Immobilized titanium dioxide catalysts were used within a photocatalytic immersion rotary body reactor, which was connected to a substream ozonation unit to remove micro-pollutants from wastewater. Within this work data on the behavior of cumulative parameters during treatment of wastewater by photocatalysis and photocatalytic ozonation are provided. The investigated parameters are spectral absorption coefficient at 254 nm (SAC254), total organic carbon (TOC) and chemical oxygen demand (COD). All experiments were carried out using secondary effluent from the same wastewater treatment plant. For the parameter SAC254, consistent concentration curves and dependencies to operational parameters of the experimental system could be measured. The measurements of the parameters TOC and COD showed greater uncertainties, although basic trends could nonetheless be observed. A good linear correlation (R2 < 0.85) between the reduction of SAC254 and 8 micro-pollutants for photocatalysis and photocatalytic ozonation was found. This confirms the suitability of the SAC254 as a control parameter for a large-scale application of a photocatalytic 4th treatment stage. A linear correlation between measured TOC and COD degradation rates was possible with a coefficient of determination of 0.58-0.86. The simultaneous decrease of TOC and COD is an indicator for a mineralization of the treated wastewater matrix.