Objective: This work aimed to investigate the carbon-, nitrogen-, iodine-containing disinfection by-products (DBPs) formation and pollution situation in different treatment processes and pipe water of a water plant in Jiangsu province China.
Methods: 12 water samples were collected from raw water, different time points after the addition of chlorine, finished water and pipe water in July, 2011. Trihalomethanes (THM(4)), haloacetic acids (HAA(6)), haloacetonitriles (HAN(s)), chloropicrin (CPs), haloketones (HK(s)), iodoform (IF) and iodoacetic acid (IAA) were detected by gas chromatography with electron capture detector (GC-ECD) after liquid-liquid extraction. Nitrosamines (NAms) were detected by gas chromatography with mass spectrometer (GC-MS) after solid-phase extraction. The concentration of DBPs was represented as the mean of duplicate samples.
Results: Most DBPs were found in water treatment processes except dibromochloromethane (0.61 µg/L), chloroform (1.64 µg/L) and N-nitrosodimethylamine (3.06 ng/L), which were detected in raw water. Pre-chlorination formed HAA(6) (5.01 µg/L), HKs (0.66 µg/L), HANs (0.57 µg/L) and NAms (98.09 ng/L). Chlorination and post-chlorination led to a dramatic increase in the levels of THM(4), HAA(6) (70.31 and 43.71 µg/L, respectively), while Nams didn't increase. In finished water, bromodichloromethane (34.12 µg/L) had the highest concentration among THM(4) (70.31 µg/L), and so was trichloroacetic acid (13.45 µg/L) among HAA(6) (43.71 µg/L). Levels of HANs, HKs, and CPs were 14.96, 2.32, 0.96 µg/L, respectively. Levels of N-nitrosodimethylamine and N-nitrosodipropylamine were 21.22, 69.43 ng/L, respectively. IAA, IF and other six NAms including N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidine, N-nitrosomorpholine, N-nitrosopiperidine and N-nitrosodibutylamine were not detected in all water samples.
Conclusion: Levels of DBPs in this water plant are relative high.and measures should be taken to control DBPs.