The aim of this study was to compare the immobilisation of metal(loid)s in two differently contaminated soils using micro zerovalent iron (ZVI) and nano zerovalent iron (nZVI) particles. Chromated ...copper arsenate-contaminated soil contained high amounts of As, Cu, Cr, and Zn, whereas mining-contaminated soil contained high amounts of As, Cu, and Pb. Contaminated soils were amended using 2% ZVI and nZVI. As determined by the leaching procedures, nZVI was more efficient in immobilising all the studied metal(loid)s in the soils compared to ZVI. The greatest immobilisation was achieved for As in both soils. The long-term stability of immobilised metal(loid)s was studied in mining-contaminated soil by performing thermal oxidation (ageing). In the ZVI and nZVI-treated soils, high retention results were achieved for As and Cu, whereas in the ZVI and nZVI-treated soils, significant desorption of Pb was observed. The results also showed that retention of metal(loid)s over a long period of time could be more effective in soils treated with ZVI, as the crystallisation of Fe in ZVI-treated soil was to a lesser extent compared to the crystallisation of Fe in nZVI-treated soil.
•nZVI was more efficient in immobilising As, Cr, Cu, Pb, and Zn compared to ZVI.•The most efficient immobilisation in two treated soils was achieved for As.•Ageing reduced reactive Fe by 2 times in the ZVI-amended soil.•Ageing reduced reactive Fe by 50 times in the nZVI-amended soil.•The long-term stability for Pb was not achieved by neither of Fe additives.
Composting is a promising source of mesophilic and thermophilic microorganisms directly involved in the decay of organic matter. However, there is a paucity of information related to bacterial and ...fungal diversity in compost and their enzymatic activities during the composting process. In this work, bacterial and fungal diversity during the mesophilic and thermophilic phases of textile waste composting was investigated as a way to explain the physical-chemical results obtained during the composting process. This was accomplished using a next-generation sequencing approach that targets either the 16S rRNA or ITS genomic regions of bacteria and fungi, respectively. It was observed that Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant bacterial phyla present at the mesophilic phase but not at the thermophilic one. Composting textile waste exhibits a sustained thermophilic profile (above 55 °C) that usually precludes fungal activity. Nonetheless, the presence of fungi at the thermophilic phase was observed. Rozellomycota, Basidiomycota, and Ascomycota were the most dominant phyla during both composting phases. Such thermophilic fungi with great ability to decay organic matter could be isolated as pure cultures and used for the bioaugmentation of textile waste composting to achieve an advanced maturity level of textile waste compost.
Nano zerovalent iron (nZVI) is one of the most widely used nanotechnologies in soil remediation, but its long-term performance can be limited due to its high reactivity and rapid ageing. The aim of ...this study was to compare the immobilisation of Cd, Cu, Ni, and Pb in artificially contaminated soil samples using nZVI and to evaluate their retention over a 1-year period. Single-metal-contaminated soil samples were amended using 0–1.05% of nZVI. Leaching, using CaCl
2
solution and a sequential extraction procedure, was performed to evaluate the immobilisation efficiency and fractionation of heavy metals before and after ageing. The results of the extractions showed that the application of nZVI initially reduced the exchangeable fraction of all heavy metals. The greatest immobilisation efficiency was achieved for Cu. The retention of heavy metals by nZVI was studied by constantly humidifying soil samples for a 12-month period. The results showed that over this period, the efficiency of nZVI treatment decreased, due to the decrease in the amount of reactive iron oxides in soil samples. Retention of immobilised heavy metals by nZVI strongly depended on their ionic radius. The highest retention results were obtained for Cu and Ni, whereas the lowest results were obtained for Cd and Pb.
Bottom ash (BA) is the main residue left by municipal solid waste incineration (MSWI). As the circular economy is strengthened, the use of BA in civil engineering is increasing, but its successful ...use is hampered by heavy metal leaching. In this study, we investigated the influence of natural weathering (6 months) on the stabilization of heavy metals (Cu, Zn, and Pb) with different particle sizes in MSWI BA. Natural weathering is the most popular and cost-effective treatment method for BA. During this process, calcium carbonate (CaCO3) is produced, which causes a reduction in heavy metal leaching. We used the following methods in the analysis: The fractionation of BA, XRF, and XRD; an extraction test (LST EN 12457-2:2003); and AAS. The results showed that the concentrations of all elements in BA decreased during natural weathering. An analysis of the mineralogical composition showed a very high (>20%) content of calcium carbonate (CaCO3). The calcium carbonate content increased by 3.2% during weathering because the Ca(OH)2 in fractions <5.6 mm and <40.0 mm was hydrolyzed to CaCO3. Our analysis showed that the metal concentrations (Cu and Pb) in untreated MSWI bottom ash eluate exceeded the limit values, and thus it cannot be used in civil engineering. After three months of stabilization, the heavy metal concentrations were less than the limit values.
The aim of this study was to investigate the properties of concrete containing various quantities of copper indium selenide (CIS) solar module waste by replacing a certain part (up to 40%) of sand. ...The obtained results have shown that an increase in the content of solar module waste resulted in an increase of the density of fresh and hardened concrete. The compressive strength of the specimens compared to the control specimens has been higher, when sand aggregate was replaced by CIS solar module waste particles from 5 to 20%. Also, a decrease in the water absorption and porosity of concrete specimens containing immobilized waste compared to those with no waste has been observed. The leaching behaviour of the concrete containing immobilized waste was also studied. The results showed that the concrete with sand aggregate replacement by waste particles between 5 and 10% has the best leaching properties. That replacement can be used for CIS solar module waste recycling in concrete production.
Municipal solid waste has become a serious problem because of rapid urbanization and great economic growth. As a result of these, huge impacts on the environment lead to a lot of problems not only ...air, soil or water pollution but human health too. One of the solutions to manage MSW problem is incineration with energy recovery that can reduce a large amount of waste in volume. But the activity of incineration plant is associated with the formation of a large amount of hazardous waste, a significant part is fly ash which is by-products of MSW contains a high number of heavy metals and salts which are very toxic. Fly ash is a really topical question today and it is important to find out how to dispose of it properly due to hazardous contents. In this study was performed the municipal solid incineration fly ash evaluation, experimental research of heavy metal composition of seven types of a concrete mixture containing different amounts of MSWI fly ash, silica nanocomposites for the determination of the best alternative and employing a SWOT analysis.
This study conducted an in-depth examination of the delamination process of multi-layer packaging waste (MLPW) recycling, intending to find an effective solution for recycling MLPW. The recycling ...process for such materials can be challenging due to the complexity of separating the different layers and components. However, this study proposed using nitric acid to facilitate delamination and recover the polymers from multilayer food packaging—the research aimed to investigate the mechanical properties of the polymers obtained through this recycling method. Our study on polymer materials exposed to chemicals revealed differences in fracture and tensile strengths among three polymers, P1, P2, and P3. P1 showed fluctuating fracture strengths between 5.11 MPa and 3.55 MPa, while P2 maintained a consistent but lower value of around 0.09 MPa. P3 exhibited a wider range from 3.19 MPa to 1.79 MPa. Tensile strength analysis showed P1 averaging 4.99 MPa and P3 3.17 MPa, with P2’s data inconclusive due to its softness. Understanding the mechanical characteristics of recycled polymers is crucial to determine their potential use in different industries, including packaging, construction, or manufacturing, thereby promoting a more environmentally friendly approach to MLPW management.
In this study, the effect of initial feedstock concentration on the microbial community structure and dynamics during textile waste composting processes was investigated using the next-generation ...sequencing approach. For this, three mixtures were prepared with different textile waste concentrations mixed with green waste and paper and cardboard waste for composting, to choose the proportion that will provide a mature final compost. A comprehensive characterization of the microbial communities associated with different textile waste concentrations during composting was achieved. It was noted that by increasing the concentration of textile waste, microbial communities (bacterial and fungal) change. Genera and species belonging to Actinobacteria, Firmicutes, Chloroflexia, Rozellomycota, Mortierellomycota, Aphelidiomycota, Ascomycota, and Mucoromycota were the most abundant in the mixtures containing either 40 or 60% of textile waste, whereas some of the species were absent at 80% of textile waste in the mix; this difference was also reflected by their enzymatic activities. Generally, these phyla are associated with composting, and they play a major role in recalcitrant molecular decaying. Ultimately, it can be concluded that the shift most likely occurred in microbial communities during composting probably owing to the interaction between changes in the nutrient concentration and microbial communities. This investigation proves that the concentration of textile waste significantly affects the microbial communities and demonstrates that a high concentration of textile waste is not suitable to grant a good maturity of compost.
The production of stable and mature compost often depends on the performance of microbes and their enzymatic activity. Environmental and nutritional conditions influence the characteristics of ...microbial communities and, therefore, the dynamics of major metabolic activities. Using three waste mixtures (textile waste mixed with either green, paper, or cardboard waste), the maturity of the compost produced was assessed by following the physico-chemical parameters and enzymatic activities provided by the microorganisms that were identified using next-generation sequencing (NGS). Among the three mixtures used, it was found that the two best mixtures showed C/N ratios of 16.30 and 16.96, total nitrogen of 1.37 and 1.39%, cellulase activities of 50.62 and 52.67 Ug−1, acid phosphatase activities of 38.81 and 68.77 Ug−1, and alkaline phosphatase activities of 51.12 and 56.86 Ug−1. In addition, several lignocellulosic species, together with those that are able to solubilize phosphate, were identified. Among those known for cellulase and acid/alkaline phosphatase activities, bacteria belonging to the Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes phyla were shown. The presence of species belonging to the Ascomycota and Basidiomycota phyla of Fungi, which are known for their ability to produce cellulase and acid/alkaline phosphatases, was demonstrated. These findings provide a basis for the production of stable and mature compost based on textile waste.
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