ASSESSMENT OF EMISSION AND DISPERSAL OF BIOAEROSOL FROM A CONTAMINATED SEDIMENT BIOTREATMENT PLANT

Abstract

Bioaerosol is constituted by bacterial cells, fungi, viruses, pollens and plant debris and may be considered as a potential source of pathogens and harmful agents. Bioaerosol’s harmfulness is potentially high at sites that can facilitate aerosolization and spreading of these particles such as waste treatment plants. Workers and people living in the surroundings of these plants are the categories that suffer the highest risk of inhalation.
The assessment of bioaerosol’s emissions and dispersal from point sources is therefore important for the protection of public health.
In this work, we used a molecular approach and we considered a sediment treatment plant in which solid wastes of anthropogenic origin such as for example sediments from canals or sewers were collected, decontaminated and possibly reused in industry.
The peculiarity of this plant was the bioremediation of solid material affected by fecal contamination, as commonly reported for wastewater, as well as by hydrocarbon contamination.
This work aimed at testing whether the different process phases 1) significantly affected the airborne microbial community structure and 2) increased the exposition of workers to potential pathogenic bacteria.
The bacterial community structure was assessed by the sequencing of 16S rRNA gene libraries through Illumina technology. The taxonomic classification showed that the airborne microbial communities during the considered plant activities (drying, sieving and biopile turning) were characterized by the presence of Actinomycetales, Bacillales, and Pseudomonadales. Conversely, when the plant was inactive, airborne microbial community structure showed rather high abundance of Bacillales (13.5%), Clostridiales (17.7%), Lactobacillales (13.5%) and Rhodobacterales (16.3%).
Non-metric Multi-Dimensional Scaling (NMDS) of both airborne particulate and treated sediment samples showed that treatment process actually influence the bacterial community composition, probably due to particle aero-dispersion.

The total amount of bacteria and the abundance of the main fecal indicators (E. coli, Enterococcus sp., Clostridium perfringens) were higher in air samples collected during the plant processes than in those collected during plant inactivity.