Which of the following is a precursor to disinfection by-products?

Natural organic matter (NOM) is a precursor to disinfection by-products because it can react with disinfectants such as chlorine, chloramine, or ozone used in water treatment processes. When these disinfectants interact with NOM, they can create a variety of by-products, including trihalomethanes (THMs) and haloacetic acids (HAAs), which are regulated due to their potential health risks.

NOM typically originates from the decay of plant and animal material in water sources, making it a common and significant factor in the formation of disinfection by-products. Effective management of NOM in water treatment systems is essential to minimize the formation of these harmful by-products.

In contrast, arsenic, nitrate, and inorganics do not directly lead to the formation of disinfection by-products. Arsenic is a toxic metalloid typically regulated due to its health risks when present in drinking water, while nitrate is an inorganic compound that poses a different set of health concerns, primarily related to its effect on infant health. Inorganics broadly refer to various non-carbon-based compounds that may be present in water but do not significantly impact disinfection by-product formation when used as disinfectants. Therefore, recognizing NOM as a key precursor helps in addressing