Development of an open-source process simulator for microalgae-based tertiary phosphorus recovery

Microalgae-based tertiary wastewater treatment has the potential to meet stringent effluent phosphorus limits, with the added benefit of producing a marketable feedstock. However, without validated models embedded in process simulators, the industry lacks the tools to evaluate the benefits and trade-offs of integrating tertiary microalgal treatment with conventional wastewater systems. In this study, an updated lumped pathway metabolic model was developed to predict effluent phosphorus concentration and biomass yield in response to dynamic influent and varying environmental conditions. The model was implemented in QSDsan – an open-source, Python-based design/simulation platform. Global sensitivity analysis was performed to prioritize model parameters for calibration. The model was then calibrated and validated using batch experiments and continuous online monitoring data from a full-scale microalgae-based tertiary wastewater treatment plant. Overall, the QSDsan-based microalgae process simulator was able to predict effluent phosphorus within 0.02–0.04 mg-P·L-1, while also capturing general trends of state variables according to nutrient availability.