Article

Development of chlorine dioxide-related by-product models for drinking water treatment.

Acres and Associated Environmental Limited, Toronto, Ont, Canada.
Water Research (Impact Factor: 4.66). 02/2002; 36(1):330-42. DOI:10.1016/S0043-1354(01)00194-4
Source: PubMed

ABSTRACT Factorial experiments were conducted using source waters from seven drinking water treatment plants in Ontario, Canada to develop statistically based model equations capable of predicting chlorine dioxide consumption and chlorite and chlorate formation upon chlorine dioxide application. The equations address raw water quality and operational parameters including pH, temperature, chlorine dioxide concentration, reaction time and water organic content (as described by non-purgeable organic carbon x ultraviolet absorbance measured at 254 nm, NPOC x UV254). Terms describing two-factor interaction effects were also included, improving the accuracy of the predictive equations in fitting measured response concentrations as evaluated through internal and external validations. Nearly 80% of the predictions for chlorine dioxide consumption and chlorite formation were observed to be within 20% of the measured levels. Over 90% of the predicted chlorate levels were within +/- 0.1 mg/L of the measured levels. Chlorine dioxide concentration and NPOC x UV254 were key parameters when developing the predictive models.

0 0
 · 
0 Bookmarks
 · 
59 Views
  • [show abstract] [hide abstract]
    ABSTRACT: We determined the disinfection efficiency of chlorine and chlorine dioxide (ClO(2)) using murine norovirus (MNV) and coliphage MS2 as surrogates for human norovirus. Experiments were performed in oxidant demand-free buffer (pH 7.2) at 5 degrees C and 20 degrees C. The extent of virus inactivation by a disinfectant was quantified using three different analytical methods: plaque, short template real-time TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR), and long template RT-PCR assays. Rapid inactivation of MNV by both chlorine and chlorine dioxide was observed by the plaque assay. According to the efficiency factor Hom model, Ct values of 0.314mg/Lmin and 0.247mg/Lmin were required for a 4-log reduction of MNV at 5 degrees C by chlorine and chlorine dioxide, respectively. Lower Ct values were required at 20 degrees C. Both long template and short template RT-PCR assays significantly underestimated the virus inactivation compared to the plaque assay. Our study demonstrates that adequate treatment of water with either chlorine or ClO(2) is likely to effectively control the waterborne transmission of human norovirus.
    Water Research 03/2010; 44(10):3243-51. · 4.66 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Despite the health risks posed by waterborne human rotavirus (HRV), little information is available concerning the effectiveness of chlorine or chlorine dioxide (ClO2), two common disinfectants of public water sources, against HRV and their effects on its genome remain poorly understood. This study investigated the effects of chlorine and ClO2 on purified HRV by using cell culture and RT-PCR to assess virus infectivity and genetic integrity, respectively. The disinfection efficacy of ClO2 was found to be higher than that of chlorine. According to the efficiency factor Hom model, Ct value (mg/L min) ranges required for a 4-log reduction of HRV at 20 °C by chlorine and ClO2 were 5.55-5.59 and 1.21-2.47 mg/L min, respectively. Detection of the 11 HRV genome segments revealed that damage to the 1227-2354 bp of the VP4 gene was associated with the disappearance of viral infectivity by chlorine. However, no complete accordance between culturing and RT-PCR assays was observed after treatment of HRV with ClO2. These results collectively indicate that the current practice of chlorine disinfection may be inadequate to manage the risk of waterborne HRV infection, and offer the potential to monitor the infectivity of HRV adapting PCR-based protocols in chlorine disinfection.
    Water Research 04/2013; · 4.66 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Effects of water characteristics, reaction time, temperature, bromide and iodide ion concentrations, oxidant doses, and pH on formation of iodinated trihalomethanes (I-THM) during oxidation of iodide-containing water with chlorine dioxide (ClO2) were investigated. Among the water samples collected from ten water sources, iodoform (CHI3) was the predominant I-THM and trace amount of chlorodiiodomethane (CHClI2) was occasionally found. CHI3 yields correlated moderately with specific UV absorbance (SUVA) (R(2)=0.79), indicating that hydrophobic aromatic content were important precursors. Longer reaction time led to continued formation of CHI3. I-THM containing bromide was also found in waters containing both bromide and iodide, but CHI3 was dominant. The formation of CHI3 was higher at 25°C than 5°C and 35°C. CHI3 formation showed an increase followed by a decrease trend with increasing ClO2 doses and iodide concentrations and the highest yields occurred at iodide to ClO2 molar ratios of 1-2. pH 8 resulted in the highest CHI3 formation. It should be noted that a high iodide concentration was spiked to waters before adding ClO2 and the results may not reflect the formation yields of iodinated THMs in real conditions, but they provide information about formation trend of I-THM during oxidation of ClO2.
    Journal of hazardous materials 11/2013; 264C:91-97. · 4.14 Impact Factor

Full-text

View
1 Download
Available from