A study used computer simulations as well as experimental data to examine the fluid dynamics within softening reactors.
Most water softening processes use a specific type of softening reactor, known as liquid-solid fluidised (LSF) bed reactors. According to a team that included researchers from Eindhoven University, Delft University, Queen Mary, Utrecht University of Applied Sciences and water cycle company Waternet, these softening reactor granular beds instead have a heterogeneous structure with local voids and instabilities, reported Phys.org.
It was originally believed that such reactors show homogeneous behavior.
According to the researchers, these findings may improve drinking water softening processes, leading to the production of high quality softened drinking water at a lower cost and with reduced CO2 emissions, reported Phys.org.
This research shows that heterogeneous mixing is the usual case, which means it will be both cost effective and lead to less potential waste.
Two Queen Mary undergraduate Chemical Engineering students, Jamila Rahman and Phoebe Berhanu, are co-authors on the paper. These students conducted the experiments as part of their Industrial Placement year at Waternet Amsterdam.
The industrial placement allowed the two to spend time working with other interns, testing the flow and particle behavior of multiple particle types, noting any differences in visible void patterns. Berhanu worked on Rapid Sand Filtration and the workings of the particles within Waternet and the UK. Rahman focused on using ImageJ to understand particle size and involvement with its fluidization behavior.
More findings from the study include:
- Liquid-solid fluidization experiments show open spaces at low velocities;
- Heterogeneous particle–fluid patterns are detected at higher fluid velocities;
- CFD-DEM simulations show good agreement with experimental observations; And
- Numerical simulations confirm the formation of local voids and instabilities.