The use of photovoltaic panels in 21st-century cities has become widespread. Renewable energy systems (RES), particularly various types of photovoltaic panels, are being installed on rooftops, shelters, bus stops, benches, and city lampposts. Globally, the development of so-called smart cities aims to maximize the use of alternative energy sources, which have a pro-environmental impact. However, despite these advancements, new risks are emerging due to the increasing use of electronics and the critical technology elements they contain. This article presents a critical analysis of the development of smart cities worldwide and in Poland, focusing on the application of photovoltaics (PV) as well as research into green solutions and advancements in PV systems. The types of solar cells used in PV panels in smart cities are analysed. Modelling and simulation of PV installed capacity in Poland have also been carried out. According to the forecast, the installed capacity of hard coal energy is projected to grow steadily over the next 10 years, while PV installed capacity is expected to increase significantly, theoretically surpassing hard coal in 2029. The article critically examines the benefits and risks of implementing photovoltaics in smart cities, addressing their environmental impact and potential future challenges stemming from the increasing amount of electronics (including PV panels) in the environment.

This study emphasizes the role of magnetic separation as a novel pretreatment strategy for the recovery of indium from ITO coatings in LCD screen glass. Previous studies have primarily focused on the magnetic separation of leaching residues. In this work, a reverse approach is proposed, and for the first time, magnetic separation was systematically applied prior to leaching. Our results demonstrate that indium accumulates in the ferromagnetic fraction, indicating its association with Fe-rich phases. In addition to Fe, the behavior of Sr and Si was also evaluated, providing a broader understanding of elemental distribution within LCD glass. This finding offers new insights into the distribution and mobility of indium during hydrometallurgical processing and highlights magnetic separation as a valuable step for improving recovery efficiency. To establish optimal leaching conditions, preliminary experiments were performed on ground LCD glass using sulfuric acid at three concentrations (0.1, 1, and 5 M) and two temperatures (21 °C and 65 °C) for both coarse (>1 mm) and fine (<1 mm) particle fractions. All residues and solid-state analyses were performed using the XRF method. Acid molarity was found to be the dominant factor controlling indium dissolution, with 5 M H2SO4 selected as the most effective leaching medium. Statistical evaluation further clarified the dissolution trends of these elements and confirmed the significance of magnetic separation in enhancing the efficiency of indium recovery.

The paper presents the possibility of recovering metals from printed circuit boards (PCBs) of spent mobile phones using the hydrometallurgical method. Two-stage leaching of Cu(II), Fe(III), Sn(IV), Zn(II), Ni(II) and Pb(II) with H2SO4 (2 and 5 M) and HNO3 (2 M) with the addition of H2O2 (10 and 30%) and O3 (9 or 15 g/h) was conducted at various process conditions (temperature—313, 333 and 353 K, time—60, 120, 240, 300 min, type and concentration of leaching agent, type and concentration of oxidant, solid–liquid ratio (S/L)), allowing for a high or total metals leaching rate. The use of two leaching stages allows for the preservation of selectivity, separation and recovery of metals: in the first stage of Fe(III), Sn(IV) and in the second stage of the remaining tested metal ions, i.e., Cu(II), Zn(II), Ni(II) and Pb(II). Removing Fe from the tested PCBs’ material at the beginning of the process eliminates the need to use magnetic methods, the purpose of which is to separate magnetic metal particles (ferrous) from non-magnetic (non-ferrous) particles; these procedures involve high operating costs. Since the leaching of Cu(II) ions with sulfuric(VI) acid practically does not occur (less than 1%), this allows for almost complete transfer of these ions into the solution in the second stage of leaching. Moreover, to speed up the process and not generate too many waste solutions, oxidants in the form of hydrogen peroxide and ozone were used. The best degree of leaching of all tested metal ions was obtained when 2 M sulfuric(VI) acid at 353 K was used in the 1st research stage, and 2 M nitric(V) acid and 9 g/h O3 at 298 K in the 2nd stage of leaching, which allowed it to be totally leached 100% of Fe(III), Cu(II), Sn(IV), Zn(II), Ni(II) and 90% Pb(II).

Energy transition is one of the basic actions taken to counteract and prevent climate change. The basic assumption of energy-related changes is its sustainable use according to the closed-loop model, as well as moving away from fossil fuels, in particular from coal, the combustion of which contributes to excessive harmful carbon dioxide emissions. One of the most popular solutions towards green energy is nuclear energy. Its use allows for a significant reduction in greenhouse gas emissions harmful to the environment and climate, but it also involves the generation of radioactive waste that requires appropriate processing. This paper presents the results of the flotation removal of barium(II) ions from a dilute aqueous solution using ionized acyclic polyethers. The basic factors determining the efficiency and kinetics of the process were defined. It has been shown that as the acidity of the attached polyether molecules increases: the flotation rate constant 1 (0.1667 min−1) < 3 (0.2468 min−1) < 2 (0.3616 min−1) and the separation degree Ba2+: 1 (86.8%) < 3 (99.3%) < 2 (99.4%). The presented results of ion flotation tests may facilitate the collective or selective separation of radioactive isotopes, i.e., Cs-137, Sr-90, Ba-133 and Co-60, from radioactive wastewater in the future. The results of the experimental work described in the article can also be used to develop individual processes for separating mixtures of radioactive isotopes (radioactive wastewater) into individual components (isotopes) and subjecting them to subsequent transformation processes. The obtained results allow us to claim that the tested organic compounds can be used in the future in the selective treatment of hazardous wastewater, which will translate into a reduction in unit costs of industrial processes. The selective recovery of individual pollutants is the basis for the next step in waste management, i.e., designing a cheap method of waste disposal, which also directly affects the economics of the process and its use in industrial conditions.

Metals such as nickel, cobalt, lithium, and manganese are widely used in lithium-ion batteries (LIBs) in electronic devices and electric vehicles. It is forecast that there will be a strong increase in the number of electronic devices and electric vehicles in the coming years. (1) Background: In this paper, the application of ultrasound waves on improving Li, Co, Mn, and Ni leaching efficiency from mixed active cathode materials from different types of LIBs is presented. (2) Methods: Environmentally friendly, low-concentrated (0.75 M) organic acids (oxalic acid, citric acid) and, additionally, sulfuric acid, were used in sonochemical and chemical leaching (stirring process) at a temperature of 60 °C. (3) Results: The results showed significantly higher leaching efficiency of metals with ultrasound-assisted treatment, especially when using organic acids. An average of 50% better leaching results were obtained for Li in oxalic acid (99.6%) and for Co (93.1%) in citric acid during sonochemical leaching. (4) Conclusions: Based on the theory of hydrogen peroxide formation during ultrasound wave transition in solutions, the role of H2O2 as one of the most effective reductants used to enhance cobalt, manganese, and nickel leaching from LIBs is indicated.

Indium as indium tin oxide (ITO) is used in a wide range of products, from transparent conducting oxide films to gas sensors and touch screens to photovoltaic panels (PVs) [...]

Purpose Germanium (Ge) is known as a Technology Critical Element (TCE) and has been widely used in electronic and industrial products. Waste electronic and electrical equipment (WEEE) containing germanium goes to WEEE treatment plants. The transfer of Ge in the environment makes it necessary to get to know its mobility, reactivity, and chemical transformations in soil. The objective of this research was to develop a methodology for germanium speciation in soil under pressure from storage, processing, and recovery from electrowaste. Materials and methods Thirty soil cores (30 cm long) were collected from an area around a WEEE plant, using a Humax soil sampler. Soil magnetometry methods were used for the first time during the determination of soil sampling points for germanium. After basic physicochemical analysis (pH, Eh, total element concentration using the ICP-MS technique), soil samples were prepared for germanium speciation. The optimisation and validation of a methodology for determining Ge species in easily-leached fractions of soil collected from areas around an electrowaste plant, was studied using Ion Chromatography-Inductively Coupled Plasma-Mass Spectrometry (IC-ICP-MS). Chromatographic conditions were optimised, taking soil matrix effects into account. Optimised Ge extraction from the soil included: extraction time, type of extractants, extraction support using shaking, and ultrasound. Results and discussion The Ge species (Ge(IV), monomethylgermanium (MMGe), and dimethylgermanium (DMGe)) were successfully separated after 12 min on a Dionex IonPac AS9-HC column with ammonium nitrate and potassium sodium tartrate as an elution phase. The highest extraction efficiency was achieved by using 100 mM NH 4 NO 3 with 1 mM potassium sodium tartrate as an extractant, that washes out Ge from soils within 4 h. In most cases, the soils contained a Ge(IV) form. Germanium methyl derivatives were only found in a few soil samples. Our research showed that germanium concentration in the studied area was as high as 7.64 mg . kg −1 , with an average concentration of 3.51 mg . kg −1 . The results allowed the creation of a correlation matrix, which identified many strong correlations. Conclusion This research confirmed the impact of a WEEE plant on the increase of the Ge content in topsoil, when in direct proximity. Increased germanium content occurred in soil samples located north of the emitter, which is consistent with the prevailing wind direction. The study confirmed that the soil magnetometry method is applicable for detecting TCE. Soil samples with the highest content of germanium had a very high magnetic susceptibility and there is a correlation between these parameters.

To unveil the potential effect of metal presence to antibiotic tolerance proliferation, four sites of surface landfills containing tailings from metal processing in Slovakia (Hnúšťa, Hodruša, Košice) and Poland (Tarnowskie Góry) were investigated. Tolerance and multitolerance to selected metals (Cu, Ni, Pb, Fe, Zn, Cd) and antibiotics (ampicillin, tetracycline, chloramphenicol, and kanamycin) and interrelationships between them were evaluated. A low bacterial diversity (Shannon–Wiener index from 0.83 to 2.263) was detected in all sampling sites. Gram-positive bacteria, mostly belonging to the phylum Actinobacteria, dominated in three of the four sampling sites. The recorded percentages of tolerant bacterial isolates varied considerably for antibiotics and metals from 0 to 57% and 0.8 to 47%, respectively, among the sampling sites. Tolerances to chloramphenicol (45–57%) and kanamycin (32–45%) were found in three sites. Multitolerance to several metals and antibiotics in the range of 24 to 48% was recorded for three sites. A significant positive correlation (p < 0.05) for the co-occurrence of tolerance to each studied metal and at least one of the antibiotics was observed. Exposure time to the metal (landfill duration) was an important factor for the development of metal- as well as antibiotic-tolerant isolates. The results show that metal-contaminated sites represent a significant threat for human health not only for their toxic effects but also for their pressure to antibiotic tolerance spread in the environment.

New technologies and the globalization of the electrical and electronic equipment market cause a continuous increase in the amount of electrical and electronic waste. They constitute one of the waste groups that grows the fastest in quantity. The development of the new generation of electrical and electronic devices is much faster than before. Recently attention has been concentrated on hydrometallurgical methods for the recovery of metals from electronic waste. In this article the role of an oxidizing agent, mainly ozone and hydrogen peroxide was presented in hydrometallurgical processes. Leaching process of printed circuits boards (PCBs) from used cell phones was conducted. The experiments were carried out in the presence of sulfuric acid and ozone as an oxidizing agent for various temperatures, acid concentration, ozone concentration. As a result, the concentrations of copper, zinc, iron and aluminum in the obtained solution were measured. The obtained results were compared to results obtained earlier in the presence of hydrogen peroxide as an oxidizing agent and discussed.

The intensive development of industry, especially the mining and metallurgy, automotive and electrical industries, as well as the growing demand, rapid consumption and "ageing" of most products, including electrical/electronic equipment, requiring regular replacement, affects the amount of Potentially Toxic Elements (PTE), including Technology Critical Elements (TCE) in the environment. This preliminary study focuses on the following TCE: Ga, Ge and Tl. The main thing they have in common is that they have not been much studied and the level of knowledge concerning the environmental impact of their use is quite slight. Additionally, content of more common PTE (As, Cd, Cu, Pb, Sb, Zn) was determined in order to discover some relationships between these both group. Soil samples were collected from topsoil (0-5 cm) and subsoil (<15 cm) in industrial area influenced by metallurgical slag dump and road traffic. Concentrations of elements were determined with High-Resolution Inductive Coupled Plasma-Mass Spectrometry (HR-ICP-MS) after HNO3 microwave digestion. Results revealed that almost all studied elements were in higher amount in the topsoil suggesting the anthropogenic pollution as a source of their content in soil. The research project received funding from the National Science Centre of Poland on the basis of the decision number UMO-2018/29/B/ST10/01522.

The article presents the assessment of solutions and dried residues precipitated from solutions after the bioleaching process of Printed Circuit Boards (PCB) utilizing the Acidithiobacillus ferrooxidans. The obtained dried residues precipitated from bioleaching solution (leachate) and control solution were tested using morphology, phase, and chemical composition analysis, with particular emphasis on the assessment of crystalline and amorphous components. The analysis of the dried residues from leachate after bioleaching as well as those from the sterile control solution demonstrated a difference in the component oxidation—the leachate consisted of mainly amorphous spherical particles in diameter up to 200 nm, forming lacy aggregates. In the specimenform control solution larger particles (up to 500 nm) were observed with a hollow in the middle and crystalline outer part (probably Fe2O3, CuFeS2, and Cu2O). The X-ray diffraction phase analysis revealed that specimen obtained from leachate after bioleaching consisted mainly of an amorphous component and some content of Fe2O3 crystalline phase, while the dried residue from control solution showed more crystalline components. The share of the crystalline and amorphous components can be related to efficiency in dissolving metals during bioleaching. Obtained results of the investigation confirm the activity and participation of the A. ferrooxidans bacteria in the solubilization process of electro-waste components, with their visible degradation–acceleration of the reaction owing to a continuous regeneration of the leaching medium. The performed investigations allowed to characterize the specimen from leachate and showed that the application of complementary cross-check of the micro (SEM and S/TEM) and macro (ICP-OES and XRD) methods are of immense use for complete guidance assessment and obtained valuable data for the next stages of PCBs recycling.

The article draws attention to the problem of the presence in waste electrical, electronic equipment (WEEE) of selected metals from the group of critical metals (germanium), strategic metals (tellurium) and highly toxic elements (thallium). Due to low content of these metals in e-waste, they are usually ignored during e-waste analysis, therefore they belong to the least-known metals in the literature. Their presence in WEEE can cause them to be concentrated in the environment during improperly e-waste processing. In the article the important applications of Ge, Te, Tl in electronic equipment, quantities identification of these metals in a variety of electronic equipment elements, paying special attention to the ability to accumulate/concentrate Ge, Te, Tl in individual fractions after the e-waste shredding and grinding process are presented. This approach is aimed at determining the possibility of these metals getting into the environment, during the storage and processing of e-waste (especially in the unit processes of disassembly, separation, shredding), in the case of uncontrolled electronic waste handling and disposal. The research project received funding from the National Science Centre of Poland on the basis of the decision number UMO-2018/29/B/ST10/01522.

Mine tailings represent a great environmental concern due to their high contents of heavy metals. Cultivation analysis of microbiota of Tarnowskie Góry (Poland) mine tailing showed the occurrence of bacteria with colony-forming units as low as 5.7 × 104 per one gram of dried substrate. Among 110 bacterial isolates identified by a combination of MALDI-TOF mass spectrometry and 16S rRNA gene sequencing, phylum Actinobacteria was dominant, followed by Firmicutes and Proteobacteria. Extremely high levels of heavy-metal resistance were observed in Arthrobacter spp., particularly for zinc (500 mg/L), lead (1500 mg/L), and cadmium (1000 mg/L). On the other hand, Staphylococcus spp. showed high tolerance to several antibiotics tested, especially ampicillin, partly due to blaZ gene presence. Due to the occurrence of antibiotic-resistant bacteria, mine tailings are not the cause of heavy-metal contamination only, but also a source of antibiotic-resistant bacteria and thus may represent a serious risk for public health.

The influence of pure and mixed culture of A. ferrooxidans and A. tiooxidans as well as different pulp density (1 and 2%) of LCD panels on the In and Sn bioleaching efficiency was investigated.Pulp density is one of the factors affecting the metals extraction efficiency during biological leaching.It has been shown that lower pulp density results in higher indium and tin dissolution.The A. ferrooxidans bioleaching system showed better metal extraction results than A. thiooxidans, especially for tin, indicating the special role of iron and A. ferrooxidans in tin recovery.The highest leaching rate of both indium (94.7%) and tin (98.2%) was obtained using iron and sulfur medium inoculated with mixed bacteria and a pulp density of 1% w/v.

The article analyzes the presence of selected metals, classified as Technology Critical Elements (TCE), in electrical and electronic devices.Metals belonging to the group of critical metals (Germanium), strategic metals (Tellurium), and very toxic elements (Thallium) were analyzed.Due to the low content of these metals in ewaste, they are usually ignored during e-waste analysis.This means that these metals belong among the least known metals in the literature on waste recycling.Their presence in e-waste can cause them to focus on the environment during improper processing of e-waste.The article discusses electronic components in which Ge, Te, Tl, and analysis of the possibility of entering the environment during recycling processes, are found.It allows determining the possibility getting of these metals into the environment, during the storage and processing of e-waste (especially in the unit processes of disassembly, separation, and shredding), in the case of uncontrolled electronic waste handling and disposal.

The paper presents an investigation on the feasibility of recovery of the highly valuable silicon carbide (SiC) from the slurry waste generated from silicon wafer production in the photovoltaic and semiconductor industry. Compared to the other techniques of recycling, a facile and low-cost method of waste treatment via heat drying followed by low-energy mixing in a shaker mixer was proposed. As the result of the treatment, the slurry waste was converted into a powdered form with dominant content of SiC. Separated SiC material was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, and sieve analysis. In addition, analyses of the bulk density, moisture content and melting test were carried out. As was confirmed by the physicochemical analyses, the dominant sieve fraction was in the range of 0.1-0.06 mm, the purity level was a minimum 99% mass of SiC, the moisture content - 0.3%, the bulk density - 1.3 g/cm3. The physicochemical characteristics of the material were crucial for understanding the material performance, assessment of the material quality and determining the perspective directions of the industrial application. The studies revealed that the material exhibited a high application potential as abrasive, especially in abrasive grinding and waterjet cutting.

The article draws attention to the problem of the presence of metals: germanium (Ge), tellurium (Te), thallium (Tl), and others (Cd, Ba, Co, Mn, Cr, Cu, Ni, Pb, Sr, and Zn) in selected waste of electrical and electronic equipment (WEEE). As a result of the growing demand for new technologies, the global consumption of TECs has also been increasing. Thus, the amount of metals in circulation, of which the impacts on the environment have not yet been fully understood, is constantly increasing. Due to the low content of these metals in WEEE, they are usually ignored during e-waste analyses. The main aim of this study was to determine the distribution of Ge, Te, and Tl (and other elements) in ground sieve fractions (1.0, 0.5, 0.2, and 0.1 mm) of selected electronic components (solar lamps, solar cell, LED TV screens, LCD screens, photoresistors, photodiodes, phototransistors) and to determine the possible tendency of the concentrations of these metals in fractions. This problem is particularly important because WEEE recycling processes (crushing, grinding, and even collection and transport operations) can lead to dispersion and migration of TCE pollutants into the environment. The quantitative composition of e-waste was identified and confirmed by ICP-MS, ICP-OES and SEM-EDS, and XRD analyses. It was found that Ge, Te, and Tl are concentrated in the finest fractions of ground e-waste, together with Cd and Cr, which may favor the migration of these pollutants in the form of dust during storage and processing of e-waste.

The aim of the study was to evaluate the application of bioleaching technique to reduce content of selected heavy metals (Zn, Cu) in sewage sludge, and hence to indicate possibilities for metals recovery from this type of waste. Bioleaching experiments were carried out with mixed bacteria Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, using leaching media: ferrous sulfate with different concentrations of Fe2+ (2 g/dm(3) and 9 g/dm(3)) and sulfuric acid (VI). Dynamics of the increase in zinc concentration in biological systems was almost identical for both 9 g Fe2+/dm(3) and 2 g Fe2+/dm(3) in samples. However, higher values of Cu concentration were achieved using a medium with iron(II) salt 9 g/dm(3) than in a 2 g/dm(3) solution. Bioleaching with 9 g Fe2+/dm(3) allowed for a nearly 20-fold reduction of zinc content and a 2-fold reduction in copper content in sewage sludge. Using 9g/ dm(3) ferrous sulfate bioleaching could dissolve 94.8% Zn and 58.9%, whereas chemical leaching dissolved 47.3% Zn and 4.2% Cu.