Characterization and removal of antibiotic residues by NFC-doped photocatalytic oxidation from domestic and industrial secondary treated wastewaters in Meric-Ergene Basin and reuse assessment for irrigation

Abstract: Antibiotics are important contaminants that have become an increasingly big problem due to the discharge of
the receiving environment. The presence of these organic based pollutants in influent wastewater can inhibit the
biological processes and resist to degradation in wastewater treatment plants. Moreover, the consumption of
agricultural products, irrigated with water containing antibiotic residues, leads to major harmful effects to the
human body through the food chain. In this study; firstly, a conventional characterization was made in terms of
COD, TOC, SS, color and of antibiotic residue characterization of untreated raw (influent) and biologically
treated (effluent) water from domestic and industrial wastewater treatment plants located in the Meriç-Ergene
Basin. After that, photocatalytic activity test was run under visible light for selected antibiotics (Erythromycin,
Ciprofloxacin, Sulphametoxasol) which were detected by HPLC MS/MS in excess amount. Finally, for the
photocatalytic oxidation, a new generation NFC (Nitrogen-Floride-Carbon)-doped titanium dioxide photocatalyst,
which has never been studied in the literature before, was prepared according to the sol-gel method without
using thermal processing. Photocatalysts were characterized by UV–vis DRS reflectance and Laser Raman
Spectra measurements. All other analyzes were made according to the standard methods. Considering the
conventional characterization results; investigated domestic wastewaters exhibited moderate characteristics
while industrial wastewater samples had strong characteristics in terms of COD, TOC and SS pollution in accordance
with the literature. By the way, contrary to expectations, antibiotic residue results have proved that the
effluent wastewater contains more antibiotics than the influent. This can be explained by the fact that, some
antibiotics in domestic wastewaters are probably already trapped in feces and cannot be purified by conventional
systems since they are released after biological treatment, as mentioned similar studies in the literature.
Moreover, by means of 7 h NFC-doped photocatalytic oxidation under visible light, beside approximately % 62 to
%79 COD and 62%–86% TOC removal, %99 to %100 removal of antibiotic residue was provided. According to
these results, domestic and industrial secondary treated wastewaters in Meric-Ergene Basin can be advance
treated, succesfully, with NFC-doped photocatalyst to remove antibiotic residues besides conventional pollutants.
This result show that Meriç-Ergene discharge criteria determined by Forest and Water Ministry of Turkey
can be provided with this new type photocatalytic process and healthy reuse of this river for irrigation will be
possible.