Assessment of air emissions from industrial kiln drying of pinus radiata wood

The nature and mass flows of atmospheric emissions from an industrial kiln, drying radiata pine (Pinus radiata D. Don) at 100°C dry bulb and 70 °C wet bulb, were assessed by measuring the concentration of chemical components in the kiln atmosphere at regular time intervals and determining air-flows and temperature differentials across the stack. The volatile organic compounds (VOC) were trapped on activated carbon and analyzed by GC-MS. The aldehydes were trapped in 2,4-dinitrophenol-hydrazine solution and the aldehyde derivatives analysed by HPLC. Polar compounds were trapped in water and then alcohols were analysed by GC and organic acids by ion exchange chromatography. The two major VOC found were αpinene and β-pinene, which made up 90% of the total discharge (405 g/m3 wood). Most of the VOC fraction was released during the early stages of drying. The release of potentially hazardous components (formaldehyde, acetaldehyde, furfural) was found to be relatively low (1.1, 8.7, and 0.1 g/m3 wood, respectively) provided that kiln emissions are well dispersed, these levels of release are unlikely to cause adverse environmental effects.