Total organic compounds released from dehumidification drying of air-dried hardwood lumber

Wood dry kilns have been identified by the Environmental Protection Agency as a potential source of significant volatile organic compound (VOC) and total organic compound (TOC) emissions. The VOC emissions from lumber drying are volatilized along with the water as both are evaporated from wet lumber. Very limited information is available on the quantity of VOC or TOC emissions from drying hardwoods and softwoods. The objective of this study was to quantify TOC amounts in commercial dehumidification kiln effluent that was used to finish drying air-dried hardwood lumber. Kiln effluent containing the TOCs for each charge was determined using a Shimadzu TOC-5000A emission measuring device both before and after an activated charcoal filter. The test results of the effluent collected before the activated charcoal filter were used to estimate the total amount of TOCs for each kiln charge. The effluent, after passing through activated charcoal, was analyzed to determine the effectiveness of the activated charcoal in removing TOCs and in reducing the pH of the effluent from the different kiln charges. The results indicated that a mixed charge of red oak and white oak lumber, dried from an initial moisture content of 21 percent, released the highest amount ofTOCs ofthe six hardwood kiln charges in this study. The study also revealed that activated charcoal was effective in reducing TOCs from the effluent of the kiln charges. In general, the pH increased after charcoal filtration and TOCs decreased.