Διερεύνηση επικινδυνότητας από αερομεταφερόμενους μύκητες του γένους Aspergillus σε μονάδα κομποστοποίησης φυτικών υπολειμμάτων

Abstract

The most common method for organic waste treatment is composting. The degradation of the organic matter during the composting process is accomplished by numerous different microorganisms, such as gram positive and negative bacteria, fungi and yeasts. Composting plants produce and release bio-aerosols, consisting of inert particles and adhering microorganisms as well as their derivatives such as mycotoxins, glycans and endotoxins. For these reasons, composting plants cause a wider public concern because of their potential health effects for staff working in these plants as well as to the public living and operating close to such plants due to biological hazards arising from composting activities. The aim of this paper is to investigate the risk of airborne fungus Aspergillus spp. in a plant residue composting plant. In the study area, a total of nine monthly visits were carried out for the purpose of collecting data and. Visits were carried out during the period April - December 2015 and data were collected according to the following procedures: open plate exposure for airborne microorganisms’ collection and development, measurement of TSP (Total Suspended Particles) in air at different operating phases of the unit, sampling compost to investigate the presence of Aspergillus spp., and receiving meteorological data in digital format from a meteorological station that was placed in the unit. The results showed that the most important factor in increasing the concentration of micro-organisms in the air associated with the operation of this unit is the generation and release of dust as there was a large difference in particles concentration (TSP) between the Upwind Sampling Point (USP - Reference Point) in comparison to the Downwind of the Main Activity Point (DAMAP) and the Main Activity Point (MAP). At points and periods where a high concentration of dust was recorded, colony forming unit (cfu) density was also recorded. The transfer of dust to neighboring industrial units and / or residential areas is given taking into account the prevailing wind tensions in the area. Wind speed seems to be a determining factor for the concentration of solid particles and the growth of micro-organisms. In analyzing the metabolites produced by strains of Aspergillus spp. on a Coconut Agar substrate, five strains of the eighty-eight (88) aggregated, which were identified as toxicogenic (TLC). The percentage of toxigenic strains, in terms of total isolates in strains of Aspergillus spp., Is 5.68%. x In conclusion, these plants are not a potential hazard to the residents, as higher levels of microbial contamination detected downstream of the facility are reduced by distance. In addition, they do not exceed the limit values proposed in the international literature, suggesting that they are not a significant risk to the health of workers and residents, also taking into account the low levels of toxicogenic microorganisms identified in the present study.