The　axial　concentration　distribution　of　the　hydrophilic　and　hydrophobic　particles,　corresponding　to　poor　and　good　attachment　to　rising　bubbles　in　water,　was　investigated　in　a　gas-liquid-solid　fluidized　bed.　The　sedimentation-dispersion　model　depicted　satisfactorily　the　axial　distribution　of　solids　holdup　by　modifying　only　the　terminal　settling　velocity,　which　considered　the　effect　of　an　additional　drag　force　resulting　from　the　attached　rising　bubbles.　This　model　explained　correctly　the　different　phenomena,　i.e.　solids　holdup　decreased　with　increasing　the　axial　height　in　the　non-attached　system,　but　increased　in　the　attached　system.