Humic substances as precursors for potentially harmful disinfection by-products

During the chlorination of drinking water, chlorine reacts with natural organic material to produce disinfection by-products, such as trihalomethanes and haloacetic acids, which are believed to be harmful to human health. The formation of these by-products is related to the aromatic carbon content of the water, for which specific ultraviolet absorbance serves as a useful surrogate. Because humic substances in water tend to have a higher aromatic carbon content and a higher specific ultraviolet absorbance than non-humic substances, they produce greater levels of disinfection by-products.