Evaluating Microbial Contaminant Removal in an Anaerobic Membrane Bioreactor Designed for the Treatment of Fecal Waste in Planetary Habitats

NASA and the University of South Florida have developed a novel Anaerobic Membrane Bioreactor (AnMBR) as a bioregenerative wastewater management system for early planetary habitats. This hybrid system employs an anaerobic microbial consortium for the bioconversion of fecal waste, coupled with an ultrafiltration membrane module for solids and cell retention. Operating since 2021, the AnMBR has consistently recovered ~2.5L/day of nutrient-rich permeate from canine fecal waste, as surrogate for human waste. The permeate has supported Bok Choy cultivation and has been used as a media in phototropic microalgae systems, with results presented at ICES 2022 and 2023. Ensuring the microbiological safety of bioregenerative, closed-loop systems treating metabolic waste is critical, especially given the complexity of fecal waste, such as its variable solids content and potential pathogens (e.g., bacteria and antibiotic-resistance genes). Tracking fecal indicator bacteria and microbial genetic markers throughout the AnMBR helps evaluate its efficacy in removing or inactivating micro-contaminants before they could potentially reach downstream systems. This conference proceeding will report on the AnMBR’s efficiency in reducing fecal indicator bacteria across treatment phases and the ability of its ultrafiltration membrane to exclude bacterial DNA from the permeate, specifically using genetic markers, such as DG37, associated with canine feces. Preliminary findings on microbial community structure within the AnMBR will also be discussed.