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

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 th...

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Bibliographic Details
Published in:Environmental technology 2019-11, Vol.40 (26), p.3492-3501
Main Authors: Medeiros, Raphael Corrêa, Daniel, Luiz Antonio, de Oliveira, Gabriela Laila, Hoffmann, Maria Teresa
Format: Article
Language:English
Subjects:
Activated sludge
Aeration
Clostridium perfringens
Coliforms
Contamination
Cryptosporidium
Cysts
E coli
Escherichia coli
Filtration
Giardia
Indicators
Microorganisms
Oocysts
Protozoa
Public health
Raw wastewater
Reactors
sanitation
Seasonal variations
Secondary treatment
sewage
Upflow anaerobic sludge blanket reactors
viability
Waste analysis
Wastewater analysis
Wastewater treatment
Wastewater treatment plants
Water pollution
Waterborne diseases
Watercourses
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Summary: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.
ISSN:0959-3330
1479-487X
DOI:10.1080/09593330.2018.1480063