Evaluation of the Potential of Agricultural Waste Recovery: Energy Densification as a Factor for Residual Biomass Logistics Optimization

Sustainable and circular agro-environmental practices: A review of the management of agricultural waste biomass in Spain and the Czech Republic

Sustainable and circular production models, such as the circular economy and circular bioeconomy, have become key mechanisms to leave behind the traditional linear model of food production. Under this approach and considering the waste biomass potential available in Spain and the Czech Republic, the main objective of this study is to analyse the most relevant aspects of the generation, use and regulation of agricultural waste biomass (AWB) in both countries. For this purpose, a scientometric analysis and systematic review of published research in the Scopus database were carried out. A complementary analysis of AWB management policies and regulations was also part of the methodology. The results show that Spain has published almost twice as much research as the Czech Republic. Furthermore, 91% of the retrieved research prioritizes the characterization and estimation of the potential of more than 15 AWB types. Among the main ones are olive residues, horticultural residues and wheat straw, which are used for producing organic amendments, bioenergy and biofuels. The results confirm that the reduction and valorization of AWB is an issue that has become more important in the last 13 years, mainly due to the policies and strategies for circular economy and circular bioeconomy. With this in mind, this study provides relevant information for governments on the aspects that need to be improved to advance in the valorization of AWB. This study also provides guidance to farmers on the reduction and/or recovery alternatives that they can implement to move towards sustainable and circular agriculture.

Effect of Walnut-Shell Additive on the Structure and Characteristics of Concrete

The partial replacement of the mineral components of concrete with natural renewable analogues in full possession of the performance characteristics of the final material, allows not only the concrete-production process to be made more environmentally friendly and inexpensive, but also to solve an important task for the agricultural industry, which is that associated with waste disposal. The scientific novelty of the work is in the obtaining of new concrete compositions by the partial replacement of coarse aggregate with a natural analogue in the form of a walnut shell, which has the maximum ratio of the strength of the composite to its density, as well as in identifying new dependencies of strength and density and their ratio on the amount of replacement of mineral coarse-aggregate walnut shell. The main goal of this article was to analyze the effect of composition factors on characteristics of concrete with partial replacement of large aggregates with walnut shells and to search for the optimal compound that would make it possible to obtain concrete with a minimum decrease in strength characteristics with a maximum decrease in concrete density. Cubes and prism laboratory samples were made from concrete of normal density with the replacement of coarse aggregate by 5, 10, 15, 20, 25 and 30%, by volume. The main mechanical properties, such as density, strength (compressive, tensile, tensile strength in bending) of the concrete samples were studied. The investigation used standard methods and scanning electron microscopy. An increase into strength characteristics up to 3.5%, as well as the maximum ratio of strength to density of concrete, was observed at a walnut-shell dosage of 5%. Effective partial replacement of coarse aggregate with walnut shells leads to a reduction in the consumption of crushed stone by up to 10% and a decrease in the mass of concrete by up to 6%.

Characterization of solid biomass briquette biofuel from the wastes of Senna auriculata and Ricinus communis using Tapioca starch for sustainable environment

Biomass energy contributes nearly 14% of the total global energy. Therefore, biomass briquettes can be effectively considered an alternate source of fossil fuels. The present study aims at utilizing Senna auriculata and Ricinus communis waste generated locally for the production of biomass briquettes with 10% of tapioca starch as binder. The biomass wastes are blended at various proportions such as 0:100 (S1), 25:75 (S2), 50:50 (S3), 75:25 (S4) and 100:0 (S5) respectively, and the concentration of binder was maintained to be constant. The characterization of the prepared biomass briquettes includes the analysis of physical characteristics, proximate analysis, elemental analysis, SEM analysis, thermogravimetric analysis, differential scanning calorimetric analysis and XRD analysis. The results of the proximate analysis have revealed that the biomass briquettes possess lower percentage in terms of moisture content, ash content, sensible fixed carbon and high percentage of volatile matter content. Energy dispersive X-ray analysis has shown that the carbon and oxygen are the major elements for all the biomass briquettes. SEM analysis has revealed that the surface of the biomass briquettes is identified with irregular surface, lumps, cavities and few deposits of carbon particles. Thermogravimetric analysis and DSC analysis have reconfirmed the spontaneous burning characteristics of biomass briquettes. XRD analysis has proved that the bonding between each element present in the biomass briquettes is either monoclinic, tetragonal, orthorhombic or anorthic.

An overview of torrefied bioresource briquettes: quality-influencing parameters, enhancement through torrefaction and applications

In recent years, the need for clean, viable and sustainable source of alternative fuel is on the rampage in the global space due to the challenges posed by human factors including fossil induced emissions, fuel shortage and its ever-rising prices. These challenges are the major reason to utilize alternative source of energy such as lignocellulosic biomass as domestic and industrial feedstock. However, biomass in their raw form is problematic for application, hence, a dire need for torrefaction pre-treatment is required. The torrefaction option could ameliorate biomass limitations such as low heating value, high volatile matter, low bulk density, hygroscopic and combustion behaviour, low energy density and its fibrous nature. The torrefied product in powder form could cause air pollution and make utilization, handling, transportation, and storage challenging, hence, densification into product of higher density briquettes. This paper therefore provides an overview on the performance of torrefied briquettes from agricultural wastes. The review discusses biomass and their constituents, torrefaction pre-treatment, briquetting of torrefied biomass, the parameters influencing the quality, behaviour and applications of torrefied briquettes, and way forward in the briquetting sector in the developing world.

Agro-residual biomass and disposable protective face mask: a merger for converting waste to plastic-fiber fuel via an integrative carbonization-pelletization framework

Incineration and landfilling offer possibilities for addressing high-rate management of COVID-waste streams. However, they can be costly and environmentally unsustainable. In addition, they do not allow to convert them to fuels and chemicals as waste-to-energy and waste-to-product technologies. Therefore, we analyzed whether integrating hydrothermal carbonization (HTC) and pelletization can allow converting the surgical face mask (SFM) and biomass to composite plastic-fiber fuel (CPFF). We blended the plastic material and corncob, peanut shell, or sugarcane bagasse at the proportion of 50:50 (%, dry mass basis) for HTC. We performed the thermal pretreatment of blends in an autoclaving reactor at 180 °C and 1.5 MPa. Then we pelletized the hydrochars in a presser machine at 200 MPa and 125 °C. By analyzing the evidence from our study, we recognized the viability of combining the SFM and agricultural residues for CPFF from comparable technical features of our products to standards for premium-grade wood pellets. For instance, the elemental composition of their low-meltable ash was not stoichiometrically sufficient to severely produce slagging and fouling in the equipment for thermal conversion. Although they contained synthetic polymers in their structures, such as polyethylene from filter layers and nylon from the earloop, they emitted CO and NOx below the critical limits of 200 and 500 mg m-3, respectively, for occupational safety. Therefore, we extended the knowledge on waste-to-energy pathways to transform SFM into high-quality hybrid fuel by carbonization and pelletization. Our framework can provide stakeholders opportunities to address plastic and biogenic waste in the context of a circular economy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13399-022-03285-4.

A Review of Biomass Briquette Binders and Quality Parameters

The adverse effect of the use of fossil fuels on the environment and public health has given rise to a sustained renewable energy research and development. An important component of global renewable energy mix is the use of loose biomass, including agricultural and forestry residues, to produce solid fuels in the form of briquettes. Briquettes play a significant role in bioenergy mix in developing and developed countries. The production of biomass briquettes often entails the collection, transportation, storage, processing, and compaction of loose biomass that meet specific quality parameters. The densification process often involves the addition of binders to improve the cohesive strength of the briquette material. This paper surveys recent literature from 2012 to 2021 to establish the current state of research on the use of binders in briquette production; and reviews current parameters used in assessing the quality of biomass briquettes with focus on mechanical and handling properties. While a number of quality parameters were identified, their assessment methodologies varied widely in the literature, thus necessitating standardization for comparability purposes. The review also includes factors affecting the wide production and adoption of biomass briquettes in most developing economies and proposes ways of overcoming the bottlenecks.

Production of Particleboard Using Various Particle Size Hemp Shives as Filler

Research was performed into the use of hemp shive as a fast-growing and carbon-storing agricultural waste material in the production of particleboard for the construction industry. Hemp shives were acquired and prepared for board production with the use of milling and sieving to reach two target groups with 0.5 mm to 2 mm and 2 mm to 5.6 mm particle size ranges. The cold pressing method was used to produce hemp boards with Kleiberit urea formaldehyde resin as a binder. The boards were made as 19 mm thick single-layer parts with a density range of 300 ± 30 kg/m³, which qualifies them as low-density boards. Exploratory samples were made using milled hemp fibers with higher density. Additional components such as color pigments and wood finishes were added to test improved features over raw board samples. Tests were performed to determine moisture contents, density range, structural properties, and water absorption amounts. Produced board bending strength reached 2.4 MPa for the coarser particle group and thermal conductivity of 0.057 ± 0.002 W/(mK). The results were compared with existing materials used in the industry or in the development stage to indicate options of developed board applications as indoor insulation material in the construction industry.

Medical Peat Waste Upcycling to Carbonized Solid Fuel in the Torrefaction Process

Peat is the main type of peloid used in Polish cosmetic/healing spa facilities. Depending on treatment and origin, peat waste can be contaminated microbiologically, and as a result, it must be incinerated in medical waste incineration plants without energy recovery (local law). Such a situation leads to peat waste management costs increase. Therefore, in this work, we checked the possibility of peat waste upcycling to carbonized solid fuel (CSF) using torrefaction. Torrefaction is a thermal treatment process that removes microbiological contamination and improves the fuel properties of peat waste. In this work, the torrefaction conditions (temperature and time) on CSF quality were tested. Parallelly, peat decomposition kinetics using TGA and torrefaction kinetics with lifetime prediction using macro-TGA were determined. Furthermore, torrefaction theoretical mass and energy balance were determined. The results were compared with reference material (wood), and as a result, obtained data can be used to adjust currently used wood torrefaction technologies for peat torrefaction. The results show that torrefaction improves the high heating value of peat waste from 19.0 to 21.3 MJ × kg−1, peat main decomposition takes place at 200–550 °C following second reaction order (n = 2), with an activation energy of 33.34 kJ × mol−1, and pre-exponential factor of 4.40 × 10−1 s−1. Moreover, differential scanning calorimetry analysis revealed that peat torrefaction required slightly more energy than wood torrefaction, and macro-TGA showed that peat torrefaction has lower torrefaction constant reaction rates (k) than wood 1.05 × 10−5–3.15 × 10−5 vs. 1.43 × 10−5–7.25 × 10−5 s−1.

Characterization of Cytisus striatus (Hill) Rothm.: Waste Biomass Energy Recovery as a Measure to Reduce the Risk of Rural Fires

Shrub species play a critical ecological role in ecosystems, covering significant areas. However, with the current development of vegetation cover, conditioned by climate change, certain species have acquired a dominant role, which suffocates the other ecosystem species in a natural monoculture model. Thus, some species, such as Cytisus striatus (Hill) Rothm., have acquired preponderance, mainly due to the dense forests they establish. This situation has contributed to the increased risk of rural fires, forcing permanent actions to control the settlements. These actions entail costs that make the continuity and permanence of control unsustainable. The energetic valorization of residual biomass resulting from operations to reduce fuel load is an option that seems viable, mainly if used in the production of biomass pellets in a mixture with other biomasses, such as Pinus pinaster or Eucalyptus globulus. The laboratory characterization tests demonstrated that the residual biomass of C. striatus presents parameters that fall within limits defined by the standard ENPlus®. The processing of this residual biomass on an industrial scale line is also feasible. However, given the configuration of the material to be processed, production lines may be necessary, especially concerning the detachment of the material. The logistical issue may also impose restrictions since the material has a low density, even when baled.