Disinfection of biotrated sanitary effluent by UV/H2O2 and O3

Author(s)

Jacqueline Aparecida Malvestiti

• Document type: Doctoral Thesis
• Press: Limeira, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Tecnologia
• Defense date: 2021-02-25

Examining board members

Renato Falcão Dantas; Márcia Dezotti; Raquel Fernandes Pupo Nogueira; Alám Gustavo Trovó; Gustavo Henrique Ribeiro da Silva

• Advisor: Renato Falcão Dantas

Abstract

UV/H2O2 and ozonation treatments are methods capable of removing various classes of contaminants and disinfecting water and wastewater. However, an effluent composition can affect the treatment efficiency delaying the inactivation of microorganisms due to the presence of reactive material that competes to react with oxidants. However, it is not yet clear how each component of sewage can affect processes based on the formation of HO• radicals. In this context, these thesis studied the influence of the main effluents components, industrial contaminants, inorganic constituents (nitrates and carbonates) and metals in the disinfection process using the UV/H2O2 and ozonation. The experiments were carried out under laboratory conditions and consists on the characterization of sanitary effluent; carrying out experiments of UV/H2O2 and ozonation, using experimental planning to verify the influence of the different operational parameters, as well as to evaluate the effects of the sanitary effluent organic matrix, constituted for seven metals (Al, Cr, Cu, Fe, Ni, Pb and Zn), carbonate, nitrate and industrial contaminants (DBP, DEHP and 4-NP), in the inactivation of fecal contamination indicators and in the final effluent toxicity. The results showed that both treatments were negatively affected by the presence of carbonate, nitrate and industrial contaminants, reducing the total coliforms and Escherichia coli inactivation. However, carbonate was the main inhibitor of disinfection. Metals, in general, had a positive influence on the inactivation of indicators, acting as catalysts. The indicators reactivation after 72h of the treatments was more important when the substances that inhibit inactivation (carbonate, nitrate and industrial contaminants) were present, however, it did not reach relevant levels that could have implications for the treated effluent reuse. The disinfection indicators had different sensitivities to the effluent spiked substances, the inactivation of E. coli being more affected than the total coliforms, which can lead to different interpretations of the degree of inhibition, depending on the disinfection indicator used. The components added to the effluent had a negative effect on the effluent toxicity, but at different levels. In general, carbonate and nitrate were the least toxic components and, the industrial contaminants, as well as metals (mainly Cr and Pb) toxic for both tests. However, the final toxicity of the effluent was reduced after the treatments. (AU)

• FAPESP's process: 16/07911-7 - Disinfection of secondary effluents by UV/H2O2
• Grantee: Jacqueline Aparecida Malvestiti
• Support Opportunities: Scholarships in Brazil - Doctorate