State-of-the-art of waste wood supply chain in Germany and selected European countries

Common operational issues and possible solutions for sustainable biosurfactant production from lignocellulosic feedstock

Surfactants are compounds with high surface activity and emulsifying property. These compounds find application in food, medical, pharmaceutical, and petroleum industries, as well as in agriculture, bioremediation, cleaning, cosmetics, and personal care product formulations. Due to their widespread use and environmental persistence, ensuring biodegradability and sustainability is necessary so as not to harm the environment. Biosurfactants, i.e., surfactants of plant or microbial origin produced from lignocellulosic feedstock, perform better than their petrochemically derived counterparts on the scale of net-carbon-negativity. Although many biosurfactants are commercially available, their high cost of production justifies their application only in expensive pharmaceuticals and cosmetics. Besides, the annual number of new biosurfactant compounds reported is less, compared to that of chemical surfactants. Multiple operational issues persist in the biosurfactant value chain. In this review, we have categorized some of these issues based on their relative position in the value chain - hurdles occurring during planning, upstream processes, production stage, and downstream processes - alongside plausible solutions. Moreover, we have presented the available paths forward for this industry in terms of process development and integrated pretreatment, combining conventional tried-and-tested strategies, such as reactor designing and statistical optimization with cutting-edge technologies including metabolic modeling and artificial intelligence. The development of techno-economically feasible biosurfactant production processes would be instrumental in the complete substitution of petrochemical surfactants, rather than mere supplementation.

Comparison of classification methods performance for defining the best reuse of waste wood material using NIR spectroscopy

Recycling of post-consumer waste wood material is becoming an increasingly appealing alternative to disposal. However, its huge heterogeneity is calling for an assessment of the material characteristics in order to define the best recycling option and intended reuse. In fact, waste wood comes into a variety of uses/types of wood, along with several levels of contamination, and it can be divided into different categories based on its composition and quality grade. This study provides the measurement of more than a hundred waste wood samples and their characterisation using a hand-held NIR spectrophotometer. Three classification methods, i.e. K-nearest Neighbours (KNN), Principal Component Analysis - Linear Discriminant Analysis (PCA-LDA) and PCA-KNN, have been compared to develop models for the sorting of waste wood in quality categories according to the best-suited reuse. In addition, the classification performance has been investigated as a function of the number of the spectral measurements of the sample and as the average of the spectral measurements. The results showed that PCA-KNN performs better than the other classification methods, especially when the material is ground to 5 cm of particle size and the spectral measurements are averaged across replicates (classification accuracy: 90.9 %). NIR spectroscopy, coupled with chemometrics, turned out to be a promising tool for the real-time sorting of waste wood material, ensuring a more accurate and sustainable waste wood management. Obtaining real-time information about the quality and characteristics of waste wood material translates into a decision of the best recycling option, increasing its recycling potential.

CuxMg1-xFe2O4-type spinels as potential oxygen carriers for waste wooden biomass combustion

Waste wood biomass is considered a renewable energy source. Combining biomass combustion with emerging clean combustion technologies such as chemical looping combustion (CLC) can yield effective and affordable carbon capture and, consequently, lead to negative net emissions of greenhouse gases. Oxygen carrier (OC) is a crucial material in CLC technology that must exhibit certain properties, such as high durability, good chemical stability during numerous red-ox cycles and, important for the combustion of solid fuels, the capability of spontaneously releasing oxygen in a process referred to as chemical looping with oxygen uncoupling (CLOU). In this work, a series of nine CuxMg1-xFe2O4 spinel-based materials were synthetized and evaluated for the first time as potential OCs for a waste biomass combustion. Their properties, such as oxygen transport capacity and reactivity with biomass (wood chips) as a fuel, were evaluated in a function of temperature (900-1000 °C). Tested oxygen carriers were characterized with an excellent oxygen transport capacity in CLOU process (up to 2.78 wt%) and good reaction rates with the fuel (up to 1.19 wt. %/min), and regeneration rates (up to 3.8 wt. %/min). High conversion of the waste biomass was also achieved (98.9 %). Moreover, new findings revealed a strong positive effect of magnesium addition on mechanical strength (crushing strength > 4 N for samples with Mg content above 0.5).

Climate effects of post-use wood materials from the building sector in a system perspective

This study investigates the climate change effects in terms of greenhouse gas emissions and radiative forcing resulting from different pathways of processing wood materials when they reach the end-of-life stage. The shares of combustion, landfill, recycling, and reuse, which vary with the pathways of post-use wood, influence the material and energy production systems. The dynamics of CO2 and CH4 emissions, together with the cumulative radiative forcing of each pathway, are evaluated from various regional system perspectives. The results show that the choice of a treatment pathway for post-use wood could strongly influence the profile of greenhouse gas emissions and, consequently, the global warming potential. Taking into account the situation of the reference material and energy production systems, the post-use wood can have unfavorable consequences for the climate, as in the case when the material and energy production systems are based on the low-carbon energy of natural gas. However, from the perspective where the treatment of post-use wood influences the quantity of forest biomass on the forest floor, the increased share of reuse and recycling contributes positively to the climate change mitigation, but only during the early stage. Under such a context, options relying on carbon capture and storage to handle biogenic CO2 emissions at energy conversion facilities could cause a cooling effect on the Earth's atmosphere.

Classification of waste wood categories according to the best reuse using FT-NIR spectroscopy and chemometrics

In Europe, the volume of waste wood is increasing. Waste wood can be reused, promoting circular economy and avoiding landfills. It can be used as a bioenergy feedstock reducing the use of fossil fuels, or be reused for producing new composite wood material. Only wood with hazardous substances needs to be disposed. To this aim waste wood samples were collected from a panel board company and several recycling centres in Italy and Denmark. The samples were assigned to waste wood categories and analysed by Near Infrared Spectroscopy. Principal Component Analysis was used to investigate sample variability and Soft Independent Modelling of Class Analogies (SIMCA) for classifying the samples according to the appropriate reuse: energy production, panel board production or landfill. The results are good, with a classification rate of 90% for virgin wood material and 86.7% for treated wood material. The classification of waste wood is key for turning it into a secondary resource.

Robust facility location in reverse logistics

As environmental awareness is becoming increasingly important, alternatives are needed for the traditional forward product flows of supply chains. The field of reverse logistics covers activities that aim to recover resources from their final destination, and acts as the foundation of the efficient backward flow of these materials. Designing the appropriate reverse logistics network for a given field is a crucial problem, as this provides the basis for all operations connected to the resource flow. This paper focuses on design questions in the supply network of waste wood, dealing with its collection and transportation to designated processing facilities. The facility location problem is studied for this use-case, and mathematical models are developed that consider economies of scale and the robustness of the problem. A novel approach based on bilevel optimization is used for computing the exact solutions of the robust problem on smaller instances. A local search and a tabu search method is also introduced for solving problems of realistic sizes. The developed models and methods are tested both on real-life and artificial instance sets in order to assess their performance.

Managing Supply Chain Activities in the Field of Energy Production Focusing on Renewables

Nowadays, the research community focuses on sustainability studies that are at the severe phase in the transformation towards a sustainable world. In addition, reducing the human impact on the environment requires a shift from traditional energy to renewables, which have increased significantly during recent decades as sustainable energy sources. Hence, this study assesses renewable energy sources and their related production phases from a supply chain management perception, screening and reviewing the integration between the supply chain management within the area of energy production focusing on renewable energy resources. The study executes a systematic review of English literature published on international scientific databases, focusing on the previous decade 2010–2020, to congregate the recently updated knowledge related to such research area. Thus, this study provides an authentic review of the literature that points to the relationship between supply chain operations and the area of renewable energy manufacturing from another side. Several literature reviews have been available concentrating on particular areas of managing renewable energy supply chains; however, no review has highlighted the practices of supply chain processes in energy production, focusing on renewables. The searching process relies on the published works that focus on such an area to be analyzed and characterized based on different methodologies they propose; thus, prospective and future research interests are delineated.

Wood waste utilization and associated product development from under-utilized low-quality wood and its prospects in Nepal

Wood waste has the potential to be used in making a variety of goods, including engineered wood products, energy generation (heat and electricity), mulching, and animal bedding. These inexpensive and underutilized feedstocks have the potential to increase the added value of wood wastes. This paper aims to review the different possibilities on wood waste utilization and their prospects in Nepal. This information helps to find the proper way for future development of wood waste to deliver the best outcomes for the environment and economy. The review is based on an in-depth examination of credible literature and official statistical data. The study showed Nepal has not utilized wood waste except for firewood and a few engineered wood products. The problem with wood waste is the lack of adaptation of advanced technologies and the lack of institutions concerned with the benefits of utilization of those waste. This review concludes that wood waste can be a potential source for the production of different materials but the government should develop effective waste management rules to maximize the value of wood waste resources.

Graphical abstract

Sustainability in wood materials science: an opinion about current material development techniques and the end of lifetime perspectives

Wood is considered the most important renewable resource for a future sustainable bioeconomy. It is traditionally used in the building sector, where it has gained importance in recent years as a sustainable alternative to steel and concrete. Additionally, it is the basis for the development of novel bio-based functional materials. However, wood's sustainability as a green resource is often diminished by unsustainable processing and modification techniques. They mostly rely on fossil-based precursors and yield inseparable hybrids and composites that cannot be reused or recycled. In this article, we discuss the state of the art of environmental sustainability in wood science and technology. We give an overview of established and upcoming approaches for the sustainable production of wood-based materials. This comprises wood protection and adhesion for the building sector, as well as the production of sustainable wood-based functional materials. Moreover, we elaborate on the end of lifetime perspective of wood products. The concept of wood cascading is presented as a possibility for a more efficient use of the resource to increase its beneficial impact on climate change mitigation. We advocate for a holistic approach in wood science and technology that not only focuses on the material's development and production but also considers recycling and end of lifetime perspectives of the products. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

High Efficiency of the Removal Process of Pb(II) and Cu(II) Ions with the Use of Fly Ash from Incineration of Sunflower and Wood Waste Using the CFBC Technology

In these research studies, fly ash (SW-FA) resulting from the incineration of sunflower (20%) and wood (80%) waste employing the circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Pb(II) and Cu(II) ions in adsorption processes. Currently, great emphasis is placed on circular economy, zero waste or climate neutrality strategies. The use of low-cost SW-FA waste seems to fit well with pro-ecological, economic and energy-saving trends. Hence, this material was characterized by various techniques, such as granulation analysis, bulk density, SEM-EDX, XRD and XRF analysis, BET, BJH, thermogravimetry, zeta potential, SEM morphology and FT-IR spectrometry. As a result of the conducted research, the factors influencing the effectiveness of the adsorption process, such as adsorbent dosage, initial and equilibrium pH, initial metal concentration and contact time, were analyzed. The maximum removal efficiency were achieved at the level of 99.8% for Pb(II) and 99.6% for Cu(II), respectively. The kinetics analysis and isotherms showed that the pseudo-second-order equation and the Freundlich isotherm models better describe these processes. The experiments proved that SW-FA can act as an appropriate adsorbent for highly effective removal of lead and copper from wastewater and improvement of water quality.

Circular Economy Practices on Wood Panels: A Bibliographic Analysis

The scarcity of natural resources and the generation of waste without adequate disposal are a worldwide concern related to the linear production model.These characteristics are present in the wood panel production. Faced with this problem, the present study aimed to identify in the literature, circular economy (CE) practices in the waste management of wood panel production processes and the possibilities for implementing new practices that incorporate circularity concepts. A systematic search was conducted to select the most relevant work on the theme. A search was done using the ScienceDirect, Web of Science, and Scopus databases by combining the following keywords: “Circular Economy” (and its possible variations), “Wood-based Panel”, and “Wood Waste”. The results evidenced circular economy practices on waste management already being used by the wood panel industry, besides potential practices to increase circularity. The changes go towards sustainable manufacturing and responsible consumption, which aims to “ensure sustainable consumption and production patterns”. Opportunities range from the extraction of raw materials to the disposal of wood panel waste at the end-of-life. The circular economy model is still recent and the process of transitioning is in its initial phase, as well as scientific research on the theme, mainly regarding the wood panel industry. Studies addressing the circular economy and wood panels are not yet widespread, pointing to a gap yet to be explored. The bibliographic review allowed identifying the existence of potential applications of circular economy in the wood panel industry; yet, this piece of research points to a broad field of exploration.

Using applied operations research and geographical information systems to evaluate effective factors in storage service of municipal solid waste management systems

One of the important elements of municipal solid waste management (MSWM) system is waste storage service. Residents deal with the system in this stage and the efficiency of waste collection element, the most expensive element of waste management system, relies on the performance of storage service. In this study, the performance of two different models including minimize facilities (MF) and maximize capacitated coverage (MCC) was investigated to find optimal locations for storage stations in Alandasht district located in Mashhad- Iran. Four effective factors including total service coverage, residential engagement, surplus container capacity devoted to each station and the ratio of the standard deviation to the arithmetic mean of solid waste allocated to each station were considered to compare these models. The MF model provided the highest service coverage by proposing 26 stations covering 98.56 percent of total residences. According to 26 stations proposed with MF model, MCC was run with 26, 27, 25 and 24 stations. MCC-27 provided the maximum attendance of residents with 54.47 percent. However, the most economical container distribution to the stations proposed with MCC-24 by presenting the minimum ratio of surplus devoted capacity to total demand, 33.74 percent. Finally, MCC-25 provided better distribution of residents to the storage stations, i.e., the minimum ratio of the standard deviation to the average solid waste devoted to stations, 22.13 percent. service area (SA) analysis applied to MF, MCC-25 and MCC-24 showed more than 60 percent of residences are located between 0 and 100 m walking distance for these analyses.