Chemical oxidation

Chemical oxidation technologies are used in the wastewater treatment field to reduce COD content, especially for non-biodegradable contaminants, both inorganic and organic.

Different oxidizing agents, such as oxygen, air, sodium hypochlorite, hydrogen peroxide, ozone and chlorine dioxide, can be used. The choice depends on the specific pollutant to be removed and the matrix composition of wastewater to be treated.

Typically, the following contaminants can be removed by oxidation:

  • Sulphides
  • Thiosulfates
  • Sulphur
  • Iron
  • Manganese
  • Cyanide
  • Nitrite

Other specific pollutants, including micropollutants, odour and colour, can be included in the above list.


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A plant consists mainly of a reactor (tank or a vessel) working under atmospheric conditions or under blanketing, where perfect mixing between wastewater and the oxidizing agent must be ensured.

Inline mixing is also possible when a liquid oxidant (e.g., NaCl0, H2O2) is used:

  • A static mixer is installed on the main process line, upstream of the reactor.
  • Downstream of the static mixer, continuous mixing operations can be provided by the reactor agitator or by external recirculation.

Gas oxidants (e.g., air or oxygen) can be gurgled from the reactor’s bottom to the top, thus enhancing turbulence and mixing in the system.

Since oxidizing capacity depends on the pH, its adjustment may be necessary upstream of the reactor or in the reactor.

Process and performances can be further enhanced by combining two oxidants (e.g., sodium hypochlorite and air).
Process vents are routed to further treatments, such as the scrubber, depending on their chemical nature and the customer’s needs.

Features and rangeability

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Chemical oxidation is the ideal technology to treat small amounts of wastewater (less than m3/day).We customise other parameters depending on the type of wastewater to be treated and on the customer’s performance expectations. Typical operating conditions are reported below:

  • Temperature: up to 120°C
  • Pressure: Atm – blanketing

Also supplied as skid mounted units to minimise installation operations at the customer’s site.

The most suitable material is selected based on the nature of the wastewater, the oxidizing agent and operating conditions.
Typical materials used are as follows:

  • Titanium alloys
  • Nickel alloys (e.g., Hastelloy® HC22, Inconel® 600)
  • Fluorinated polymers

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Key benefits

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  • Near complete wastewater detoxification, thus resulting in increased biodegradability
  • Suitable to treat even small quantities of wastewater
  • Low pressure and temperature process
  • Reduced environmental footprint
  • High versatility and flexibility
  • Maximum energy savings
  • High automation level
  • Reliability


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A wide range of applications are possible for both municipal and industrial wastewater to remove different kind of contaminants, both inorganic and organic.

Chemical oxidation technologies address the needs of the following different industries:

  • Chemicals
  • Mining
  • Oil & Gas
  • Pharmaceutical
  • Power

Deep neutralization is a treatment option for sulfidic and naphthenic spent caustic water to reduce sulphides and mercaptan content.

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For greater reduction, including for harder to degrade contaminants, wet oxidation plants are the alternative solution.

A wide range of industrial processes generates extensive wastewater compositions and, whether easy or difficult to treat, each type of wastewater requires a customised process and a bespoke plant design.

We provide support to our customers conducting tests at the laboratory and pilot plant scale, including feasibility studies leveraging our R&D centre and multidisciplinary teams.

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Want to know more about our chemical oxidation plants?

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