Field Survey on Generation Patterns of Airborne Fungi in a Livestock Manure Composting Plant in South Korea

Abstract

Airborne fungi emitted from livestock manure composting plants are one of the major harmful factors causing respiratory disease for workers and nearby residents. Their generation of emissions is relatively high compared to other workplaces. This study investigated the emission characteristics of airborne fungi generated in livestock manure composting plants and utilized them as basic data to prevent workers' health. The livestock manure composting plants selected for the survey in this study were according to the fermentation mode, including screw type, rotary type and natural dry type. The field evaluation period was from September 2019 to August 2020 and was surveyed monthly. The equipment for collecting airborne fungi was a six-stage cascade impactor. An analysis of the quantification and qualification of airborne fungi was conducted through a culture method and identification technique, respectively. The mean levels of airborne fungi in livestock manure composting plants were 1143 (+/- 106)CFU m(-3) for screw type, 552 (+/- 146)CFU m(-3) for rotary type and 434 (+/- 73)CFU m(-3) for natural dry type, respectively. Based on the results obtained from this study, the livestock manure composting plant operated by screw type showed the highest concentration of airborne fungi, followed by the rotary type and natural dry type. The monthly concentration of airborne fungi was the highest in June and the lowest in February, regardless of the livestock manure composting plant type. The concentration range of airborne fungi corresponding to the respiratory particle diameter was 40 to 60% relative to the concentration of all airborne fungi. The correlation relationship between airborne fungi and environmental factors (temperature, relative humidity, particulate matter and odor) was not found to be significant in livestock manure composting plants. The predominant genera of airborne fungi identified were Aspergillus spp., Cladosporium spp. and Penicillium spp.