A quantitative study was carried out on bacterial emissions
from swine manure in a lab-scale composting. The bacterial emissions
pattern during composting strongly depended on the process
temperature. A positive relationship was found between airborne
culturable bacteria emissions and the temperature profile in the
compost pile. A negative correlation between airborne endotoxin
concentration and compost temperature was found during the
thermophilic phase of composting. This finding demonstrates that
the temperature is an excellent indicator of bacterial emissions as
well as the biological activity during the composting process. With
regard to bacterial emission factors, that have not been previously
reported, emission factors of bacteria and endotoxin were found to
be 11.2–13.5 CFU/g dry swine manure and 0.5–0.9 EU/g dry swine
manure, respectively. Gram-negative bacteria were predominantly
identified in the effluent gas generated during composting. Thus, if
the compost pile can attain consistently high temperature, substantial
consideration should be given to approaches that ensure
that the biohazard risk at the source is minimized and that the
exposure of workers to generated bioaerosols is reduced. The information
presented in this study could be useful for designing and
operating field-scale applications of organic waste composting
with respect to occupational safety and sanitary management