Study of the application of ultraviolet radiation technology in water treatment processes

Abstract

This study investigated the effects of different treatment methods for producing drinking water on various parameters, including the survival of an opportunistic pathogenic bacteria. The work included two approaches: monitoring data analysis obtained along the treatment line, including ultraviolet (UV) radiation, provided by the company Águas do Norte, and experimental assays to evaluate the effect of UV radiation on the removal of carbapenem-resistant Klebsiella pneumoniae and some genes related with antibiotic resistance. Microbiological, chemical, and physical characteristics of raw, filtered, treated with chlorine, and treated with chlorine/UV water were compared based on statistical analysis. This evaluation showed that the treatment is particularly effective in the removal of microorganisms and turbidity. The additional treatment with UV radiation, compared to chlorine treatment, did not show significant differences in the improvement of most of the analyzed parameters. The survival of two strains of K. pneumoniae of clinical (KP2-448) and environmental (SM1) origin was studied at the laboratory scale. Quantitative PCR (qPCR) was used to evaluate the variation of antibiotic resistance genes (blaKPC, blaOXA-1, and sul1), and others related (intl1, qacED1). The results showed varied responses regarding UV-C exposure and subsequent recovery. Ultraviolet (UV) radiation survival assays reinforced its impact on the persistence and bacterial viability. The analysis of the blaKPC/phoE ratio showed a tenfold increase in the relative abundance of the blaKPC gene in the clinical strain of K. pneumoniae after the regrowth phase. In both approaches, it was also done a search for 10 antibiotic resistance biomarkers, that were most of them absent, with exception of the intl1, qacED1 e sul1 genes. These collective insights offer a deeper understanding of antibiotic resistance dynamics and water treatment efficacy, guiding future research directions for optimized strategies.

Date of Award	24 Oct 2023
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Ivone Vaz-Moreira (Supervisor), Adriano José Pereira de Magalhães (Co-Supervisor) & Célia Manaia (Co-Supervisor)