Which delivers the best ozone generation performance?
When designing an industrial ozone system, one of the most important decisions is the choice of feed gas.
Whether the application involves water treatment, wastewater reuse, aquaculture, food processing or industrial oxidation, the gas supplied to the ozone generator has a direct impact on system performance.
The two most common options are:
- Dry Air
- PSA Oxygen (Pressure Swing Adsorption)
While both can be used to produce ozone, their performance characteristics differ significantly.
At OXYTRADING UK, we regularly find that feed gas selection has a greater influence on overall treatment efficiency than the ozone generator model itself.
Understanding how ozone is produced
Industrial ozone generators operate using corona discharge technology. An electrical field splits oxygen molecules (O₂) into oxygen atoms, which then recombine to form ozone (O₃).
The efficiency of this conversion depends on several factors, including:
- Oxygen concentration
- Gas purity
- Humidity levels
- Temperature
- Pressure
- Generator design
The higher the oxygen concentration entering the ozone cell, the greater the amount of ozone that can be produced.
This is why feed gas selection is a critical engineering decision.
Dry air: the traditional approach
Historically, many ozone generators operated using dried compressed air.
Atmospheric air contains approximately:
- 21% oxygen
- 78% nitrogen
- 1% other gases
Before entering the ozone generator, the air must be compressed, filtered and dried to very low humidity levels.
Advantages of dry air
Dry air systems offer several benefits:
- Lower initial investment
- No oxygen generation equipment required
- Suitable for small ozone outputs
- Simpler installation for some air-treatment applications
For low-capacity ozone systems, dry air may still be a viable option.
Limitations of dry air
Despite its simplicity, dry air presents several drawbacks:
- Lower ozone concentration
- Higher electrical consumption
- Reduced mass transfer efficiency
- Potential formation of nitrogen oxides (NOx)
- Increased maintenance requirements
These limitations become more significant as ozone demand increases.
PSA oxygen: the industrial standard
PSA (Pressure Swing Adsorption) technology produces oxygen from ambient air using molecular sieve adsorption beds.
Modern PSA systems typically generate oxygen with a purity of 90% to 95%.
Compared with atmospheric air, this represents more than four times the available oxygen concentration.
This higher oxygen purity dramatically improves ozone generation efficiency.
Ozone concentration comparison
The most visible difference between dry air and PSA oxygen is the ozone concentration that can be achieved.
Typical values are:
| Feed Gas | Ozone Concentration |
|---|---|
| Dry Air | 20–60 g/Nm³ |
| PSA Oxygen | 80–160 g/Nm³ |
| Liquid Oxygen (LOX) | 120–200 g/Nm³ |
Depending on generator technology, PSA oxygen can produce two to four times higher ozone concentrations than dry air.
This allows more ozone to be transferred into the process while reducing gas volumes and equipment size.
Energy efficiency
Energy consumption is another major consideration.
Producing ozone from oxygen-rich feed gas requires less electrical energy per kilogram of ozone produced.
In general:
- Dry air systems consume the most energy
- PSA oxygen systems offer significantly improved efficiency
- Liquid oxygen systems provide the highest performance but may involve additional logistics costs
For most industrial projects, PSA oxygen provides the best balance between investment cost and operating efficiency.
Improved ozone transfer into water
Generating ozone is only part of the water treatment process.
The ozone must also be dissolved efficiently into water.
Higher ozone concentrations generally result in:
- Improved mass transfer efficiency
- Better Venturi injector performance
- Smaller contact tanks
- Reduced ozone losses
- Higher oxidation potential
As a result, two systems producing the same ozone mass output may achieve very different treatment results depending on their feed gas and system design.
Reduced NOx formation
One often overlooked benefit of PSA oxygen is the reduction of nitrogen-related by-products.
When dry air passes through a corona discharge, nitrogen molecules can react to form:
- Nitric oxide (NO)
- Nitrogen dioxide (NO₂)
- Nitric acid compounds
These substances may contribute to:
- Corrosion
- Increased maintenance
- Reduced equipment lifespan
Because PSA oxygen contains very little nitrogen, NOx formation is dramatically reduced.
This contributes to greater reliability and lower maintenance costs over time.
When should you choose dry air?
Dry air may still be appropriate for:
- Small ozone generators
- Odour control systems
- Air disinfection applications
- Portable equipment
- Budget-sensitive projects
For modest ozone production requirements, the simplicity of dry air can be attractive.
When is PSA oxygen the best option?
PSA oxygen is generally recommended for:
- Industrial water treatment
- Wastewater treatment plants
- Aquaculture and RAS systems
- Irrigation water treatment
- Cooling tower treatment
- Water reuse projects
- Food and beverage processing
- Advanced oxidation processes (AOP)
For most industrial applications above a few tens of grams of ozone per hour, PSA oxygen quickly becomes the preferred solution.
Ozone performance depends on more than the generator
Many buyers focus exclusively on ozone generator output ratings.
However, the performance of an ozone system also depends on:
- Oxygen generation quality
- Cooling systems
- Injection technology
- Hydraulic design
- Contact time
- Process automation
- Off-gas destruction systems
This is why successful ozone projects require an engineering-led approach rather than simply selecting a generator from a catalogue.
At OXYTRADING UK, we evaluate each project individually to determine the most effective combination of ozone generation, transfer technology, automation and safety systems.
For most industrial water treatment applications, PSA oxygen offers the best balance of performance, efficiency and operating cost.
Compared with dry air, PSA oxygen typically provides:
- Higher ozone concentrations
- Improved transfer efficiency
- Lower energy consumption
- Reduced NOx formation
- More compact system designs
- Better treatment performance
While dry air remains suitable for certain small-scale applications, PSA oxygen has become the industry standard for demanding industrial processes.
By combining the right ozone generator, oxygen source, injection technology and process engineering, businesses can maximise treatment efficiency while minimising operating costs.
At OXYTRADING UK, we support industrial clients throughout the entire project lifecycle, from feasibility studies and pilot testing to system design, installation, commissioning and maintenance.