Performance of a small-scale wastewater treatment plant for removal of pathogenic protozoa (oo)cysts and indicator microorganisms

Author(s)

Medeiros, Raphael Correa ^[1] ; Daniel, Luiz Antonio ^[2] ; de Oliveira, Gabriela Laila ^[2] ; Hoffmann, Maria Teresa ^[2]

Affiliation

^[1] Univ Fed Santa Maria, Dept Engn & Environm Technol, Linha 7 Setembro, BR 386, Km 40, BR-98400000 Frederico Westphalen, RS - Brazil

^[2] Univ Sao Paulo, Sao Carlos Sch Engn, Hydraul & Sanitat Dept, Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: ENVIRONMENTAL TECHNOLOGY; v. 40, n. 26, p. 3492-3501, NOV 23 2019.
• Web of Science Citations: 1

Abstract

The protozoa Giardia and Cryptosporidium are associated with numerous outbreaks of waterborne diseases worldwide. This study aimed to evaluate the concentration of Giardia spp. cysts, Cryptosporidium spp. oocysts, total coliforms, Escherichia coli and Clostridium perfringens in raw wastewater and their removals at UASB reactor, activated sludge system (operated conventionally and extended aeration) and slow sand filtration. Giardia spp. cysts were present in 100% and Cryptosporidium spp. oocysts in 31.4% of the analysed wastewater samples. The UASB reactor followed by activated sludge system obtained approximately 2.0 log of removal for total coliforms and E. coli, whereas for C. perfringens and Giardia spp. cysts, it obtained 1 log. There was a high percentage of (oo)cysts still viable after secondary treatment, therefore, the risk of contamination of water courses and, consequently, for public health is considerable. However, after tertiary filtration, no (oo)cysts were found in any of the filtered effluent samples, being a good option for future reuse. Seasonal variations did not affect the concentrations and removals of microorganisms observed. Lack of correlations of concentrations of indicator microorganisms and (oo)cysts raise caveats and doubts regarding the true microbiological quality when using only indicator microorganisms. (AU)

• FAPESP's process: 10/07902-1 - Assessment of the behavior of protozoa Giardia spp. and Cryptosporidium spp. and indicator microorganisms in the wastewater treatment and in river water
• Grantee: Raphael Corrêa Medeiros
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 11/08653-8 - Removal and inactivation of indicator microorganisms, Giardia spp. cysts and Cryptosporidium spp. oocysts in wastewater treatment plants
• Grantee: Luiz Antonio Daniel
• Support Opportunities: Regular Research Grants