Municipal wastewater spiramycin removal by conventional treatments and heterogeneous photocatalysis

This study assessed the effects and removal options of the macrolide spiramycin, currently used for both in human and veterinary medicine- with a special focus on advanced oxidation processes based on heterogeneous TiO₂^_assisted photocatalysis. Spiramycin real concentrations were investigated on a seasonal basis in a municipal wastewater treatment plant (up to 35μgL^-1), while its removal kinetics were studied considering both aqueous solutions and real wastewater samples, including by-products toxicity assessment. High variability of spiramycin removal by activated sludge treatments (from 9% (wintertime) to >99.9% (summertime)) was observed on a seasonal basis. Preliminary results showed that a total spiramycin removal (>99.9%) is achieved with 0.1gL^-1 of TiO₂ in aqueous solution after 80min. Integrated toxicity showed residual slight acute effects in the photocatalytic treated solutions, independently from the amount of TiO₂ used, and could be linked to the presence of intermediate compounds. Photolysis of wastewater samples collected after activated sludge treatment during summer season (SPY 5μgL^-1) allowed a full SPY removal after 80min. When photocatalysis with 0.1gL^-1 of TiO₂ was carried out in wastewater samples collected in winter season (SPY 30μgL^-1) after AS treatment, SPY removal was up to 91% after 80min.