Microbiological and chemical characterization of coastal hospital wastewater in Oran, Algeria: Implications for public and livestock health under a One Health framework.

Background and aim: Hospital effluents are a major source of environmental contaminants, harboring pathogenic bacteria, toxic trace metals, and high organic loads. This study aimed to evaluate the bacteriological and physicochemical profiles of wastewater discharged from three coastal hospitals in Oran, Algeria, and to assess the associated public and livestock health risks under the One Health approach.

Materials and methods: A cross-sectional study was conducted from January 2023 to February 2024, involving monthly sampling at three hospitals and one drainage collector. Twenty-six composite samples were collected at three peak daily intervals. Bacteriological analysis targeted Escherichia coli, Staphylococcus aureus, and Salmonella spp. using selective media, membrane filtration, and biochemical confirmation. Physicochemical parameters, including biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), dissolved oxygen (DO), pH, and conductivity, were analyzed using standard American Public Health Association methods. Trace metals (lead [Pb], cadmium, nickel, copper [Cu], zinc) were quantified through atomic absorption spectrometry.

Results: All effluents contained pathogenic bacteria, with peak concentrations of E. coli (up to 34.5 × 10⁶ colony-forming units [CFU]/100 mL), S. aureus (up to 4.5 × 10⁶ CFU/100 mL), and persistent Salmonella spp. detected primarily in warmer seasons. All S. aureus and Salmonella isolates exhibited resistance to multiple antibiotics. Physicochemical assessment revealed elevated BOD_{5 (}190 mg/L-398 mg/L), COD (200 mg/L-590 mg/L), and COD/BOD₅ ratios <2.5, indicating high organic pollution with partial biodegradability. Trace metal concentrations, particularly Pb and Cu, exceeded the World Health Organization discharge guidelines in all samples. Contaminant levels were highest in summer, correlating with increased hospital activity and temperature.

Conclusion: Untreated hospital wastewater in Oran poses a serious threat to public and environmental health. The presence of multidrug-resistant bacteria and toxic metals highlights the urgent need for dedicated hospital wastewater treatment infrastructure. Grazing livestock and marine ecosystems exposed to these effluents are at risk of bioaccumulation and infection. Regulatory enforcement, routine monitoring, and the implementation of sustainable green hospital plans are essential to safeguard health under the One Health paradigm.