Erythromycin residues concentration in urban wastewater discharged into the Persian Gulf marine environment (a case study: Bandar Abbas city)

As pharmaceutically active compounds (particularly antibiotics) are known emerging contaminants (EC), their occurrence in the environment has high health risks for the living organisms and the public. The effluent of wastewater treatment plants (WWTPs) is the most important source of residues of these compounds in the environment. The urban wastewater of Bandar Abbas is discharged into the marine environment of the Persian Gulf at the rate of 500 to 700 L/s, which could be a potential source of pharmaceutical contamination for the marine ecosystem.

In this research, two main wastewater discharge stations at Gursuzan and Suru were sampled during three phases between December 2020 to February 2021. The concentration of Erythromycin residues, as the first antibiotic clinically used to treat human infections, was assessed by high performance liquid chromatography (HPLC) method.

Data analysis showed that mean (± 95% CI) concentration of Erythromycin in Suru and Gorsuzan stations were 16 ± 1.53 and 19 ± 5.86 μg/L, respectively; which their differences did not differ significantly (p>0.05). Pooled data also indicated that the wastewater discharge contained 13.2 to 23.50 μg/L of Erythromycin (α=0.05). Considering the discharge of high volume of Bandar Abbas wastewater effluent into the Persian Gulf (500-700 L/s) as well as the data obtained from this study, the results of the simulation model showed that 5184×104 L Bandar Abbas municipal wastewater is discharged into the Persian Gulf marine ecosystem daily. This volume contains 0.877×103-1.02×103 g active residues of Erythromycin antibiotic (α=0.05).

The present study is the first report of contamination of residues of medicinal compounds into the Marine Environment of the Persian Gulf by urban wastewater. Regarding the high volume of wastewater discharged, which calls for immediate actions to be taken.