Effects of Pre-Ozonation on the Removal of THMs Precursors by Coagulation
Date Issued
2008
Date
2008
Author(s)
Chang, Pin-Cheng
Abstract
Due to the characteristics of high concentrations of dissolved organic carbon (DOC), low turbidity and low alkalinity in the Tai-Lake source water in Kinmen, the DOC is difficult to remove by conventional treatment processes. However, the introduction of the enhanced coagulation based on disinfectant/disinfection by-product Rule (D/DBP Rule) again would result in the formation of high trihalomethanes beyond the drinking water quality standard (80μg/L) in Taiwan. As a result, the purpose of this study was intended to evaluate the effect of pre-ozonation on the performance of coagulation and formation of trihalomethanes, to separate the hydrophobic and hydrophilic fractions of natural organic matters (NOMs), and to develop at DOC removal model in enhanced coagulation.he results of this investigation reveal that the ozone doses and pH levels would influence the coagulation performance significantly. The pH levels and ozone doses were held at 9 and 0.45 mgO3/mgDOC, respectively. The removal efficiency of THMFP was about 60%. In addition, the results of the DAX-8 resin separation process indicate that the specific THMFP for hydrophobic and hydrophilic organics are 57.3 and 98.7 ugTHMFP/mgDOC, respectively. This suggests that hydrophilic organics are significant precursors of THMs. The introduction of pre-ozonation have a positive effect on hydrophobic organic removal, but an insignificant on hydrophilic organics.n the comparison of competitive and non-competitive adsorption models for the hydrophilic and hydrophobic organics, the non-competitive adsorption models could successfully predict the hydrophilic and hydrophobic DOCs removal in the enhanced coagulation process.
Subjects
Pre-ozonation
Enhanced coagulation
Natural organic matter (NOM)
Hydrophilic
Hydrophobic
Trihalomethanes
Type
thesis
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