Advanced Oxidation Processes: A solution for challenging industrial wastewater treatment

Reverse osmosis is one of the most effective technologies for industrial wastewater treatment. It successfully removes a large percentage of dissolved contaminants and produces high-quality water. However, certain pollutants remain difficult to eliminate, including pharmaceutical residues, textile dyes, pesticides, PFAS compounds, and other persistent organic contaminants.

This is where Advanced Oxidation Processes (AOPs) become essential. Rather than replacing reverse osmosis, they complement it by breaking down pollutants that are difficult to remove using conventional treatment methods.

What are advanced oxidation processes?

Advanced Oxidation Processes (AOPs) are not a single technology but a group of treatment methods designed to generate hydroxyl radicals (•OH)—one of the most powerful oxidizing agents known.

These radicals break down persistent organic compounds into simpler substances such as carbon dioxide, water, and inorganic salts. As a result, contaminants that resist biological treatment or conventional purification methods can be effectively degraded.

Why are AOPs becoming increasingly important?

Environmental regulations for industrial wastewater are becoming more stringent every year. Today, treatment facilities are expected to remove not only conventional pollutants but also emerging contaminants such as:

• pharmaceutical residues;
• pesticides;
• PFAS compounds;
• microplastics;
• persistent organic pollutants.

Traditional biological treatment processes are often unable to remove these substances completely. At the same time, industries require technologies that provide high treatment efficiency, support water reuse, and can be integrated into existing treatment facilities.

Main Types of Advanced Oxidation Technologies

Ozonation (O₃)

Ozone is one of the most widely used advanced oxidation methods. It attacks organic contaminants directly or through the formation of hydroxyl radicals.

It is commonly used for:

• textile wastewater decolorization;
• pulp and paper wastewater treatment;
• drinking water treatment.

Ozonation is particularly effective for breaking down dye molecules, with color removal often achieved within just a few minutes.

UV/H₂O₂

In this process, ultraviolet light breaks down hydrogen peroxide to generate hydroxyl radicals.

The technology is relatively simple to implement and is often added as an additional treatment stage in existing wastewater treatment plants.

The best performance is achieved when treating clarified water with low turbidity and low concentrations of suspended solids.

Fenton and Photo-Fenton Processes

The Fenton process combines iron ions and hydrogen peroxide to generate hydroxyl radicals.

Its main advantages include:

• high efficiency in treating wastewater with high organic loads;
• simple process design.

Its primary limitation is the need to operate under acidic pH conditions, followed by treatment of the resulting iron sludge.

Photocatalysis

Photocatalysis uses catalysts—most commonly titanium dioxide (TiO₂)—which generate highly reactive oxidizing species when exposed to ultraviolet light.

One of its greatest advantages is that the catalyst is not consumed during the reaction. However, industrial applications remain limited due to relatively high costs and specific equipment requirements.

Electrochemical Oxidation

In this method, oxidation reactions occur directly on the surface of specialized electrodes.

The technology has proven particularly effective for treating:

• pharmaceutical wastewater;
• PFAS compounds;
• cyanides;
• highly toxic industrial wastewater.

Its main advantages are a high level of automation and the elimination of chemical reagent consumption.

Advanced Oxidation Processes should not be viewed as an alternative to reverse osmosis, but as a complementary technology. While reverse osmosis membranes efficiently separate dissolved contaminants, AOPs destroy persistent organic compounds that are difficult to remove by conventional treatment methods.

As industrial wastewater becomes increasingly complex and environmental standards continue to tighten, the future of water treatment will rely on intelligently designed hybrid treatment systems. In this context, Advanced Oxidation Processes are becoming an essential component of sustainable and high-performance industrial water treatment.