A process for treating water containing dissolved organics, for example, oil sands process-affected water, using petroleum coke is provided, comprising: removing petroleum coke from a coking operation; forming a petroleum coke/water slurry by adding the water to be treated to the petroleum coke; and mixing the slurry for a sufficient time in a carbon adsorption reactor to allow the petroleum coke to adsorb a substantial portion of the dissolved organics from the water.