PURPOSE: To provide a method of purifying secondary treated water of excrementitious matter, comprising the steps of aerating the secondary treated water of excretitious matter, thereby subjecting the same to bobble separation, and then oxidizing polluting and coloring matters with ozone, while utilizing residual ozone by adding the same to aerating air, whereby it is enabled to omit ozone decomposing means and thus to make the apparatus simple, compact and economical.
CONSTITUTION: Secondary treated water of excrementitious matter, subjected to anaerobic biological treatment and chemical oxidation, is adjusted to pH 3 to 5, and it is bubbled by supplying air from aerating plate 3. After bubbling separation, it is introduced into ozone tank 7, where it is aerated with ozonied air supplied from ozone generator 10 to remove COD and coloring matter. Here, exhaust gas of the tank 7 is supplied to compressor 4 to add the same to air to be aerated from aerating plate 3. Thus, the exhaust gas from ozone tank 7 is utilized for the above bubbling separation of the secondary treated water of excrementitious matter. After removing COD and coloring matters from the secondary treated water, it is neutralized with alkali and then discharged to the outside.
NAKAYAMA SHIGEKI
EZAKI KENJI
