Efficacy of Ozone to Reduce Chlorinated Disinfection By-Products in Quebec (Canada) Drinking Water Facilities

Abstract

The impact of ozonation on the reduction of chlorinated disinfection by-products formation was investigated in 15 full-scale and lab-scale drinking water facilities of Québec (Canada). Total trihalomethanes (TTHM) and the sum of six haloacetic acids (HAA6) were measured after chlorination under uniform formation conditions (UFC). Results showed that before ozonation TTHM and HAA6 average concentrations were 89.4 and 45.3 μg/L, respectively. In full-scale ozonation conditions TTHM-UFC and HAA6-UFC reductions averaged respectively 27 and 32%. After lab-scale ozonation at a O 3 /C of 1:1, a decrease of only 9% of TTHM was calculated, while for HAA6, reduction was not significantly impacted (30%). For BDOC, average concentrations of 0.13, 0.46, and 0.69 mg C/L were measured before and after and lab-scale ozonation, respectively. Chlorine demand (Cl 2 D) and immediate ozone demand (IOD) were found to be the most appropriate indicators to evaluate NOM reactivity after ozonation.

Ozone application in different industries: A review of recent developments

“…Usually, a very small ozone residual is maintained until disinfection is complete, at which point, all ozone disappears; a small chlorine dose is also added at this point to keep a residual in the distribution system. Additional advantages of ozonation for this application include its capability of decreasing chlorinated disinfection by-products [74] , the excellent water quality aesthetics (including odour, colour, taste, turbidity) it confers post-treatment [75] , and the exceptional capability to degrade a series of emerging contaminants that threaten water supplies [76] , [77] . For these reasons, ozone has been more widely considered in drinking water than wastewater treatment.…”

Full-Scale Granular Activated Carbon and Chloramine Pretreatment of Drinking Water for Aquifer Storage and Recovery

“…Secondary factors, such as temperature, pH, and the presence or absence of bromide, are also important, particularly for the type of DBP species formed and rate of formation. 9 Extensive research has been conducted to quantify the impacts of DBP formation resulting from changing the pH 10 and temperature of water samples, 11 reducing precursors through biological treatment 12,13 or other advanced treatment processes, 14 and modifying disinfectant contact time. 9,15 There are two regulated classes of DBPs in the United States for chlorine-based disinfection systems, total trihalomethanes (TTHMs) and haloacetic acids (HAAs); however new species of DBPs are being continuously discovered, with some researchers having reported up to 700 variant DBPs in existence.…”

“…Secondary factors, such as temperature, pH, and the presence or absence of bromide, are also important, particularly for the type of DBP species formed and rate of formation . Extensive research has been conducted to quantify the impacts of DBP formation resulting from changing the pH and temperature of water samples, reducing precursors through biological treatment , or other advanced treatment processes, and modifying disinfectant contact time. , …”