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Microbial control in closed environmental systems, such as those of spacecraft or proposed base missions is typically limited to disinfection in the potable water system by a strong chemical agent such as iodine or chlorine. However, biofilm growth in the environmental system tubing threatens both the sterility of the potable water distribution as well as operational problems with wastewater systems. In terrestrial systems, biofilm has been recognized for its difficulty to control and eliminate as well as resulting operational problems. In order to maintain a potable water source for crew members as well as preventing operational problems in non-sterile systems, biofilm needs to be considered during system design. While biofilm controls can limit biofilm buildup, they are typically disruptive and cannot completely eliminate biofilm. Selenium coatings have shown to prevent initial biofilm attachment as well as limit attached growth on a variety of materials.

When compared to physical and chemical processes for wastewater treatment in space, the benefits of biological systems include reduced storage and handling of waste material, lower energy requirements and plant growth system compatibility. An advanced membrane reactor (AMR) was constructed to treat ammonium-rich simulated wastewater. The effluent pH was approximately 6.3, and ammonium and TOC reduction rates were greater than 60 percent and 99 percent, respectively. The experimental results demonstrate that this technology may be suitable for space applications. However, the long-term performance of these systems should be investigated.