An Updated Modeling Study on Nutrient Deprivation as a Biofilm Mitigation Strategy for Long Term Space Missions

Spacecraft wastewater processing systems are environments where bacterial biofilm growth can cause problems in daily operation. As crewed missions explore beyond the ISS to the Moon and Mars, long periods of system dormancy will be necessary, making biofilm control more challenging. Previously reported preliminary mathematical models of biomass growth, as a function of nutrient availability, were developed to understand the biofilm accumulation in the WPA system under daily operation and potential dormancy conditions. These models were since updated to reflect the effect of oxygen availability, as well as the tank cycling during daily operation. This paper describes the updated models and compares the influence of various nutrient and energy limitations on the biomass product, in order to provide insight on the nutrient deprivation strategy for biofilm mitigation.