Biological Treatment of a Synthetic Space Missions Wastewater Using a Kombucha-Bioreactor

Efficient water recycling is imperative for the sustainable presence of humans during long-duration and deep-space missions, where resupply from Earth is not a viable option. This study proposes a kombucha-based photobioreactor (Kombucha-PBR) as a novel biological approach for the treatment of wastewater generated in space habitats. Kombucha, a symbiotic microbial consortium of bacteria and yeasts, produces bacterial cellulose and demonstrates high stability and resistance to contamination, making it suitable for closed-loop bioprocessing in microgravity conditions. The reactor was evaluated using synthetic wastewater formulated by NASA, which was representative of spacecraft effluents. Treatment performance was assessed through the removal of chemical oxygen demand (COD) and total nitrogen (TN). Following an initial adaptation phase, the system demonstrated stable performance, with a decrease in ammonia concentrations from 200 mg·L⁻¹ to 44 mg·L⁻¹ (>80% removal efficiency) and an average COD removal of 81% after 30 days. The fixed-bed configuration provided an extensive surface area for the growth of biofilm, thereby enabling simultaneous carbon and nitrogen removal whilst minimising energy requirements and operational complexity. The findings demonstrate that the Kombucha-PBR offers a compact, low-energy, and microgravity-compatible solution for regenerative water recovery. Its integration into spacecraft life support systems has the potential to significantly advance sustainable resource management and autonomy for future long-term space missions.