METHOD FOR CONTROLLING WATER CONTENT TO CONSTANT IN SCREW PRESS AND DEVICE FOR CONTROLLING WATER CONTENT TO CONSTANT

摘要

PPROBLEM TO BE SOLVED: To provide a control method for controlling a water content to a constant in a screw press which carries out concentration dehydration by adding purified water sludge, polymer flocculant and waste paper to sewage water sludge; and its device. PSOLUTION: The screw press includes a pressure controller 13 for a raw liquid supplying pump SP and a controller 14 for controlling the rate of flow to a constant for controlling a screw axis 21a. The screw press includes: a sewage water and purified water mixing tank 3 for pouring purified water sludge into sewage water sludge; a sludge adjustment tank 6 for adding waste paper to the sewage water and purified water mixed sludge; and an agglomerate mixing tank 10 for chemically feeding a polymer flocculant into the adjustment sludge. The press is also provided with a purified water sludge injection controller 4 for increasing/decreasing purified water sludge injection ratio S1 against the fluctuation of the sewage sludge and a waste paper, chemical injection controller 19 for controlling a chemical feeding rate A1 and a waste paper adding rate P1 by increasing/decreasing the chemical feeding rate A1 and the waste paper adding rate P1 in accordance with the fluctuations of measured cake water W and the sewage water sludge. Dewaterability is improved by decreasing the relative cake water, by forming a flock by absorbing sludge particles and by lowering the water content. PCOPYRIGHT: (C)2010,JPO&INPIT