POLYMERS FOR USE IN THE MONITORING AND TREATMENT OF WATERBORNE PROTOZOA - Biomaterial Applications: Macro to Nanoscales - page 58

cysts and a second filtration step is performed, this time with a membrane
filter. Next the (oo)cysts are subjected to centrifugation, followed by spe-
cific separation using immunomagnetic beads. Finally, the (oo)cysts are
removed from the beads, placed on a microscope slide and fluorescently
stained before they are examined under the microscope by a highly trained
technician.

FIGURE 3.2

EPA1623 Method.

The figure illustrates the stages in the EPA1623 method which is wide-
ly used for the monitoring of the protozoan (oo)cysts Cryptosporidium and
Giardia (illustration is for Cryptosporidium , though the steps are identi-
cal), along with the recovery rates and timings.
Each stage of the monitoring process reduces the initial 1000 L to
smaller and smaller volumes eventually reaching the 50-100 mL for the
microscope slide. Throughout the process there are significant losses of
(oo)cysts with acceptable recovery rates for this method at just over 10%.
Water companies in the UK report around 30% recovery as an average. It
is clear from the above discussion that sample processing is key to the ef-
fective monitoring of waterborne protozoan. It is extremely unlikely that
any detection technology could reliably detect to the single (oo)cysts level
in 1000 L.
Drawbacks of this approach are that time required for detection, the
potentially low recovery rates, the need of expensive fluorescent reagents
as well as the requirement for highly trained technicians and lab equip-