To simplify a following treatment such as biological treatment and wet air oxidation and discard operation by phase separating a mixture of a waste caustic soda stream, an acid aq. soln. and a water unmiscible org. solvent from a propylene oxide and styrene monomer simultaneous production method, and recovering each phase separately.
The waste caustic soda stream is preferably distilled to concentrate it, and water is separated and circulated as a process water, and a light org. matter is recovered as a fuel. The obtained concentrated aq. waste caustic soda being a tower bottom stream is mixed, for example, with a sulfuric acid aq. soln. and a high-boiling org. solvent such as heavy org. matter residue generated by the production method. In this way, Na present as NaOH and org. Na salt is converted to Na2SO4 and incorporated in a water phase after phase separation. On the other hand, an org. component is moved to an org. phase since solubility thereof is lowered in an acidic salt water. The separation is increased with the org. solvent, and a fuel value of the heavy org. matter residual is improved by the movement of the Na to the water phase, and the water phase in which the org. matter is reduced is easily discarded by a usual means.
BAANAADO KUTSUKAA
RAJIENDORA ESU ARUBARU
| JPH0672911A | 1994-03-15 |