A persistent antibiotic partitioning and co-relation with metals in wastewater treatment plant—Chlortetracycline

Abstract The addition of high concentration of chlortetracycline (CTC) antibiotic to livestock feed and its resistance toward degradation results in accumulation of CTC in the environment. The strong chelation activity of CTC with metal ions has impact on numerous factors, such as solubility, stability, degradation, and antibacterial activity of CTC in wastewater treatment plant (WWTP). Further, no studies have been carried out on the chelation behavior of CTC with metal ions and its effect on removal efficiency from WWTP. This study attempts to provide the information about CTC distribution in wastewater (WW) and wastewater sludge (WWS) and the role of CTC–metals complexation on this behavior. The analytical method developed in this study combines an existing pre-treatment technique of solid-phase extraction (SPE) with laser diode thermal desorption (LDTD) coupled with tandem mass spectrometry (MS/MS). LDTD–MS/MS analysis has been recently developed to enhance the high throughput capacity in MS by reducing LC–MS/MS runs of 5–30 min to 10–30 s in LDTD–MS/MS run. This study considered the most common, polluting and efficient metal ions (Al(III), Ca(II), Co(II), Cu(II), Fe(III), Mg(II), Ni(II) and Zn(II)) which have a tendency to complex with CTC in WW. Chlortetracycline–metal complex and its mobility in WWTP were well-correlated which showed that CTC concentration in WWS was higher than the WW. These results showed that the water soluble CTC became insoluble and/or relatively less soluble after chelation with metal ions. Furthermore, the results signify the importance of chelation property of CTC and serve as a tool in determining the wastewater treatment plant matrix to be treated and also the type of treatment method to be used.