Until recently, not much was known about Cryptosporidium
removal by filtration during nonideal
operating periods. With the exception of
formalin-inactivated oocysts, no reliable, quantitative
surrogates for live oocysts have been demonstrated for
a variety of operational conditions and filtration
regimes. In this article, the authors demonstrate that
oocyst-sized microspheres may be a useful tool for
demonstrating and quantifying conventional and inline
filter performance when data are available over a
wide range of oocyst and microsphere removals.
Oocyst-sized microspheres are easier, safer, and less
expensive to work with than Cryptosporidium. In
addition, this approach may be useful to utility managers
in assigning log removal credits for regulatory
purposes.
This work provides an approach for determining a
realizable, quantitative surrogate relationship between
oocysts and oocyst-sized microsphere removals by
filtration. The article also emphasizes that, to be accurate,
process evaluations must consider all operating
periods, not just optimized operation. Includes 22 references, tables, figures.