additive process that can be scaled to fit processing demands. The technology can be used in the transporting or storage of waste or other water sources due to the technology’s ability to prevent microbial growth.