Dissolved Natural Organic Matter (DOM) represents a wide-range of organic molecules present in water resources. DOM is considered to be harmless for human consumption but causes aesthetic issues in waters such as color and taste and odors and leads to the potential formation of harmful by-products. Its removal is one of the main objectives of treatment plants and its concentration and type directly impact all the units used for its removal. Today, monitoring of DOM at treatment plants is based mainly on the analysis of UV absorbance at 254nm (UV254) and possibly Dissolved Organic Carbon (DOC) concentration. This is due to the simplicity of use of these methods which do not require lab intensive treatments. These methods, alongside parameters such as turbidity and conductivity, give a simple firsthand idea of the difficulty to treat a resource. However, these methods have not been well correlated to treatment issues such as Disinfection By-Product (DBP) formation or membrane fouling except for the simple observation that minimizing DOM content minimizes these issues. A more detailed characterization of DOM could therefore lead to a finer optimization of treatment through proper monitoring. Fluorescence Excitation-Emission Matrix (FEEM) analysis is the leading tool for such a purpose as it provides fast characterization of DOM and instrumentation has recently been developed for its online monitoring. The objective of our study is to evaluate the ability of FEEM to highlight treatment specific differences above and beyond what can be done with DOC and UV254. A dozen plants will be characterized completely from raw water to treated water. Preliminary data from 5 sites show that FEEM is able to highlight significant differences between water samples though further data is required to evaluate whether these differences are linked to an impact on water treatment efficiency. The data from these sites also show that the methods selected underscore the increased removal linked with the use of more advanced treatment units such as activated carbon and membrane filtration. The additional data to be produced will help evaluate whether these new methods are sufficient for removal optimization at the plant level or whether more advanced analytical methods are needed to understand issues such as DBP formation. The results will thus define a guideline for treatment plant optimization through proper selection of on-site monitoring tools.

Characterization and monitoring of dissolved organic matter at drinking water treatment plants: Methods and application

253rd National Meeting (2017)

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