Why is it important to drinking water authorities?

NOM has a significant impact on all aspects of drinking water treatment.

Coagulation/flocculation

 NOM is responsible for the majority of the coagulant demand. Therefore waters with high dissolved organic carbon (DOC) levels usually have a high coagulant requirement, and consequent high treatment costs.

Activated carbon adsorption

Where activated carbon is used for the removal of micro-contaminants (eg tastes and odours, algal toxins, pesticides), NOM competes strongly for adsorption sites, and the amount of activated carbon required is increased (in the case of powdered activated carbon ) or the lifetime of the carbon is drastically reduced (granular activated carbon).

Disinfection, oxidation

NOM exerts a high demand for chemicals, such as chlorine, chloramine, ozone, thus increasing the costs associated with their application. In addition, the reaction between oxidants and NOM can produce by-products, some of which are known to be harmful to health at high concentrations.

Membranes

NOM is responsible for fouling of membranes, reducing the flux, resulting in higher frequency of backwashing and cleaning membrane systems.

Distribution system water quality

NOM serves as a substrate for bacterial growth. This may lead to regrowth in the distribution system where a sufficient disinfectant residual cannot be maintained.
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