Teresa Serra, Aina Barcelona and Jordi Colomer, together with other members of the Physics Department, publish the paper entitled “Daphnia magna filtration efficiency and mobility in laminar to turbulent flows” in the Science of the Total Environment (STOTEN) journal. STOTEN is an international multi-disciplinary journal for publication of original research on the total environment, which includes the atmosphere, hydrosphere, biosphere, lithosphere, and anthroposphere.

In this publication, the members of the Environmental Physics research group explain that Daphnia are filter feeder organisms that prey on small particles suspended in the water column. Since Daphnia individuals can feed on wastewater particles, they have been recently proposed as potential organisms for tertiary wastewater treatment. However, analysing the effects of hydrodynamics on Daphnia individuals has scarcely been studied. This study focuses then, on quantifying the filtration and swimming velocities of D. magna individuals under different hydrodynamic conditions. Both D. magna filtration and movement responded differently if the flow was laminar or if it was turbulent. In a laminar-dominated flow regime Daphnia filtration was enhanced up to 2.6 times that of a steady flow, but in the turbulent-dominated flow regime D. magna filtration was inhibited. In the laminar flow regime D. magna individuals moved freely in all directions, whereas in the turbulent flow regime they were driven by the streamlines of the flow. A model based on Daphnia-particle encountering revealed that the filtration efficiency in the laminar regime was driven by the length of the D. magna individuals and the shear rate imposed by the system.

This study was conducted within the framework of the Wastewater Treatment and Reuse research line, and of the INNOQUA project from the European Union’s Horizon 2020 research and innovation program (ARES 2016).