Methods and systems for treating caustic materials are disclosed. In one exemplary embodiment, a method for treating caustic materials includes the steps of providing a first caustic solution stream including phenolic constituents and naphthenic constituents, mixing the first caustic solution stream with an acid solution, and separating phenolic acids from the first caustic solution stream. The method further includes further mixing the first caustic solution stream with additional acid solution and separating naphthenic acids from the first caustic solution stream. Still further, the method includes providing a second caustic solution stream including sulfidic constituents, mixing the first caustic solution stream with the second caustic solution stream to form a combined caustic solution stream, and oxidizing the sulfidic constituents of the combined caustic solution stream.