PURPOSE: To continuously supply a dilute liq. at all times by transferring a fresh dilute soln. previously produced from an org. flocculant dilution tank in accordance with the water level lowering signal from an org. flocculant storage tank in which a fixed amt. of a dilute org. flocculant soln. is stored.
CONSTITUTION: A dilute org. flocculant soln. to be used in the flocculation of sewage is stored in an org. flocculant storage tank 1. A fresh dilute soln. of a specified concn. is produced from an original org. flocculant soln. in an org. flocculant dilution tank 4 and stored when the dilute soln. is the tank 4 is consumed, and this fresh dilute soln. is transferred to the tank 1 when the level of the dilute soln. in the tank 1 lowers to a specified value. Besides, the org. flocculant stock soln. is stored in a tank 11, and a specified amt. of the stock soln. is supplied to the tank 4 in which water is supplied to a specified level when the dilute soln. is produced in the tank 4. As a result, the dilute soln. can be supplied even while the dilute org. flocculant soln. is produced.