Resources, Volume 13, Issue 5 (May 2024) – 10 articles

Gypsum binders and the products based on them are widely in demand in the construction materials market, which is due to their easy production technology, lower energy consumption, and low environmental impact in relation to Portland cement. Not only natural gypsum (NG), but also phosphogypsum (PG), which is a by-product of the synthesis of orthophosphoric acid from phosphorite rock, can be used as a source of raw materials for the production of gypsum materials. PG is produced annually in large quantities throughout the world. In chemical composition, PG mainly consists of calcium sulfate dihydrate CaSO₄·2H₂O, so it is a good potential analogue of natural gypsum, which is used as the main component of gypsum building materials. Thus, the useful recycling of PG as a technogenic resource with valuable properties will expand the raw material base for the production of gypsum materials. This approach to handling technogenic resources fits well with the principles of a circular economy. However, like any technogenic resource, PGs from different enterprises normally differ in their deposits of the original phosphate rock and production technologies. Therefore, PG contains a large number of undesirable impurities, the proportion and composition of which vary over a wide range. This feature does not allow for predicting the properties of PG-based materials without a preliminary detailed study of PG. This research was aimed at carrying out a comprehensive study of the characteristics of PGs from three different industrial plants to evaluate their relationship with the properties of gypsum materials based on them. It was found that PGs have significant differences in their structural and morphological characteristics both in relation to each other and in relation to NG. Also, binders based on PG and NG have significant differences in their physical properties. The average density, compressive strength, and flexural strength for the PG binders with equal workability are lower than those of NG binders. At a water/solid ratio (W/S) < 0.7, all PG binders exhibit comparable compressive strength to NG binders. Thus, PG can act as an alternative to natural gypsum in gypsum binders. Full article

The genus Spondias has two species of native trees from Brazil that deserve to be highlighted: Spondias tuberosa (“umbu”) and Spondias mombin (“cajá”). Their fruit contain bioactive compounds which have been associated with several biological activities. However, they remain little exploited in the development of food and pharmaceutical products. In this perspective, the present review summarizes the literature data about the physicochemical and nutritional characteristics, bioactive compounds, potential health benefits, and industrial applications of these fruit, including their pulp, seed, and peel. The current scenery mapping for scientific articles was performed in the Scopus and Web of Science databases. The study also considered patent applications collected in the Derwent database. Results showed an increase in scientific publications in recent years for both species. Many applications are related to food technology; nevertheless, due to the composition of their non-edible fractions, they have the potential for use in biorefinery, being their use an opportunity for bioeconomy. Thus, this review provides a comprehensive overview of these Brazilian native fruit to offer a theoretical foundation and valuable data for future investigations and exploitation. Full article

Chymotrypsin from the digestive organs of bigfin reef squid, a major commercial squid species in Thailand, was purified to 41-fold with 5.7% yield by a sequential purification process including ammonium sulfate precipitation, size exclusion, and ion exchange chromatography. According to SDS-PAGE, the molecular weight of purified chymotrypsin was 43 kDa. Native-PAGE analysis revealed a single band for this purified enzyme. The optimum pH and temperature for chymotrypsin activity of the purified enzyme were a pH of 7.0 with a temperature of 55 °C. The purified chymotrypsin remained stable throughout a wide range of pH levels (6–11) and at relatively high temperature (55 °C). It was significantly inhibited by PMSF and TPCK. The values of the kinetic constants K_m and K_cat were found to be 1.33 mM and 31.46 s⁻¹, respectively. The purified chymotrypsin has the N-terminal amino acid IVGGQEATPGEWPWQAALQV. This study provided new information about the biochemical properties of pure chymotrypsin from bigfin reef squid, which will be useful in the future investigation, aquaculture, and application of bigfin reef squid. Full article

Despite notable achievements in the development and application of the remediation of metal-contaminated soils, the search for and study of promising immobilizing agents continues. This article presents a new approach to using brown coal and activated carbon and their application for metal stabilization. An experiment was conducted to test Medicago falcata L. on soils from industrial areas contaminated with varying levels of lead (Pb), cadmium (Cd), chromium (Cr), zinc (Zn), copper (Cu), and nickel (Ni) with the addition of carbons. This plant is a stress-tolerant leguminous species. In this study, the total content of metals in soil and the available forms to plants (single extractions with 0.02 M ethylenediaminetetraacetic acid, EDTA) were determined, along with metal contents in the plant. The use of carbons lowered the phytoavailable forms of metals for plants and thus, resulted in a reduction in the phytotoxicity of the soils. The contents of the tested metals in the roots and shoots were lower than in the combinations of soils with no carbon added. The activated carbon had a stronger effect on limiting the availability of metals than brown coal in relation to plants growing on soils without added carbon; the percentage of reduction for the shoots was Cr (18.2%) > Zn (11.5%) > Ni (10.7%) > Cu (10.3%) > Cd (8.9%) > Pb (2.4%) and Cu (13.3%) > Cr (12.5%) > Zn (10.5%) > Pb (9.0%) > Ni (5.7%) > Cd (4.6%) for roots. Metals reduced the growth of Medicago falcata L. roots from 44 to 21%, while the growth of shoots was reduced from 25 to 2%. Adding carbons to soils in all combinations resulted in a decrease in the following pollution indices: pollution index (PI), pollution load index (PLI), and non-carcinogenic (HQ) and carcinogenic risk factors (ILCR). Full article

Although the Circular Economy (CE) has made remarkable technological progress by offering a wide range of alternative engineering solutions, an obstacle for its large-scale commercialization is nested in the adoption of those business and financial models that accurately depict the value generated from resource recovery. Recovering a resource from a waste matrix conserves natural reserves in situ by reducing demand for virgin resources, as well as conserving environmental carrying capacities by reducing waste discharges. The standard business model for resource recovery is Industrial Symbiosis (IS), where industries organize in clusters and allocate the process of waste matrices to achieve the recovery of a valuable resource at an optimal cost. Our work develops a coherent microeconomic architecture of Chemical Leasing (Ch.L.) contracts within the analytical framework of the Sherwood Plot (SP) for recovering a Value-Added Compound (VAC) from a wastewater matrix. The SP depicts the relationship between the VAC’s dilution in the wastewater matrix and its cost of recovery. ChL is engineered on the SP as a financial contract, motivating industrial synergies for delivering the VAC at the target dilution level at the market’s minimum cost and with mutual profits. In this context, we develop a ChL market typology where information completeness on which industry is most cost-efficient in recovering a VAC at every dilution level determines market dominance via a Kullback–Leibler Divergence (D_KL) metric. In turn, we model how payoffs are allocated between industries via three ChL contract pricing systems, their profitability limits, and their fitting potential by market type. Finally, we discuss the emerging applications of ChL financial engineering in relation to three vital pillars of resource recovery and natural capital conservation. Full article

The climate challenges posed by the European Union are particularly difficult for emerging and developing economies. This causes reluctance to undertake them and even denial of their validity. For this reason, this article seeks to answer the question of whether it is possible to carry out an effective transformation of energy resources in the developing economies of the Visegrad Group. Analyses in this area are conducted in a long-term, 58-year research perspective (1965–2022) and concern the Czech Republic, Hungary, Poland, and Slovakia. The effectiveness of the examined transformation is assessed in two dimensions as follows: (1) resource and (2) emission, which are then synthesized using a multi-criteria analysis. This research shows that an effective resource transformation aimed at a zero-emission economy is possible even in emerging and developing economies, although it undoubtedly requires time and consistency in the implementation of the once-chosen energy policy. Hungary—a leader in assessed climate effectiveness—has systematically decarbonized while reducing the use of total non-renewable resources. The Hungarian resource transition strategy assumed the use of nuclear energy and an increase in the share of renewable resources. The result of these activities is a quite diversified energy mix, which is greater resource self-sufficiency and low carbon dioxide emissions. The Czech Republic also achieved a similar strategy and results. Poland and Slovakia coped much worse with the climate challenge: although they gave up coal, they replaced it largely with other non-renewable resources. It is worth emphasizing that Poland has managed to significantly increase the use of renewable resources, and nuclear energy and hydropower have also appeared in the Slovak mix. Nevertheless, this did not allow for achieving good climatic results. Full article

Chert, a by-product rock of sand quarrying, has historically posed economic challenges for aggregate production, resulting in significant “waste” accumulation in quarries. Our study investigates the effect of microwave irradiation on the mechanical properties of chert gravel, a mineralogically homogenous material composed of fine quartz grains. The results, which demonstrate that increased irradiation time leads to a substantial decrease in chert gravel strength (by a factor of 4–6 for 2.5 min of irradiation), underscore the potential impact of this research on comminution processes. With quenching altering the fractional content of the samples after the crushing test, reducing the Gravel-to-Sand ratio, this study is driven by the promising potential of crushed chert gravel as a pivotal aggregate within the concrete and asphalt industries, offering a practical solution to their material needs. The urgent need to rehabilitate previously utilized quarry areas, offering an environmentally beneficial solution for which we all should be responsible, motivated the present study. Full article

Modern forestry systems rely on typologies of forest types (FTs). In Argentina, several proposals have been developed, but they lack unified criteria. The objective was to compare different approaches, specifically focusing on (i) phenoclusters (functional forests based on vegetation phenology variations and climate variables) and (ii) forest canopy cover composition by tree species. We conducted comparative uni-variate analyses using data from national forest inventories, forest models (biodiversity, carbon, structure), and regional climate. We assessed the performance of phenoclusters in differentiating the variability of native forests (proxy: forest structure), biodiversity (proxy: indicator species), and environmental factors (proxies: soil carbon stock, elevation, climate). Additionally, we proposed a simple FT classification methodology based on species composition, considering the basal area of tree species. Finally, we compared the performance of both proposals. Our findings showed that classifications based on forest canopy cover composition are feasible to implement in regions dominated by mono-specific forests. However, phenoclusters allowed for the increased complexity of categories at the landscape level. Conversely, in regions where multi-specific stands prevailed, classifications based on forest canopy cover composition proved ineffective; however, phenoclusters facilitated a reduction in complexity at the landscape level. These results offer a pathway to harmonize national FT classifications by employing criteria and indicators to achieve sustainable forest management and conservation initiatives. Full article

As global fish consumption rises, a large amount of waste is generated that is generally neglected. Considering the value embedded in these resources, sustainable methods become more important in extracting valuable ingredients from fish processing residues. Enzymatic hydrolysis is a fast and easily reproducible method for recovering protein ingredients and obtaining valuable by-products. To confirm its advantages, an environmental and economic impact assessment is essential. This study overviewed the sustainability and economic viability of extracting protein compounds and oil from Atlantic mackerel processing residues using enzymatic hydrolysis. Life cycle assessment (LCA) and life cycle cost analysis (LCCA) methods were employed. It was found that the climate change impact of the whole process was 0.073 kg CO₂-eq per 1 g of fish protein hydrolysate (FPH). As the process produces FPH as the main product and fish oil as the by-product, economic allocation was used to distribute the impacts of FPH and fish oil. The findings of the LCCA showed that producing 1 g of FPH costs EUR 3.68. The contribution analysis indicated the crucial role of electricity and fish in environmental impacts. To ensure the accuracy of the calculation, the results of an LCA study published previously were recalculated. The sensitivity analysis showed that the results were susceptible to the region and source of electricity production. This research provides valuable insights into the sustainability and economic aspects of using enzymatic hydrolysis for extracting protein ingredients and oils from Atlantic mackerel. This can inform future investigations of environmentally friendly and economically viable solutions for extracting fish ingredients. Full article

This study focuses on temperature and snowfall conditions in Poland, both of which were analyzed from 1981 to 2020. A 40-year record of daily snow fraction time series values was reconstructed using a unique and global multi-source weighted-ensemble precipitation (MSWEP) product, which provided a spatially and temporally consistent reference for the assessment of meteorological conditions. The average states and trends in snow fraction and temperature were analyzed across several years, focusing on the 6-month cold season (November–April). The impact of temperature on the snow fraction pattern was assessed by introducing a snow fraction sensitivity index. To predict short-term changes in snow conditions, a proxy model was established; it incorporated historical trends in the snow fraction as well as its mean state. This study provides clear evidence that the snow fraction is principally controlled by increases in temperature. A warming climate will thus cause a decline in the snow fraction, as we observed in vast lowland areas. Given the ongoing global warming, by the 2050s, snow-dominated areas may go from covering 86% to only 30% of the country’s surface; they will be converted into transient rain–snow areas. Our results demonstrate that a decline in snow water resources has already occurred, and these resources are expected to diminish further in the near future. New insights into the sensitivity of the snow fraction to climate warming will expand our collective knowledge of the magnitude and spatial extent of snow degradation. Such widespread changes have implications for the timing and availability of soil and groundwater resources as well as the timing and likelihood of floods and droughts. Thus, these findings will provide valuable information that can inform environmental managers of the importance of changing snowfall conditions, guiding them to include this aspect in future climate adaptation strategies. Full article