How to Set Up a Scrubber + Ozone System? Metal or Plastic?

Introduction

In industrial stack odor removal, ozone alone is not always sufficient. Particularly in high-flow, humid, and particulate-laden stack gases, a pre-washing stage is essential before ozone treatment. When a scrubber system is brought in at this point and properly integrated with ozone, the result is a highly powerful solution.

However, there is a mistake frequently seen in the field: a scrubber built from the wrong material will shorten its own service life while simultaneously reducing the efficiency of the ozone system. In this article, we cover how a scrubber + ozone system should be set up — and address the most critical material selection question: metal or plastic?

Scrubber + Ozone: Why Do They Work Together?

A wet scrubber brings stack gas into contact with a liquid curtain, capturing coarse particulates, dust, and moisture load. However, a scrubber alone cannot adequately remove odor compounds — particularly sulfur- and nitrogen-based organic compounds.

Ozone breaks down these compounds through chemical oxidation. But ozone rapidly loses efficiency in gas streams carrying high particulate and moisture loads.

When the two are combined, the system logic works as follows:

[Stack Gas Inlet] ↓ [Scrubber — Particulate, moisture, and coarse odor removal] ↓ [Ozone Injection — Chemical oxidation of remaining odor compounds] ↓ [Clean Gas — Stack outlet]

The scrubber "prepares" the gas; ozone "finishes" it. Each is half a solution on its own — together, they form a complete one.

The Most Critical Question: Metal or Plastic?

Scrubber material selection directly determines the system's service life and reliability. The two most common options on the market are PP/HDPE (plastic) and 316L stainless steel.

PP/HDPE (Polypropylene/High-Density Polyethylene) Scrubber

Advantages:

• Low initial investment cost
• Lightweight, easy to install
• High chemical resistance to acidic gases (HCl, HF, H₂SO₄)
• No corrosion risk

Disadvantages:

• Maximum operating temperature of 60–70°C — risk of deformation and melting above this limit
• Not suitable for high-temperature gases containing particulates and ash
• Weak against UV exposure and thermal fatigue over time
• Low resistance to mechanical impact

Where it should be used: Applications where gas temperature stays below 60°C, involving clean, particulate-free acidic gases — galvanizing, chemical plants, acid bath exhausts.

Where it should not be used: Feed mills, rendering plants, foundries, meat processing, welding exhausts — in these applications, stack gas temperatures can reach 80–150°C with high particulate and ash content.

316L Stainless Steel Scrubber

Advantages:

• Withstands operating temperatures of 200°C and above
• Mechanical robustness against ash, particulates, and abrasive gases
• Long service life — 15–20 years with proper maintenance
• Easy to clean and maintain
• Chemically compatible with ozone gas

Disadvantages:

• Higher initial investment cost compared to plastic scrubbers
• Heavier — may require lifting equipment during installation
• May require additional protective measures in very high HCl environments

Where it should be used: Feed mills, rendering, meat processing, foundries, cement, welding — all industrial applications where high temperature, high particulate load, and organic odor occur together.

What We Have Learned in the Field

We have observed firsthand, on multiple occasions, why plastic scrubbers fail in feed mill applications. In rendering and drying stacks, gas temperatures can reach 100–130°C. At these temperatures, the PP body gradually deforms, the internal packing media collapses, and the system becomes non-functional.

Furthermore, in welding and heat treatment applications, the ash and metal particulates carried in stack gas physically abrade the plastic casing. The result: a system that fails prematurely and is difficult to repair.

316L stainless steel scrubbers operate reliably under these conditions. While the initial investment is higher, a five-year total cost of ownership comparison consistently shows stainless steel to be the more economical choice.

System Installation Steps

A correctly installed scrubber + ozone integration system consists of the following components:

1. Stack Gas Analysis — Before the system is built, the stack gas temperature, flow rate, moisture content, particulate load, and odor composition must be measured. Without this analysis, neither the right scrubber nor the correct ozone dose can be determined.
2. Scrubber Design — Based on analysis results, the scrubber material (316L or PP), tower dimensions, packing media, circulation pump, and nozzle system are selected.
3. Pre-Cooling (If Required) — If gas temperature exceeds 80°C, adding a pre-cooler ahead of the scrubber is recommended. This both extends scrubber service life and improves ozone efficiency — ozone decomposes rapidly at high temperatures.
4. Ozone Injection Point — Ozone is injected either at the scrubber outlet or into the scrubber circulation water. Both methods have advantages; the choice is made based on the facility profile.
5. Residual Ozone Monitoring — An ozone sensor is installed at the system outlet to track residual ozone levels. This step is mandatory for worker safety and OHS compliance.
6. Commissioning and Measurement — After the system is commissioned, an accredited odor measurement is carried out to document the OUE/m³ value. At OCS Ozon, we commit to bringing results below the legal limit of 1,000 OUE/m³.

Decision Guide: Which Scrubber Is Right for You?

Conclusion

The scrubber + ozone combination is the most effective and sustainable solution for industrial stack odor removal. However, the success of this system depends largely on correct material selection and proper design.

Using a plastic scrubber in high-temperature, particulate-laden stack gas applications may appear to offer a cost advantage in the short term — but over time, it significantly reduces both system reliability and odor removal efficiency.

At OCS Ozon, we conduct stack gas analysis for every facility and design the right scrubber material and ozone integration together. If you would like to request a free technical assessment for your facility, please get in touch with us.