• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.399-405
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• 2010

In order to quantify removal efficiency of Cryptosporidium in water treatment process and evaluate factors influencing removal efficiency of Cryptosporidium in each step of water treatment process, large pilot plant system ($100m^3/day$) and Cryptracer, surrogate of Cryptosporidium, were used. The removal efficiency of Cryptracer was around 0.8~1 log in coagulation process and 3.3~4.8 log in sand filtration process under ordinary environmental conditions. Factors influenced removal efficiency of Cryptracer were high fluctuate turbidity and water temperature. High fluctuate turbidity made difficult to adjust optimum PAC concentration, caused to drop removal efficiency of coagulation process (0.5 log). Inadequate coagulation process influenced to sand filtration process (2.1 log), caused to decline of removal efficiency in the whole process (2.6 log). Low temperature below $2^{\circ}C$ also influenced coagulation process (0.6 log). Therefore, It is shown that careful attention in the control of Cryptosporidium is needed in flood period, when high fluctuate turbidity would be, and winter period of low temperature.