Using Effluent from a Hybrid Anaerobic Membrane Bioreactor Treating Fecal Waste for Hydroponic Fertigation of Pak Choi

Challenges for future deep space ECLSS will include providing potable water, supplying nutritious food, and managing wastes generated by the crew. With next to no readily available resources to sustain human life on the Moon and Mars, nothing can be considered a waste, and every resource, including all organic wastes generated by the crew (e.g., fecal), should be deemed for recovery and reuse. Fecal waste aboard the International Space Station (ISS) is currently treated as solid waste and not recycled in any capacity. The high-water content (fecal material being ~75% water), complexity, and the presence of pathogens make fecal waste difficult to stabilize and process. However, fecal material contains considerable fractions of carbon, nitrogen, phosphorus, and minerals which after stabilization, can be recovered and used as plant fertilizer. There is considerable research about growing food in Lunar and Martian greenhouses but a major limitation for plant growth will be continuously supplying fertilizer salts. Recognizing the need for a bioregenerative approach to fecal waste, an organic processor assembly (OPA) unit was developed through collaboration between the University of South Florida and NASA’s Kennedy Space. OPA is a hybrid, physical-biological treatment technology that couples an anaerobic bioreactor with a tubular ultrafiltration membrane. OPA is designed to treat and recover resources from the solid organic waste stream of a crew of four astronauts on an early planetary base. Aspects of OPA’s long-term operations and water quality treatment analysis were presented at ICES 2022. This conference paper will present preliminary research regarding the downstream use of OPA’s nutrient-rich effluent, produced from an actual fecal influent, in supporting the growth of extra dwarf bok choy from germination to maturity. Overall, OPA1 is an enabling technology demonstrating its potential to minimize fecal storage volume and assist in waste management, while additionally offsetting fertilizer demand.