Produced water, for example from a steam assisted gravity drainage (SAGD) or cyclic steam stimulation (CSS) heavy oil recovery operation, is treated to recover water that is re-used to create steam. The produced water is treated in one or more thermal treatment devices such as an evaporator and a crystallizer. The thermal treatment device is seeded, for example with a calcium or magnesium salt. The thermal treatment device produces a blowdown or slurry comprising super-saturated solids and organic compounds. A solvent is added to the blowdown or slurry. The solids precipitate and are separated from the blowdown or slurry. The solvent may be recovered for re-use in treating more blowdown or slurry.