Refractory Organics
Targeted transformation of persistent compounds that show poor removal in conventional biological treatment.
Compound-specific evaluation requiredAdvanced Oxidation • Light-Activated CatalystCatalytic
Catalytic
Oxidation
A photocatalytic advanced oxidation process for transforming selected refractory organics, colour-forming compounds and trace contaminants through catalyst-generated reactive species.
Discuss Your WastewaterExplore Advanced OxidationReactor PrincipleLight + catalyst + oxidant generate reactive chemistry within a controlled reactor.
•OH h+ O2•−
CONTAMINATED WATER IN →→ TREATED WATER OUT
This schematic is conceptual. Catalyst form, light source, oxidant, hydraulics and separation are selected for the actual application.
PhotocatalyticLight activates a suitable catalyst surface
Radical-BasedReactive species drive oxidation reactions
TargetedBest suited to defined difficult contaminants
ValidatedTrials establish dose, energy and reaction time
Technology Position
Photocatalytic oxidation uses a light-activated catalyst to accelerate oxidation reactions that conventional treatment may not achieve efficiently.
In photocatalysis, light energy is absorbed by a catalyst or catalyst–substrate system. Where the catalyst has suitable electronic properties, irradiation can generate electron–hole pairs. These can interact with water, hydroxide and dissolved oxygen to form highly reactive species, including hydroxyl radicals.
The defining feature of an advanced oxidation process is the controlled generation and use of highly reactive oxidising species. Titanium dioxide is a widely studied photocatalyst, but an industrial process does not necessarily require TiO2 or the same UV arrangement for every application.
YWT evaluates catalytic oxidation as part of the complete treatment train—not as an isolated reactor. Pretreatment, turbidity, colour, catalyst recovery, residual oxidant, downstream biology and final polishing all influence whether the process is technically and economically appropriate.
Simplified Reaction Pathway
From light absorption to contaminant transformation
The pathway below communicates the operating principle. Actual reaction mechanisms and intermediates depend on the catalyst, light wavelength, oxidant, water matrix and target compound.
01
hν
Light AbsorptionA suitable wavelength delivers energy to the catalyst surface.02
e−/h+
Charge GenerationElectron–hole pairs form and migrate to reactive surface sites.03
•OH
Radical FormationWater, hydroxide and oxygen participate in producing reactive species.04
R
Organic AttackReactive species attack susceptible bonds in the target contaminant.05
CO₂
TransformationThe contaminant is transformed toward smaller, more oxidised products.Conceptual pathway: catalyst + light → e−/h+ → reactive species → contaminant transformation → CO2 + H2O + inorganic ions, where mineralisation is sufficiently complete.
Treatment Train
A controlled reactor needs the right water around it
Catalytic oxidation performance depends strongly on optical transmission, competing radical demand and mass transfer. The plant arrangement must therefore address the complete wastewater matrix.
01Segregate & EqualiseDefine the target stream and smooth flow, concentration, pH and temperature variation.
02Remove InterferenceControl suspended solids, oil, turbidity or species that block light and consume radicals.
03Condition the FeedAdjust pH and introduce the selected catalyst and oxidant under controlled conditions.
04Catalytic ReactorProvide light intensity, hydraulic contact, catalyst exposure and mass transfer.
05Reaction HoldMaintain the validated energy, catalyst loading, oxidant dose and residence time.
06Separate / RecoverRetain, recover or separate catalyst where the selected configuration requires it.
07Verify PerformanceMeasure target-compound conversion, toxicity, colour, COD fraction or other acceptance criteria.
08Polish / RecycleIntegrate with biological, adsorption, membrane, disinfection, recycle or discharge treatment.
Design principle: do not size the reactor only on bulk COD. Identify the target compound, competing oxidant demand, absorbance, catalyst activity and required endpoint before scale-up.
Potential Applications
For streams that require more than conventional oxidation
Suitability is application-specific and must be demonstrated against representative wastewater.
Colour Reduction
Oxidative breakdown of selected chromophoric structures in industrial wastewater and polishing applications.
UV absorbance and matrix colour affect designTrace Contaminants
Advanced polishing where low-concentration organic contaminants remain after primary and secondary treatment.
Define target and detection limitToxicity Reduction
Pretreatment or polishing intended to reduce inhibitory effects before biology or final discharge.
Verify toxicity after oxidationBiodegradability Improvement
Partial oxidation intended to convert selected refractory molecules into intermediates more amenable to biological treatment.
Avoid excessive oxidation where biology can finish the workReuse Polishing
An advanced-treatment barrier used with filtration, adsorption or membranes where treated water is intended for reuse.
Integrate with the complete reuse trainEngineering Basis
Performance depends on chemistry, optics and reactor design
Target CompoundIdentity, concentration, structure, reaction pathway and required endpoint.
Water MatrixCOD fractions, alkalinity, chloride, carbonate, nitrate, colour and radical scavengers.
Optical ConditionUV transmittance, turbidity, suspended solids and reactor path length.
CatalystMaterial, activity, support, loading, fouling, life and recovery method.
Light SystemWavelength, intensity, electrical efficiency, sleeve fouling and maintenance.
Oxidant & pHType, dose, residual control, reaction pH and downstream compatibility.
HydraulicsFlow regime, mixing, contact time, short-circuiting and mass transfer.
What the Design Must Prove
- Conversion: the parent contaminant reaches the agreed target.
- By-products: intermediates do not create a greater downstream risk.
- Mineralisation: COD or TOC reduction is measured where complete oxidation is required.
- Energy: specific energy per unit volume or contaminant removed is established.
- Catalyst stability: fouling, deactivation, attrition and replacement are understood.
- Residual control: oxidant and catalyst carryover are compatible with the next stage.
- Operability: cleaning, lamp access, monitoring and safe shutdown are practical.
Technology Clarity
Photocatalytic oxidation is not electro-oxidation
Photocatalytic Oxidation
Uses light energy and a catalyst to generate reactive species at or near the catalyst surface. Its design is governed by optical transmission, catalyst properties, wavelength and photochemical reaction conditions.
Catalytic Electro-Oxidation
Uses applied electrical energy and electrodes to drive direct or mediated oxidation. Its design is governed by current density, electrode material, conductivity, mass transfer and electrochemical operating conditions.
From Sample to Scale-Up
Testing defines the application boundary
YWT develops the process progressively so the result is based on representative water and measurable acceptance criteria.
01 CharacteriseIdentify targets, matrix and variability.
02 ScreenSelect catalyst, light and oxidant options.
03 OptimiseEstablish pH, dose, energy and contact time.
04 DemonstrateVerify conversion, by-products and downstream effect.
05 EngineerScale reactor, controls, cleaning and integration.
Technical qualification: Catalytic oxidation does not provide identical performance for every contaminant or wastewater matrix. Removal, mineralisation, energy consumption, oxidant demand, catalyst life and scale-up must be established through representative testing and an agreed design basis.
Have a refractory contaminant or difficult polishing duty?
Share the wastewater source, target compound, concentration range, flow, COD and TOC, colour, pH, conductivity, turbidity, UV transmittance, existing treatment and required endpoint.
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