Background and purpose: Karaj River is the biggest aquatic ecosystem in Alborz province which is exposed to a variety of pharmaceutical pollutants. These pollutants have adverse effects of on surface water, biota and even humans. This research aimed to evaluate the level of contamination caused by widely used antibiotics in Karaj River, effluent, and wastewater treatment plants in 20 stations.
Materials and methods: Sample preparation and filtration was done and concentrations of pharmaceutical pollutants were measured using HPLC (mobile phase). Data analysis was performed in SPSS V21.
Results: The mean concentrations of antibiotics in Karaj River were as follow: amoxicillin 2.305, erythromycin, 2.229, gentamicin 2.231, and cephalexin 2.325 µg/l. In treatments plants higher concentrations of these antibiotics were found: amoxicillin 7.240, erythromycin 7.301, gentamicin, 7.390, and cephalexin 6.779 µg/l. In wastewater treatment plants the mean concentrations of amoxicillin, erythromycin, gentamicin, and cephalexin were 5.289, 5.362, 5.344, and 4.608 µg/l, respectively.
Conclusion: According to the significant positive correlation between the concentration of such pollutants in water samples, sewage and wastewater, the main reasons for entering these pollutants are believed to be the pharmaceutical residue discharges in urine and sanitary sewer network, septic tanks and sewage discharge of untreated aquaculture facilities in Karaj River. Inefficient treatment processes in controlling and reducing antibiotics are the main causes of high concentration of these pollutants in the environment that needs urgent control.