CuO/SBA-15 catalyst for the catalytic ozonation of mesoxalic and oxalic acids. Water matrix effects

•Catalytic ozonation of organic acids using CuO/SBA-15 as catalyst was studied.•The effect of inorganic anions on the ozonation process was determined.•The non-catalytic process was severely affected. Catalytic ozonation was almost unaffected.•Under non-catalytic ozonation in STP effluent, oxalic acid was depleted by precipitation.•Under catalytic ozonation in STP effluent, oxalate was depleted by ozone oxidation.