Physicochemical, Heavy Metal and Microbiological Evaluation of Kality Wastewater Treatment Plant: Treatment Efficiency and Implications for Antimicrobial Resistance Within a One Health Nexus
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Date
2025
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Addis Abeba University
Abstract
Background: Antimicrobial resistance (AMR) poses a growing threat to global health and economic stability. Wastewater treatment plants (WWTPs) serve as critical hotspots for resistant pathogens due to contaminants of emerging concerns (CECs). Understanding the role of CECs in AMR within WWTPs and One Health domains is essential for effective mitigation. However, gaps remain in wastewater-based AMR epidemiology and its driving factors. This study aimed to evaluate CECs of Kality WWTP along antimicrobial resistance and efficiency of treatment within one health nexus. Methods: A cross-sectional study was conducted at Kality WWTP and its surrounding areas. A total of 173 samples were aseptically collected from wastewater, humans, and cattle near and downstream to the WWTP. Physicochemical parameters, bacteria load, and heavy metals-including lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), manganese (Mn), and cadmium (Cd) – were analyzed for using inductively coupled plasma optical emission spectrometry. To ascertain quantitative parameters, triplicate independent replication sets were utilized. E. coli was isolated, identified, and tested for extended spectrum beta lactamase (ESBL) and carbapenemase producing (CP) E. coli using the double disk synergy test and the modified carbapenem inactivation method, respectively. Data analysis employed logistic regression and one-way ANOVA, with statistical significance set at p < 0.05. Results: Overall, 20.23% (35/173) of E. coli isolates were confirmed using iochemical and supplementary tests. The AMR study showed 97.1% of the isolates demonstrated multidrug resistances (MDR), with 20% of them were ESBL and 5.7% were CP E. coli. Isolates from the trickling filter exhibited co-resistance, both ESBL and CP E. coli, emphasizing rise of resistance mechanisms within the WWTP. The findings indicated a notable 1.47 log reduction in bacterial load, with an overall removal efficiency of 96.5%. Although effective removal rates were recorded for most physicochemical parameters and heavy metals, the concentrations of Cd (6.9%) and Mn (21.6%) remained high in the effluent.
Conclusions: These findings underscore the critical role of WWTP as hotspots for MDR pathogens and highlight the need for improved wastewater treatment and sanitation practices to safeguard the environment and public health within a one health nexus.
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Keywords
Antimicrobial resistance, Bacterial load, Carbapenemase and ESBL producing, E. coli, Heavy metals, One health, Removal efficiency, WWTP