Biological Treatment and Reuse of Human Space Exploration Wastewater

Extending a human presence in the solar system requires in-situ resource recycling. Entrapped Mixed Microbial Cell (EMMC) process may be considered an alternative to achieving this aim. The intent of this investigation is to develop an operational criteria, process performance and economic evaluation to meet NASA needs. A double-layer EMMC configuration bioreactor of 7L at a packing ratio of 17.1% operated at an HRT of 6 hours, continuous aeration (1-1.2L/L/day), temperature of 25 o C ±2 was tested. The organic loading rate fluctuated 1.0-4.5 mg/L/day. The EMMC process performance reached a steady state ~20 days. It demonstrated discharge efficacy of TCOD >94%, SCOD >97% removal, no solids generated, and an average nitrogen removal of 35. 9%. Simultaneous removal organics and nitrogen may be attributed to the long sludge retention times that EMMC achieves because it allows for slow growing bacteria such as nitrifiers to thrive. It would cost $0.08 to treat 10 gallons of wastewater a day (twice as much as water needed to treat). The EMMC reactor design depending on the design can treat 60% to 100% of daily wastewater within one day. It also requires considerably less space compared to physiochemical treatment processes and if integrated with other systems may be capable to renovate water to levels permissible for human consumption.