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

Abstract

ABSTRACT. For the use of sewage sludge, it is extremely important to consider the microbiological aspect of this byproduct that poses direct and indirect risks to public health as for its inadequate handling and use. This study aimed to quantify Giardia spp. cysts and Cryptosporidium spp. oocysts and infer their viability in sludge samples from two sewage treatment plants. The method used consisted of three successive centrifugations followed by immunofluorescence assay and staining with propidium iodide. Samples were 100% (14/14) positive for cysts and 57.1% (8/14) for oocysts, with higher concentrations and mean viability above 75%. The change in the treatment of activated sludge, from extended aeration to conventional system, caused no difference in the concentration and viability of (oo)cysts.

Sanitary and environmental aspects of sewage sludge management

“…Other parasites of the protozoan family are also present. Corrêa Medeiros and Antonio Daniel (2018) observed the presence of protozoan cysts in 100% of the samples they controlled and the presence of oocysts in more than half the same samples. A change in sludge treatment had no impact on the concentration and viability of these protozoan forms.…”

Drinking water treatment by multistage filtration on a household scale: Efficiency and challenges

“…Samples from the non-woven blanket cleaning water, the DGF drain and the HSSF biological layer were concentrated by triple centrifugation at 1,500 x g for 15 min, following the Medeiros and Daniel (2018) protocol. Samples were kept in 50 mL Falcon tubes for centrifugation at 1,500 x g for 15 min.…”

Household slow sand filters in continuous and intermittent flows and their efficiency in microorganism’s removal from river water

“…Supernatant was discarded until the pellet was 5 mL, and then it was mixed for homogenisation. After another centrifugation (1,500 x g; 15 min), the supernatant of each sample was discarded until 1 mL pellet was left for analysis.Samples from the non-woven blanket cleaning water, the DGF drain and the HSSF biological layer were concentrated by triple centrifugation at 1,500 x g for 15 min, following theMedeiros and Daniel (2018) protocol. Samples were kept in 50 mL Falcon tubes for centrifugation at 1,500 x g for 15 min.…”