Growth of Tetraselmis suecica and Dunaliella tertiolecta in Aquaculture Wastewater: Numerical Simulation with the BIO_ALGAE Model

This study investigates and compares the uptake of nutrients (nitrogen, phosphorus) and the growth of Tetraselmis suecica and Dunaliella tertiolecta in aquaculture wastewater. The obtained data were used to implement and calibrate the microalgae-bacteria model BIO_ALGAE to simulate the bioremediation and the biomass production of these species. The microalgae were cultivated in batch conditions for 7 days using 120-L vertical column photobioreactors. In the first 4 days, after which the algal density reached a steady state, the average biomass production was 83.7 ± 4.4 mg/L/day for T. suecica and 56.4 ± 5.1 mg/L/day for D. tertiolecta. The two species were able to remove more than 96% of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP). The total lipid content was analyzed at the end of the 7 days; T. suecica and D. tertiolecta had different lipid content: 75.8 ± 1.6% and 23.2 ± 2.0%, respectively. The BIO_ALGAE model fits very well the experimental data of both species in terms of biomass and nutrient uptake and could be an effective tool to predict the production of microalgae using aquaculture wastewater as growth media, obtaining at the same time the removal of nutrients from wastewater and the production of biomass to be used as feed. In particular, this mathematical model can be applied to forecast the performance under different operating conditions, for the design, optimization, and control of the process in aquaculture systems.