Biological Risks from Long-Term Storage of Wood Chips

Abstract

Renewable energy sources based on wood are becoming increasingly important and popular. However, their increased consumption is inevitably connected with questioning their quality [1][2]. Quality is in specific cases determined by the method of production and the storage process [3][4]. The quality of wood chips is at present evaluated according to the calorific value and moisture content, which are often influenced, besides the wood species itself, by weather conditions and storage method [5][6][7][8][9]. The increased number of plants using wood chips as a source of energy is connected with raising the question of health and safety hazards associated with the production and storage of wood chips. The factors most hazardous for human health are represented by the hazards associated with the activity of fungi and moulds in Pol. J. Environ. Stud. Vol. 26, No. 6 (2017), 2633-2641 AbstractThe aim of our study was to monitor and analyze the main biological hazards connected to the long-term storage of wood chips for energy production. The analysis was carried out in four high-capacity storage yards of the town heating plants in the Banská Bystrica self-governing region in Slovakia. Five samples were taken from each pile of a rectangular shape and volume over 4,000 m 3 ; the sampling was carried out at the beginning of the monitoring period and at the end of the monitoring period (after one year). Thirtyfour species of microscopic fungi were identified (18 at the beginning of the monitoring period and 16 at the end of the monitoring period). Thirty-three of them can potentially cause severe diseases. Fungi of the genus Aspergillus, causing severe diseases, were identified as the most abundant. The research confirmed that if the length of storage time is more than a year, the potential hazards for human health increase due to the increasing number of spore-forming pathogens. Following the monitoring of atmospheric conditions the highest increase of harmful spores was recorded at the average annual temperature of 10ºC and precipitation of over 1,000 mm a year.

Overview of Health and Safety Risks in the Process of Production and Storage of Forest Biomass for Energy Purposes—A Review

“…In total, 25 species of fungi and molds were identified during the storage of 80% wood chips from Beech (Fagus sylvatica), and 20% Spruce and White Fir (Picea abies, Abies alba) in large-capacity piles in four urban-type heating plants, of which 24 may pose a risk to human health. The most frequently identified species were species of the genera Aspergillus, Mucor, and Trichoderma [100]. This research continued in the following years, while in 2017-2022 the most frequently identified microorganisms were Penicillium sp., Aspergillus brasiliensis, Aspergillus unguis, Aspergillus flavus, and yeast [101].…”

“…Of the risks in this phase, the largest number of works is devoted to the risks of the production of spores of phytopathogens and fungi threatening human health [118]. Work [100] confirmed high numbers of phytopathogen colonies even in chip samples taken from a depth of 0.5 m. In two heating plants, the highest numbers of colonies of identified fungi and molds were quantified in samples from a depth of 0.5 m. It is obvious that the sampling location has no significant influence on the occurrence of health-threatening microorganic fungi and molds. In the case of larger piles, even a shallower depth of 0.5 m does not have a significant effect on the occurrence of toxicogenic micromycetes.…”

“…With the increase in the number of operations using wood chips as an energy source, issues of health and safety risks during their storage are becoming more and more common. From this point of view, the risks associated with the activity of fungi and molds in piles of wood chips (Figure 3) and the inhalation of wood dust when handling wood chips are evaluated as the most risky factors for human health [97][98][99][100][101]. Examples of smaller piles of wood species are Beech (Fagus sylvatica), Poplar (Populus tremula), and Spruce (Picea abies).…”

Specification of Negative Effects Applying the Theory of Constraints Tool: a Case Study

“…The analysis shows that the cause A (background highlighted in gray), i.e. the inappropriate inventory management and stockholding (warehouse) management, results in the creation of all constraints and needs to be solved immediately [24]- [26].…”

Forest chip drying in self-heating piles during storage as affected by temperature and relative humidity conditions

“…The mechanisms of self-heating include respiration of microorganisms and surviving tree parenchyma [15,16], thermo-oxidative reactions between oxygen and exposed lignocellulosic material [17], and condensation of water vapor [18]. The heating provides favourable conditions for microbial and fungal colonisation and accelerates the biologic decomposition of the biomass, and carries risks for self-ignition or the production of pathogenic spores, which can cause serious damage to human health [19][20][21]. There are a multitude of factors which influence the decomposition rate of the biomass and self-heating in the storage piles, such as initial moisture content of the material [22], pile size and shape [12], particle size [23], and weather conditions [24].…”