PURPOSE: To enhance phosphate removal efficiency, in a method wherein excretion is mixed with return sludge to be subjected to anaerobic treatment while the treated mixture is subjected to aerobic treatment and, after solid-liquid separation, a part of the separated activated sludge is returned, by adjusting the BOD/ MLSS ration in the anaerobic treatment to a specific value or less.
CONSTITUTION: Excretion 5 is introduced into an anaerobic tank 1 while diluted to a proper concn. by dilution water 6 and, at the same time, the return sludge 7 from a solid-liquid separation tank 3 is introduced into the anaerobic tank 1 to perform anaerobic treatment. After treatment, the treated mixture is introduced into an aerobic tank 2 to be subjected to aerobic treatment while the treated one is subsequently subjected to solid-liquid separation in the solid-liquid separation tank 3. The treated water 8, from which org. substances and phosphorus are removed, is discharged and a part of the separated activated sludge 9 is used as the return sludge 7 while the remainder is discharged as excessive sludge 10. The BOD/MLSS ratio in the anaerobic treatment is set to 0.025 or less.
OOI MASAO
SHIBATA MASAHIDE
| JPS58196890A | 1983-11-16 |