The Role of Catalytic Ozonation in Removing COD from Wastewater
In modern industrial wastewater treatment, deep removal of chemical oxygen demand (COD) has long been a technical difficulty. Catalytic ozonation, an efficient advanced oxidation technology, markedly improves the oxidising efficiency of ozone through the use of catalysts and has become a key solution for COD removal.
Mechanism: from direct oxidation to radical catalysis
Conventional ozonation relies mainly on direct oxidation by the ozone molecule (redox potential 2.07 eV), which limits oxidation efficiency and leaves pollutants incompletely treated. Catalytic ozonation adds a catalyst to the ozone system, greatly enhancing ozone decomposition and generating hydroxyl radicals (·OH) of stronger oxidising power (redox potential 2.8 V). These radicals oxidise non-selectively and efficiently degrade a wide range of organic pollutants.
By lowering the activation energy, the catalyst accelerates the self-decomposition of ozone in water and markedly raises the hydroxyl radical concentration. Under catalysis, ozone and wastewater enter the catalytic oxidation tower together; as they pass through the catalyst bed a large number of hydroxyl radicals are produced, which break chains and open rings, converting large recalcitrant molecules into smaller ones and finally mineralising them to carbon dioxide and water.
Key breakthroughs in catalyst technology
SINOKLE has made an important breakthrough in heterogeneous catalysts, using a range of transition metal oxides and precious metals as catalytic components and, through precise formulation optimisation and controlled sintering, developing catalyst systems of high adaptability and catalytic activity.
The SINOKLE ozone catalyst series
The technology offers the following innovations:
Innovative support structure: high-porosity microporous forming raises the specific surface area of the support to 250–300 m²/g, far above the 50–100 m²/g of conventional supports, markedly increasing active site density and raising the catalytic reaction rate by more than 3 times.
Surface modification: atomic layer deposition is used to make the catalyst hydrophilic, creating a superhydrophilic surface whose resistance to organic fouling is 90% higher, effectively preventing contamination, scaling and plugging and ensuring long-term stable operation.
Optimised mechanical properties: staged precision temperature-controlled sintering maintains high mechanical strength (150 N per granule) while keeping annual attrition below 0.3%, giving a catalyst service life of more than 5 years.
Process integration and efficiency gains
SINOKLE has developed the CDOF (cyclonic dissolved-air ozone flotation) unit, which organically combines multiple catalytic ozonation, cyclonic technology and dissolved-air flotation into one highly efficient integrated treatment system.
The system offers clear technical advantages:
Much faster reaction: the patented reactor design cuts effective reaction time from the conventional 90 minutes to within 15 minutes, with ozone utilisation above 99.98%.
Much lower operating cost: the ozone dosing ratio is only 1/5–1/2 of the conventional process, operating costs fall by 30%–50% and the footprint shrinks to 1/3 of the conventional process.
Intelligent control for stable operation: a DCS/PLC automatic control system monitors tail-gas concentration, effluent ORP and pH in real time and automatically optimises the operating strategy as water quality changes.
Verification in practice
The technology performs outstandingly in difficult wastewaters such as petrochemical, pharmaceutical and landfill leachate treatment. Operating data show an absolute COD removal of 1.1–1.5 g O₃ per g COD, with oxidation efficiency 2–5 times that of conventional processes. In landfill leachate treatment, COD removal exceeds 90% and effluent quality is stably compliant.
Through technical innovation and system optimisation, catalytic ozonation has solved the problem of treating high-COD wastewater, providing a reliable technical route for advanced industrial wastewater treatment and playing an important role in promoting green manufacturing and sustainable development.
