When Ozone Alone Stops Working: A Heterogeneous Catalyst Route for Refractory COD

Petroleum refining, oilfields, chemical production, new-energy manufacturing, landfill leachate and industrial-park effluent share a familiar profile: COD is high, biodegradability is poor, colour is deep and the refractory organic fraction is large. Conventional trains struggle to reach deep compliance, and stable reuse is usually out of reach. The gap between what ozone is supposed to do and what it actually achieves in a contactor is where catalytic oxidation comes in.

SINOKLE (Shenzhen) Technology Co., Ltd. is a high-tech enterprise and a specialist R&D manufacturer of ozone catalysts. Backed by more than 30 core patents and internationally leading preparation technology, the company has built out a series of heterogeneous ozone catalysts whose selling points are efficient hydroxyl-radical generation, no metal leaching, long service life and broad-spectrum adaptability. The offer is an integrated catalytic route covering advanced oxidation, plant upgrading and retrofit, and reclaimed-water reuse.

The mechanism: solid catalysis working with ozone

The catalyst lowers the activation energy of ozone decomposition so that hydroxyl radicals form rapidly. Those radicals carry a redox potential as high as 2.8 V and attack organics non-selectively, breaking chains, opening rings and mineralising refractory compounds all the way to CO2 and H2O.

Several design features support that. Because catalysis is heterogeneous, the solid is easy to separate from the treated water; there is no metal-ion leaching and no secondary pollution, which matters wherever heavy-metal discharge limits apply. The multi-stage pore structure, with high porosity and large specific surface area, raises mass-transfer efficiency and lifts ozone utilisation by over 30%. Multiple active sites, built from transition-metal and precious-metal components, form a multi-centre catalytic system that tolerates complex, high-salt and high-toxicity water. The net effect across a whole advanced-oxidation train is better biodegradability, strong decolourisation and deep COD reduction, which is what makes it useful as an upgrading technology.

The product series

• Carbon-based ozone catalyst KHC-F1001: a high-specific-surface-area carbon carrier combining adsorption with catalysis, aimed at petrochemical oily wastewater and industrial-park effluent where COD removal is the priority.
• Silica-alumina ozone catalyst KHC-F2001: resistant to high temperature and to acid and alkali, with high mechanical strength and an extremely low wear rate, giving a service life above five years. Suited to landfill leachate and high-salt wastewater.
• Dedicated custom catalyst KLE-HEC-200 series: industry-specific formulations for fine chemicals, kitchen waste, metal smelting, papermaking and municipal wastewater, tuned for targeted high-efficiency catalysis.

Eight advantages that show up in operation

Deep degradation is the first: refractory organics are mineralised, COD falls and colour drops, with stable compliance or reuse quality at the outlet. Ozone utilisation improves enough to save over 30% of the ozone demand compared with conventional ozone oxidation, which moves both the energy bill and the operating cost. There is no metal leaching, so the process is green and safe by construction. Service life is long, with high-strength moulding and a very low annual wear rate giving a normal life of at least five years. The catalyst tolerates complex water, resisting high salt and poisoning and operating stably across pH 3-10. Biodegradability improves enough to shorten the overall flowsheet, allowing efficient coupling of advanced oxidation with a biological stage. Engineering adaptability is strong, since the catalyst can be paired with the CDOF ozone catalytic oxidation integrated unit, which is skid-mounted, fully automatic and small. And the technology is protected by invention, utility-model and PCT international patents.

Performance data

The catalytic mechanism is heterogeneous catalysis with efficient hydroxyl-radical generation. Carriers are carbon-based, silica-alumina or customised. Specific surface area reaches up to 1286 m2/g, giving abundant active sites. Mechanical strength exceeds 150 N per grain, so the material resists breakage. Service life runs above five years with extremely low annual loss, and the applicable pH range of 3-10 covers most industrial streams. Target wastewaters include oily wastewater, landfill leachate, high-salt wastewater, fine chemicals, industrial parks and municipal sewage.

Against the alternatives

Set against traditional ozone oxidation and Fenton or homogeneous catalysis, the differences are mostly economic. Conventional ozone oxidation gives average efficiency with low ozone utilisation and high operating cost, though it produces no secondary pollution; its applicable range is limited. Fenton and homogeneous catalysis oxidise more effectively but generate iron sludge and metal residues, need strongly acidic conditions around pH 3-4, and carry medium operating cost from sludge handling and chemicals. SINOKLE heterogeneous ozone catalysis delivers very high oxidation efficiency with utilisation improved by over 30%, no metal leaching and therefore no secondary pollution, low operating cost from ozone saving and long life, a working pH window of 3-10, and a service life above five years without frequent replacement. In practice it covers the full range of refractory wastewater scenarios.

Where it is deployed

The catalyst combines with the CDFU hydrocyclone flotation unit, the CDOF ozone-catalysis integrated unit and the SiC membrane filter to build a full train of pretreatment, advanced oxidation and deep filtration. Applications include the deep treatment of petroleum refining and oilfield oily wastewater; high-concentration organic streams such as landfill leachate and kitchen waste; fine chemicals, pharmaceuticals, metal smelting and papermaking; deep upgrading and reuse of industrial-park and municipal sewage; and new-energy and dyeing or printing wastewater with high colour and refractory organics. Product has been delivered to projects in Poland, Congo, Chad, Sierra Leone, Bangladesh and Japan, with stable and reliable performance reported across them.

SINOKLE integrates R&D, design, manufacturing and engineering services from a 26,000 m2 production base with automated lines and a complete testing system. For plants facing refractory COD, the choice is usually not whether to oxidise but whether the oxidant is being used efficiently.