Experimental and numerical insights into heterogeneous liquid-solid behaviour in drinking water softening reactors

Liquid-solid fluidisation is frequently encountered in drinking water treatment processes, for instance seeded crystallisation softening processes. For modest superficial fluid velocities, liquid–solid systems are generally considered to be homogeneous, as reported literature. However, during experiments with calcite grains, open spaces of can observed between the fluidised particles, even at relatively low velocities. Moreover, significant heterogeneous particle–fluid patterns detected higher Such behaviour beneficially or adversely affect chemical efficiency. To obtain information about voids bulk regions, complementary Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) simulations were performed and compared experimental results validation. Simulations using different inlet velocities fractionised granules obtained from full-scale reactors. Here, analysed bed height, voidage pressure drop system. Furthermore, images visually formation voids. The showed distinct differences void fraction cross-section column. It shown that throughout range exists cannot neglected. heterogeneity onset observations found agree reasonably well.