Magnetic nanoparticles that are employed for most water remediation applications have to be surface modified in order to enhance the colloidal stability. However, these stabilized magnetic nanoparticles exhibited poorer magnetic separability as compared to the non-stabilized counterparts. The present work demonstrated a magnetic sedimentation technique (coupled with pre-flocculation) as a strategy to induce rapid separation of these stabilized nanoparticles. The stabilized nanoparticles used as model system here were negatively charged; while poly(diallyldimethylamonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) were used as flocculant to induce bridging flocculation and depletion flocculation, respectively. Steady state time of the magnetic sedimentation was found to successfully decrease from similar to 600 s to similar to 200 s, when the stabilized nanoparticles were pre-flocculated by 1000 ppm PDDA or PSS. Meanwhile, the initial sedimentation rate was improved from 4.24 x 10(-3)/s to >= 0.01/s. Nevertheless, particles that were flocculated by PDDA were harder to be recovered than the one flocculated by PSS. Also, it was found that increase the flocculant concentration and molecular weight not necessary enhance the separation efficiency. Here, 10000 ppm of high molecular weight flocculant was found to render in a slower magnetic sedimentation. Such phenomenon might attribute to the increase in solution viscosity and/or occurrence of depletion re-stabilization. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.