Factorial analysis of the trihalomethane formation in the reaction of colloidal, hydrophobic, and transphilic fractions of DOM with free chlorine

Department of Environmental Chemistry, IIQAB-CSIC, Jordi Girona 18-26, 08026, Barcelona, Spain.
Environmental Science and Pollution Research (Impact Factor: 2.83). 04/2010; 17(8):1389-400. DOI: 10.1007/s11356-010-0320-4
Source: PubMed


This study focuses on the factors that affect trihalomethane (THMs) formation when dissolved organic matter (DOM) fractions (colloidal, hydrophobic, and transphilic fractions) in aqueous solutions were disinfected with chlorine.
DOM fractions were isolated and fractionated from filtered lake water and were characterized by elemental analysis. The investigation involved a screening Placket-Burman factorial analysis design of five factors (DOM concentration, chlorine dose, temperature, pH, and bromide concentration) and a Box-Behnken design for a detailed assessment of the three most important factor effects (DOM concentration, chlorine dose, and temperature).
The results showed that colloidal fraction has a relatively low contribution to THM formation; transphilic fraction was responsible for about 50% of the chloroform generation, and the hydrophobic fraction was the most important to the brominated THM formation.
When colloidal and hydrophobic fraction solutions were disinfected, the most significant factors were the following: higher DOM fraction concentration led to higher THM concentration, an increase of pH corresponded to higher concentration levels of chloroform and reduced bromoform, higher levels of chlorine dose and temperature produced a rise in the total THM formation, especially of the chlorinated THMs; higher bromide concentration generates higher concentrations of brominated THMs. Moreover, linear models were implemented and response surface plots were obtained for the four THM concentrations and their total sum in the disinfection solution as a function of the DOM concentration, chlorine dose, and temperature. Overall, results indicated that THM formation models were very complex due to individual factor effects and significant interactions among the factors.
In order to reduce the concentration of THMs in drinking water, DOM concentrations must be reduced in the water prior to the disinfection. Fractionation of DOM, together with an elemental analysis of the fractions, is important issue in the revealing of the quality and quantity characteristics of DOM. Systematic study composed from DOM fraction investigation and factorial analysis of the responsible parameters in the THM formation reaction can, after an evaluation of the adjustment of the models with the reality, serves well for the evaluation of the spatial and temporal variability in the THM formation in dependence of DOM. However, taking into consideration the natural complexity of DOM, different operations and a strict control of them (like coagulation/flocculation and filtration) has to be used to quantitatively remove DOM from the raw water.
Assuming that this study represents a local case study, similar experiments can be easily applied and will supply with relevant information every local water treatment plant meeting problems with THM formation. The coagulation/flocculation and the filtration stages are the main mechanisms to remove DOM, particularly the colloidal DOM fraction. With the objective to minimize THMs generation, different unit operation designed to quantitatively remove DOM from water must be optimized.

Download full-text


Available from: Pedro Rodrigues, Jan 23, 2014
1 Follower
42 Reads
  • Source
    • "In order to verify if these two experimental factors affect the stability of BMDM a factorial analysis strategy was used.[20] [21] [22] [23] A central composite experimental design response surface methodology was selected to study the effect of chlorine concentration and DOM concentration on the degradation percentage of BMDM. To identify the chlorinated by-products of BMDM incorporated in the two sunscreens, a liquid–liquid extraction step was performed before analysis by LC–MS. "
    [Show abstract] [Hide abstract]
    ABSTRACT: 4-tert-Butyl-4’-methoxydibenzoylmethane (BMDM) is a widely used UVA filter. In this work we have studied the effect of chlorine and dissolved organic matter (DOM) concentrations on the stability of UV filter (BMDM) present in two commercial sunscreen cream formulations in water. An experimental design was used to assess the effect of the two experimental factors on the degradation of BMDM. Higher concentrations of chlorine lead to higher degradation percentages of BMDM and higher concentrations of DOM inhibit its degradation. Moreover, a mono and a dichloro derivate of BMDM were identified as by-products.
    Environmental Technology 11/2014; 36(10). DOI:10.1080/09593330.2014.988184 · 1.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The effects of the concentration of dissolved total organic carbon (TOC), the TOC/Br− ratio, bromide ion levels, the chlorine to ammonia-N ratio (Cl:N), the monochloramine dose and the chlorine dose on the formation of trihalomethanes (THMs) (including chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) from chlorination were investigated using aqueous humic acid (HA) solutions. The profile of the chloramine decay was also studied under various bromide ion concentrations. Monochloramine decayed in the presence of organic material and bromide ions. The percentage of chloroform and brominated THMs varied according to the TOC/Br− ratio. Total THMs (TTHMs) formation increased from 112 to 190 μg/L with the increase concentrations of bromide ions from 0.67 to 6.72 mg/L, but the chlorine-substituted THMs were replaced by bromine-substituted THMs. A strong linear correlation was obtained between the monochloramine dose and the formation of THMs for Cl:N ratios of 3:1 and 5:1. These ratios had a distinct effect on the formation of chloroform but had little impact on the formation of bromodichloromethane or chlorodibromomethane. The presence of bromide ions increased the rate of monochloramine decay. Key wordsTrihalomethanes (THMs)-Humic acid (HA)-Bromide-Monochloramine CLC numberTU991.2-X5
    Journal of Zhejiang University - Science A: Applied Physics & Engineering 08/2010; 11(8):606-612. DOI:10.1631/jzus.A1000100 · 0.88 Impact Factor
  • Bone 01/2011; 48(1). DOI:10.1016/j.bone.2010.10.137 · 3.97 Impact Factor
Show more