Assessment of the Accuracy of A Method Used for Quantification of Ascaris Eggs in Sewage Sludge

Abstract

The application of sewage sludge on arable and grassland soils is dependent on the assurance that the concentrations of pathogens present in the biosolids do not pose health risks to either individuals or animals. Therefore, the use of appropriate protocols for the detection and quantification of pathogens in sludge samples is essential. An ideal method for the quantification should provide high sensitivity, accuracy and precision, but shall also follow a program that ensures the quality of the data produced. Methodologies that ensure accurate and reliable responses in a short period of time are also desirable. Therefore, this work aimed at the assessment of the accuracy of the method specified by the U.S. Environmental Protection Agency (USEPA) and used for the quantification of viable Ascaris eggs eventually present in biosolids. This study was carried out using samples of anaerobic sewage sludge collected from two drying beds, one receiving sludge from an upflow anaerobic sludge blanket reactor, and the other receiving sludge from a septic tank.

Potentials and challenges in the isolation and detection of ascarid eggs in complex environmental matrices

“…In order to reduce the volume of the sample, sedimentation is conducted to separate solid particles, including the eggs, from the liquid phase. Efficacy and velocity of sedimentation is influenced by various factors like the sample matrix, viscosity of the matrix, the matrix-liquid ratio, size and density of eggs, their properties to coagulate with other particles as well as the size and shape of the container used for sedimentation ( da Rocha and Braga, 2016 ). The duration of sedimentation depends on these factors and can therefore vary greatly.…”

“…To circumvent egg-particle adherence, detergents are often supplemented to flotation solutions. However, it should be considered that salts tend to precipitate when certain detergents, such as Tween®20/40/80, are present ( da Rocha and Braga, 2016 ). Another important point in selecting a flotation solution constitutes the reliability, reproducibility and the hazardousness of the substance.…”