Emerging pollution, antimicrobial resistance, and the applicability of biochar adsorbents: A comprehensive study in African water systems

Abstract

The impacts of antimicrobial resistance (AMR) extend far beyond clinical settings, permeating into agriculture and the economy, precipitating dire consequences such as compromised treatment efficacy, diminished agricultural productivity, and substantial economic burdens. This study aimed at investigating the occurrences, composition and distribution of antimicrobial pollutants and further study the remediation of lamivudine and ciprofloxacin from synthetic solutions onto JS biochar using a response surface methodology (RSM) based on optimal design. Results indicates identification of Klebsiella spp., Proteus spp., Pseudomonas aeruginosa, and Escherichia coli and were resistant to at least 1 of the tested antibiotics, indicating their presence in wastewater and urban receiving waters. Higher proportion of multi-drug resistance (MDR) in Escherichia coli,83%, than Klebsiella spp., 68.5% and Pseudomonas aeruginosa, 20%. All bacterial species highly resisted penicillin (P), while showed less resistance to gentamycin (CN). The isolates contained sulphonamide resistant genes (Sul 1 and Sul 2), tetracycline-resistant genes (Tet A, Tet B – 1, and Tet D) and β-lactamases (bla CTX-M and bla SHV), and Escherichia coli harboured more MDR genes (39%), followed by Klebsiella spp., 22%. JS biochar was amorphous, with porous, rough surface and potential functional groups for adsorption of contaminants. Further, results indicate increase in carbon content of JS biochar from 64.25-87.93 (wt.%) and nitrogen from 2-2.29 (wt.%) when calcination temperature increased from 400℃ to 600℃, with highest surface area of 261.2 m2/g and adsorption capacity of 555.55 mg/g for ciprofloxacin and 400 mg/g for lamivudine. Lamivudine removal had a model regression coefficient R2 , adjusted R2, and predicted R2 of 0.9934, 0.9761, and 0.8340, respectively. While for the ciprofloxacin model, the regression coefficient R2, adjusted R2,and projected R2 were 0.9968, 0.9891, and 0.8023, respectively. The maximum experimental removal efficiency of lamivudine and ciprofloxacin onto JS biochar reached 84.9% and 94.46%, respectively. Isotherm data indicated lamivudine and ciprofloxacin adsorption onto JS biochar followed the Freundlich isotherm. The study identified antimicrobial residues as well as the presence of antibiotic resistant bacteria in water. It also demonstrated the effectiveness of JS biochar adsorbent for remediation of lamivudine and ciprofloxacin from synthetic water, indicating future improvement and use in mitigating antimicrobial resistance.