Occurrence and Removal of Macrolides in Municipal Wastewater Treatment Plants: A Review

Introduction: Macrolides are a group of antibacterial agents. Given their clinical importance, and the consistent rise in resistance among pathogenic bacteria, macrolides have been the targets of extensive research. Materials and Methods: This review considered the number of macrolides in different wastewater and the removal of these drugs. The antibiotics were frequently detected in influents and effluents, ranged from ng/L up to lower μg/L. In influent, the highest concentrations of clarithromycin (6080 ng/L), roxithromycin (>103 ng/L), erythromycin (3900 ng/L), and azithromycin (1949 ng/L) were detected in Croatia, Chinese, USA, and Singapore municipal wastewater treatment plants, respectively. Results: The removal efficiency of macrolides during wastewater treatment processes varies and is essentially dependent on a combination of macrolides physicochemical properties, location of municipal wastewater, and the operating conditions of the treatment systems. The application of alternative techniques, including membrane separation, activated carbon adsorption, advanced oxidation processes, biodegradation, and disinfection were the dominant removal routes for macrolides in different wastewater treatment processes. A combination of these techniques can also be used, leading to higher removals, which may be necessary before the final disposal of the effluents or their reuse for irrigation or groundwater recharge. Conclusion: Many antibiotics cannot be removed completely in wastewater treatment processes and would enter into the environment via effluent and sludge. The molecular structure of macrolides and their load-bearing capacity has led to the advantage of biological treatment over other treatments. However, the main part of the treatment has been done using biological treatment.