Long Term Biological Treatment of Space Habitation Waste Waters in a One Stage MABR: Comparison of Operation for N and C Oxidation With and Without Simultaneous Denitrification

Aerobic biological stabilization has been previously demonstrated for full size MABR’s (CoMANDR 1.0, CoMANDR 2.0, and R-CoMANDR) over operating periods of ~1 year. These systems have successfully treated a variety of possible habitation waste streams including an ISS (urine + flush and humidity condensate) and Early Planetary Base (EPB) wastewater (urine, flush water, hygiene wastewater, and laundry). Biological stabilization has a number of advantages including: 1) elimination of hazardous pre-treat chemicals; 2) production of NOx species (that can be easily rejected by evaporative or membrane systems); 3) elimination of volatile organic constituents; 4) a low pH effluent that facilitates membrane and distillation processes; and 5) an effluent that produces a better quality and less hazardous brine for water recovery. Previous work has primarily evaluated aerobic operation in which organic carbon and nitrogen is converted to CO2 and NOx-, respectively. An alternative to aerobic operation would be to include anoxic operation to promote denitrification and production of N2 gas. This allows for production of make-up gas as well as reduces the O2 demand and can increase ammonia oxidation efficiency. We evaluated the operation of a full scale (2 crew/day) MABR operated to perform oxidation of organic carbon and nitrogen with and without simultaneous reduction of oxidized N to N2 gas, simultaneous nitrification denitrification (SNDN). The system was challenged with a variety of space habitation wastewaters ranging from an ISS composition to a possible EPB waste stream under both continuous and on-production feeding modes. The system has been operated for over 2.5 years. We report on an overall comparison of aerobic oxidation and SNDN operational regimes to evaluate the system with the best overall attributes to support recycling of space habitation waste streams.