Occupational Hygiene at a Dry Waste Treatment Plant in Finland

A company owned by 15 municipalities in central Finland operates a waste management system on behalf of its owner municipalities. The waste disposal system in the municipalities is based on the source separation of waste. The company's waste processing plant, which is the largest in Finland, has been in operation since fall 1997. The plant processes the dry waste fraction by separating out the residual organic waste and metals and producing recycled fuel from the remainder. Since the beginning the company has carrying out occupational hygiene measurements in the dry waste plant as a mean of monitoring the exposure of employees to microbes, endotoxins, dust, and noise. The influence of the waste treatment technique and the quality of the waste on the formation and disappearance of microbes has been of importance. The concentrations of airborne microbes (bacteria, fungi, and actinomycetes), both viable and the non-viable, were determined with an Andersen six-stage impactor and by the CAMNEA method. The fungi were identified. Dust concentrations and endotoxins were measured according to Finnish Standard No. 3860 (1988). Also the noise level was determined. The measurements were made when energy waste and dry waste were processed at the same time and when the dry waste was processed alone. Hygienic problems appeared to be greater during handling of the two waste types at the same time: the concentrations were then greater after the metal delimiter and on the sieve. The concentration of 163 endotoxins was on average 1350 ng/m3, which exceeds all recommended occupational threshold limits. Problems were also revealed at other measurement points in the process hall. As expected, concentrations were fairly low in the coffee room. The findings led to immediate changes in the process, work safety measures, and protection guidelines. Studies towards long-term improvements were initiated as well.