# Innovative Approaches for Minimizing Disinfection
## 3 DBPs
### DBPs Precursors--Natural Organic Matter (NOM)  
Natural organic matter (NOM) is widely regarded as the primary precursor of DBPs. It consists of a complex blend of organic materials with diverse hydrophobic and hydrophilic components, naturally occurring in water sources due to various hydrological, biological,and geological processes. NOM's molecular structure and chemical composition can vary depending on the location and time. NOM displays a broad spectrum of chemical compositions, molecular sizes, functional group chemistries, solubilities, and polarities. Due to its diverse composition, NOM does not have a defined set of functional groups, size distributions, acid-base properties, or chelating capabilities [20,21]. The prevailing view is that the main precursors of DBPs in NOM are hydrophobic compounds with molecular weights typically between 1 and 10 kilodaltons (kDa) [22]. The makeup of a humic substance differs based on the source water, and whether it originates from surface water (from lakes, rivers, or watersheds), wastewater, or groundwater influenced by different human activities. Given this intricate structural and compositional diversity, the process by which DBPs are formed from NOM remains unclear [23]. Organic substances are present in all water types, with the highest concentrations typically found in surface waters, lower concentrations in infiltration waters, and the weakest in groundwater. The removal of NOM during the water treatment process is a key objective. These substances add color to the water, aid in the transport of micropollutants, and can adversely affect the taste and odor of the water. Humic substances are estimated to comprise approximately half of water's total organic carbon content [24]. The decrease in NOM can impact the efficiency of chlorine disinfection by influencing the necessary amount of disinfectant and the formation of DBPs. It is recognized that the biologically resistant fractions of humic and fulvic acids in NOM, typically originating from external sources, exhibit higher reactivity with chlorine. The reduction in NOM can impact the effectiveness of chlorine disinfection in a couple of ways: (a) decreasing NOM levels can lower the chlorine demand, meaning less chlorine is required to achieve the desired disinfection, (b) the biologically refractory humic and fulvic acid fractions from allochthonous (external) sources are more reactive with chlorine. Lowering these NOM components can reduce the formation of potentially harmful DBPs during the disinfection process. In other words, reducing the NOM content of the water can make chlorine disinfection more efficient by minimizing the chlorine dose needed and limiting the generation of undesirable DBPs as byproducts. This is a crucial consideration in water treatment processes. A conventional drinking water treatment process typically involves a series of steps, including coagulation, flocculation, sedimentation, filtration, and disinfection to treat the incoming raw water. The main goals are to reduce the total organic carbon (TOC) content and turbidity to the required levels and to produce final water with minimal taste and odor concerns. Apart from these parameters, the treated water must also meet regulatory standards like the total coliform rule, maximum residual disinfectant level (MRDL), and Stage II Disinfectants and Disinfection Byproducts (D/DBP) Rule. In recent years, numerous feasible distribution system models have been investigated to assist water utilities in making informed operational decisions. However, advanced technologies aimed at enhancing the efficiency of TOC removal have often been associated with high costs and increased complexity. Striking a balance between TOC reduction and chlorination disinfection has been a significant concern for environmental regulators and utility managers since the late 1970s, when research began to elucidate the direct relationship between the formation of THMs and the reaction between TOC and free chlorine.