Removal of Cryptosporidium spp. oocysts and Giardia spp. cysts at a Waste Water Treatment Plant Garcia, in Blumenau, SC, Brazil

Abstract

Giardia spp. and Cryptosporidium spp. are responsible for a number of outbreaks of gastroenteritis, particularly associated with the consumption of contaminated water. The cysts and oocysts of these protozoa are resistant to environmental variations, as well as to most of the physical, chemical and microbiological processes used in water treatment and sewage plants. This study therefore aimed to detect and evaluate the removal of Giardia spp. and Cryptosporidium spp. in a combined system anaerobic / aerobic Waste Water Treatment Plant (WWTP) located in the city of Blumenau, SC, Brazil. For the study of cysts and oocysts, samples of effluents and sludge from the WWTP were concentrated by filtration using a membrane of cellulose esters and by centrifugation, followed by direct immuno-fluorescence assay (RID) using the MerifluorÒ diagnostic kit. The analysis followed the standards published in APHA (2012) to obtain the physical, chemical and microbiological parameters. High concentrations of Giardia spp. (Max. 900,000 L^-1 cysts) were detected in 83.3% of the analyzed points. Oocysts Cryptosporium spp. were detected at high concentrations (max. 300,000 oocysts L^-1) in 66.6% of the analyzed points. Neither cysts nor oocysts were detected in treated effluent samples. Thus, the combined system of the Garcia WWTP showed a 99.9% efficiency rate for the removal of resistant forms of pathogens, contributing to the reduction of environmental contamination by these pathogens present in the domestic sewage of Blumenau, SC.