Antti Haapala

Utilization of agricultural and forest industry waste and residues in natural fiber-polymer composites: A review

Natural fiber-polymer composites (NFPCs) are becoming increasingly utilized in a wide variety of applications because they represent an ecological and inexpensive alternative to conventional petroleum-derived materials. On the other hand, considerable amounts of organic waste and residues from the industrial and agricultural processes are still underutilized as low-value energy sources. Organic materials are commonly disposed of or subjected to the traditional waste management methods, such as landfilling, composting or anaerobic digestion. The use of organic waste and residue materials in NFPCs represents an ecologically friendly and a substantially higher value alternative. This is a comprehensive review examining how organic waste and residues could be utilized in the future as reinforcements or additives for NFPCs from the perspective of the recently reported work in this field.

Optical monitoring of activated sludge flocs in bulking and non-bulking conditions

This study introduces a novel optical monitoring method to image and characterize activated sludge flocs and to study the dependency of sludge settling properties on the floc structure. The novel method can easily analyse thousands of particles in a short timeframe using the developed image analysis program. The main advantage of this method is its applicability for in situ use because the only required pre-treatment is sample dilution. This study tested real process samples from activated sludge plants treating wastewater from a pulp mill. The sludge samples were collected in bulking and non-bulking situations, and the image analysis results were compared to the settling speed of the samples. The structure of the activated sludge flocs was clearly different in bulking sludge situations as characterized by more fragile and elongated flocs. Additionally, excessive amounts of filamentous bacteria hold the flocs apart, hindering sludge settling. These results show that this method is suitable for studying and optimizing activated sludge processes.

Refractive index matching improves optical object detection in paper

The demand for high-quality recycled pulp products has increased the need for an efficient deinking process. Assessing process efficiency via residual ink on test sheets has so far been limited to the sheet surface due to the poor transparency of paper. A refractive index matching method was studied to obtain a quantitative measure of particles within the volume of a paper sheet. In actual measurements a glass plate with etched lines from 8.5 ?m to 281.1 ?m wide was placed beneath the layers of cleared paper, and visible lines were counted with a microscope. Three different paper grades were tested with transparentizing agents. A diffusion theory-based regression model was used to find a correlation between transparency, paper grammage and paper thickness. These equations enable the determination of the size of an object detectable from a paper with a certain transparentizing agent or the parameters of a test sheet needed to detect objects of a known size. Anise oil was found to be the better of the two agents used, and they both had better transparentizing ability than air or water. The transparent paper grammage of the paper grades was determined for all the tested media. Papers transparency was found to depend more on papers thickness than grammage.

Cellulose Nanofibrils from Nonderivatizing Urea-Based Deep Eutectic Solvent Pretreatments

Deep eutectic solvents (DESs) are a fairly new class of green solvents applied in various fields. This study investigates urea-based DES systems as novel pretreatments for cellulose nanofibril production. In the experiments, deep eutectic systems having urea and ammonium thiocyanate or guanidine hydrochloride as a second component were formed at 100 °C and then applied to disintegrate wood-derived cellulose fibers. The DES-pretreated fibers were nanofibrillated into three different levels of mechanical treatments with a microfluidizer, and their properties were analyzed. Moreover, nanofibril films were fabricated by solvent casting method. Both DES systems were able to loosen and swell the cellulose fiber structure as indicated by the increase in the lateral dimension of the fibers. Nonpretreated birch cellulose fibers had difficulties in mechanical nanofibrillation as clogging of the chamber occurred often. However, cellulose nanofibrils with widths ranging from 13.0 to 19.3 nm were successfully fabricated from DES-pretreated fibers with both systems. Translucent nanofibril films generated from DES-pretreated cellulose nanofibrils had good thermal stability and mechanical properties, with tensile strengths of approximately 135-189 MPa and elastic modulus of 6.4-7.7 GPa. Consequently, both urea-based DESs showed a high potential as environmentally friendly solvents in the manufacture of cellulose nanofibrils.

Porous thin film barrier layers from 2,3-dicarboxylic acid cellulose nanofibrils for membrane structures.

To fabricate a strong hydrophilic barrier layer for ultrafiltration (UF) membranes, 2,3-dicarboxylic acid cellulose nanofibrils with high anionic surface charge density (1.2 mekv/g at pH 7) and a width of 22 ± 4 nm were used. A simple vacuum filtration method combined with a solvent exchange procedure resulted in a porous layer with a thickness of ∼ 0.85 μm. The fabricated membranes reached high rejection efficiencies (74-80%) when aqueous dextrans up to 35-45 kDa were filtrated to evaluate the molecular weight cut-offs (MWCO). A linear correlation between the barrier layer thickness and the flux rate was observed in all tested cases. Further optimization of the barrier layer thickness can lead to an even more effective structure.

Services in the forest-based bioeconomy – analysis of European strategies

ABSTRACT The increasing role of services for business making has been recognised in the forest-based sector, yet a systematic analysis of this emerging phenomenon is lacking. The current study derives from service research three perspectives for analysis: services activities separate from primary production and manufacturing–processing, services outputs separate from tangible products, and service as strategic, that is, business model consideration how value is created. Document analyses have been carried out to examine how these perspectives are identifiable in the European-level bioeconomy and forest-based sector strategies, as well as in a number of major strategic partnerships beyond the bio-based industries, that is, the research and innovation programmes of processing industries, manufacturing, energy-efficient buildings and green vehicles. The upstream and downstream strategies tend to differ on their approach to services. This paper contributes to the forest sector research by introducing two distinct perspectives from the service research literature to address the increasing role of services in the context of evolving bioeconomy: (1) explicating the role of services in the bioeconomy supply chains in order to improve efficiency and existing processes and (2) elaborating service as a means to better understand the changing business models and modes of value creation which may lead to system-level changes.

Condensed conifer tannins as antifungal agents in liquid culture

Abstract In the last decades, many wood preservatives have been prohibited for their ecotoxicity. The present article is focusing on the conifer-derived condensed tannins as environment-friendly options for the substitution of artificial wood preservatives. Eight different tannin fractions were extracted from spruce cones, spruce barks, and pine cones. The parameters of tannin extraction, such as the methods of purification and concentration of active components in the extracts, have been investigated. The cone and bark extracts were tested for the growth inhibition of eight brown-rot fungi, three white-rot fungi, and four soft-rot fungi in liquid cultures. The cone tannins provided a more efficient fungal growth inhibition than bark tannins. Purification increased the antifungal properties of the extracts. The growth of brown-rot fungi was inhibited by the tannins already at low concentrations. However, the extracts were not effective against the white-rot or soft-rot fungi. More investigation is needed concerning the tannin source and the purification procedure of the extracts before tannins can be considered as an ecologically benign wood preservative.

Reviewing wood biomass potentials for energy in Europe: the role of forests and fast growing plantations

ABSTRACT Wood biomass for energy is largely produced in Europe from forest land resulting from silvicultural and management practices or from agricultural land in the form of fast growing plantations. The present paper reviews and compares the estimated current potentials for wood biomass production in 25 countries in Europe. The potentials are divided attending to these sources to identify the most suitable method of wood biomass production on a country level, based on its current forest and agriculture levels of production. Data has been collected and compiled from previous models and estimations. The total aggregated available potential in Europe is 76 Mm3 of wood biomass from the forests, with an additional 90 Mm3 from increasing the utilization of forest lands, and 98 Mm3 from fast growing plantations (dedicating 5% of current agricultural land). Germany and France showed high potentials both from agriculture and forest; Finland and Sweden had most of its potential from forest sources; and Spain, Poland, and UK from fast-growing plantations. When considered together, Europe presents a large potential for wood biomass production for energy, and each country should develop different policy strategies of promotion attending to the most available source to realize this potential efficiently.

Numerical estimation of mould growth on common single-family house building envelopes in boreal conditions

Building guidelines vary greatly from one country to another; hence, significant regional variations in climate patterns should be acknowledged in building design. This study applied the mathematical mould-growth model to simulate common residential single-family building structures in different locations across Finland. The aim of this work was to show the degree of significance to which local differences in climate can influence mould-growth risk in the time frame of a few years. The mould-growth scenarios were analysed in common house walls, and numerical hygrothermal simulations were carried out to determine the conditions inside the wall structures. The risk of mould growth on the structures in different locations was modelled during 6–10 years of exposure to local weather conditions. Significantly higher mould-growth risk was observed in coastal locations, whereas the drier inland and northernmost locations performed much better. The local climate conditions were seen to affect the structural mould sensitivity.

Bioeconomy potential - focus on Northern Finland

The paper contributes towards improving the understanding over the potential of bioeconomy by focusing on a regional context. The study is realised by applying a combination of PESTEL analysis, resource analysis and analysing true and potential cases with high bioeconomy relevance and potential for substantial commercial volume. Hence, this article combines approaches of strategy development and analyses cases in bioeconomy context with a specific regional perspective. The results provide an overview on the potential of bioeconomy, particularly that of Northern Finland, but also the entire country. The article brings forward sustainability considerations aside from demonstrating the complexity inherent to the topic. Opportunities and potential are demonstrated by presenting case examples. The findings can benefit both the academia and those involved in planning and implementing relevant actions towards bioeconomy - both in general and in the selected setting.