The laboratory-scale filtration tests of Giardia cysts and Cryptosporidium
oocysts in both 2 mm-Phi glass beads and 2 mm-Phi polystyrene beads filters
were conducted to investigate their filtration behaviors. The protozoan pa
rasites were used as target particles. while the chemical system altered by
changing the electrolyte concentration and pH, The results significantly i
ndicate that ionic strength have a positive effect on the removal efficienc
ies for Giardia cysts and Cryptosporidium oocysts. The removal efficiency o
f two filters for Giardia cysts slightly decreased from pH 2.4 to 8.7 and d
ecreased significantly in pH as pH up to 8.7, while that for Cryptosporidiu
m slightly rippled beyond pH 8.7, and with the decrease in pH up to pH 8.7.
The experimental collision efficiencies from the interactions between coll
oids and the filter media were calculated with a semi-empirical approach of
the single sphere model and clean-bed filtration theory. The results also
indicated that experimental collision efficiencies for (oo)cysts correspond
ed to the (oo)cysts removal efficiencies in all trials, and oocysts exhibit
s higher collision efficiencies than cysts. (C) 2001 Elsevier Science Ltd.
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