Removal of Antibiotics from Wastewater by Comparison of Coagulation, Membrane and Adsorption Methods

In the present study, oxytetracycline (OTC) was selected as a medical contaminant with an organic structure to increase the efficiency and feasibility of comparison with other research studies. Therefore, the removal of OTC from medicinal effluents using different methods; namely, activated carbon, bentonite adsorption, iron(III) chloride coagulation, membrane filtration and reverse osmosis (RO), was investigated. Results indicated that the removal of soluble antibiotics in the factory wastewater by adsorption method was between 35% and 77%, at a pH of 6.5 and the total dissolved solids (TDS) and OTC concentration were reduced by 55% and 77%, respectively. In the coagulation method, where the suitable pH ranges from 5.5 to and 7.5, the optimal dosage of iron (III) chloride coagulation was between 40 and 100 mg/l, which resulted in 98.7% of OTC removal. It was concluded that the highest OTC adsorption of 98.7% in the RO membrane and TDS removal were obtained at a pressure of 9 bars. All the experiments on these membranes were performed within 4 months and the membranes still performed well. Therefore, it is concluded that long-term operation has little effect on the performance of the membrane and this membrane is a suitable membrane for the concentration of OTC. Finally, the RO is defined as the suitable method for OTC removal, after passing once through the membrane, while the other methods are proper to be used in the pre-treatment of medicinal wastewater.