Occurrence and separation of Cryptosporidium oocysts in drinking water treatment

The presence of Cryptosporidium sp in Czech drinking water sources was moni tored. High numbers of Cryptosporidium oocysts were found in the Slezska Ha rta reservoir after 1997 summer floods. The influence of iron (III) coagula nt dose, mixing conditions and preozonation on the removal efficiency of Cr yptosporidium oocysts was studied. Low mixing intensity produced flocs with poor settling features. The efficiency of sedimentation expressed as resid ual iron after sedimentation was proportional to removal efficiency of oocy sts. Both underdosing or overdosing of iron (III) coagulant resulted in dec rease of COD, turbidity and oocyst removal. Preozonation positively influen ced removal efficiency of oocysts in the conventional drinking water treatm ent train studied.