Comparison of methods for the concentration ofCryptosporidiumoocysts andGiardiacysts from raw waters

Abstract

This study compared the recovery of Cryptosporidium oocysts and Giardia cysts ((oo)cysts) from raw waters using 4 different concentration-elution methods: flatbed membranes, FiltaMax foam, Envirochek HV capsules, and Hemoflow ultrafilters. The recovery efficiency of the combined immunomagnetic separation and staining steps was also determined. Analysis of variance of arcsine-transformed data demonstrated that recovery of Cryptosporidium oocysts by 2 of the methods was statistically equivalent (flatbed filtration 26.7% and Hemoflow 28.3%), with FiltaMax and Envirochek HV recoveries significantly lower (18.9% and 18.4%). Recovery of Giardia cysts was significantly higher using flatbed membrane filtration (42.2%) compared with the other 3 methods (Envirochek HV 29.3%, FiltaMax 29.0%, and Hemoflow 20.9%). All methods were generally acceptable and are suitable for laboratory use; 2 of the methods are also suitable for field use (FiltaMax and Envirochek HV). In conclusion, with recoveries generally being statistically equivalent or similar, practical considerations become important in determining which filters to use for particular circumstances. The results indicate that while low-turbidity or "finished" waters can be processed with consistently high recovery efficiencies, recoveries from raw water samples differ significantly with variations in raw water quality. The use of an internal control with each raw water sample is therefore highly recommended.

Detection of viable hookworm ova from wastewater and sludge

“…However, the recovery rates of ova using HFUF from raw wastewater were found to be highly variable (0.3-35%) between the WWTPs. Such discrepancy again could be attributed to the variable solid contents present in wastewater samples in time and space (Simmons et al, 2001;Ferguson et al, 2004). The turbidity of raw wastewater collected from both the WWTPs were much higher (246-286 NTU) than the treated wastewater (86-197 NTU).…”

“…This could be attributed to the low suspended solid content of treated wastewater making it possible to pass through the membrane using the membrane filtration method. It has been previously reported that ova were better retained on the membranes during filtering of water samples compared to a potential loss of ova during floatation (Nieminski et al, 1995;Ferguson et al, 2004). Because of the high solid contents and turbidity, the membrane filtration method was not suitable for processing raw wastewater and sludge samples.…”

“…The recovery rate of this method can range from 65-74% from wastewater samples (Maya et al, 2006). This method, however, is laborious and time-consuming due to the requirement of multiple steps of washing and concentrating the samples (Ferguson et al, 2004).…”

“…Several methods have also been used to recover various microorganisms including ova from water and soil samples. Those include centrifugation (Whitmore and Carrington, 1993;Higgins et al, 2003), hollow-fiber ultrafiltration (HFUF) (Simmons et al, 2001;Ferguson et al, 2004;Hill et al, 2005;Hill et al, 2007), filtration (Nieminski et al, 1995;Maya et al, 2006;Alli et al, 2011), and flotation (US EPA, 1999;Bowman et al, 2003;de Victorica and Galván, 2003;Bastos et al, 2013).…”

“…This method, however, is laborious and time-consuming due to the requirement of multiple steps of blending, washing, settling, filtering, floating and centrifuging (Ferguson et al, 2004). The recovery rate of this method is reported as being suboptimal and variable depending on the matrices (65-74% and 26-82% from raw wastewater and sludge) (Bowman et al, 2003;Maya et al, 2006;Bastos et al, 2013).…”