Hydrogen peroxide in household water treatment and disinfection technologies

• Ano de defesa: 2022
• Autor(a) principal: Silva, Kamila Jéssie Sammarro
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Água para consumo; Drinking water; Inativação de microrganismos; Microorganism inactivation; ODS 6; Oxidação; Oxidation; Point-of-use; Ponto de uso; SDG 6
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/18/18138/tde-05092022-151337/

This thesis was divided into chapters aiming to approach hydrogen peroxide application in household water treatment (HWT) and disinfection technologies by both literature analysis and experimental research, according to aims and hypotheses presented in Chapter 1. Chapter 2 consisted of a review on H2O2 as a standalone disinfectant in the last decade and indicated it has not been much explored in sanitation, less even in HWT. Results from content analysis revealed a knowledge gap for this disinfectant at the household level, as well as practical knowledge research gap due to lack of real-life applications and inconsistencies in operational conditions among the analyzed papers published in the last 10 years. Such opportunities for research were explored in the following chapters. Potentials and constraints of liquid H2O2 individual use in domestic settings were discussed in Chapter 3, which presented a preliminary assessment of hydrogen peroxide compared to chlorine, a classic disinfectant in water treatment plants and at the point of use. Chlorine disinfection efficiency based exclusively on Escherichia coli inactivation was insufficient at the tested conditions and H2O2 was more efficient than chlorine in inactivating Phi X174 bacteriophage. This chapter also indicated that photometric assays may be misleading to evaluate organic matter oxidation by H2O2. Chapter 4 presented effects of the water matrix when H2O2 was applied as a preoxidant, for conditioning natural source waters to a (non-specified) main HWT to follow. Hence, lower concentrations and exposure times were explored (if compared to Chapter 3). Results for H2O2 preoxidation indicated a reduction in virus and E. coli contamination levels in river water, implying that this pretreatment may improve microbiological quality of such matrix prior to other treatments, particularly considering the presence of natural catalysts that might have enhanced oxidation performance for clarification and disinfection. H2O2 preoxidation of groundwater for reducing microbiological load was not encouraged at the tested doses, but further research on H2O2 may help improving the lifespan of the main HWT. A combined treatment was proposed and tested in Chapter 5, and it was based on pasteurization, a well-known intervention for water decontamination in households, assisted by H2O2, leading to satisfactory removals of E. coli and at a wide range of conditions for temperature and hydrogen peroxide dose at a fixed contact time. Empirical models were proposed for inactivation of both target organisms, and synergistic effects were obtained for E. coli inactivation. In Chapter 5, H2O2 has shown to be a possibility 13 for increasing robustness of pasteurization setups for HWT. Overall, this thesis elucidated some of the possibilities and drawbacks of the application of hydrogen peroxide in households and provided background and insight for future work on its implementation as a point-of-use or point-of-entry disinfectant, as well as for design of water treatment systems that include this oxidant at the household level.