Janka Dibdiakova

Research Scientist

(+47) 974 80 384
janka.dibdiakova@nibio.no

Place
Ås H8

Visiting address
Høgskoleveien 8, 1433 Ås

To document

Abstract

Background: The emerging cellulosic bioethanol industry will generate huge amounts of lignin-rich residues that may be converted into biogas by anaerobic digestion (AD) to increase the output of energy carriers from the biorefnery plants. The carbohydrates fraction of lignocellulosic biomass is degradable, whereas the lignin fraction is generally considered difcult to degrade during AD. The objective of this study was to investigate the feasibility of biogas production by AD from hydrolysis lignin (HL), prepared by steam explosion (SE) and enzymatic saccharifcation of birch. A novel nylon bag technique together with two-dimensional nuclear magnetic resonance spectroscopy, pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS), and Fourier transform infrared (FTIR) spectroscopy was used to identify recalcitrant and degradable structures in the lignin during AD. Results: The HL had a lignin content of 80% which included pseudo-lignin and condensed-lignin structures resulting from the SE pretreatment. The obtained methane yield from HL was almost twofold higher than the theoretical methane from the carbohydrate fraction alone, indicating that part of the lignin was converted to methane. Characterization of the undegradable material after AD revealed a substantial loss of signals characteristic for carbohydrates and lignin–carbohydrate complexes (LCC), indicating conversion of these chemical components to methane during AD. The β-O-4′ linkage and resinol were not modifed as such in AD, but major change was seen for the S/G ratio from 5.8 to 2.6, phenylcoumaran from 4.9 to 1.0%, and pseudo-lignin and condensed-lignin were clearly degraded. Scanning electron microscopy and simultaneous thermal analysis measurements demonstrated changes in morphology and thermal properties following SE pretreatment and AD. Our results showed that carbohydrate, LCC, pseudo-lignin, and condensed-lignin degradation had contributed to methane production. The energy yield for the combined ethanol production and biogas production was 8.1 MJ fuel per kg DM of substrate (4.9 MJ/kg from ethanol and 3.2 MJ/kg from methane). Conclusion: This study shows the beneft of using a novel bag technique together with advanced analytical techniques to investigate the degradation mechanisms of lignin during AD, and also points to a possible application of HL produced in cellulosic bioethanol plants.

To document

Abstract

Charcoal seems one of the most promising bio-reducer because of its high coke replacement ratio in blast furnaces. Nevertheless, biochar materials are subject self-combustion during storage, handling and transport, and need to be studied in order to understand and limit these phenomena. Heat-based methods: were employed to compare and determine the self-ignition parameters of four types of fresh biochar (Quercus pubescens, Cyclobalanopsis glauca, and Trigonostemon huangmosun, Bambusa vulgar) that are used as bioreducers in the silica industry. This study assumed that spontaneous combustion arises from exothermic oxygen chemisorption to fresh biochar surface. Sample mass, heat flow and CO2 desorption were measured. The weight increased very rapidly as soon as the gas stream was changed from N2 to air accompanying the heat generation for each material. Desorption isotherms were found to depend on the nature of the feedstock confirming that bamboo biochar was the most reactive one under air exposure.

To document

Abstract

Biomass from forestry sector provides an important contribution to meet the government's targets for increasing bioenergy production and utilization. Characterization of forest residues is critical for exploiting and utilizing them for energy production purpose. In present work, stem wood, stem bark, branches, top of trees from downy birch forest were sampled from different sites in South Norway and subjected to heating value and ash content measurement. Properties of different parts of trees vertically along the tree trunk and radially along the branch and crown level were assessed via the statistical model. The heating value of stem wood was in range 18.14-18.57 MJ/kg, of stem bark 18.50-18.72 MJ/kg and of branch wood 18.21-18.50 MJ/kg. The vertical dependence of heating value of downy birch stem wood was similar to that of stem bark. Regular decreasing of heating value towards the tree top was observed. Significantly higher heating value at level p<0.05* of stem bark than the one of stem wood was observed. The ash content of downy birch branch wood did vary axially along the branch whereas there are only slight differences of ash content of branch within the crown. The stem bark has the highest ash content in range 2.0-2.5%, followed by branch wood in range of 1.0-1.6% and the lowest for stem wood in range of 0.3-0.5%.

Abstract

Characterization of biomass ash melting and thermal behavior is crucial to prevent and reduce ash related problems in biomass-fired boilers, In present work, ash melting behaviours of spruce saw dust and bark were investigated by simultaneous thermal analysis (STA), The decomposition stages of sawdust and bark biomass were characterized by four peaks, respectively, The four peaks are the first relatively small one at temperatures about 317-341 °C, a second large peak at 419-451 °C, a small third peak at 860-1000 °C and a small endothermic peak at 1290-1400 °C, DSC curves of bark sample at both heating rates were shifted towards lower temperatures than DSC curves of sawdust fuels, On average, the degradation process starts 5 °C earlier and the second exothermic peaks in both heating rates are found even 20 °C earlier, The remaining residue of bark samples was approximately two times higher than that of sawdust, The ignition temperatures of both spruce and pine bark were slightly shifted to higher temperatures compared to those of spruce and pine sawdust samples, STA experiments of exanimated biomass fuels indicated that their critical melting temperatures lie in the range of 860-1000 °C, The information obtained in this study qualifies the STA method as a suitable and rather simple method for the determination of ash melting and thermal behavior of woody biomass. © 2016 ETA-Florence Renewable Energies.

To document

Abstract

Efficient and profitable biomass combustion is often limited by ash related operational problems. Knowledge of the ash melting and sintering is of important, in terms of predict and reduce ash-related problems in biomass-fired boilers. In this study, chemical composition and melting behaviors of ashes from the four parts of P. sylvestris trees were investigated. The four parts from Pinus sylvestris trees are stem wood, bark, branch base and twigs. A simultaneous thermal analyzer (STA) was used to characterize the melting behavior of selected biomass fuels in oxidizing atmosphere. Ash melting process was identified as the distinctive endothermic peaks on recorded DSC curves. The results showed that the stem wood of pine contains higher contents of most of the ash forming matters than other tree parts. Chemical composition of ashes from four parts of the pine tree is dominated by element Ca, K, Mg, Mn, P and Si. The K, Na and P contents in the twigs are significantly higher than that of stem wood, bark, and branch base indicating high tendency of ash melting and slagging. STA experiments indicated that the melting process of the studied fuel ashes start in the temperature range of 930-965 °C. Scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometry (EDX). Analyses results showed that the stem wood ash remains loose structure even after 1000 °C sintering treatment. But the ashes originated from top branch show sign of sintering at 1000 °C. The obtained results of present work can be considered as useful information within an industry interest for a prediction of the forest biomass ash melting behavior.

To document

Abstract

Biomass from forestry sector is able to provide an important contribution to meet the government’s targets for increasing bioenergy use. Traditionally it has been stem wood which is used as raw material for energy. For a deeper understanding of trees, knowledge is required not only of the stem wood, but also of the branches and tree tops. Research complex on Norway's industrially important tree species - Scots pine (Pinus sylvestris L.) forest residues (stem wood, stem bark, branches, top of trees) moisture content, basic density and effective heating value were analysed in 2 sampling plots, depending on site index quality in South Norway forest. The vertical dependence of bark proportion was observed. The pattern was similar for both site indexes, lower bark content in the bottom part of stem, slightly increasing approximately to 35 % of the tree height and so increasing towards the tree top. The vertical dependence of bark thickness of Scots pine trees showed an increasing trend towards the top. Bark was significantly thicker near the base than near the top. Bark proportion may be a relevant aspect for the utilization of Scots pine forest residues as potential biomass feedstock. Considerable variations in qualitative properties between stem wood, stem bark and branch wood of Scots pine along the stem were observed. The basic density of stem wood was in range 308.2-418.3 kg/m3, of stem bark 265.1-364.2 kg/m3 and of branch wood 400.5-579.2 kg/m3. The basic density of stem wood was higher in the lower part of stem, vertically decreasing towards to tree top. Contrary, the basic density of stem bark decreased to 40 % height and then slightly increasing again towards the top. The axial dependence of basic density in stem bark was different than the one in stem wood, more regular. Branch density decreased moderately within the axial direction along the crown. Scots pine branch wood exanimated in this study was denser in the bottom part crown towards less denser branches positioned in the top crown section. More else a clear variation pattern was apparent in basic density variations along the branch. Density declined from the branch base outward first rapidly and then levelled. The highest basic density was found for the branch base. There was not found relationship between basic density of stem wood, stem bark, branch wood and site index quality of stands. The average moisture content of stem wood and stem bark harvested in early spring season increased axially from the base toward tree top, within significantly more pronounced variations on the tree base compare to tree top. Stem bark had relatively higher moisture content compare to stem wood. The moisture content in stem wood was in range 39.9-90.2 %, in stem bark 42.8-94.3 % and in branch wood 43.5-62.8 %. The effective calorific value of stem wood was in range 5.09-5.40 kWh/kg, of stem bark 5.11-5.51 kWh/kg and of branch wood 5.16-5.49 kWh/kg. The vertical dependence trend of effective calorific value for Scots pine stem wood was similar to that for stem bark. Regular decreasing pattern towards the top was observed. We observed significantly higher calorific value at level p<0.05* in stem bark than in stem wood. Elevated effective calorific value of stem bark and branch wood make these materials a valuable industrial energy source for bioenergy in Norway.

To document

Abstract

Woody biomass from the forest sector is an abundant resource for renewable energy generation. Conventional woody biomass materials such as timber and stem are normally high quality solid fuels for combustion applications in terms of ash related operational problems. Recently, new raw woody materials such as forest residue are gaining interests for energy production purpose. Forest residue is the remaining fraction after harvest and outtake of the wood timber, including tree tops, branches and barks. Compared to conventional woody biomass, the forest residue has a wide variation of ash content and concentration of ash forming matters. The aim of this work was to characterize and investigate different parts from Norway spruce trees regarding ash content, ash composition and ash melting and slagging behaviors. Different parts from spruce tree were studied in present work including stem wood, bark, branch and twigs. The ash content and ash melting temperature of the four fuel samples were measured through following standard procedures. Concentrations of main ash forming elements were analyzed by an inductively coupled plasma optical emission spectroscopy (ICP-OES). The ashes from stem wood, bark and twigs were further investigated by a scanning electron microscopy equipped with energy dispersive X-Ray analysis (SEMEDX) and X-Ray diffractometry (XRD). The results showed that the branches and twigs contain higher contents of ash forming matters than that of the stem wood. Chemical compositions of ashes from four parts of the spruce tree are dominated by Ca, K, and Si. The K and Na contents in the branches and twigs are significantly higher than that of stem wood and bark, indicating high tendency of ash melting and slagging. The melting points of ashes from branch and twigs were 100-200 °C lower than those of the ashes from stem wood and bark, respectively. SEM-EDX and XRD analysis, melting of ashes from branch and twigs are mainly attributed to formation and fusion of low temperature melting alkali silicates. Copyright © 2014,AIDIC Servizi S.r.l.

Abstract

A wide range of forest products and industries have been examined in life cycle analyses (LCA). Life cycle data are essential for identifying forestry operations that contribute most to carbon emissions. Forestry can affect net CO2 emissions by changing carbon stocks in biomass, soil and products, by supplying biofuels to replace fossil fuels as well as by establishing new forests. The transport of forest products is crucial to greenhouse gas (GHG) emissions. We conceptualize the chain from seed production, silviculture, harvesting, and timber transport to the industry as a system. Inputs to the system are energy and fuel, the output represents GHG emissions. The reference functional unit used for the inventory analysis and impact assessment is one cubic meter of harvested timber under bark. GHG emissions from forestry in East Norway were calculated for the production of one such unit delivered to the industry gate in 2010 (cradle-to-gate inventory), showing that timber transport from the forest to the final consumer contributed with more than 50 % to the total GHG emissions. To assess uncertainty of model approaches, the LCA was conducted with two different models, SimaPro and GaBi, both using the Ecoinvent database with data adapted to European conditions.

Abstract

A wide range of forest products and industries have been examined in life cycle analyses (LCA). Life cycle data are essential for identifying forestry operations that contribute most to carbon emissions. Forestry can affect net CO2 emissions by changing carbon stocks in biomass, soil and products, by supplying biofuels to replace fossil fuels as well as by establishing new forests. The transport of forest products is crucial to greenhouse gas (GHG) emissions. We conceptualize the chain from seed production, silviculture, harvesting, and timber transport to the industry as a system. Inputs to the system are energy and fuel, the output represents GHG emissions. The reference functional unit used for the inventory analysis and impact assessment is one cubic meter of harvested timber under bark. GHG emissions from forestry in East Norway were calculated for the production of one such unit delivered to the industry gate in 2010 (cradle-to-gate inventory), showing that timber transport from the forest to the final consumer contributed with more than 50 % to the total GHG emissions. To assess uncertainty of model approaches, the LCA was conducted with two different models, SimaPro and GaBi, both using the Ecoinvent database with data adapted to European conditions.

Abstract

The use of forest biomass for bioenergy purposes, directly or through refinement processes, has increased in the last decade. One example of such use is the utilization of logging residues. Branch biomass constitutes typically a considerable part of the logging residues, and should be quantified and included in future forest inventories. Airborne laser scanning (ALS) is widely used when collecting data for forest inventories, and even methods to derive information at the single-tree level has been described. Procedures for estimation of single-tree branch biomass of Norway spruce using features derived from ALS data are proposed in the present study. As field reference data the dry weight branch biomass of 50 trees were obtained through destructive sampling. Variables were further derived from the ALS echoes from each tree, including crown volume calculated from an interpolated crown surface constructed with a radial basis function. Spatial information derived from the pulse vectors were also incorporated when calculating the crown volume. Regression models with branch biomass as response variable were fit to the data, and the prediction accuracy assessed through a cross-validation procedure. Random forest regression models were compared to stepwise and simple linear least squares models. In the present study branch biomass was estimated with a higher accuracy by the best ALS-based models than by existing allometric biomass equations based on field measurements. An improved prediction accuracy was observed when incorporating information from the laser pulse vectors into the calculation of the crown volume variable, and a linear model with the crown volume as a single predictor gave the best overall results with a root mean square error of 35% in the validation.

To document

Abstract

The use of forest biomass for bioenergy purposes, directly or through refinement processes, has increased in the last decade. One example of such use is the utilization of logging residues. Branch biomass constitutes typically a considerable part of the logging residues, and should be quantified and included in future forest inventories. Airborne laser scanning (ALS) is widely used when collecting data for forest inventories, and even methods to derive information at the single-tree level has been described. Procedures for estimation of single-tree branch biomass of Norway spruce using features derived from ALS data are proposed in the present study. As field reference data the dry weight branch biomass of 50 trees were obtained through destructive sampling. Variables were further derived from the ALS echoes from each tree, including crown volume calculated from an interpolated crown surface constructed with a radial basis function. Spatial information derived from the pulse vectors were also incorporated when calculating the crown volume. Regression models with branch biomass as response variable were fit to the data, and the prediction accuracy assessed through a cross-validation procedure. Random forest regression models were compared to stepwise and simple linear least squares models. In the present study branch biomass was estimated with a higher accuracy by the best ALS-based models than by existing allometric biomass equations based on field measurements. An improved prediction accuracy was observed when incorporating information from the laser pulse vectors into the calculation of the crown volume variable, and a linear model with the crown volume as a single predictor gave the best overall results with a root mean square error of 35% in the validation.

Abstract

An increasing demand for forest biomass to energy is leading to a more intensive harvesting of timber, also including an exploitation of the crown biomass. This sets new demands for forest inventory systems to generate more detailed information about the forest biomass fractions. Norway has unutilized forest resources, which can be used for bioenergy. These also include Norway spruce (Picea abies (L.) Karst.). The material was sampled from three different locations in Southern Norway from west to east. Each location was represented with tree different site indices. Vertical profiles of branch weight, length and diameter were studied. The effect of different tree and site characteristics were used to predict the profiles. Significant differences were found between the geographical locations studied after adjusting for tree height and diameter in breast height. Branches from the western site were longer and had a greater mass compared to branches from the other two locations. The branch diameter distribution indicated that the east location had larger branch size, while branches in middle and west site had smaller sizes. This study highlights the range of branch variability within locations, but indicates that Norway spruce branch biomass in Norway may be considered as a valuable raw material.

To document

Abstract

The presented article deals with the assessment of combined impact of temperature and flow of oxidising atmosphere, its oxygen concentration and heat flux on the ignition time of isotactic polypropylene (PP). The ignition time was determined in a specially adapted hot air Setchkin furnace at temperatures (450 and 600 °C), density of heat flux (12.4 and 26.4 kW m−2), flows of oxidation mixture (6 and 8 L min−1) and volume oxygen concentrations (3, 9, 15, 21, 27, 33, 39, 45 and 50 %). Obtained data allows us to assume that the temperature influence on PP induction period of ignition increases with decreasing flow rate of oxidising atmosphere. At the flow of oxidising mixture equal to 6 L min−1 and temperature of 600 °C, oxygen concentration had only a negligible impact on the the induction period of ignition in the analysed period. From the presented results, the induction period of ignition depends on the temperature and also on the flow rate of oxidising mixture and oxygen concentration in it. In addition, heat flux has a significant influence on the induction period. However, the quantification of the heat flux influence was not possible with the applied experimental device.

To document

Abstract

The paper focuses on the use of thermogravimetric analysis (TGA) as a fast method for estimating the change of lignocellulosic materials during fungal degradation in laboratory trials. Traditionally, evaluations of durability tests are based on mass loss. However, to gain more knowledge of the reasons for differences in durability and strength between wooden materials, information on the chemical changes is needed. Pinus sylvestris sapwood was incubated with the brown rot fungus Gloeophyllum trabeum and the white rot fungus Trametes versicolor. The TGA approach used was found to be reproducible between laboratories. The TGA method did not prove useful for wood deteriorated by white rot, but the TGA showed to be a convenient tool for fast estimation of lignocellulosic components both in sound wood and wood decayed by brown rot.

Abstract

The paper focuses on the use of thermogravimetric analysis (TGA) as a fast method for estimating the change of lignocellulosic materials during fungal degradation in laboratory trials. Traditionally, evaluations of durability tests are based on mass loss.However, to gain more knowledge of the reasons for differences in durability and strength between wooden materials, information on the chemical changes is needed. Pinus sylvestris sapwood was incubated with the brown rot fungus Gloeophyllum trabeum and the white rot fungus Trametes versicolor.The TGA approach used was found to be reproducible between laboratories. The TGA method did not prove useful for wood deteriorated by white rot, but the TGA showed to be a convenient tool for fast estimation of lignocellulosic components both in sound wood and wood decayed by brown rot.

Abstract

A comparable series of specimens from spruce wood were pre-treated with sodium hydroxide, sodium hydroxide and hydrogen peroxide, or per-acetic acid sequences. The pre-treatments reduced the yield of pulps and their Kappa number noticeably, diminished the degree of polymerization moderately, and increased their brightness. One-step peroxide bleaching of pulps from the pre-treated spruce wood resulted in their higher brightness compared to bleached pulp from sound wood. From the viewpoint of improved properties of pulp, the most efficient were the sodium hydroxide/per-acetic acid and per-acetic acid/sodium hydroxide sequences. The pre-treatments did not influence mechanical strength of the obtained pulps significantly.

To document

Abstract

To achieve optimal utilisation of logging residues for energy, it is important to know how different handling and storage methods affect fuel properties. The aim of this study was to model how the moisture content and dry matter losses of logging residues develop during storage. Logging residues were collected from five different stands of spruce and pine during different seasons of the year and stored in the same location. The logging residues were stored in covered piles of bundled residues and loose residues. Only minor differences were found in the moisture content profiles between piles of bundles and loose residues. Logging residues located in the centre of both types of piles had considerably lower moisture content than the outer parts. The moisture content significantly affected dry matter loss, with the highest dry matter losses being found in the samples with the least favourable drying conditions. The dry matter losses varied between 1 and 3% per month. Significantly higher dry matter losses were found in the spruce bundles than in the pine bundles. Seasoned logging residues had the lowest dry matter loss, while the logging residues harvested and piled in the autumn had the highest loss.

Abstract

A series of comparable specimens of spruce wood were submitted to chemical pre-treatments. Chemical pre-treatments were carried out with diluted sodium hydroxide, or sodium hydroxide and then by hydrogen peroxide, or per-acetic acid. All pre-treatments modified the chemical composition of wood and led to its weight loss. The pre-treatments resulted in a complete deacetylation, and partial delignification of wood and did not cause apparent loss of cellulose. Chemical alterations of the pre-treated spruce wood were markedly reflected in its improved digestibility under conditions of kraft cook. The obtained pulps were characterized with apparently reduced content of residual lignin, lower yield, moderate drop in DP, higher brightness and better optical properties (colour and lightness) of both unbleached and bleached pulps.

Abstract

A series of comparable specimens of hornbeam wood were submitted to pre-treatments by white-rot fungi and by alkali, or alkali followed by oxidation agents. The pre-treatments caused weight loss of wood and modified its physical properties and chemical composition.All pre-treatments reduced axial permeability of the test specimens in wet state (w FSP). The pre-treatments of the test specimens by diluted sodium hydroxide, or sodium hydroxide followed by hydrogen peroxide, however increased rate of diffusion in direction parallel to grain. The pre-treatments also made the kinetics of wood/water interactions in its initial phase much higher, especially when the white-rot fungi were used.The chemical pre-treatments of hornbeam wood caused its extreme final swelling, and on the other hand, a careful drying to initial moisture content resulted in its deep collapse. An increased rate of wood/water interactions, higher uptake of water and higher diffusion coefficients of wood pre-treated by alkali may play a positive role in the pulping processes.

Abstract

A series of comparable specimens of hornbeam wood were submitted to fungal and chemical pretreatments. Two strains of erosive white-rot fungi (P. chrysosporium and T. versicolor) and a lignin-selective fungus C. subvermispora were used. Chemical pretreatments were carried out with diluted sodium hydroxide, or sodium hydroxide and then by hydrogen peroxide, or per-acetic acid. Both biotic and abiotic pre-treatments modified the chemical composition of wood and were accompanied by its weight loss. The applied fungi apparently delignified the specimens, however at the expense of cellulose, especially when the erosive strains of fungi were used. The chemical pretreatments caused deep deacetylation, and milder delignification of wood and did not cause an apparent loss of cellulose. Biotic pretreatments of hornbeam wood, despite their marked delignification effect, led to unexpected increase in the contents of residual lignin in the resulting kraft pulps. On the other hand, pulping of the chemically pre-treated chips yielded pulps with low contents of residual lignin and much higher brightness.