The pH value has a certain effect on the ozone
oxidation as shown in Fig.5. CODCr removal was
approximately linear with reaction time (0-100 min) at
different pH value. Generally compared to acid condition,
alkaline condition advanced the ozone reaction to a
degree. Whereas pH value of the original photographic
processing wastewater just ranged from 11.0 to 13.0, it
was not necessary to adjust pH value for the wastewater
treatment process.