An Optimum Biological Reactor Configuration for Water Recycling in Space

Biological pre-treatment of early planetary/lunar base wastewater has been extensively studied because of its predicted ability to offer equivalent system mass (ESM) savings for long term space habitation. Numerous biological systems and reactor types have been developed and tested for treatment of the generally unique waste streams associated with space exploration. In general, all systems have been designed to reduce organic carbon (OC) and convert organic nitrogen (ON) to nitrate and/or nitrite (NO_x ^-). Some systems have also included removal of the oxidized N in order to reduce overall oxygen consumption and produce additional N₂ gas for cabin use. Removal of organic carbon will generally reduce biofouling as well as reduce energy and consumable cost for physiochemical processors. The focus of this paper is to compare the performance achieved by several biological systems as well as their volumetric loading capacities in order to assess the overall efficacy of biological pre-treatment and aid in the selection of optimal bioreactor systems.