David A. Reckhow
Natural organic matter (NOM) is the main source of organic precursors for organic disinfection byproducts (DBPs) in treated drinking water.Aquatic NOM is a heterogeneous mixture consisting of both hydrophobic and hydrophilic compounds. The hydrophobic fraction includes humic substances, primarily humic acids and fulvic acids. In most waters, fulvic acid is considered to be the major portion of the hydrophobic fraction. Humic substances are formed by decaying vegetative matter, such as lignin. Lignin is found in plants and is quite resistant to biodegradation, yet it is reactive with oxidants, such as chlorine. Thus, water continuing higher amounts of aromatic hydrophobic humic material tend to form higher DBP levels. The hydrophilic fraction of NOM primarily consists of aliphatic carbon and nitrogen bearing compounds such as carbohydrates, proteins and amino-acids.