Sequential Disinfection: case study of full-scale WWTP

Authors

DOI:

https://doi.org/10.6008/CBPC2179-6858.2018.003.0013

Keywords:

Chlorination, Disinfection, Sinergism, UV Irradiation

Abstract

Domestic wastewater, depending on the treatment process applied, may still have high concentrations of pathogenic microorganisms. Thus, the disinfection step is importante in order to decrease risks to public health. This research aimed to investigate the addition of a chlorination step prior to disinfection with ultraviolet irradiation, in the inactivation of Giardia spp. cysts, Cryptosporidium spp. oocysts and indicator organisms - E. coli, total coliforms and Clostridium perfringens - in a full-scale WWTP. The presence of Giardia cysts was observed in all samples of disinfected wastewater. The (oo)cysts of Giardia and Cryptosporidium remaid viable, 70 ± 15.1% and 59 ± 12%, respectively, after the highest CT applied during chlorination. The bacterium Clostridium perfringens, like protozoan (oo)cysts, proved to be quite resistant to chlorination compared to total coliforms and E. coli.. This same relation of efficiencies was also verified for ultravioleta irradiation. Synergistic effects were found for E. coli, Clostridium perfringens and Giardia spp. in two sequential disinfection trials. Only after application of 8 mg.L-1 of chlorine in sequence to UV irradiation, the microbiological design goal of the WWTP for E. coli was reached: 10³ CFU per 100 mL.

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Author Biographies

Raphael Corrêa Medeiros, Universidade Federal de Santa Maria

Departamento de Engenharia e Tecnologia Ambiental. Área de saneamento ambiental; tratamento de água e águas residuárias; epidemiologia aplicada; qualidade da água.

Luci Sartori, Universidade de Araraquara

Professora Doutora na Universidade de Araraquara (Uniara). Mestrado, Doutorado e Pós doutorado pela Universidade de São Paulo (EESC-USP). Bacharelado e licenciatura em química pela Universidade Federal de São Carlos (UFSCar). Pesquisadora EESC-USP nas seguintes áreas de concentração: engenharia sanitária, tratamento de águas de abastecimento e residuárias; desinfecção de águas de abastecimento e residuárias; flotacão; polímeros como auxiliar de floculação na flotação; desinfecção com ozônio, cloro, ultravioleta e ácido peracético e; reúso de águas residuárias na agricultura. Experiência profissional em empresa pública municipal de saneamento, responsável pela chefia e monitoramento da Estação de Tratamento de Esgoto de São Carlos, São Paulo (ETE Monjolinho). 

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Published

2018-05-23

Issue

Vol. 9 No. 3 (2018): Revista Ibero-Americana de Ciências Ambientais - Fev, Mar 2018

Section

Engenharia Sanitária

License

The CBPC - Companhia Brasileira de Produção Científica (Brazil CNPJ: 11.221.422/0001-03) the material rights of the published works. The rights relate to the publication of the work anywhere in the world, including rights to renewals, expansions and dissemination of the contribution, as well as other subsidiary rights. All electronically published works may subsequently be published in printed collections under the coordination of this company and / or its partners. The authors preserve the copyright, but are not allowed to publish the contribution in another medium, printed or digital, in Portuguese or in translation.