Formation Mechanisms, Toxicological Risks, and Control Strategies for Disinfection Byproducts in Disinfected Cellar Waters of Karst Regions

Cellar water is widely used as a drinking water source in rural regions across many parts of the world. However, large seasonal variations in rainfall and the use of a variety of sources result in considerable variations in water quality, and an excessive microbial load is common. The formation and health risks associated with disinfection byproducts (DBPs) generated during treatment were investigated in dissolved organic matter (DOM) from water samples collected from 13 cellars in the Guangxi region, and the seasonal formation patterns of 51 DBPs were compared for HOCl, NH2Cl and ClO2 treatments. The dominant DBPs were trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs), which increased with pH, and peaked in winter with DBP formation in the order: HOCl > NH2Cl > ClO2. Hydrophobic DOM and fractions smaller than 1 kDa exhibited the greatest formation potential for carbonaceous DBPs, whereas hydrophilic DOM favored the formation of nitrogenous and iodinated DBPs. However, unregulated HANs and iodinated HAAs were identified as primary contributors to overall DBP toxicity, thus highlighting the need for targeted DBP control strategies and providing new insights into overlooked risks associated with cellar water disinfection.