RoundRobinInvestigation ofMethodsforRecovering Human Enteric Viruses FromSludge

Toselect atentative standard methodfordetection ofviruses insludge theAmerican Society forTesting and Materials D19:24:04:04 Subcommittee TaskGroupinitiated roundrobincomparative testing oftwoproceduresthat, after initial screening ofseveral methodologies, were foundtomeetthebasic criteria considered essential bythetask group.Eight task groupmemberlaboratories agreed toperform roundrobin testing ofthe twocandidate methods, namely, TheEnvironmental Protection Agency orlowpH-AIC13 methodandtheGlass orsonication-extraction method. Fivedifferent typesofsludge were tested. Foreachparticular typeofsludge, a single laboratory was designated tocollect thesludge ina single sampling, makesamples, andshipittothe participating laboratories. Inmostcases,participating laboratories completed allthetestswithin 48h of sample arrival. Toestablish thereproducibility ofthemethods, eachlaboratory tested eachsludge samplein triplicate forthetwocandidate virus methods. Eachprocessed sludge sample was quantitatively assayed for viruses bytheprocedures ofeachindividual roundrobinlaboratory. Toattain a more uniform standard of comparison, a sample ofeachprocessed samplefromalllaboratories was reassayed withone cell lineand passagenumberbya single laboratory (Environmental Protection AgencyEnvironmental Monitoring and Support Laboratory, Cincinnati, Ohio). Whenthedatawere statistically analyzed, theEnvironmental Protection Agency method was found toyield slightly higher virus recoveries forallsludge types, exceptthe dewatered sludge. Theprecisions ofbothmethods were notsignificantly different. Onthebasis ofthese and several other considerations bothmethods arerecommended astentative American Society forTesting and Materials standard methods.