| 摘要 |
<p>PURPOSE:To prevent the decomposition of a lower layer part due to the increase of anaerobic organism layers by returning a part of a treated product obtained in the oxidation treatment in a contact oxidation vessel to a contact digestion vessel, and treating again the product along with low-concn. waste water. CONSTITUTION:The purified waste water is charged into an aerobic contact oxidation vessel B through a discharge pipe 9 at the upper part of a vessel, circulated in the vessel B by a circulating flow of air supplied from an air supply pipe 13, brought into contact with an aerobic organism film of an aerobic filter bed 12, and purified by the oxidation of low molecular organic substances to gaseous carbonic acid and water and the oxidation of ammonium ions to nitric acid and nitrous acid. The purified water is discharged to the outside of the system through a purified water discharge pipe 14. A part of the purified water is simultaneously returned to a contact digestion vessel A through a purified water return pipe 15 equipped with a pump, and anaerobically treated along with the newly supplied waste water. The denitrification by the reduction of nitric acid, nitrous acid, etc. formed in the contact oxidation vessel B is carried out.</p> |
