Background: Despite numerous benefits related to the utilization of biomass as an alternative source of energy, the handling of biomass creates a risk for the power industry workers of exposure to harmful microbiological agents. The purpose of this study was to evaluate the exposure of the workers to such agents at a power plant co-firing biomass with coal. This assessment was based on quantitative and qualitative characteristics of bioaerosols, supplemented with the analysis of biomass samples.
Material and methods: Air samples were collected with both MAS and Andersen six-stage impactors. Two different kinds of biomass samples used in the co-firing technological process were collected: sunflower seed peel pellet and wood chips. Bacterial and fungal concentrations were assessed in the air and biomass samples, and isolated microbial colonies were identified to the genus and/or species level.
Results: Bacterial and fungal concentrations at workplaces ranged between 5.1 x 10(2) cfu/m3 and 2.0 x 10(4) cfu/m3, and between 2.2 x 10(2) cfu/m3 and 2.3 x 10(4) cfu/m3, respectively. The highest concentrations were determined at workplaces related to reloading, screening and biomass transport via conveyor belts to silos. Fungi representing the genus Aspergillus, including A. fumigatus, A. niger, A. flavus and Gram-negative rods of the genus Citrobacter, Pseudomonas and Rahnella prevailed in the air at all investigated workplaces. Bacterial and fungal concentrations in biomass samples amounted to 1.8 x 10(6) cfu/g and 1.1 x10(6) cfu/g, respectively. The qualitative analysis revealed that the composition of species in the biomass samples was similar to that observed in the air at workplaces.
Conclusions: Workers engaged in the biomass combustion technology are exposed to bioaerosol containing potentially pathogenic bacteria and fungi.