Removal of the veterinary antibiotics oxitetracycline from contaminated water by solar distillation

Veterinary oxytetracycline (OTC) is a persistent contaminant to conventional water treatments. The present study aims to remove OTC from contaminated water through an alternative technology that is distillation via solar energy, being a promising solution in regions with a high incidence of solar radiation. The experimental research was carried out at the State University of Paraiba (UEPB). A cascade-type solar distiller was used to treat the contaminated water, which was collected in an artesian well and combined with the antibiotic at a concentration of 30.0 mg.L-1. Meteorological parameters were evaluated, and temperature profiles obtained. The heat transfer coefficients were determined. After the distillation process, the presence of the OTC substance was no longer detected, which indicates removal of at least 99.67 % and the distilled water productivity reached 2282.05 mL.m(-2).day(-1). Moreover, considering the physical chemical analyzes of the contaminated and distilled waters, reductions were achieved for pH values, electrical conductivity, turbidity, apparent color and chlorides, and a maximum reduction level of 100.0 % for total hardness, sodium and potassium in distilled water. This shows that the solar distillation process is suitable for obtaining quality water that meets current legislation in Brazil and the world. It is concluded that the solar distillation system used has a real capacity for veterinary OTC removal and water production.