PURPOSE: To easily correspond to a change in the treatment amount of waste water and to treat waste water with high accuracy by providing a plurality of line mixers in a waste water pipeline and providing a detection means composed of a pH meter and a control fluid supply means on the upstream side of each of the line mixers.
CONSTITUTION: Waste water is allowed to flow to a waste water pipeline 1 and the pH values of the waste water are measured on the upstream sides of respective line mixers 3a, 3b by detection means 4a, 4b. A control means 7 inputs the detection signals from the detection means 4a, 4b to generate control signals so as to set the measured pH values to set pH values to control the injection amounts of a control fluid from supply means 5a, 5b. The injected control fluid and waste water are mixed by the line mixers 3a, 3b. This control mixing is carried out by the line mixers of a plurality of stages. By this method, waste water can be continuously treated and treatment capacity becomes large and the correspondence to a change in the treatment amount of waste water is easily taken and control treatment can be carried out with high accuracy.
KIMURA KEISUKE
YOSHIDA KIYOSHI
