A promising microalgal wastewater cyclic cultivation technology: Dynamic simulations, economic viability, and...

The microalgal wastewater cyclic cultivation technology (AWC²T) proposed in this study helps address the challenges surrounding water scarcity and ecological sustainability in a clean, resource-efficient, and affordable manner. A novel microalgae growth model (AGM) elucidating the growth mechanisms of microalgae in the AWC²T system was established for dynamic simulations and design optimization. The recycled wastewater accelerated the growth rate of microalgae, and increased biomass and lipids content by 11% and 37.65%, respectively, after 8 batches of cultivation. The accumulated soluble algae products (SAPs) enhanced microalgae growth by providing nutrients and regulating metabolism. In addition, scenario simulations illustrated the excellent long-term performance of the AWC²T system. 100% recycling of microalgal wastewater could save 0.3% N and 54.36% P. The techno-economic analysis (TEA) and life cycle assessment (LCA) explored how economic and sustainability principles can be embedded into the life cycle of microalgae production. The AWC²T led to outcomes vastly superior to non-cyclic technology by enabling the high-level recovery of resources, providing substantial benefits, enhancing contingency and risk resistance, and offsetting a host of unintended environmental effects.