Wastewater System Efficacy and Environmental Impact: Hawassa Referral Hospital, Ethiopia

Abstract

Hospitals generate significant amounts of infectious and hazardous wastewater, making proper treatment essential. This study aimed to evaluate the characteristics of sewage produced by Hawassa Referral Hospital, the effectiveness of its treatment process, and the potential environmental contamination. Sampling was done periodically (March to October 2024) from 11 locations. Both sampling and analysis were carried out employing standard methods.  Statistical analysis, mean, standard deviation, and a correlation matrix were prepared using physicochemical parameters. The mean concentration of BOD₅ (188.6mg/L), COD (485.5mg/L), TSS (282.9mg/L), EC (312.7µS cm^–1), PO₄^–3 (18.63 mg/L), NO₃^–(18.7mg/L) and turbidity (153.2 NTU) were higher than the maximum permissible level of effluent discharged to lake water while TDS (494mg/L) and SO₄^–2 (37.3mg/L) were below the limit. The concentration of all heavy metals, except Cr⁺⁶, Zn⁺², and Hg⁺², was higher than the Maximum Contaminant Level (MCL). The level of all parameters except (Hg⁺², Pb⁺², Cd^+2, and Ni⁺²) had a significant (P < 0.05) difference between each sampling spot. Likewise, the average Total coliform (TC) and Faecal coliform (FC) were greater than the effluent standard discharged to the lake. As for the performance of each unit of Ponds, Facultative Ponds had good performance on downsizing FC, TC, BOD, TSS, TDS, and Fe⁺³ than other ponds. Alternatively, Maturation Ponds had better performance in dropping of SO₄^–2 and TKN than other Ponds. Likewise, Fish Pond exhibited good reduction of COD and PO₄^3–. Conversely, Fish Ponds performed poorly in reducing FC, Fe⁺³, Mn^+2, and Zn⁺², despite showing good results for TC and FC. Evidently, the Waste Stabilization Ponds (WSPs) were inefficient in treating wastewater, primarily due to poor physical and process design, inadequate waste management practices (identification, sorting, and disposal), and insufficient operation and maintenance. The elevated levels of most wastewater components in samples from the Littoral Zones of Hawassa Lake suggest a potential environmental risk in this area, particularly along the discharge route.