Daniel Stratev

Fungal pretreatment of pine wood to reduce the emission of volatile organic compounds

Abstract Sterilized pine wood strands were treated with the ascomycete Ophiostoma piliferum (Cartapip 97™) in an attempt to reduce aldehyde emissions through degradation of aldehyde-forming precursors. Wooden boards were then produced from the treated strands by means of a laboratory press. VOC emissions of these boards were characterized and the concentrations of seven major substances were followed for a period of 28 days in Markes μ-CTE micro-chambers employing Tenax-TDAS/GC/MS analytics. Boards made from treated strands showed a highly significant (P<0.001) reduction in aldehyde emissions by 70% compared to the control boards, while differences in the monoterpene emissions were not significant (P>0.05). Wood extractives from treated and untreated strands were also analyzed by GC/MS after milling and acetone/water extraction. A marked decrease of C18 unsaturated fatty acids was detected in agreement with the reduction of aldehyde emissions, and the monosaccharides as indicators of fungal growth were depleted and stilbenes and lignans were partially degraded.

Industrial waste water for biotechnological reduction of aldehyde emissions from wood products

Abstract Pine wood particles were treated with effluents from the wood-board manufacturing industry or from a communal clarification plant, and the effect of these treatments on aldehyde emissions of wood material was tested. Pine wood strands were treated in the same manner and strand boards were produced from the treated material on a laboratory scale. The 28-day volatile organic compound emissions of the boards were determined in a microchamber using Tenax-TDAS/GC-MS analytics. Boards made from treated strands exhibited significantly lower aldehyde emissions compared to control boards. Analyses of microflora and of wood extractives confirmed that microbial metabolism in industrial effluents consumed unsaturated fatty acids (UFAs) present in wood. As UFAs are the source of aldehyde emissions due to auto-oxidation, the aldehyde emission was consequently reduced. A routine treatment of wood raw material with properly chosen industrial effluents may therefore be regarded as a cost-reducing and efficient method for the utilisation of industrial waste waters.

Biological control of sapstain fungi: From laboratory experiments to field trials 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Abstract Sapstain fungi, which reduce the value of pine wood, were isolated from an industrial wood yard in north-eastern Germany. The predominant wood discolouring species on the industrial wood yard and in the forests of the investigated region was Sphaeropsis sapinea (syn. Diplodia pinea), but Ophiostoma minus was also found. These fungi were challenged with antagonistic micro-organisms in laboratory trials and in field experiments. Amongst the tested microorganisms only strains of filamentous fungi (Trichoderma sp. and Phlebiopsis gigantea) could control the sapstain fungi on pine wood blocks efficiently. Although P. gigantea was unable to inhibit stain formation completely, the wood was bleached by this fungus in later incubation stages. In two field trials, sapstain on pine wood logs was successfully retarded for a period of 10 and 12 weeks, respectively, with a white sporulating mutant of Trichoderma harzianum. Thus, the concept using filamentous fungi as antagonists against sapstain developed under laboratory conditions also proved to be valid under natural conditions in forest eco-systems.

From model rooms towards a modelled indoor environment

This paper is divided into two parts: In the first part, the model room VOC measurement concept is evaluated with specimens from different construction materials in order to estimate the safety margins when using day 28 as the time point for indoor air quality assessment. Safety margins between 2 and 20 were estimated for softwood-based products. In the second part, the theoretical restrictiveness of ECA-IAQ Report 18 derivative schemes (like AgBB or NH 105) towards the indoor-related industrial production in central Europe was evaluated.

Measuring VOC emissions from wood-based building products under real room conditions in idealised model rooms

Abstract Two model rooms were constructed out of OSB and CLT and applied as a large scale test method for emissions of volatile organic compounds (VOC) from wood based building products over a period of 23 weeks. The measured VOC emissions show terpene and aldehyde emissions in both model rooms. Emissions from all identified substances declined over time to a low value. In the CLT model room terpene emissions exceeded aldehyde emissions. Terpenes declined from 65 to 11 μg m−3 (83%), whereas aldehydes declined from 28 to 5 μg m−3 (82%). In the OSB model room aldehyde emissions were higher and declined from 247 to 51 μg m−3 (79%). Terpene emissions decreased from 59 to 23 μg m−3 (61%).