Abstract: A system for dewatering slurries comprises a tower including a stack of forward osmosis (FO) cells. Each FO cell comprises a first portion for holding a feed slurry, a second portion for circulating a draw solution comprising an osmotic agent, and a semi-permeable membrane in between the first portion and the second portion. The first portion includes an agitation mechanism for mixing the feed slurry. During operation of the system, the feed slurry is transported downstream through the stack for dewatering to a predetermined solids content.