Abstract:
Objective To investigate the distribution of disinfection byproducts, trihalomethanes (THM)s and haloacetic acids (HAAs), in rural drinking water supplied through centralized water supply systems in Jiangsu Province and its influencing factors.
Methods In the dry and wet seasons of 2023, 5 154 drinking water samples (covering all rural villages and towns) were collected, including 115 finished water samples and 5 039 terminal water samples. According to the Standard Examination Method for Drinking Water (GB/T 5750-2023), the drinking water samples were analyzed for the concentrations of THMs (trichloromethane CF, dibromochloromethane DBCM, bromodichloromethane BDCM, and bromoform BF) and HAAs (dichloroacetic acid DCAA and trichloroacetic acid TCAA). The results were evaluated using the Standards for Drinking Water Quality (GB 5749-2022). The rank sum test was used to compare the concentrations of THMs in the drinking water across different groups.
Results In 2023, the detection rates of CF, DBCM, BDCM, BF, DCAA, and TCAA in the rural drinking water in Jiangsu Province met the requirements as specified in GB 5749-2022. The detection rates of THMs and HAAs were 83.46% and 25.70%, respectively. The median concentrations (M) of THMs and HAAs were 32 and 2 μg/L, respectively. The concentration of THMs was higher in wet seasons (M=33 and 29 μg/L, respectively) than in dry seasons. The concentration of THMs was higher for lake water sources than for river water sources and reservoir water sources (M=43, 30, and 29 μg/L, respectively). The concentration of THMs was higher in terminal water than in finished water (M=32 and 25 μg/L, respectively). The concentration of THMs was significantly higher in water disinfected with sodium hypochlorite than in water disinfected with liquid chlorine, monochloramine, and compound chlorine dioxide (M=34, 30, 27, and 14 μg/L, respectively) (P < 0.05).
Conclusion The concentrations of THMs and HAAs in the rural drinking water in Jiangsu Province meet the relevant standard. However, the detection rates of THMs are high, making it a key indicator for risk management of disinfection byproducts. The concentrations of THMs are influenced by seasons, water sources, disinfection method, and water treatment processes.