Bioaerosol Emission Rate and Plume Characteristics during Land Application of Liquid Class B Biosolids

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• 作者：Benjamin D. Tanner ; John P. Brooks ; Charles N. Haas ; Charles P. Gerba ; and Ian L. Pepper
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：March 15, 2005
• 年：2005
• 卷：39
• 期：6
• 页码：1584 - 1590
• 全文大小：566K
• 年卷期：v.39,no.6(March 15, 2005)
• ISSN：1520-5851

文摘

This study investigated bioaerosol emission rates andplume characteristics of bioaerosols generated duringland application of liquid Class B biosolids. In addition, itcompared the rate of aerosolization of coliphages and totalcoliform bacteria during land application of liquid ClassB biosolids to the rate of aerosolization during land applicationof groundwater inoculated with similar concentrations ofEscherichia coli and coliphage MS2. Air samples were takenimmediately downwind of a spray applicator as it appliedliquid (~8% solids) biosolids to farmland near Tucson,Arizona. Air samples were also collected immediatelydownwind of groundwater seeded with MS2 and E. coliapplied to land in an identical manner. Air samples, collectedwith liquid impingers, were taken in horizontal andvertical alignment with respect to the passing sprayapplicator. Vertical and horizontal sample arrays made itpossible to calculate the flux of microorganisms through avirtual plane of air samplers, located 2 m downwind ofthe passing spray applicator. Neither coliphages nor coliformbacteria were detected in air downwind of sprayapplication of liquid Class B biosolids. Based on limits ofdetection for the methodology, the rate of aerosolization duringland application of liquid biosolids was calculated to beless than 33 plaque forming units (PFU) of coliphage and 10colony forming units (CFU) of coliform bacteria permeter traveled by the spray applicator. The rate ofaerosolization during land application of seeded groundwaterwas found to be, on average, 2.02 × 10³ CFU E. coli and3.86 × 10³ PFU MS2 aerosolized per meter traveled by thespray applicator. This is greater aerosolization than wasobserved during land application of biosolids. Becauseconcentrations of coliphages and coliforms were similarin the liquid biosolids and the seeded water, it was concludedthat some property of biosolids reduces aerosolization ofmicroorganisms relative to groundwater. Additionalexperiments utilizing a novel air sampling protocol showedthat the duration of bioaerosol exposure immediately (2m) downwind of biosolids spray application is brief and theplume of bioaerosols generated is discrete. Additional airsamples showed that aerosolization of coliphages andcoliform bacteria after liquid biosolids have been appliedto land does not occur at detectable levels.