Tracking Airborne Legionella and Legionella pneumophila at a Biological Treatment Plant

Abstract

Biological treatment plants are frequently used to degrade organic substances in wastewater from wood refinement processes. Aeration ponds in such plants provide an optimal growth environment for many microorganisms, including Legionella species. To investigate whether legionellae could be dispersed as aerosols from the ponds and transported by the wind, the wetted-wall cyclone SASS 2000(PLUS) and the impactors MAS-100 and STA-204 were used to collect air samples directly above, upwind, and downwind of aeration ponds during a 4-month period. Computational fluid dynamics was used a priori to estimate the aerosol paths and to determine suitable air-sampling locations. Several Legionella species, including Legionella pneumophila, were identified in air samples at the biological treatment plant using microbiological and molecular methods. L. pneumophila was identified up to distances of 200 m downwind from the ponds, but, in general, not upwind nor outside the predicted aerosol paths. The highest concentration level of viable legionellae was identified directly above the aeration ponds (3300 CFU/m3). This level decreased as the distance from the aeration ponds increased. Molecular typing indicated that a single clone of L. pneumophila was dispersed from the ponds during the period of the study. Thus, our study demonstrated that aerosols generated at aeration ponds of biological treatment facilities may contain L. pneumophila, which then can be transported by the wind to the surroundings. The methods used in this study may be generically applied to trace biological aerosols that may pose a challenge to environmental occupational health.

Airborne Legionella bacteria from pulp waste treatment plant: aerosol particles characterized as aggregates and their potential hazard

“…Even though the CFU numbers (legionellae) analyzed here are much higher than that found in air near Legionella sources (e.g. 5 9 10 3 CFU/m 3 Blatny et al 2008;Mathieu et al 2006), an impact on cell viability due to the XMX-2CV sampler's physical properties would Fig. 2 The airborne particle size distribution and concentration at FFI, Kjeller (2.4 lm) (a) and Borregaard (3.5 lm) (b) expressed in log-probability plot to estimate median particle size.…”

“…Particle size information was collected from this site as Blatny et al (2008) have shown that the highest concentration of particles was directly above these ponds and that their concentration decreased downwind of the ponds. In practice, it was not convenient to measure particle size at other sites.…”

“…It has been speculated that infectious Legionella bacteria may be dispersed up to 10 km from the source (Nguyen et al 2006), while simple room humidifiers may disseminate legionellae up to distances of three meters (Woo et al 1986). The aeration ponds as a part of Borregaard's biological treatment facility contained Legionella at up to 10 10 CFU/l (Allestam et al 2006;Blatny et al 2008) and airborne legionellae may be disseminated up to 200 m downwind . Typical concentrations of airborne legionellae up to about 5 9 10 3 CFU/m 3 have been detected above aeration ponds Mathieu et al 2006).…”

Negative ions detection in air using nano field-effect-transistor (nanoFET)

“…Recently, a number of consumer products utilizing ion-generating technology have become available to eliminate airborne pollutants, such as dust or cigarette smoke, allergens and viruses from immediate breathing spaces [5,6]. These devices work by generating a flow of negative ions that charge and bind together with airborne particulate matter.…”

Development of Rapid Assessment Method to Determine Bacterial Viability Based on Ultraviolet and Visible (UV-Vis) Spectroscopy Analysis Including Application to Bioaerosols

“…The monitoring of bioaerosols is essential for controlling air quality, assessing exposure in health risk evaluation studies, identifying bioaerosol emission sources, and estimating the performance of air cleaning devices. Exposure to bioaerosols can affect human health in variety of ways including infectious diseases, acute toxic reactions, and allergies (Terzieva et al, 1996;Lee et al, 2004;Rule et al, 2007;Blatny et al, 2008). The Severe Acute Respiratory Syndrome (SARS) and the threat of avian flu are natural examples illustrating profound, daily impacts of bioaerosols on public health (Ratnesar-Shumate et al, 2008).…”