Antibiotic Residues in Effluent from the Cocody-Angré University Hospital Center (UHC), Côte d’Ivoire

Abstract

This study assessed the occurrence and removal of amoxicillin (AMX), ceftriaxone (CTR) and gentamicin (GM) in effluents from the Cocody-Angré University Hospital Center, Côte d’Ivoire. Four sampling campaigns were conducted between 24 November and 28 December 2023 at the inlet and outlet of the hospital wastewater treatment plant. Daily composite samples were analysed for physicochemical parameters and antibiotic residues using HPLC-UV methods. The raw effluent showed a high organic and suspended-solids load, with chemical oxygen demand (COD) of 449.5 mg O₂/L, biochemical oxygen demand (BOD₅) of 112.26 mg O₂/L and suspended solids (SS) of 227 mg/L. The COD/BOD₅ ratio was 4.00, indicating low biodegradability. Median inlet concentrations were 0.63 µg/L for AMX, 0.55 µg/L for CTR and 1.06 µg/L for GM. Treatment reduced COD by 68%, BOD₅ by 59% and SS by 73.56%. Antibiotic removal differed markedly among the three compounds: CTR decreased by 83.63%, GM by 19.81%, whereas AMX showed a negative removal rate of −65.07%, with a higher outlet concentration than inlet concentration. These findings indicate that the existing biological treatment reduced conventional pollution indicators but did not achieve consistent removal of all investigated antibiotic residues. The results support careful evaluation of additional treatment options for limiting pharmaceutical micropollutant discharge from hospital wastewater.