Abstract: An improved apparatus for treating waste water containing volatile and corrosive substances by steam-stripping to remove the volatile and corrosive substances from the waste water. The apparatus has a liquid pooling zone installed at a part over the waste water supplying part of a stripper tower and liquid distributor at the top of the tower, and pipe arrangement is prepared to recycle liquid drawn from the liquid pooling zone to the liquid distributor. In the pipe arrangement, a cooler for the recycling liquid is installed. Serious corrosion can be avoided utilizing this apparatus.