Occurrence, Distribution and Regulatory Assessment of Trihalomethanes and Haloacetic Acids in a Tropical Urban Drinking Water Supply System

Abstract

Objective: To evaluate the concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) in three water treatment plants (WTPs) supplying Salvador-BA, comparing the results with national and international drinking water quality limits.   Theoretical Framework: Chlorine, widely used for water disinfection due to its high microbiological efficiency, reacts with natural organic matter, generating disinfection by-products (DBPs), particularly THMs and HAAs, which are toxic and carcinogenic and whose formation depends on water characteristics and the treatment applied.   Method: Monitoring data from three WTPs supplying Salvador between 2019 and 2022, including THM and HAA concentrations and physicochemical water parameters, were analyzed using data provided by the water utility's central laboratory. A total of 381 THM and 148 HAA analyses were evaluated during the dry and rainy periods.   Results and Discussion: Approximately 60% of the mean THM concentrations exceeded the USEPA limit, and 50% exceeded the values set by Brazil, Canada, and the WHO. For HAAs, in WTPs 1 and 2, 68.8% exceeded the USEPA limit, and 25% exceeded the Brazilian and Canadian limits. Organic carbon, cyanobacteria, and high temperatures favored the formation of these compounds.   Research Implications: The findings reinforce the need to optimize treatment processes, control organic matter in source waters, and expand continuous monitoring of DBPs, thereby contributing to water safety and regulatory compliance.   Originality/Value: This study presents an integrated assessment of THMs and HAAs in Salvador's WTPs, reducing knowledge gaps regarding DBPs in tropical regions and supporting water management and public health policies.