Optimization of a Membrane-aerated biological reactor in preparation for a full scale integrated water recovery test

Water recycling is a fundamental component of life support systems due to the substantial contribution of water to the total equivalent system mass. Optimizing the integrated water recycling systems is essential in any efforts to enable long term space habitation. Membrane aerated biological reactors (MABRs) have proven to be an efficient and sustainable pretreatment process for extra terrestrial wastewater recycling applications in closed loop life support systems. The CoMANDR (Counter-diffusion Membrane Aerated Nitrifying Denitrifying Reactor) system can be used to treat unstabilized wastewater composed of urine, hygiene water, humidity condensate, and laundry water. The operation and assessment of the CoMANDR is in support of the integrated systems test to be implemented by Johnson Space Center pairing a biological reactor with a forward/reverse osmosis unit to treat the aforementioned waste stream. After a two month start up period we have systematically evaluated the CoMANDR performance for a variety of loading rates and verified the operation of the system under pressurized conditions. Results support the ability of the system to effectively reduce organic carbon by over 90% and convert up to 70% of the total influent N to non-organic forms (e.g. NO_x or N₂). Operation has been demonstrated using both air and pure O₂, although in each case further control refinements are required to help maximize the denitrification potential of the reactor. We have also demonstrated that for at least up to 3 weeks, CoMANDR can be put into recycle and brought back on line with no start up required supporting the ability to intermittently operate the system.