Method of treating photographic waste liquid

1. A method of treating photographic waste liquid, comprising:

adjusting photographic waste liquid so as to have a COD/ammoniacal nitrogen ratio of 3 or below; performing a physicochemical oxidation treatment to the adjusted photographic waste liquid; and then performing a biological treatment to the treated photographic waste liquid, wherein the physicochemical oxidation treatment of the photographic waste liquid is an electrolytic oxidation treatment.

2. The method of treating photographic waste liquid as described in claim 1 , wherein the photographic waste liquid having been subjected to the physicochemical oxidation treatment is subjected to the biological treatment directly or in a state of water dilution having a dilution factor of 1 to 4, wherein the dilution factor is defined as a ratio of (volume of waste liquid after dilution with water) to (volume of undiluted waste liquid).

3. The method of treating photographic waste liquid as described in claim 1 , wherein the photographic waste liquid is further adjusted so as to have a sulfur content of 5 g/L to 20 g/L.

4. The method of treating photographic waste liquid as described in claim 1 , wherein the biological treatment is an activated-sludge treatment.

5. The method of treating photographic waste liquid as described in claim 1 , wherein the biological treatment is a treatment with microorganisms immobilized in a carrier.

6. The method of treating photographic waste liquid as described in claim 1 , wherein the photographic waste liquid is color photographic waste liquid.

7. The method of treating photographic waste liquid as described in claim 1 , wherein the photographic waste liquid contains a hardly biodegradable compound.