Essential to extended human exploration and utilization of space is providing a clean supply of potable water as well as water for washing. Although recycling of wastewater is necessary for long-term space missions due to the limited capacity of water storage, it is challenging to produce stable and healthy water from the wastewater stream of hygiene water (hand, body, clothes, and dish washing), condensate water, and urine.  The pollutants in the wastewater can pose a threat to human health. Organic and inorganic contaminants such as urea, ammonia, halogenated carbons, and heavy metals are of concern because of their harmful effects on humans. Microorganisms that may be pathogenic or clog water lines are also of concern. 

   Recently, membrane technology has drawn attention. Membrane filtration is a regenerable technology that requires replacement far less often than conventional filtration (usually 1~2 per one year in commercial membrane plants). Membrane filtration such as Reverse Osmosis (RO) also removes ions, proteins, and organic chemicals which are generally very difficult to remove using conventional treatment. Moreover, membrane is an absolute filtration method, so its treatment efficiency and performance are stable and predictable. 
   We are currently woking on the development of rotating RO membrane system. Dynamic rotating membrane filtration, which can produce a high shear rate, may be helpful to obtain high rejection of organic pollutants. 
   The figure shows the reduction in Total Organic Carbon (TOC), Total Nitrogen (T-N), detergent, and ions (conductivity) using RO in a stirred cell apparatus to process wastewater.