Researchers Find No Staph. aureus Bacteria In Air Tests at Land Application Sites

Problem:

Community groups opposed to land application of biosolids often form loose networks, putting forth allegations that S.aureus is found in biosolids and causes adverse health effects and even death. A new allegation, Pepper said, claims that irritant chemicals in the environment increase a person’s susceptibility to the bacteria. The bacteria are prevalent, found in 25% of children, 20% to 40% of adults and 90% of hospitals

Challenge:

The data from the university’s tests filled a scientific void. No study has been conducted, until this one, to see whether there was a link between the bacteria and land application. Because of the void, land appliers and wastewater treatment plants were left without a strong argument to counter those who oppose the practice. Many of the groups have been successful in arguing county commissioners to limit land application. Approximately 200 counties across the county currently ban or severely limit the land application of biosolids.

Solution:

In what could be useful information for government agencies, biosolids land application companies, and municipal wastewater treatment plants, scientists have concluded that the chance of someone contacting Staphylococcus aureus through the air is “exceedingly low”.

Researchers from the University of Arizona took five air samples near raw sewage sites and 23 samples from land application sites, including eight from Class A sites and 15 that were using Class B material. Samples were taken from trucks loading and unloading the biosolids. Some samples were taken within six feet of the land-application activities.

The results of the study were presented at the Joint Residuals and Biosolids Management Conference and Exhibition, held Feb. 19-22 in Baltimore, and sponsored by the Water Environment Federation and the American Water Works Association. Ian Pepper, the director of the Environmental Research Laboratory at the university, provided the research team’s results.

Although the bacteria were detected in three out of the five raw sewage air samples, “it was never detected in 23 biosolids land-application samples,” Pepper said. The doctoral students working on the study “wanted to find something,” eagerly were placing the detection equipment close to and downwind from the trucks spreading the material.

“This study provides the scientific evidence for an absence of S.aureus in land-applied biosolids,” Pepper said.

Contact: Ian Pepper, University of Arizona, (502) 626-3328.

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