Tetracycline antibiotics as precursors of dichloroacetamide and other disinfection byproducts during chlorination and chloramination

Abstract

Pollution of natural water and even source water with pharmaceuticals is problematic worldwide and raises concern about the possibility of disinfection byproduct (DBP) formation during subsequent water treatment. In this study, the formation of DBPs, especially dichloroacetamide (DCAcAm), was investigated during chlorination and chloramination of tetracyclines, which are a class of broad-spectrum antibiotics. DBPs including DCAcAm were formed during chlorination and chloramination of tetracycline (TC). Although the concentrations and theoretical cytotoxicity of the DBPs formed from TC were affected by the contact time, disinfectant dose, and pH, DCAcAm was the main contributor determining the yields and cytotoxicity of the measured DBPs. The DCAcAm yields from four tetracycline antibiotics ranged from 0.43% to 54.26% for chlorination. For chloramination, the DCAcAm yields reached 44.57%, and the nitrogen in DCAcAm mainly came from tetracycline antibiotics rather than chloramines. ClO 2 pre-oxidation and UV photolysis decreased DCAcAm formation during chlorination and chloramination of TC. The high yields observed in this study suggest that tetracycline antibiotics are possible precursors of DCAcAm.

The Effect Review of Various Biological, Physical and Chemical Methods on the Removal of Antibiotics

“…Similarly, Efraim et al [89] found that electrogenerated active chlorine had a better removal effect on antibiotics; the removal rate of ciprofloxacin and norfloxacin was close to 100%, and the removal rate of levofloxacin was about 75%. Although the chlorination method has a better removal effect on antibiotics, the byproducts generated by the chlorination method are often more toxic, which further limits the research and application of the chlorination method [90]. For example, He et al [91] found that the antibiotic fleroxacin forms halogenated disinfection byproducts during the chlorination degradation process, and the oxidative degradation products have higher biological toxicity.…”

Chloramine Disinfection of Levofloxacin and Sulfaphenazole: Unraveling Novel Disinfection Byproducts and Elucidating Formation Mechanisms for an Enhanced Understanding of Water Treatment

“…Previous studies have found that antibiotics can be transformed into N-DBPs by reacting with the disinfectant chloramine; for example, metronidazole could be oxidized by monochloramine disinfectant to form dicholoacetamide (DCAcAm) [ 32 ] and oxytetracycline could form the N-nitrosodimethylamine (NDMA) [ 33 ], which have been cited as research priorities by the U. S. EPA owing to their greater cytotoxicity and genotoxicity than currently regulated C-DBPs (e.g., THMs) [ 34 ]. The intricacies of DBP formation during disinfection are challenging to elucidate due to the influence of various factors such as pH values [ 35 ], disinfectant concentration, and inorganic ions [ 36 , 37 , 38 ]. Previous studies have highlighted the pH-dependent yield of NDMA during chloramine disinfection, emphasizing the significant impact of pH on DBP formation [ 33 ].…”