 
Researchers Use Bacteria to Recycle Water in Space
Life support systems for space habitats must be compatible with the formidable constraints of space flight: zero gravity, low mass, low power consumption, high reliability, low reliance on resupply, and low human attention. The challenge of designing a water supply for such missions is being addressed at CU-Boulder's College of Engineering and Applied Science through a unique collaboration between researchers in environmental and aerospace engineering. Professor JoAnn Silverstein of environmental engineering and David Klaus, a research associate in the BioServe research center in Aerospace Engineering Sciences, are working together to develop a bioprocessor system that uses bacteria growing in a biofilm to help treat wastewater comprised of urine and wash water. Engineering students Alison Keith, Ryan Snow, Steven Johnstone, and David Waller are also working on the project, funded by a grant from NASA to the Allied Signal Aerospace Corporation, which is supporting research activities in the College. Biological processes have been used to treat wastewater on Earth for decades. However, the treated water is typically discharged to a stream or other water body where it is further purified by natural chemical and biological processes before it is reused by people. NASA's goal is that reclaimed wastewater will be used directly for washing, drinking, and food preparation. So, typical biological wastewater treatment processes must be enhanced to allow as close to 100 percent direct water recycling as possible. Target wastewater contaminants are organic carbon and nitrogen, similar to domestic sewage, but much more concentrated. Because bacteria are very efficient in oxidizing the organic carbon compounds and converting wastewater nitrogen compounds to nitrogen gas, NASA is interested in developing a bioprocessor for water recycling with removal of 90-95 percent of the total organic carbon and 50-75 percent of the nitrogen. So far, laboratory research using the bench-scale bioprocessor shown has demonstrated that over 97 percent of the total organic carbon in the wastewater is destroyed and 70 percent of the nitrogen is converted to nitrogen gas, a desirable by-product for maintaining space cabin atmosphere. Research is now underway to miniaturize the laboratory system to a bioprocessor that can be tested aboard the Space Shuttle sometime during 2000-2001. While this project is focused on the special needs of the space environment, advanced recycling technologies developed at CU-Boulder also may benefit preservation of water resources on Earth.  Engineering Home |
Space exploration involving flights of months- or even years-long duration, such as would be required to get to Mars or some future planetary habitat, will require advanced life support systems for sustaining supplies of air, water, and food.