Optimization of Methodologies to Isolate Cryptosporidium, Giardia and Phage from Raw andTreated Sewage

摘要

The identification and quantification of pathogens in raw and treated wastewater is important forrnmonitoring the efficiency of treatment processes. An assessment of the efficacy of wastewaterrntreatment also has implications for influent water quality for drinking water operations. Treatedrnwastewater effluent may harbor infectious pathogenic microorganisms such as enteroviruses,rnCryptosporidium and Giardia even after standardized treatment processes. The development ofrnmethods to recover Cryptosporidium, Giardia, and enteroviruses from sewage have not been wellrnestablished. Consequently, detailed investigations of the impact of treated sewage on surface waterrnhave not been reported. In this study, ultrafiltration and immunomagnetic separation (IMS)rnmethodologies were optimized to determine and quantify the presence of the target organisms in rawrn(influent) and treated sewage at three wastewater treatment facilities: Las Cruces, NM, El Paso, TX,rnand Juarez, MX. One liter influent grab samples were centrifuged and the pellets were processed byrnIMS and indirect fluorescent antibody (IFA) for Cryptosporidium and Giardia and the supernatant wasrnprocessed by ultrafiltration for phage. Raw sewage seeded recoveries of Cryptosporidium and Giardiarnranged from 42-81% (SD 3-10) and 27-53% (SD 6-10), respectively (n=3 for each site). The recoveryrnfor endogenous phage in raw sewage ranged from 32-50% (SD 10-45) (n=2-4 for each site). Ten literrneffluent grab samples were concentrated by ultrafiltration and the pellets were processed by IMS andrnIFA for Cryptosporidium and Giardia and the supernatant was further concentrated by spin columnrnfor phage. Three replicate challenges were done for each site and recoveries of Cryptosporidium andrnGiardia ranged from 12-25% (SD 4-14) and 1-30% (SD 0.5-21), respectively. Results from this studyrnwill help evaluate the impact that treated wastewater may have on pathogen loads in environmentalrnwaters.