Metal Emissions Research Articles

Influence of aerosol acidity and organic ligands on transition metal solubility and oxidative potential of fine particulate matter in urban environments

The adverse health effects of air pollution around the world have been associated with the inhalation of fine particulate matter (PM2.5). Such outcomes are thought to be related to the induction of oxidative stress due to the excess formation of reactive oxygen species (ROS) in the respiratory and cardiovascular systems. The ability of airborne chemicals to deplete antioxidants and to form ROS is known as oxidative potential (OP). Here we studied the influence of aerosol acidity and organic ligands on the solubility of transition metals, in particular iron (Fe) and copper (Cu), and on the OP of PM2.5 from Canadian National Air Pollution Surveillance urban sites in Toronto, Vancouver, and Hamilton. Using chemical assays and model simulations of the lung redox chemistry, we quantified ROS formation in the lung lining fluid, targeting superoxide anion (O2•-), hydrogen peroxide (H2O2), and hydroxyl radical (•OH), as well as the PM2.5 redox potential (RP). Experimental •OH formation (OPOH) showed high correlations with RP and model-predicted ROS metrics. Both aerosol acidity and oxalate content enhanced the solubility of transition metals, with oxalate showing a stronger association. While experimental OP metrics were primarily associated with species of primary origin such as elemental carbon, Fe, and Cu, model-predicted ROS were associated with secondary processes including proton- and ligand-mediated dissolution of Fe. Model simulations showed that water-soluble Cu was the main contributor to O2•- formation, while water-soluble Fe dominated the formation of highly reactive •OH radical, particularly at study sites with highly acidic aerosol and elevated levels of oxalate. This study underscores the importance of reducing transition metal emissions in urban environments to improve population health.

Characteristics of waste dry battery powder and its enhancement effect on the physicochemical properties of asphalt binder

The rationalized recycling of waste dry batteries is of great significance to the circular development of resources. In this research, the feasibility of using waste dry batteries in asphalt modification was discussed. Waste dry battery powder (WDBP) was extracted from discarded zinc-manganese dry batteries, and its composition, micromorphology and heavy metal emissions were characterized. Further, the modified asphalts with different WDBP contents were also prepared, and the enhancement effect of WDBP on the physicochemical properties of the binder was evaluated. The results indicate that WDBP mainly contains inorganic carbon and metal oxides. Under acid rain and neutral environment, the heavy metals from WDBP are mainly Zn, Mn and Cd, and their concentrations exceed the concentration limits of Class I surface water in China. The heavy metals in WDBP can be physically solidified for the use of WDBP in asphalt modification. Meanwhile, WDBP can enhance the flow deformation resistance of the binder at the medium-high temperatures, further improve its rutting resistance. However, the WDBP may be have adverse impact on the low-temperature cracking resistance of asphalt, and the WDBP modified asphalt (WDBP-MA) is more suitable for the application in the areas with heavy traffic and hot climate. In addition, the WDBP can enhance the aging resistance of asphalt. Overall, the conclusions confirm the feasibility of applying WDBP to asphalt modification, which can provide a new approach for rational recycling of waste batteries and development of modified asphalt.

First principles insights into the interaction mechanism of iron doped thermally activated kaolinite with Cd and Pb pollutants in organic solid waste incineration flue gas

Incineration of organic solid wastes is accompanied by the heavy metal emission through flue gas. As an inexpensive and efficient heavy metal adsorbent, the improvement of kaolinite adsorption performance for heavy metals has drawn widespread interests. In this work, the interaction mechanisms between various kaolinite surfaces and Cd/Pb species are explored through first principles calculations. The results show that the combination of Fe doping and dehydroxylation enhances the activity of kaolinite surfaces, analysis of adsorption configurations reveal that both Cd and Pb species are immobilized through chemisorption on the -H + Fe surface. At the microscopic level, further electronic structure analysis shows that the composite modified kaolinite surface has more electron transfer and more pronounced orbital hybridization and overlap compared to the original kaolinite surface, demonstrating that the modification means of dehydroxylation and Fe doping indeed enhanced the activity of the kaolinite surface, especially the activity of the O atoms in the vicinity of the Fe atom and that the O atoms are more efficiently bonded as ionic connecting Cd/Pb species for the purpose of trapping Cd/Pb species. This study points out the research direction and provides basic theoretical support for the development of new kaolinite adsorbents in the future.

Centennial-scale source shift in potentially toxic metal(loid)s in Yangtze River

Estuarine sedimentation is an important historical record of potentially toxic metal (PTM) emissions from human activities that can be used to improve environmental management. However, the contribution of different human activities to PTM deposition has not been accurately estimated, and their coupled relationship with riverine organic matter is typically not considered. In this study, we reconstruct the century-scale PTM depositional history of sediment cores from the Yangtze Grand Delta. Eight potential metal sources (PMSs) were identified using positive matrix factorization, and the results of lagged correlation determined the PMSs associated with the riverine discharge of the Yangtze River. Riverine PTMs were predominantly composed of Cr (79.0%), Ni (77.3%), and Pb (64.1%) but were deprived in Cu (34.9%). Glomalin-related soil protein (GRSP), which is a typical terrestrial refractory carbon, has a strong affinity for Cu, and contributed to 2.82–22.6% Cu deposition. The change in the PMS is mainly related to power generation, whereas the GRSP-bound PTM is mainly related to road construction and transportation. We advocate for responsible management of human activities in river catchments, particularly on coal-based power generation and road transportation, to maintain ecological security and promote the overall achievement of the Sustainable Development Goals.

Experimental and theoretical-based study of heavy metal capture by modified silica-alumina-based materials during thermal conversion of coal at high temperature combustion

Heavy metals emitted from coal combustion can easily pose many threats. In this study, five modified additives based on kaolin were prepared for reducing the emission of heavy metals from high temperature coal combustion and characterized by XRD, FT-IR, XRF, BET, SEM and zeta potential. The heavy metal retention characteristics of the additives under high temperature (900–1300 °C) coal combustion were investigated by static and dynamic experiments, and the results showed that pseudo-boehmite-metakaolin (BMK) was the most effective additive, and the ability of heavy metal capture was Cr > Zn > Pb > Cd, and the dynamic experiments were better than the static experiments. The quantum chemical models of heavy metals (monomers, oxides and chlorides), kaolin and adsorbent-active substances were developed and optimized, and the adsorption energy was calculated. The morphological changes of the active substances were taken into account in the simulation, and new mathematical models for adsorption energy calculation were proposed, which effectively solved the extreme results of adsorption energy calculation and made a comprehensive evaluation of heavy metal adsorption for the whole studied temperature range system. The mechanism of heavy metal adsorption on the active substance was further investigated by the simulations. Heavy metal atoms can form covalent or ionic bonds with O atoms of the active substance, Cl atoms of heavy metal chlorides can be covalently bonded or non-bonded with Al atoms of the active substance, and O atoms of heavy metal oxides can combine with Al atoms of the active substance to form ionic bonds. This study sheds new light on the control of heavy metals in high-temperature coal combustion, the methods for the optimization of simulation and the adsorption mechanism of heavy metals on relevant reactive substances. The method has a promising potential for large-scale application due to its simple preparation, low cost and significant effect.

The Accumulation of Heavy Metals in Shower System Biofilms: Implications for Emissions and Indoor Human Exposure

Biofilms play a crucial role in absorbing various metals from water, including copper, lead, iron, chromium, nickel, zinc, cadmium, and barium. While their presence was revealed in shower system biofilms, the factors affecting metal accumulation in shower system biofilms were poorly explored. This study aimed to investigate the capacity of shower hose biofilms to accumulate heavy metals, in particular in biofilms growing in energy-efficient showerhead systems, and evaluate the potential emission in water and aerosols of metal pollutants during showering. The adsorption efficiency of various metals in biofilms was assessed by ICP/MS and revealed that biofilms accumulate metals as they age and as biofilm biomass increases, indicating a potential influence of heavy metals on biofilm ecology. Furthermore, the study examined the emission of heavy metals during showering and found that it was sporadic and limited primarily to copper and zinc. These findings raise concerns regarding the role of biofilms in both retaining and releasing metal contaminants in water distribution systems, as well as the associated risk of inhalation during showering. By shedding light on the accumulation dynamics of heavy metals in shower hose biofilms and their potential emission patterns, this research highlights the need for further investigation into the impact of biofilms on water quality and human exposure to metal pollutants. The findings underscore the importance of considering biofilm-related processes when addressing the overall management of heavy metal contamination in shower systems and its potential implications for public health.

Effects of High and Low Aerotechnogenic Emissions of Heavy Metals on Wild Plants

This article presents the results of research on the influence of polymetallic-dust aerial emissions on the pollution levels in the soil and plants by heavy metals, which have been under the impact of the “Severonickel” smelter complex on the Kola peninsula (Russia) for more than 40 years. Research using soil and plant indicators was carried out at monitoring plots in the years 1980–1999 (with high aerotechnogenic emissions) and 2000–2019 (with low aerotechnogenic emissions). The organic horizon (forest litter) of the Al-Fe-humus podzol, assimilation organs of Vaccinium myrtillus L., V. vitis-idaea L., V. uliginosum L., Empetrum hermaphroditum Hagerup, and Pinus sylvestris L. as well as tree rings of Scots pine were used for bioindication research. The content of heavy metals was determined using the AAS method. During these time periods, the emissions of polymetallic dust decreased 3.5 fold, while the level of forest litter contamination with heavy metals in the buffer and impact zones increased by 2–5 times, resulting in increased phytotoxicity of the soil and reduced habitat quality for forest plants. At present, the content of Ni and Cu in the leaves (needles) of the plant indicators in the impact zone has decreased by 3–8 times compared with 1980–1999 but their elevated levels pose a potential health risk. The decrease in atmospheric emissions of pollutants led to a 1.5-fold increase in the width of the annual rings of pine trunks in the impact zone, which may indicate the beginning of the recovery of pine-trunk-wood productivity.

Investigation of potential metal emissions from galvanic anodes in offshore wind farms into North Sea sediments

To evaluate potential metal emissions from offshore wind farms (OWFs), 215 surface sediment samples from different German North Sea OWFs taken between 2016 and 2022 were analyzed for their mass fractions of metals and their isotopic composition of Sr. For the first time, this study provides large-scale elemental data from OWFs of the previously proposed galvanic anode tracers Cd, Pb, Zn, Ga and In. Results show that mass fractions of the legacy pollutants Cd, Pb and Zn were mostly within the known variability of North Sea sediments. At the current stage the analyzed Ga and In mass fractions as well as Ga/In ratios do not point towards an accumulation in sediments caused by galvanic anodes used in OWFs. However, further investigations are advisable to evaluate long-term effects over the expected lifetime of OWFs, especially with regard to the current intensification of offshore wind energy development.

Sediment geochemical records of water quality deterioration in lake Jiren, a remote alpine lake on the southeastern margin of the Tibetan Plateau

Limited human activities in catchments make remote alpine lakes valuable sites for studying the evolution of lake environments in response to climate change and atmospheric deposition; however, this issue remains rarely studied owing to the scarcity of monitoring data. In this study, water quality evolution in Lake Jiren, a remote alpine lake on the southeastern margin of the Tibetan Plateau, over the past two centuries was reconstructed through geochemical analyses of aliphatic hydrocarbons, major and trace elements, and organic matter (OM) pyrolysis products in a dated sediment core, and the associated drivers were identified by temporally comparing the geochemical results with document records. All geochemical data demonstrated that the lake water remained relatively pure until 1947, after which the n-alkane and αβ-hopane proxies indicated eutrophication and petroleum contamination. The OM pyrolysis proxy hydrocarbon index indicated more eutrophic conditions after 1957. Concurrently, hypolimnetic deoxygenation increased, as indicated by redox-sensitive proxies, such as the enrichment factors (EFs) of molybdenum (Mo). These proxies recorded further intensification of deoxygenation after 1976. The EFs for other trace elements indicated cadmium contamination after 1967. The greater anthropogenic emissions of reactive nitrogen, petroleum products, and heavy metals in East and South Asia since approximately 1950 and the subsequent atmospheric transport of these materials to the lake might be the basic driver of water quality deterioration. Eutrophication induced by nitrogen deposition was responsible for increased hypolimnetic deoxygenation by enhancing phytoplankton productivity and OM input. The further intensification of deoxygenation was attributed to climate warming since the 1970s, as prolonged water column stratification under this condition decreased oxygen input from the epilimnion to the lake bottom. These findings may be beneficial for understanding the natural and anthropogenic effects on the water quality of alpine lakes and help in the environmental management of Lake Jiren and other alpine lakes.

Mechanism of arsenic distribution and migration during iron extraction by copper slag-steel slag combined reforming: A potential solution to refractory wastes

In this study, a combined reforming and reduction smelting of copper slag-steel slag was proposed to recover iron (Fe) from solid waste while lowering the environmental risks associated with the management of such waste. In this process, copper slag was mixed with steel tailing to sinter, and made into pellets after magnetic separation. These two products were extracted by a smelting reduction process to obtain Fe, with a recovery rate of 98.63% and a grade of 92.91%. The migration and enrichment behaviors of arsenic (As) in the process were studied, and its mechanism was analyzed by X-ray diffraction, electron probe micro-analyzer, and X-ray photoelectron spectroscopy. The sequential extraction procedure was adopted to analyze the occurrence form of the hazardous As in the copper slag, while leaching tests allowed evaluating the environmental risk of the slag upon reduction smelting. The results proved that such reduction slag represent a stable and low-risk material. However, As was dispersed and released in each procedure of the process, potentially propagating its hazards into subsequent processes and life cycles. This study highlights the potential of an alternative route for the treatment of waste copper slag while recovering Fe from it. The reformed copper slag has strong adaptability, and the smelting reduction method exhibits a high recovery rate of Fe and low-risk reduction slag that can be widely used. It provides a valid reference for the safe management of heavy metal emissions and environmental risk awareness and helps to achieve large-scale consumption of copper slag and steel slag.

Methods of determining the amount of harmful particles released into the environment as a result of car tire wear

This article describes determining methods of metal emissions in the composition of small particles coming by brake mechanisms details and tire wear as a result of vehicle movement, and dust to be formed by comparative analysis on asphalt-concrete roads of different compositions. A significant contributor to particulate matter in cities is traffic-related sources. Traffic-related particles can be divided into exhaust particles released by the incomplete combustion of fuel and the volatilization of lubricants during combustion and formed by brake mechanism parts, tire wear and road surface wear, and accumulated due to turbulence caused by road traffic. The method of determining the metal concentration in the formed particles gives information on the physico-chemical properties of the particles.

Investigation of the nanometal levels in the atmosphere of Chakan high tech industrial Park, Chakan (MH), India

Nanometals contained in airborne particles pose a public health risk since they can enter people's respiratory systems and cause lung damage. In general, air pollution is defined as any substance that has been discharged into the atmosphere and has the potential to seriously harm both the environment and living creatures. The current study was conducted in India's Chakan High Tech Industrial Area, which is affected by various industries, such as automotive, electric, power, and iron smelting, which may contribute to environmental air pollution. Sampling of PM2.5 was carried out by high-volume samplers with cascade impactors over two year (2021 and 2022) at two separate locations, one in an industrial park and the other in a residential area. The heavy metals linked to the particulate matter were identified using inductive coupled plasma optical emission spectrometry (ICP-OES). Results revealed that the industrial park had higher levels of particle pollution than the residential neighborhood of Chakan. The primary sources of toxic metal emissions into the atmosphere are industrial and commercial activity. Thankfully, none of the nanometals' concentrations exceeded the limits set by the World Health Organization (WHO) and India's Air (P&CP) Act of 1981. This study was conducted to help identify and measure the concentration of nanometals in air, with the aim of protecting both the environment and living beings from potential harm. Further research will be needed to protect people from the numerous diseases, respiratory conditions, and other health issues brought on by exposure to air pollution in this region.

Emission Characteristics, Speciation, and Potential Environmental Risks of Heavy Metals from Coal-Fired Boilers: A Review

Coal-fired boilers, including coal-fired power plants (CFPPs) and coal-fired industrial boilers (CFIBs), are an important area for achieving sustainability globally as they are one of the globally important sources of anthropogenic emissions of heavy metals (HMs) due to huge amount of coal consumption. To date, the investigation of atmospheric emission characteristics, speciation, and potential environmental risks of HMs from coal-fired boilers has received widespread attention and achieved significant progress. To characterise the emissions of HMs from coal-fired boilers, research is currently being carried out in the areas of (1) studying the release of HMs from coal combustion processes, (2) developing emission factors and emission inventories, and (3) revealing the cross-media partitioning of HMs between different output streams. Research on the chemical forms of HMs in waste from coal-fired boiler is currently focused on chemical valence and speciation components. The sequential chemical extraction method is currently the most widely used method for investigating the chemical fractionations of HMs in wastes from coal-fired boilers. Studies indicate that different HM elements display differentiated characteristics of speciation in waste from coal-fired boilers. Early studies on potential environmental risk and ecological risk caused by HMs are usually based on actual monitoring values of HMs in the target environmental media. The risk assessment code method and the leaching toxicity method are the most widely used method to study the potential environmental risk of HMs in waste from coal-fired boilers. With the implementation of global carbon emission reduction strategies, the scale of coal-fired boilers and air pollution control technologies are bound to change in the future. Therefore, as an important component of global efforts to achieve sustainable development, more research is needed in the future to improve the accuracy of emission inventories, reveal the mechanisms of HM chemical transformation, and establish methods for potential environmental risk assessment at regional scales.

Don’t Believe the Hype(r): The Yellow Supergiants of Westerlund 1

Yellow hypergiants (YHGs) are often presumed to represent a transitional post-red supergiant (RSG) phase for stars ∼30–40 M ⊙. Here we present visual-wavelength echelle spectra of six YHG candidates in the Galactic cluster Westerlund 1, and we compare them to known YHGs, IRC +10420 and Hen 3-1979. We find that the six YHG candidates do not exhibit any metal emission lines, nor do they show strong Hα emission, and as such do not meet the criteria necessary to be classified as YHGs. In conjunction with their moderate luminosities of = 4.7–5.4 estimated from optical/infrared photometry, we suggest instead that they are normal yellow supergiants (YSGs) with more modest initial masses around 15–20 M ⊙. This adds additional support to the hypothesis that Wd1 is a multiage cluster with an older age than previously assumed, and is not a ∼5 Myr old cluster caught at a very specific transitional point when single-star evolution might yield Wolf–Rayet stars, luminous blue variables, RSGs, and YHGs in the same cluster. Nevertheless, the population of YSGs in Wd1 is very unusual, with YSGs outnumbering RSGs, but with both spanning a large luminosity range. Here, we discuss evolutionary scenarios that might have led to the high fraction of YSGs. The number of YSGs and their significant luminosity spread cannot be explained by simple population synthesis models with single or binary stars. Even with multiple ages or a large age spread, the high YSG/RSG ratio remains problematic. We suggest instead that the objects may experience a prolonged YSG phase due to evolution in triple systems.

GIS-based emission inventory of heavy metals from road transport and NMVOCs associated with biomass burning for megacity Delhi

Clean air is an essential requirement for human health and well-being. The rapid evolution in urbanization poses a risk to human health. The significance of robust emission inventory has intensified with scientific advancement in air quality improvement. A comprehensive GIS-based emission inventory of heavy metals and NMVOCs from road transportation, road dust, and biomass burning covering the megacity of Delhi has been prepared in this study for the base year 2018. The emission of heavy metals from biomass burning and road dust was estimated by computing the chemical constituents of PM2.5. The emission of heavy metals from all sources is estimated as 695.202 Mg/year, with Zinc (Zn ∼ 48%) having the highest emissions, followed by Copper (Cu ∼ 21%). The share of road transportation emissions was 78%, followed by resuspended road dust emissions at 4%. The emissions of 23 NMVOCs (1.158 Gg/year) were calculated from biomass burning (fuelwood, agricultural residue, dung cake, and coal) with Dung cake (∼58%) and fuelwood (∼41%) as the major contributors. The maximum emission was ethene (∼29%), and the minimum was isopropyl benzene (∼0.06%). The finding of this study will assist environmental policymakers and stakeholders in developing mitigation methods to reduce emissions and enhance air quality.

Spatial trend and source apportionment of metals in wet atmospheric precipitation: a study on drying Urmia Lake implications, NW Iran

ABSTRACT During this decade, the drying of Urmia Lake resulted in devastating tragedies in the region, resulting in the emission of toxic metals into the atmosphere. Urmia city’s wet atmospheric depositions were analysed to assess the quantity and spatial trends of numerous heavy metals and sodium (Na), as well as their sources. Wet precipitation was collected as rainwater, and the concentration of metals was determined using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The mean concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), and sodium (Na) were 0.14, 0.18, 1, 3.7, 2.9, 5.6, 6.3 µg/L, and 2.6 mg/L, respectively, following the sequence Na > Zn > Ni > Cu > Pb > Cr > Cd > As. To identify the sources of these metals, enrichment factor analysis and principal component analysis (PCA) were employed. The enrichment factor analysis revealed that Na and As exhibited relatively low enrichment factors suggesting natural sources, whereas Zn, Cd, Cr, Cu, Ni, and Pb were highly enriched, indicating significant contributions from anthropogenic sources. The distribution map of Urmia City demonstrated that the northern and western parts of the city were highly polluted with As, Ni, Cr, and Zn. PCA analysis revealed that the emissions from vehicles and fuel combustion were the primary sources of Cd, Cr, Cu, Ni, and Pb, whereas the drying of the Urmia lake is the primary source of Na, As, and Zn. The process of the lake bottom drying likely releases these metals into the atmosphere, leading to their deposition in the surrounding areas.

The impact of pollutant emissions from co-incineration of industrial waste in municipal solid waste incinerators

A large amount of industrial solid waste (including waste plastics, textiles, wood, etc., which are byproducts of industrial production) urgently needs to be treated. Incineration is undoubtedly the most efficient and convenient method. The existing municipal solid waste incineration plants can be transformed to burn such industrial wastes. However, the potential risks associated with high levels of heavy metals in industrial waste and the air pollution caused by co-incineration pose significant challenges to the co-incineration disposal of industrial solid waste. The change of physical and chemical properties of municipal solid waste and the emission characteristics of flue gas pollutants after co-incineration of industrial waste were studied by means of material flow simulation and experiment. In addition, experiments were designed to study the effects of temperature, calcium sulfur ratio and chlorine content on heavy metal emission during the incineration of industrial waste. The results showed that co-incineration of a certain proportion of industrial waste significantly increased the calorific value of municipal solid waste, but excessive mixing of plastic and paper industrial waste would increase the ash content. Co-incineration of plastic industrial waste can significantly increase HCl, and with the increase of temperature, the transformation of Cl to HCl is more thorough. The increase of temperature can promote the migration of Cr, Pb and Se elements to the gas phase. When Cr, Pb, and Se elements are present in the gas phase, they can combine with other gases and aerosols to form particulate matter and toxic substances, causing air pollution. When Ca/S is 1, Ba, Mn, Ni, Zn can effectively reduce the retention rate of elements in the ash. Under certain conditions, chlorine in industrial waste plastics will react with Zn to form tiny particles and low boiling point chlorides, which will increase its volatility. The mineral components in the ash can also be used for making ceramsite and building materials. These results will provide reference for the pollutants controlling during co-incineration of industrial waste and municipal solid waste process.

The challenges of identifying Population III stars in the early Universe

ABSTRACT The recent launch of JWST has enabled the exciting prospect of detecting the first generation of metal-free, Population III (Pop. III) stars. Determining characteristics that robustly signify Pop. III stars against other possible contaminants represents a key challenge. To this end, we run high-resolution (sub-pc) cosmological radiation hydrodynamics simulations of the region around a dwarf galaxy at z ≥ 10 to predict the emission line signatures of the Pop. III/Pop. II transition. We show that the absence of metal emission lines is a poor diagnostic of Pop. III stars because metal-enriched galaxies can maintain low [O iii] 5007 Å that may be undetectable due to sensitivity limits. Combining spectral hardness probes (e.g. He ii 1640 Å/H α) with metallicity diagnostics is more likely to probe metal-free stars, although contamination from Wolf−Rayet stars, X-ray binaries, or black holes may be important. The hard emission from Pop. III galaxies fades fast due to the short stellar lifetimes of massive stars, which could further inhibit detection. Pop. III stars may be identifiable after they evolve off the main sequence due to the cooling radiation from nebular gas or a supernova remnant; however, these signatures are also short-lived (i.e. few Myr). Contaminants including flickering black holes might confuse this diagnostic. While JWST will provide a unique opportunity to spectroscopically probe the nature of the earliest galaxies, both the short time-scales associated with pristine systems and ambiguities in interpreting emission lines may hinder progress. Special care will be needed before claiming the discovery of systems with pure Pop. III stars.

Co-pyrolysis of industrial sludge with phytoremediation residue: Improving immobilization of heavy metals at high temperature

Phytoremediation as an attractive technology for the degradation or removal of pollutants from the environment inevitably produces large amounts of heavy metal-accumulated plants. Although pyrolysis is effective in treating the generated biomass, the problem of considerable emissions of heavy metals into the atmosphere has not received deserved attention. In this study, industrial sludge (IS) was attempted as an additive to improve the immobilization performance of pyrolysis for heavy metals at high temperature. Based on the separate pyrolysis and co-pyrolysis experiments of IS and the phytoremediation residue (PR) rich in Cd, Pb and Zn at 350–750 °C, the results showed that, compare to separate pyrolysis, introducing IS to PR pyrolysis system could reduce the emission of heavy metals while enhancing their stability in resultant biochar. It was also found that the complexation of heavy metals with functional groups, the combination of heavy metals with π electrons and the formation of heavy metal crystalline compounds could be the main reasons improving the immobilization of heavy metals during co-pyrolysis. Correspondingly, the heavy metal ecological risk evaluation indicated that the biochar obtained from feedstocks containing IS was at no risk or low risk while other biochar possessed a higher risk. This study demonstrated that IS additive was able to optimize the migration and transformation behavior of heavy metals in hyperaccumulator biomass during pyrolysis, which provides new insights into the environmentally sound treatment of heavy metal-rich biomass.

Acoustic monitoring of steel production in the ladle-furnace unit

A method of implementing acoustic control of the steel-making process in a ladle-furnace unit using a step-by-step acoustic event recognition model is proposed. The use of the developed model makes it possible to predict metal emissions with an accuracy of 96 %.