Search

Abstract: Once again Swedish forest industries are supposed to face a new threatening shortage of wood. Therefore, demonstration of new ideas of producing wood for pulp and fuels (heat, ethanol, hydrogen gas, dimethylether, electricity) in the most southern part of Sweden was very welcome. One example of new ideas is that some farmers planted hybrid poplars on abandoned farming land at Sångletorp (33ha), Johannesholm (15ha), Kadesjö (11ha) and Näsbyholm (2ha) in the southernmost part of Sweden in 1991. Some of these plantations were harvested in 2004, but some are still growing. The harvested wood had been used for pulp and fuel. The results of the harvest and of the plantations that are still growing are analysed here from an economic, ecologic and energy point of view. [Copyright &y& Elsevier]

Medicinal and aromatic plants (MAPs) are plants that have various uses for human health, nutrition, and well-being. They are sources of herbal medicines, dietary supplements, cosmetics, fragrances, spices, and other products. However, the production and utilization of MAPs also pose challenges and opportunities for environmental sustainability and economic viability. This work offers a wide-ranging review of the sustainable practices and circular economy approaches for the valorization of MAPs. The review discusses the importance and value of MAPs, as well as the principles and benefits of the circular economy, a sustainable model that aims to minimize waste and make the most of resources. The review identifies and analyzes various circular economy approaches for valorizing MAPs, like resource optimization through sustainable cultivation, waste minimization in harvesting and processing, closed-loop supply chains, product diversification and upcycling, circular design thinking for MAP-based products, recycling and reusing MAP-based waste, eco-certification and consumer awareness, and collaborative networks and knowledge sharing. The review paper provides examples and case studies of successful implementation of these approaches, as well as the challenges and limitations that need to be addressed. [ABSTRACT FROM AUTHOR]

This review paper provides an overview of various types of photobioreactors (PBRs) that could be used for the production of polyhydroxyalkanoates (PHAs) using anoxygenic photoheterotrophs, with a focus on the design and operation of these systems. The paper highlights the potential of different PBRs based on reactor geometry and growth mode, and also examines the advantages and disadvantages of each PBR type and summarizes their suitability for PNSB-PHA production. The optimization of reactor design and operation is crucial for maximizing PNSB growth and PHA productivity. The self-immobilization of bacteria in granular sludge is a promising technology for wastewater treatment and the production of PHAs, while grooved-surface PBRs and porous-substrate PBRs have limitations due to difficult biomass harvesting in the former and the presence of aerobic conditions incongruent with PNSB culturing in the latter. Limitations exist with all solutions for maximizing rapid growth and maintaining high biomass concentrations due to the requirements of phototrophic growth. [ABSTRACT FROM AUTHOR]

With the increasing scarcity of available forest for harvesting, there is a potential need for alternatives to wood fibers for pulp and paper production. Hemp is considered to be a good source of long and strong fibers. In this study, the effect of the harvesting age of hemp stems on their chemical composition and the biomass produced by the plants were studied. Hemp stems were harvested at ages of 30, 60, 90, and 120 days. Standard TAPPI procedures were used for chemical analyses of the stems. There was little variation observed in the percentage of the constituents such as lignin, hemicellulose, and α-cellulose with the plant growth. However, a very significant decrease was seen in the percentages of extractives, ash, and silica with plant growth. The rate of increase of biomass was higher in the first half of the growing period, i.e., from 30 to 60 days, compared to the second half, from 60 to 90 days. On the basis of the chemical constituents and the biomass produced, it is concluded that hemp grown for the pulp and paper industry should be harvested between 60 and 90 days for optimal results. [ABSTRACT FROM AUTHOR]

Forest biomass harvest has the potential to provide feedstocks for energy production to offset fossil fuel consumption. However, concerns have been raised regarding the ecological sustainability of removing additional biomass from forests, in particular the impacts on biodiversity. In this paper, we used a suite of ground-dwelling arthropod taxa (ground beetles, spiders, and rove beetles) to measure community compositional changes along a gradient of biomass removal treatments 7 years postharvest, and compared against reference. Based on multivariate regression trees, changes in species composition reflected the intensity gradient of the biomass removal treatments or stand attributes associated with the level of forest floor disturbance across all arthropod groups. For each arthropod group, changes in composition were defined primarily by reductions or loss of abundant forest associated species and increases in the number and abundance of species associated with more xeric conditions and increased disturbance intensity. There were no differences between full-tree and tree-length treatments. Overall, results indicated a strong arthropod response to the removal of overstory, forest floor disturbance, and reductions in understory cover mostly resulting from the glyphosate applications. Arthropod recovery would benefit from overstory retention, reduction in forest floor disturbance, and judicious use of glyphosate. [ABSTRACT FROM AUTHOR]

Seas, marine, and coastal regions are integral and essential parts of our ecosystem. Many scientific approaches have been taken to ensure the sustainable use of marine resources. Artificial intelligence (AI) plays a vital role in harvesting resources so that the system regenerates itself for the long term. This paper develops a two-input and two-output fuzzy logic-based model to predict the fisheries' remaining biomass after harvesting and maintaining a high revenue level in the Bangladesh Sundarbans region. Fishing & tourism are taken as input parameters, and revenue & biomass are taken as output parameters. A total of 20 rules (IF-THEN type) have been generated in the fuzzy rule editor of Fuzzy Inference System (FIS), considering all possible combinations between input–output parameters. The data which we obtained from the real ecosystem exactly corresponds to the results that we got from our proposed model. Our fuzzy logic model yields valid predictions of the remaining biomass level without compromising profit, only by controlling the harvesting and tourist entry. [ABSTRACT FROM AUTHOR]

Carbon fixed by agricultural crops in the US creates regional CO2 sinks where it is harvested and regional CO2 sources where it is released back into the atmosphere. The quantity and location of these fluxes differ depending on the annual supply and demand of crop commodities. Data on the harvest of crop biomass, storage, import and export, and on the use of biomass for food, feed, fiber, and fuel were compiled to estimate an annual crop carbon budget for 2000 to 2008. With respect to US Farm Resource Regions, net sources of CO2 associated with the consumption of crop commodities occurred in the Eastern Uplands, Southern Seaboard, and Fruitful Rim regions. Net sinks associated with the production of crop commodities occurred in the Heartland, Northern Crescent, Northern Great Plains, and Mississippi Portal regions. The national crop carbon budget was balanced to within 93 to 99% yr-1 of total carbon uptake during the period of this analysis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central European Agriculture is the property of Journal of Central European Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, nonlinear mathematical models have been proposed for comparative study of dynamics of CO2 with respect to vegetation biomass considering different growths of vegetation biomass, such as logistic, regrowth and regrowth with delay. Here we have considered harvesting of vegetation biomass due to external factors. Conditions for boundedness, local and global stability of equilibrium points and persistence has been derived for the models. Numerical simulations has been carried out to support analytical results and analyse bifurcation with respect to parameters (growth rates, catchability coefficient and depletion rate of CO2 due to vegetation biomass). Model analysis reveals that, as compared to logistic growth, regrowth allows us a large span for harvesting in which system remains stable. Model analysis also shows that the model in which we have considered regrowth, density of vegetation biomass and concentration of CO2 bifurcate negligibly with respect to different parameters as compared to logistic growth. Since often there exist a time lag for regrowth so we have also calculated critical value of lag after which system get unstabilized. [ABSTRACT FROM AUTHOR]

Algae are currently used in many areas, including dietetics, pharmacy, cosmetology and to increase the nutritional value of food and animal feed due to their chemical composition. They are a source of extremely valuable molecules, including polyunsaturated fatty acids and pigments. Algae are also a valuable source of protein and almost all essential vitamins. They are rich in pigments such as chlorophyll, carotenoids and phycobiliproteins. These substances have a wide range of commercial applications. Due to its very intensive use, the demand for this plant raw material is constantly growing. Therefore, the methods of growing and harvesting algae are constantly improved in order to maximize the cultivation effect while minimizing costs and energy inputs. Future research should focus on improving algae cultivation and harvesting systems, with an emphasis on the possibility of genetic modifications that would allow even more efficient algae cultivation. This review summarizes methods of micro- and macroalgae cultivation, the chemical composition of selected algae species, which are important from the pharmaceutical, dietary and cosmetic points of view and therapeutic and dietary applications of compounds derived from different algae species. The key conclusion drawn from this article is that algae are an extremely valuable raw material, rich in numerous macro- and micronutrients necessary for humans, the acquisition of which is part of the currently important strategy of ecological policy for obtaining raw materials for various industries. [ABSTRACT FROM AUTHOR]

An age structured model of a fishery is studied where two fishing fleets, or fishing agents, are targeting two different mature age classes of the fish stock. The agents are using different fishing gear with different fishing selectivity. The model includes young and old mature fish that can be harvested, in addition to an age class of immature fish. The paper describes the optimal harvesting policy under different assumptions on the objectives of the social planner and on fishing selectivity. First, biomass yield is maximized under perfect fishing selectivity, second, equilibrium profit (rent) is maximized under perfect fishing selectivity, and third, equilibrium profit is maximized under imperfect fishing selectivity. The paper provides results that differ significantly from the standard lumped parameter (also surplus production, or biomass) model. [ABSTRACT FROM AUTHOR]

Biomass has become a popular alternative to satisfy expanding energy demand and as a substitute for fossil fuels and phased-out nuclear energy in Europe. The European Union White Paper stipulates that the utilization of biomass shall increase to 1566 TWh by 2010. However it is often overlooked that the forest resources are already, to a large extent, used by the forest industries. When promoting biomass for energy generation the consequences for the forest industries also need to be considered. Sweden is an excellent case study, as there are vast quantities of forest resources, nuclear power is starting to be phased out, there are restrictions on expanding hydropower and the political desire exists to “set an example” with respect to carbon dioxide emissions. This paper attempts to estimate and analyse the supply of two types of forest resource, namely, roundwood and harvesting residues derived from final harvesting and commercial thinnings. Two separate supply curves are estimated: one for roundwood and one for harvesting residues. The cost structure is based on an economic-engineering approach where the separate cost components are constructed from the lowest cost element into aggregates for labour, capital, materials and overhead costs for each forest resource. The results indicate an unutilized economic supply of 12 TWh of harvesting residues in Sweden. However, after these 12 TWh have been recovered it becomes more profitable to use roundwood for energy purposes than to continue extracting further amounts of harvesting residues. [ABSTRACT FROM AUTHOR]

Sustainable, clean, renewable energy without negotiating contiguous environment is a challenging task mainly comprises of natural resource management which involves operational efficiency, waste minimisation and energy recovery. Disposal of untreated industrial wastewater with chemical nutrients especially compounds containing nitrogen and phosphorous lead to eutrophication and related environmental issues that affect the recycling processes of bio system. Biotransformation of pollutants using microalgae has proven to be proficient and economic method of wastewater treatment due to their adaptability of growing in various wastewater streams and also useful in the process of CO fixation. Moreover this technology has the competence of producing bio fuels as an alternative energy resource in the form of bio diesel, bio ethanol and biogas. In this review paper, the applicability of microalgae cultivation in industrial wastewater treatment has been discussed extensively including the processes involved, influencing operational parameters such as study mode, cultivation mode and time, method of aeration, pH and intensity of light. Further, the cultivation methods, harvesting techniques involved in the treatment process have been presented. In addition, the analysis on removal efficiency of algal treatment, biomass productivity and lipid content of the cultivated biomass has been discussed widely which possibly will be helpful in adopting the process integration in industrial wastewater treatment with bio energy production. [ABSTRACT FROM AUTHOR]

This paper presents analyses of the thermophysical and chemical properties of eleven perennial crop species harvested in one-year rotation cycles. The crops included four species grown for biomass in the form of straw, five species producing semi-wood biomass, and two species yielding wood biomass. The research comprised three consecutive crop harvests. In each harvesting season, biomass samples for analyses were taken on six dates at one-month intervals. Thermophysical and chemical properties of the biomass were significantly differentiated within the main experimental factors and their interactions. The biomass produced by Virginia mallow had the best quality parameters as solid fuel. In fact, it achieved the lowest water content and the highest lower heating value during all of the analyzed seasons and harvest dates. The biomass of the species yielding straw or semi-wood products attained better quality as solid fuel on later harvest dates. In turn, the quality of willow biomass remained practically unchanged between the harvest dates. [ABSTRACT FROM AUTHOR]

BACKGROUND An optimal valorization of plant biomasses to produce biofuels requires a good knowledge of the available contents and molecular composition of the main chemical components, which changes with the harvesting date. Therefore, we assessed the influence of harvesting date on the chemical characteristics of various energy crops in the context of their conversion to biofuels. RESULTS We showed that the biomass chemical composition, enzymatic digestible organic matter, bioethanol and thermal energy production potential for each species are impacted by the harvesting date. The proportion of enzymatically digestible organic matter decreases as the harvesting date is delayed. This is related to the increase in cellulose and lignin contents. The suitability of the biomasses for bioethanol production increases with harvest stage, as the total carbohydrates content increases. The suitability of the biomasses as a source of thermal energy increases according to the harvesting date as the proportion of organic matter increases and the content of mineral compounds decreases. For all investigated energy conversions, the best harvesting period is autumn, because the significantly higher crop dry matter yield largely compensates for the sometimes slightly less favorable chemical characteristics. CONCLUSION While the biomass composition of energy crops changes with harvest stage, the dry biomass yield per unit area is the main factor that controls the total amount of chemical components, digestible organic matter, bioethanol and thermal energy that can be expected to be harvested per unit area. The biomass compositions presented in this paper are essential to investigate their suitability for bioenergy conversion. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The paper presents the main results of a long-term follow-up study conducted on the first truck-mounted slash bundler deployed on the Alps. Data collection covers the 58-month period from the commissioning of the machine in January 2004 to the completion of this study in October 2008. During this period, the machine worked all across the Alps, covering Austria, Germany and Italy from its Swiss base. Frequent travelling can be considered a general condition for Alpine operations, where operators must deal with comparatively small and scattered landings: a highly mobile truck-base unit is most suited to these conditions, which require frequent relocation. The study also highlights a typical Alpine annual usage pattern, with activity peaks during the summer and lows in mid-winter, due to bad weather conditions. It also shows a growing usage trend, with usage levels almost doubling in 4 years, as the new technology receives widespread appreciation. Gross bundling productivity averages 10 bundles or about 4.5 green metric tons per worksite hour, while diesel consumption is below 1 l per bundle. The skill of individual operators can account for differences in productivity of up to 30%. The findings of this research provide further insight into the results obtained from a number of shorter studies conducted on the same machine by several scientific institutions across Central Europe. [ABSTRACT FROM AUTHOR]

Abstract: This paper considers the optimal joint harvest of prawns and poultry in a linked bioeconomic system. Through the cultivation process, poultry and prawns are reciprocal predators of one another. Prawns of non-marketable quality are fed to the birds, and birds which perish (in greater numbers in the face of increased density) are fed to prawns, along with a lot of other things that one does not usually consider prawns to eat (hogs, broken rice, etc.). The paper derives optimality conditions for the joint “effort” imposed in each of these industries, where effort is somehow analogous to the control variable in classical Gordon–Schaefer fishery problems. Growth of both species is governed by parameters as well as externally applied nutrients and the biomass of the other species available as supplemental nutrition. Analysis of the boundedness of this dynamical system is discussed. The conditions for local and global stability are derived. Finally, an optimal harvesting policy is discussed by applying Pontryagin’s Maximal Principle. Due to linearity of the objective function with respect to the control variable, the solution is bang-bang in this control and the best policy is to reach the singular equilibrium as quickly as possible by switching to the singular control. [Copyright &y& Elsevier]

Working times observed during different harvesting phases in a poplar short rotation coppice (second rotation) were calculated. The main objective of the work was to evaluate the yard productivity and the economic gain in order to furnish good indications to the field operators about the harvesting planning. A comparisons between productivity and economic features was carried out on observed (experimental yard) and optimized data (optimized yard), the latter characterized by the absence of the inproductive times due to suboptimal yard organization. The harvested gross time as a function of distance covered by machine was assessed using linear regressions methods. The observed average biomass in plantation was 47.32 t ha-1. The harvesting gross average productivity observed in experimental yard was 34.20 t h-1 and the optimized was 54.16 t h-1. The working ability was 0.76 and 1.18 ha h-1 for experimental and optimized yard, respectively. The final product (chips) costs estimated was 9.81 euro t-1 and 444.46 euro ha-1 in the experimental yard. The optimized yard was 22-24% more efficient . This paper demonstrates the feasibilty to estimate harvesting times and costs per hectare using linear regressions with good approximation when the standing biomass in plantation is known. [ABSTRACT FROM AUTHOR]

In this work, we examine a predator–prey model that considers the implicit marine reserve in prey species and a linear function of critical biomass level. The model's basic properties (existence, uniqueness, positivity, boundedness, and permanence) and equilibrium points are determined. We obtain three equilibrium points: the trivial equilibrium point, the equilibrium point where there is no harvest, and the co-existing equilibrium point. The local and global stability of each equilibrium point of the model is explored. Moreover, the interior equilibrium point is always globally asymptotically stable, and the system experiences no limit cycles around the interior equilibrium point. Numerical simulations are conducted to illustrate the theoretical results obtained. Finally, we find overlapping conditions regarding the dynamics between the model we developed and a model that considers a constant critical biomass level for certain parameters. [ABSTRACT FROM AUTHOR]

Microalgal biomass represents a sustainable bioresource for various applications, such as food, nutraceuticals, pharmaceuticals, feed, and other bio-based products. For decades, its mass production has attracted widespread attention and interest. The process of microalgal biomass production involves several techniques, mainly cultivation, harvesting, drying, and pollution control. These techniques are often designed and optimized to meet optimal growth conditions for microalgae and to produce high-quality biomass at acceptable cost. Importantly, mass production techniques are important for producing a commercial product in sufficient amounts. However, it should not be overlooked that microalgal biotechnology still faces challenges, in particular the high cost of production, the lack of knowledge about biological contaminants and the challenge of loss of active ingredients during biomass production. These issues involve the research and development of low-cost, standardized, industrial-scale production equipment and the optimization of production processes, as well as the urgent need to increase the research on biological contaminants and microalgal active ingredients. This review systematically examines the global development of microalgal biotechnology for biomass production, with emphasis on the techniques of cultivation, harvesting, drying and control of biological contaminants, and discusses the challenges and strategies to further improve quality and reduce costs. Moreover, the current status of biomass production of some biotechnologically important species has been summarized, and the importance of improving microalgae-related standards for their commercial applications is noted. [ABSTRACT FROM AUTHOR]

In the technological process of maintaining grapevine plantations, an important role is played by the winter pruning processes that are carried out during the vegetative rest period. As a result, a large amount of biomass that can be exploited by winegrowers can be used to obtain industrial bio–fuel or used as a source of energy in its own regime to reduce heating costs in the cold season. The experiment was carried out on four varieties of economic interest from the Murfatlar vineyard: Fetească neagra, Cabernet Sauvignon, Sauvignon blanc and Fetească regală. Several factors were analyzed: the average biomass removed from 30 vines of each variety, the method of biomass harvesting, the time and fuel consumption per hectare, the average weight of the biomass before and after drying and the total mass obtained after drying for each variety. The results showed weight differences between varieties. For the Fetească neagra variety, the weight at the time of collection was 645.84 kg/ha, for the Fetească regală variety, the weight reached 155.16 kg/ha. In the conventional way, the fuel consumption following the wood material collection operations reached 11.6 liters per hectare, while, through the baling and transport process, the consumption was 8.3 L/ha, registering a difference of 3.3 L/ha. After storage and drying, differences in moisture loss were recorded, thus in Fetească neagră the moisture decreased by a percentage of 24.573%, and in Fetească regală which recorded a loss of 33.657% of the initial weight. The average collection time was 2 hours and 24 minutes per hectare and did not show significant differences between varieties because the slope and elevation are the same for all the varieties examined. [ABSTRACT FROM AUTHOR]

Copyright of Zpravoday Hnede Uhli is the property of Brown Coal Research Institute, j.s.c. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)