Emission characteristics and health risk assessment of volatile organic compounds produced during municipal solid waste composting.

ABSTRACT

Municipal solid waste degradation during composting generates volatile organic compounds (VOCs), which can pose health risks the staff at the composting site and people living nearby. This problem restricts the widespread application of composting techniques. The characteristics of VOCs emitted from different units at a composting plant and the health risks posed were investigated in this study. A total of 44 VOCs (including alkanes, alkenes, aromatic compounds, halogenated compounds, oxygenated compounds, and sulfur-containing compounds) were identified and quantified. The highest VOC concentration (15484.1 ±â€¯785.3 µg/m3) was found in primary fermentation, followed by the tipping unit (10302.1 ±â€¯1334.8 µg/m3), composting product (4693.6 ±â€¯1024.3 µg/m3), secondary fermentation (929.9 ±â€¯105.2 µg/m3), and plant boundary (370.4 ±â€¯75.8 µg/m3). The mean VOC concentration was 6356.0 µg/m3. The main compounds emitted during primary fermentation were oxygenated and those emitted from the tipping unit were alkenes. Health risk assessments indicate that VOCs did not pose unacceptable non-carcinogenic risks i.e., the HR values were <1 and carcinogenic risks (CR) values were <1.0 × 10-4. These results indicate that VOC emissions do not pose health risks to the staff at the composting site or to people living nearby. However, the cumulative non-carcinogenic and carcinogenic risks posed by the VOC mixture were high, especially for the primary fermentation unit emissions. Therefore, protecting the staff working near the primary fermentation unit should be a priority. Measures should be taken to minimize cumulative non-carcinogenic and carcinogenic risks because people are exposed to a mixture of VOCs mixture rather than to a single type of VOC.