CHEMICAL AGENT INJECTION CONTROL METHOD IN WATER PURIFYING PLANT

摘要

PURPOSE:To perform the proper injection of a chemical agent, by a method wherein the pH and the alkalinity of treated water after a flocculant is injected are measured and the injection amount of an alkali agent is controlled according to the larger value of the respective injection rates of an alkali agent calculated according to the deviations with prescribed values. CONSTITUTION:Raw water is guided to a chemical agent mixing basin 6 from an intake port 1 through a screen 3, a precipitation basin 4 and a water arrival well 5 and sent to a floc forming basin 7 while mixed with a flocculant 13. The micro-floc-containing flocculated water is sent to a precipitation basin 8 to perform precipitative removal of flocs. Fine particles are removed in a filter basin 9 while treated water is sent to a chlorine culvert 10 where chlorine and an alkali are injected agent. The alkalinity and the ph of the treated water after the flocculant 13 is injected are measured in the downstream side of the mixing basin 6 and the injection amount of the alkali agent is corrected according to the larger alkali agent injection amount of the respective alkali agent injection amounts calculated according to the deviations with the prescribed values of the alkalinity and the pH.