Tanner Benjamin D, Brooks John P, Haas Charles N, Gerba Charles P, Pepper Ian L
Department of Microbiology and Immunology, University of Arizona, Tucson, Arizona 85721, USA.
Environ Sci Technol. 2005 Mar 15;39(6):1584-90. doi: 10.1021/es0404466.
This study investigated bioaerosol emission rates and plume characteristics of bioaerosols generated during land application of liquid Class B biosolids. In addition, it compared the rate of aerosolization of coliphages and total coliform bacteria during land application of liquid Class B biosolids to the rate of aerosolization during land application of groundwater inoculated with similar concentrations of Escherichia coli and coliphage MS2. Air samples were taken immediately downwind of a spray applicator as it applied liquid (approximately 8% solids) biosolids to farmland near Tucson, Arizona. Air samples were also collected immediately downwind of groundwater seeded with MS2 and E. coli applied to land in an identical manner. Air samples, collected with liquid impingers, were taken in horizontal and vertical alignment with respect to the passing spray applicator. Vertical and horizontal sample arrays made it possible to calculate the flux of microorganisms through a virtual plane of air samplers, located 2 m downwind of the passing spray applicator. Neither coliphages nor coliform bacteria were detected in air downwind of spray application of liquid Class B biosolids. Based on limits of detection for the methodology, the rate of aerosolization during land application of liquid biosolids was calculated to be less than 33 plaque forming units (PFU) of coliphage and 10 colony forming units (CFU) of coliform bacteria per meter traveled by the spray applicator. The rate of aerosolization during land application of seeded groundwater was found to be, on average, 2.02 x 10(3) CFU E. coli and 3.86 x 10(3) PFU MS2 aerosolized per meter traveled by the spray applicator. This is greater aerosolization than was observed during land application of biosolids. Because concentrations of coliphages and coliforms were similar in the liquid biosolids and the seeded water, itwas concluded that some property of biosolids reduces aerosolization of microorganisms relative to groundwater. Additional experiments utilizing a novel air sampling protocol showed that the duration of bioaerosol exposure immediately (2 m) downwind of biosolids spray application is brief and the plume of bioaerosols generated is discrete. Additional air samples showed that aerosolization of coliphages and coliform bacteria after liquid biosolids have been applied to land does not occur at detectable levels.
本研究调查了液态B级生物固体土地施用过程中生物气溶胶的排放速率和羽流特征。此外，还比较了液态B级生物固体土地施用过程中噬菌体和总大肠菌群的雾化速率与接种了相似浓度大肠杆菌和噬菌体MS2的地下水土地施用过程中的雾化速率。在亚利桑那州图森市附近的农田上，当喷雾器施用液态（固体含量约8%）生物固体时，在其下风向立即采集空气样本。同样以相同方式将接种了MS2和大肠杆菌的地下水施用于土地，并在其下风向立即采集空气样本。用液体冲击式采样器采集的空气样本，相对于经过的喷雾器呈水平和垂直排列。垂直和水平样本阵列使得能够计算通过位于经过的喷雾器下风向2米处的空气采样器虚拟平面的微生物通量。在液态B级生物固体喷雾施用的下风向空气中未检测到噬菌体和大肠菌群。基于该方法的检测限，计算得出液态生物固体土地施用过程中的雾化速率低于喷雾器每行进1米产生33个噬菌体噬菌斑形成单位（PFU）和10个大肠菌群菌落形成单位（CFU）。发现接种地下水土地施用过程中的雾化速率平均为喷雾器每行进1米有2.02×10³CFU大肠杆菌和3.86×10³PFU MS2雾化。这比生物固体土地施用过程中观察到的雾化程度更高。由于液态生物固体和接种水的噬菌体和大肠菌群浓度相似，得出结论：生物固体的某些特性相对于地下水降低了微生物的雾化。利用一种新颖的空气采样方案进行的额外实验表明，在生物固体喷雾施用下风向立即（2米处）生物气溶胶暴露的持续时间很短，并且产生的生物气溶胶羽流是离散的。额外的空气样本表明，液态生物固体施用于土地后，噬菌体和大肠菌群的雾化未达到可检测水平。
