Removal of phosphorus from sewage

Abstract

Abstract PURPOSE: To activate the phosphorus metabolism of microorganisms and to remove phosphorus from sewage at a high efficieny, by mixing the sewage with a recycled sludge, adding Na 2 S to the mixture, and then subjecting the mixture to an anaerobic treatment followed by an aeration treatment. CONSTITUTION: A sewage 1 to be treated is mixed with a recycled sludge 2 in the anaerobic treatment vessel 3, to which is added Na 2 9 and maintained in the vessel 3 for a predetermined period. The addition of Na 2 S enhances the anaerobic character of the vessel 3, which is detected by measuring an oxidation reduction potential in the vessel 3. The Na 2 S is added at such a rate that the oxidation-reduction potential is maintained at lower than +100mV. After the anaerobic treatment in the vessel 3, the solution mixture is carried to an aeration vessel 4 and subjected there to a usual aeration treatment using activated sludge. The oxidation- reduction potential in the vessel 3 is usually +250mV or more, under which microorganisms absorb phosphorus and accumulate therein. Therefore, after the separation of solid from the aerated solution in the precipitating vessel 5, the phosphorus content of the treated solution 6 is extremely lowered, while a large amount of phosphorus is accumulated in the excessive sludge 8 and discharged outside the system. The recycled sludge 2 is recycled to the vessel 3 and treated again. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Arimasa Miyaji
• 👤 Tetsuro Fukase
• 👤 Masahide Shibata

Bibliographic Details