Supported titanium dioxide catalysts were used in a photocatalytic flat cell reactor to remove organic micropollutants from real wastewater. Catalysts based on stainless steel mesh with a porous coating made of titanium dioxide nanoparticles with predominantly anatase modification were used. The influence of the retention time, light output, and the effect of hydrogen peroxide on the degradation were examined. The kinetics of the degradation of the parent substances was determined by LC-MS/MS. As a result, first-order degradation kinetics could be confirmed for all substances. The irradiance had no linear influence on the degradation of the compounds. Hydrogen peroxides were added to the wastewater to be treated as electron acceptors and boosters and alone had no great oxidative effect on the parent substances. The combination of photocatalysis with the addition of hydrogen peroxide as an electron acceptor had great synergetic effects which can reduce the required energy of the process through a short retention time. The process is suitable for the removal of micropollutants from wastewater.

Photocatalytic disintegration is a novel approach to eliminate pollution. The method utilizes the semiconductor titanium dioxide to degrade organic molecules in the presence of ultraviolet (UV) light. In this study, it is shown how the capabilities of several types of catalyst designs degrade the non-polar substance diesel fuel and the polar substance methylene blue. The floating design of foam glass coated with titanium dioxide could reduce the concentration of diesel fuel by 329 mg/L in 16 h; the submerged designs for coated glass fiber and coated steel grid could reduce methylene blue concentration by 96.6% after 4 h and 99.1% after 6 h, respectively. It could be shown that photocatalysis is a promising cost- and energy-efficient method for managing air and water pollution. It can be established as a low-technology method without requiring the use of a conventional source of energy, given an adequate amount of sun hours, or as an additional cleaning stage in water treatment plants using UV-LEDs.

Carrier-bound titanium dioxide catalysts were used in a photocatalytic ozonation reactor for the degradation of micro-pollutants in real wastewater. A photocatalytic immersion rotary body reactor with 36 cm disk diameter was used, which was irradiated using UV-A LEDs. The rotating disks were covered with catalysts based on stainless steel grids coated with titanium dioxide. The dosing of ozone was carried out through the liquid phase via an external enrichment and a supply system transverse to the flow direction. The influence of irradiation power and ozone dose on the degradation rate for photocatalytic ozonation was investigated. In addition, the performance of the individual processes photocatalysis and ozonation were studied. The degradation kinetics of the parent compounds were determined by LC-MS/MS. First-order kinetics were determined for photocatalysis and photocatalytic ozonation. A maximum reaction rate of the reactor was determined, which could be achieved by both photocatalysis and photocatalytic ozonation. At a dosage of 0.4 mg /mg DOC, the maximum reaction rate could be achieved using 75% of the irradiation power used for sole photocatalysis, allowing increases in the energetic efficiency of photocatalytic wastewater treatment processes. The process of photocatalytic ozonation is suitable to remove a wide spectrum of micro-pollutants from wastewater. HIGHLIGHT within the work, reaction rates for the degradation of micropollutants in real wastewater matrix are presented. due to the number of investigated pollutants as well as the practical investigation conditions, a more precise evaluation of the use of photocatalysis and photocatalytic ozonation for wastewater treatment is possible.

Supported titanium dioxide-based photocatalysts were investigated for the degradation of pharmaceuticals under irradiation with UVÀ A LEDs. Focus of the presented research was placed on the degradation kinetics under different matrix influences and energy flux densities of UVÀ A radiation. The chemical parameters, pH, orthophosphate, nitrogen concentration and background organic concentration were investigated. The results were evaluated by time-resolved measurement of the concentrations and by calculating and plotting the first-order degradation rate. The results showed clear differences in the rates of degradation of each compound, with diclofenac being the most easily degraded and metoprolol the most resistant. When the influence of energy flux density was examined, a linear relationship between degradation rate and the square root of energy flux density was confirmed. The organic background matrix has a strong influence on the degradation kinetics of the compounds. Nitrogen and orthophosphate slow down the degradation much less than the organic background matrix. Investigating the pH influence, it could be shown that almost no degradation is detected in the basic pH range. The results were illustrated with the help of a radar diagram, which can show all dependencies at a glance.

Immobilized titanium dioxide catalysts were used within a photocatalytic immersion rotary body reactor, which was connected to 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 is 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 of 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.