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Efficacy of Ozone to Reduce Chlorinated Disinfection By-Products

Jun 30, 2020 11:00:00 AM / by De Nora


The scientific journal Ozone Science and Engineering published an article entitled: Efficacy of Ozone to Reduce Chlorinated Disinfection By-Products in Quebec (Canada) Drinking Water Facilities, authored by Ladji Meite; Macellin Fotsing and Benoit Barbeau. The following post is a summary of that article.

The impact of ozonation on the reduction of chlorinated disinfection by-products (DBPs) formation was investigated in 15 full-scale Quebec’s WTPs using ozonation as part of their treatment.

The most common locations for the ozonation process were respectively post-ozonation (9), intermediate ozonation (3), and pre-ozonation (3).

Sampling campaigns were replicated for each WTP in warm waters (June–August) as well as cold waters (November–April). Samples were collected before and after full-scale ozonation and were chlorinated in the laboratory to perform DBPs measurements under uniform formation conditions (UFC) tests. A lab-scale ozonation was also performed on each sample to standardize ozonation conditions of all investigated waters. As part of the research, total trihalomethanes (TTHM) and the sum of six haloacetic acids (HAA6) were measured after chlorination 

In full-scale ozonation conditions, TTHM-UFC and HAA6-UFC reductions averaged respectively 27 and 32%. 

Chlorinated DBPs: Trihalomethanes (THM) and halogenated acetic acids (HAA)

Water utilities electing to use chlorine as part of their drinking treatment process must manage chlorinated disinfection by-products (DBPs) formation. Disinfection byproducts can be harmful to human health. 

Trihalomethanes (THM) and halogenated acetic acids (HAA) are the two groups of chlorinated DBPs most often regulated under various international legislations


Ozone is a powerful oxidant recognized for its disinfectant and oxidizing action in water treatment. It is mainly used for disinfection, iron and manganese removal, improvement in tastes and odors and organic micropollutants control (Reckhow 1999). The production of microbiologically safe drinking waters, especially for the control of resistant microorganisms such as Cryptosporidium, has also been a major driver for ozone implementation (Ran et al. 2010; Talbot et al. 2012).

This process is commonly implemented in drinking water facilities of Quebec, with a first usage dating back as early as 1956 (Ste-Thérèse, QC). Over the last decade, tightening of disinfection by-products regulation has led to its implementation in many surface water treatment plants around the world.

Source: Efficacy of Ozone to Reduce Chlorinated Disinfection By-products in Quebec (Canada) Drinking Water Facilities, Ladji Meite, Marcellin Fotsing and Benoit Barbeau, 2014

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Tags: ozone, total trihalomethanes, chlorine demand, natural organic matter, haloacetic acids

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