AWWA WQTC65852

To date, most Cryptosporidium inactivation studies have been done at the bench scale. The problem with designing full-scale reactors is that the Cts (disinfectant concentration x exposure time, based on time that 10% of influent water reaches the effluent) from batch reactors do not account for the system hydraulics. As a result, direct quantification of disinfection performance is preferred to better evaluate Cryptosporidium inactivation. Alternatives include the use of biological (Kim et al., 2002) and non-biological (Chiou et al., 1997; Marinas et al., 1997, 1999; Baeza and Ducoste, 2004) surrogate indicators. Non-biological indicators are of particular interest, since no special biological facilities are needed. Direct quantification can be made with the surrogate, since it already takes into account system hydraulics. The non-biological surrogate indicators that have been used for chemical disinfection performance are fluorescent dye polystyrene microspheres. These non-biological microspheres have been used by Chiou et al. (1997) to mimic Giardia inactivation with ozone disinfection, by Marinas et al. (1999) to mimic Cryptosporidium inactivation with ozone disinfection in batch and full-scale water treatment plants, and recently by Baeza and Ducoste (2004) to mimic Cryptosporidium sequential disinfection in batch reactors. All of these studies have shown promising results in using microspheres to mimic microbial inactivation. However, no study has used microspheres with sequential disinfection in a continuous flow system to mimic Cryptosporidium inactivation. Hence, this study was performed to evaluate this nonbiological approach in continuous-flow sequential disinfection processes. Includes 19 references, tables, figure.