Real scale environmental monitoring of zoonotic protozoa and helminth eggs in biosolid samples in Brazil

Abstract

Biosolid is the product of the activated sludge treatment system and its final disposition is subject of ongoing discussion as this residue can therefore harbor a great number and variety of pathogens. This study was aimed to (1) monitor the presence of Giardia and Cryptosporidium in biosolid samples from a treatment plant in Campinas, SP, Brazil, (2) observe Giardia cyst wall morphological integrity in treated samples using scanning electron microscopy (SEM) and (3) verify the presence and viability of helminth eggs. Cysts were present in 33.3 % of the samples, whereas oocysts were detected in 8.3 %. Viable Ascaris sp. Toxocara sp. and similar to Trichuris sp. eggs were found through the use of Mexican Official Norm. Results demonstrate the difficulties inherent in working with biosolid as factors such as temperature, ionic strength and pH influenced the recovery of cysts and oocysts. Pores and ruptures were not observed in cyst wall visualized by SEM following 45 days of exposure to sunlight, only minimal morphological changes. These observations emphasize both the importance of adequate treatment of sewage sludge and the need to develop appropriate techniques for the detection of Giardia and Cryptosporidium in this type of sample. This is the first time that a study was done in a real scale for biosolid samples in determining the presence of pathogenic protozoa as Giardia and Cryptosporidium in Brazil, and also observed minimal cyst wall damage after sunlight treatment.

<b>Quantification and analysis of the viability of (oo)cysts of pathogenic protozoa in sewage sludge

“…Khouja et al (2010) reported 40% of positive samples for Giardia spp. These results were also higher than those reported by Bonatti and Franco (2014). Only for Cryptosporidium, the positivity of the samples was lower than that verified by Iacovski, Barardi, and Simões (2004).…”

“…The significant concentration of cysts and oocysts in the sludge were greater than that found by Graczyk et al (2008), of approximately 27 Giardia cysts and 14 Cryptosporidium oocysts per gram of STP sludge and that reported by Bonatti and Franco (2014), of up to 4800 Giardia cysts per gram and Gerba, Tamini, Pettigrew, Weisbrod, and Rajagopalan (2011), with concentrations of 10 to 1000 Giardia cysts per gram and 100 to 2000 Cryptosporidium oocysts per gram.…”

Surveillance of Giardia and Cryptosporidium in sewage from an urban area in Brazil

“…In Brazil, these organisms have been found in a variety of samples from different sources including raw water, spring water, bottled water, treated sewage, raw sewage, sewage sludge, and vegetables (ALMEIDA et al, 2015;BONATTI & FRANCO, 2016;BRANCO et al, 2012;FRANCO & CANTUSIO, 2002;SANTOS et al, 2011;TIYO et al, 2015).…”

Remoção de cistos <i>Giardia</i> spp. e oocistos de <i>Cryptosporidium</i> spp. em sistemas de tratamento combinado (anaeróbio/físico-químico) de água residuária

“…O interesse pelo uso agrícola do lodo de esgoto vem crescendo mundialmente por razões econômicas e ambientais (IACOVSKI et al, 2004;BONATTI & FRANCO, 2014).…”

“…no lodo de esgoto que será destinado à aplicação na agricultura. Além da falta de dados no Brasil sobre a presença desses protozoários no lodo (BONATTI & FRANCO, 2014).…”