SEWAGE TREATMENT METHOD AND APPARATUS

摘要

PURPOSE:To enhance the separation efficiency of the suspended substance contained in raw water to be treated by mixing the raw water to be treated with pressurized air dissolved water under atmospheric pressure to bond fine air bubbles to the suspended substance in the raw water to be treated to float and separate the suspended substance and subsequently filtering treated water to subject the same to biological treatment. CONSTITUTION:At the time of the treatment of sewage, sand and sludge in sewage are removed to obtain raw water to be treated. This raw water to be treated is mixed with pressurized air dissolved water formed by introducing compressed air into water in a pressure tank 37 by a compressor 43 in an inflow passage 34 to be introduced into a float separation tank 36 and fine air bubbles generated from the pressurized air dissolved water are bonded to the suspended substance in the raw water to be treated to float and separate the suspended substance by the buoyancy of air bubbles. The obtained treated water is filtered by a filter device 33 to be sent to a biological treatment device 34 and the org. matter in the pretreated water is decomposed and removed under the aeration due to an air diffusing blower 48. At the time of the backwashing of the biologtical treatment device 34, backwashing waste water is returned to the inflow passage 35 through a waste water storage tank 62 to be subjected to float separation treatment.