Performance of a Full Scale MABR (CoMANDR 2.0) for Pre-treatment of a Habitation Waste Stream Prior to Desalination.

摘要

Recycling waste water is a critical and crucial step to support sustainable long term habitation in space. Water is one of the largest contributors to the cost of space travel and the associated life support systems. In closed loop life support systems, membrane aerated biological reactors (MABRs) through biological reactions can reduce the dissolved organic carbon (DOC) and ammonia (NH3) concentration as well as decrease the pH of the waste water, leading to a more stable solution with less potential to support biological growth or promote carryover of un-ionized ammonia as well as producing a higher quality brine. We have previously demonstrated the successful performance over a 1 year period of a demonstration size MABR system, CoMANDR 1.0 (Counter-diffusion Membrane Aerated Nitrifying Denitrifying Reactor). This system was able to generally achieve DOC reductions of >90% and ammonium conversion rates of >50% over a range of loading rates. However, due to the very high specific surface area (SSA) (260 m2/m3) the system had poor hydraulic performance after one year of continual operation. The CoMANDR 2.0 system was developed to evaluate the impact of reduced specific surface area (200 m2/m3) as well as investigate the impact of low total air flow in to the system and forced hibernation periods (periods of no human habitation). The system was fed daily with un-stabilized wastewater composed of donated urine, ersatz hygiene water, humidity condensate, and laundry water. The liquid side system was continually monitored for pH, TDS, DO, and Temperature, and the influent and effluent monitored daily for DOC, TN, NOx, and NH4. The gas side system was continuously monitored for O2, CO2, and N2O was monitored intermittently in the effluent gas. 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. NOx or N2). We have also demonstrated that for at least up to 4 weeks, CoMANDR may be placed in a recycle mode and can be brought back on line with no start up required supporting the ability to intermittently operate the system. Additionally, the system could handle low air and oxygen (80 mL/min) flow rates with a loading of 20 L/day and achieve high carbon removal.