A combined respirometer–titrimeter for the determination of microalgae kinetics: Experimental data collection and modelling

The potential of microalgae for wastewater treatment has recently led to significant surge in research towards economically more viable and technologically optimised systems. In this context, mathematical modelling has not been used to its full capacity. In this work, a combined respirometric–titrimetric unit for determination of microalgae kinetics and an experimental protocol is proposed. It was found that overall oxygen production was lower than stoichiometrically expected, which could be attributed to CO2-transfer to the gas phase. A basic model for microalgae growth on inorganic carbon and oxygen production is proposed and was successfully calibrated using several respirometric–titrimetric datasets. The model structure was based on the activated sludge models (ASMs) and can now be extended with impact of additional degrees of freedom. To our knowledge it is the first time that a respirometric–titrimetric approach is applied to microalgae and used to calibrate an ASM based kinetic model.

► A microalgae respirometer–titrimeter and protocol was developed.
► Significant stripping of CO2 takes place even without aeration.
► Recovery of HCO3 was higher than 90% both from DO and proton production data.
► Different respirograms were successfully modelled and kinetics determined.