APPARATUS AND METHOD FOR CRYSTALLIZATION/ DEPHOSPHORIZATION

摘要

PROBLEM TO BE SOLVED: To stably keep dephosphorization effect high and to easily separate even a precipitated crystal by providing liquid drain pipes to upper and lower parts stirring waste water to which magnesium is added and the pH of which is adjusted by alkali to precipitate crystals of a magnesium phosphate compd. SOLUTION: The mixed liquid conditioned in a raw water conditioning tank 1 is introduced into a fluidized bed reaction tank 2 from a mixed liquid introducing pipe D and stirred at a slow speed by a stirrer 9 so that formed crystals do not flow out of an upper liquid drain pipe E and is not sedimented on the bottom part of the fluidized bed reaction tank to react phosphorus and magnesium in waste water to precipitate crystals of a magnesium phosphate compd. The liquid stagnated in the fluidized bed reaction tank 2 for a predetermined time to be reacted is drawn out of the upper liquid drain pipe E to be supplied to a fixed bed filter apparatus 3 and fine floes in the liquid are filtered off during the downward flow of the liquid through a filter bed 10 and unreacted phosphorus in the fluidized bed reaction tank is deposited on the surfaces of crystals to keep phosphorus removing efficiency high.