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PRELIMINARY COMPARATIVE STUDY OF METHODS TO EXTRACT VIRUS FROM RAW AND PROCESSED SEWAGE SLUDGES
RHODES, E., B. MCMINN, N. BRINKMAN, J. CASHDOLLAR, AND G. FOUT. PRELIMINARY COMPARATIVE STUDY OF METHODS TO EXTRACT VIRUS FROM RAW AND PROCESSED SEWAGE SLUDGES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-07/118, 2007.
The objectives of this task are to:
Two simple virus extraction techniques were compared to an EPA standard method for detection of human enteric viruses in raw sewage sludge and class A biosolids. The techniques were used to detect both indigenous and seeded virus from a plant that distributes class A material produced by a heat drying process. Virus titers were measured using a plaque assay, a quantal assay and an integrated cell culture-reverse transcription-polymerase chain reaction (ICC-PCR) assay. The best extraction technique overall for detection of indigenous and seeded virus by plaque, quantal, and ICC-PCR assays was a simple chloroform-based technique. The detection of indigenous virus in raw sludge was similar for all three methods by the plaque assay, giving an average of 50±21 PFU/4 grams of sludge. Recovery of seeded virus from raw sludge averaged 0.7% for the EPA versus 22±17% for the other two techniques. Recovery of seeded virus from class A biosolids was similar for all techniques, averaging 95±24%. Both the quantal and the ICC-PCR assays outperformed the plaque assay for virus detection. Virus titers were generally 2->10 fold higher by these assays than by the plaque assay.