Waste Particles Research Articles

Long-range transport and deposition on the Arctic snowpack of nuclear contaminated particulate matter

The primary environmental concern related to nuclear power is the production of radioactive waste hazardous to humans and the environment. The main scientific and technological problems to address this are related to the storage and disposal of the nuclear waste and monitoring the dispersion of radioactive species into the environment. In this work, we determined an anomalously high 14C activity, well above the modern natural background, on surface and seasonal snow sampled in early May 2019 on glaciers in the Hornsund fjord area (Svalbard). Due to the lack of local sources, the high snow concentrations of 14C suggest long-range atmospheric transport of nuclear waste particles from lower latitudes, where nuclear power plants and treatment stations are located. The analysis of the synoptic and local meteorological data allowed us to associate the long-range transport of this anomalous 14C concentration to an intrusion event of a warm and humid air mass that likely brought pollutants from Central Europe to the Arctic in late April 2019. Elemental and organic carbon, trace element concentration data, and scanning electron microscopy morphological analysis were performed on the same snow samples to better constrain the transport process that might have led to the high 14C radionuclide concentrations in Svalbard. In particular, the highest 14C values found in the snowpack (> 200 percent of Modern Carbon, pMC) were associated with the lowest OC/EC ratios (< 4), an indication of an anthropogenic industrial source, and with the presence of spherical particles rich in iron, zirconium, and titanium which, altogether, suggest an origin related to nuclear waste reprocessing plants. This study highlights the role of long-range transport in exposing Arctic environments to human pollution. Given that the frequency and intensity of these atmospheric warming events are predicted to increase due to ongoing climate change, improving our knowledge of their possible impact to Arctic pollution is becoming urgent.

Influence of polyvinyl alcohol coated porous Al2O3 ceramic waste particles on cement properties in geothermal applications

To improve the low strength of the existing geothermal temporary sealing cement (GTSC) and figure out the influence of PACW on cement performances in geothermal applications, the hard porous Al2O3 ceramic waste (PACW) was introduced into oil well cement. The water-soluble PVA was coated on PACW particles to wrap the porous ceramic at relatively low temperature for geothermal drilling, and dissolve in water at ≥ 90 ℃ for hot water flow. The compressive strength, hydrates, pore structures and interface transition zone of cement with raw or modified PACW were tested. The results showed that 10% raw and modified PACW enhanced the compressive strength of oil well cement by 57.69% and 60.31% respectively, during the 90 ℃ water immersing. For the cement containing 10% raw and modified PACW, thermal weight loss related to degradation of hydrates and CH increased, meso pores fraction rose to 52.73% and 51.93 % respectively, and the deeper etch pits on surfaces of the mineral suggested the promoting effect of PACW on cement hydration. The promoted cement hydration and formed hydrates with their filling effect contributed to the cement strength enhancement. As the thermal weight loss attributed to AFm increased after immersion, the thermodynamic parameters of the possible transformation reaction of AFt to AFm were calculated. The standard molar Gibbs free energy change of the reactions are negative, and microstructure images showed that the PACW surface was covered by lots of flaky AFm crisscrossed with large hexagonal AFt crystals, proving that the alumina in PACW participated in and promoted the transformation of AFt to AFm. In addition to reservoir protection, simplifying construction procedures and reducing the time cost of geothermal development, the high-strength GTSC will further strengthen the hole wall and reduce the risk of borehole collapse.

CFD-DEM simulations of municipal solid waste gasification in a pilot-scale direct-melting furnace

A multiphase CFD-DEM model was built to simulate the waste-to-energy gasifying and direct melting furnace in a pilot demonstration facility. The characterizations of feedstocks, waste pyrolysis kinetics, and charcoal combustion kinetics were first obtained in the laboratory and used as model inputs. The density and heat capacity of waste and charcoal particles were then modelled dynamically under different status, composition, and temperature. A simplified ash melting model was developed to track the final fate of waste particles. The simulation results were in good agreement with the site observations in both temperature and slag/fly-ash generations, verifying the CFD-DEM model settings and gas-particle dynamics. More importantly, the 3-D simulations quantified and visualized the individual functioning zones in the direct-melting gasifier as well as the dynamic changes throughout the whole lifetime of waste particles, which is otherwise technically unachievable for direct plant observations. Hence, the study demonstrates that the established CFD-DEM model together with the developed simulation procedures can be used as a tool for the optimisation of operating conditions and scaled-up design for future prototype waste-to-energy gasifying and direct melting furnace.

Sapropel as a Binding Material for Wood Processing Waste in the Development of Thermal Insulation Biocomposite

When developing new innovative building materials, their performance characteristics as well as their environmental friendliness are important. It is difficult to produce a fully ecological material for building envelopes, because there is a lack of ecological binding materials on the market, good binding materials are very expensive, and cheaper ones have poorer adhesive properties and performance characteristics. In this work, natural organic sapropel was used as an ecological binder. Before use, an organic sapropel was additionally mechanically activated. Its activation efficiency was evaluated on the basis of consistency and tensile strength. Sapropel activation increased its consistency from 112 to 168 mm and its tensile strength from 466 to 958 kPa. Wood processing waste was used as a filler for the thermal insulation biocomposite. Additionally, the wood waste was chopped to regulate the density and main performance properties of the biocomposite. The density of the biocomposite was also regulated using different amounts of sapropel and the degree of compaction of the composite mixture. In this work, the influence of the amount of sapropel, the level of compression of the biocomposite mixture, and the size of the wood waste particles on the thermal conductivity and compressive stress of the biocomposite was analyzed. It was found that the compression level had the greatest influence on both the compressive stress and thermal conductivity, up to 12 times and 43.3%, respectively.

Synthesis and experimental investigation of physical behavior of coconut shell particular and walnut shell particular filled epoxy polymer composites

The present work focuses on the selection of argo waste CSP/WSP fillers due to their light weight, biodegradability, low density, abundant availability, and easy process-ability. In a controlled laboratory environment, the impact of different weight percentages of CSP/WSP (argo waste) particles (2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 wt%) loaded into epoxy resin (LY 556) using a moulding process was investigated. The physical characteristics of developed composites are characterised and investigated, such as density, dimensional stability, as well as moisture content. It is observed from experimental work that the dimensional stability of CSP/WSP (1:1) reinforced epoxy based composites is better at 2.5 wt% of particulates.

Optimization of Fluidized-Bed Process Parameters for Coating Uniformity and Nutrient-Release Characteristics of Controlled-Release Urea Produced by Modified Lignocellulosic Coating Material

Controlled-release fertilizers are employed in precision agriculture to optimize technology-enabled farming without environmental deterioration. In this study, almond-shell lignocellulosic waste particles are chemically processed to synthesize a coating suspension for the production of controlled-release urea (CRU) in a Wurster fluidized-bed reactor. The interactive effect of process parameters such as atomizing air pressure (Pair), fluidized-bed temperature (Tfb), spray rate (Rspray), and fluidizing-air flow rate (Qair) on the (i) coating-film uniformity of CRU particles and (ii) longevity of nutrient-release from CRU is reported. CCRD is used with RSM to design the experiments for the optimization of nutrient-release performance and coating-film uniformity in terms of a coefficient-of-variance (CoV) of film thickness. The regression models indicate a good prediction of coating-film uniformity and nutrient-release time, with R2 = 0.971 and R2 = 0.98, respectively. The optimum conditions for coating-film uniformity are determined to be Pair = 3.5 bar, Tfb = 80 °C, Rspray = 0.15 mL/s, and Qair = 72 m3/h, with a predicted CoV film thickness of 11.5%. Similarly, Pair = 3.2 bar, Tfb = 78 °C, Rspray = 0.125 mL/s, and Qair = 75 m3/h are the optimum conditions for nutrient-release performance, with a prediction nutrient-release time = 56 h. The experimental validation yields a CoV of film thickness = 12.6% and a nutrient-release time = 49.5 h, indicating good agreement between predicted and experimental values. In addition, Tfb appears to be the most significant parameter.

Surface Modified Synthetic Plastic Aggregate for Concrete – Experimental and Analytical Studies

In order to reduce the plastic waste accumulation, and also to decrease consumption volume of natural resources for concrete production, in this paper, an attempt is made to produce novel lightweight coarse aggregate using PET based plastic waste. Use of plastic aggregate normally reduces the strength of concrete primarily due to smoother surface and poor bonding with adjacent cement matrix. Towards improving the bonding characteristics with cement matrix, different surface treatment procedures employing dispersion of sand and ceramic waste particles were tried. Experimental study consisted of using different percentages of plastic aggregate as partial replacement for conventional coarse aggregate. The mechanical properties of concrete such as workability, density, compressive strength and flexural-tensile strength were determined. Correlations studies to predict the concrete strength based on percentage of replacement, and equation relating compressive and flexural-tensile strengths of the concrete were also conducted. The studies indicated that it is possible to improve the bonding property of plastic aggregate for achieving strength and integrity similar to that of control concrete.

Preparation and Properties of Environmentally Friendly Resin-Based Artificial Stones Fabricated from Ceramic Waste

The rapid development of the traditional ceramic industry contributes considerably to economic advancements; however, the ecological hazards caused by the large amount of sintered ceramic wastes generated during ceramic production and discarded at landfill sites are becoming increasingly severe. To realize the large-scale resource utilization of ceramic waste, sintered ceramic waste was used in this study to partially replace natural quartz sand, and new environmentally friendly artificial stones were fabricated by using vacuum vibration molding and inorganic/organic composite curing technology. The effects of ceramic waste addition and particle size on the mechanical strength, surface hardness, wear resistance, stain resistance, and microstructure of artificial stone materials were investigated. The results showed that the replacement of quartz sand with 40–55% ceramic waste significantly improved the mechanical strength of artificial stone and maintained sufficient surface hardness and wear resistance. When 45% of ceramic waste powder (particle size ≥ 120 mesh) was added, the bending strength of the artificial stone was 64.4 MPa, whereas when 55% of ceramic waste particles with different particle sizes were added, the maximum compressive strength was 158.7 MPa. Good wear resistance and sufficient Moh’s hardness of 5.5–6.5 was obtained for all the samples. The prepared ceramic waste artificial stone also had a dense microstructure and low water absorption and porosity, which are helpful for improving stain resistance.

Hyperspectral Imaging Sorting of Refurbishment Plasterboard Waste

Post-consumer plasterboard waste sorting is carried out manually by operators, which is time-consuming and costly. In this work, a laboratory-scale hyperspectral imaging (HSI) system was evaluated for automatic refurbishment plasterboard waste sorting. The HSI system was trained to differentiate between plasterboard (gypsum core between two lining papers) and contaminants (e.g., wood, plastics, mortar or ceramics). Segregated plasterboard samples were crushed and sieved to obtain gypsum particles of less than 250 microns, which were characterized through X-ray fluorescence to determine their chemical purity levels. Refurbishment plasterboard waste particles &lt;10 mm in size were not processed with the HSI-based sorting system because the manual processing of these particles at a laboratory scale would have been very time-consuming. Gypsum from refurbishment plasterboard waste particles &lt;10 mm in size contained very small amounts of undesirable chemical impurities for plasterboard manufacturing (chloride, magnesium, sodium, potassium and phosphorus salts), and its chemical purity was similar to that of the gypsum from HSI-sorted plasterboard (96 wt%). The combination of unprocessed refurbishment plasterboard waste &lt;10 mm with HSI-sorted plasterboard ≥10 mm in size led to a plasterboard recovery yield &gt;98 wt%. These findings underpin the potential implementation of an industrial-scale HSI system for plasterboard waste sorting.

Cardanol-based adhesive with reduced formaldehyde emission to produce particleboards with waste from bean crops.

Free formaldehyde is a carcinogen whose emission reduction in particleboard has been studied recently to mitigate this environmental and human health problem. One alternative to reduce the emission of formaldehyde in particleboards is by using adhesives produced from natural sources. Cardanol-formaldehyde is an environmentally friendly adhesive made with cashew nut liquid, a byproduct from the cashew chain. This work aimed to produce particleboard using cardanol-formaldehyde in place of urea. In addition, different proportions of bean straw wastes were used to replace pine wood. The combination of eco-friendly adhesive and lignocellulosic waste particles could result in a product that meets market demands while being environmentally nonaggressive. Cardanol-formaldehyde promoted a higher modulus of elasticity (MOE) (1172MPa) and modulus of rupture (MOR) (4.39MPa) about panels glued with urea-formaldehyde, which presented a MOE of 764MPa and MOR of 2.45MPa. Furthermore, the cardanol-formaldehyde adhesive promoted a 93% reduction in formaldehyde emission, with a reduction from 16.76 to 1.09mg/100g oven-dry board for particleboards produced with cardanol-formaldehyde, indicating potential as an adhesive in the particleboard industry.

Redesigning the appearance of recycled containers for packaging applications: The effect of paper waste physicochemical properties on the performance of paperboards with obvious recycled content

AbstractSignificant efforts have been made over the past decade to facilitate the recognition of environmentally friendly packaging and promote sustainability. Yet, consumers remain confused by the excess of labels and claims used to communicate sustainability. In our previous work, we modified the appearance of recycled fibre‐based packaging by incorporating visible particles of fibre‐based waste. This strategy enabled consumers to better identify packages with a high recyclability level, enhancing their environmental perception towards sustainable products. However, the incorporation of such large waste particles proved to be detrimental to the mechanical properties of the paperboards. In this study, we further investigate the influence of the physicochemical properties of the added fibre‐based waste on packaging performance. Using a similar strategy to enhance the environmental perception, we herein studied the effect of mixed office waste (MOW), old magazines (OMG), and polylactic acid (PLA) paper cups. The presence of hydrophobic and difficult‐to‐process and difficult‐to‐disperse waste, such as the PLA paper cups, significantly altered the mechanical performance of the paperboards, whereas more hydrophilic and easy‐to‐disintegrate waste (MOW and OMG) had a lesser effect regardless of the size of the particles. Strength agents such as cationic starch (CS) and cellulose microfibrils (CMFs) successfully restored the properties of the paperboards containing MOW and OMG but were less effective for PLA paper cups. A multi‐ply strategy overcame the limitations of CS and CMFs using the redesigned paperboard as an outer ply for aesthetic purposes and a 100% recycled inner ply for restoring strength.

Metal mobility and bioaccessibility from cyanide leaching heaps in a historical mine site

Unlike acidic sulfide mine wastes, where metal/loid mobility and bioaccessibility has been widely studied, less attention has been paid to alkaline cyanide heap leaching wastes. Thus, the main goal of this study is to evaluate the mobility and bioaccessibility of metal/loids in Fe-rich (up to 55%) mine wastes resulting from historical cyanide leaching activities. Wastes are mainly composed of oxides/oxyhydroxides (i.e. goethite and hematite), oxyhydroxisulfates (i.e. jarosite), sulfates (i.e., gypsum, evaporitic sulfate salts), carbonates (i.e., calcite, siderite) and quartz, with noticeable concentrations of metal/loids (e.g., 1453–6943 mg/kg of As, 5216–15,672 mg/kg; of Pb, 308–1094 mg/kg of Sb, 181–1174 mg/kg of Cu, or 97–1517 mg/kg of Zn). The wastes displayed a high reactivity upon rainfall contact associated to the dissolution of secondary minerals such as carbonates, gypsum, and other sulfates, exceeding the threshold values for hazardous wastes in some heap levels for Se, Cu, Zn, As, and sulfate leading to potential significant risks for aquatic life. High concentrations of Fe, Pb, and Al were released during the simulation of digestive ingestion of waste particles, with average values of 4825 mg/kg of Fe, 1672 mg/kg of Pb, and 807 mg/kg of Al. Mineralogy may control the mobility and bioaccessibility of metal/loids under rainfall events. However, in the case of the bioaccessible fractions different associations may be observed: i) the dissolution of gypsum, jarosite and hematite would mainly release Fe, As, Pb, Cu, Se, Sb and Tl; ii) the dissolution of an un-identified mineral (e.g., aluminosilicate or Mn oxide) would lead to the release of Ni, Co, Al and Mn and iii) the acid attack of silicate materials and goethite would enhance the bioaccessibility of V and Cr. This study highlights the hazardousness of wastes from cyanide heap leaching, and the need to adopt restoration measures in historical mine sites.

Impacto dos resíduos de rocha dolomítica na acidez do solo e absorção de Ca e Mg por cevada e trigo

ABSTRACT The dumps of dolomite dropouts from road construction occupy huge arable areas in north-western Russia. Although coarse dolomite particles neglected as a liming material due to its slow solubility, we hypothesise that they can serve as a cheap and long-lasting liming material. The weight loss of dolomite particles of various sizes from the dump applied to Albic Retisol and its effect on assimilation of Ca and Mg by barley and wheat were studied. The pot experiment with 300 g soil was conducted for 30 days in a laboratory phytotron. Results showed that coarse particles of dolomite waste had a positive effect on soil acidity already at the initial phases of the experiment. In the process of dissolution of dolomite, all forms of soil acidity decreased. The cultivation of barley had a stronger effect on the dissolution of dolomite particles than the cultivation of wheat. Barley plants accumulated Ca by 1.1-1.4 times higher than wheat, other factors being identical. The relationship between the yield of green biomass and the accumulation of calcium and magnesium in the plants were empirically described using regression analysis. Results of this preliminary study showed that the by-products from dolomite stone processing can be effectively used for reclamation of strongly acidic soil in north-western Russia. This has the dual benefit of reducing the burden on the environment and reclaiming acidic soils. Further studies should include soil microbiological and biological parameters to trace the effect of root activities and dolomite dissolution rate on a field scale.

Maritime Computing Transportation, Environment, and Development: Trends of Data Visualization and Computational Methodologies

This research aims to characterize the field of maritime computing (MC) transportation, environment, and development. It is the first report to discover how MC domain configurations support management technologies. An aspect of this research is the creation of drivers of ocean-based businesses. Systematic search and meta-analysis are employed to classify and define the MC domain. MC developments were first identified in the 1990s, representing maritime development for designing sailboats, submarines, and ship hydrodynamics. The maritime environment is simulated to predict emission reductions, coastal waste particles, renewable energy, and engineer robots to observe the ocean ecosystem. Maritime transportation focuses on optimizing ship speed, maneuvering ships, and using liquefied natural gas and submarine pipelines. Data trends with machine learning can be obtained by collecting a big data of similar computational results for implementing artificial intelligence strategies. Research findings show that modeling is an essential skill set in the 21st century.

A sustainable one-pot method to transform seashell waste calcium carbonate to osteoinductive hydroxyapatite micro-nanoparticles.

We have developed a straightforward, one-pot, low-temperature hydrothermal method to transform oyster shell waste particles (bCCP) from the species Crassostrea gigas (Mg-calcite, 5 wt% Mg) into hydroxyapatite (HA) micro/nanoparticles. The influence of the P reagents (H3PO4, KH2PO4, and K2HPO4), P/bCCP molar ratios (0.24, 0.6, and 0.96), digestion temperatures (25-200 °C), and digestion times (1 week-2 months) on the transformation process was thoroughly investigated. At 1 week, the minimum temperature to yield the full transformation significantly reduced from 160 °C to 120 °C when using K2HPO4 instead of KH2PO4 at a P/bCCP ratio of 0.6, and even to 80 °C at a P/bCCP ratio of 0.96. The transformation took place via a dissolution-reprecipitation mechanism driven by the favorable balance between HA precipitation and bCCP dissolution, due to the lower solubility product of HA than that of calcite at any of the tested temperatures. Both the bCCP and the derived HA particles were cytocompatible for MG-63 human osteosarcoma cells and m17.ASC murine mesenchymal stem cells, and additionally, they promoted the osteogenic differentiation of m17.ASC, especially the HA particles. Because of their physicochemical features and biological compatibility, both particles could be useful osteoinductive platforms for translational applications in bone tissue engineering.

Engineering Properties of Lightweight Mortars Containing Wood Waste Particles

Utilization of wood waste particles (WWP) is important for environmental and economic concern. This study focuses on the behavior of mortars having WWP with various amounts. Incorporation of WWP brings about the advantages such as decrease in the mass and cost of the mortar. In the present study, the proportions of the wood waste particles replacing the crushed sand in the mortars by volume were 0, 10, 20, 30 and 40 %. Physical, mechanical and capillary absorption properties have been investigated. In addition, microstructure of the mortars has been examined with optical microscope. As compared to control specimen, dry bulk density decreased from 2.2 to 1.5 kg/m3, apparent porosity increased about 2 folds, and water absorption increased about 4 folds, for sample in which 40 % of crushed sand was replaced with WWP. Mechanical values reduced with increasing WWP amount. On the other hand, during compressive and flexural strength tests, samples containing WWP presented a gradual decrease in strength, thus they exhibited a more ductile behavior.

Analysis of gas–solid two-phase flow and structure optimization of mobile shot blasting machine recovery device

To address the problem of low efficiency of recycling process waste by gas–solid two-phase flow of the shot blasting machine recycling device, a method and structure by increasing the negative pressure value and optimizing the outlet pipe position are proposed. Computational fluid dynamics (CFD), discrete element method (DEM) and discrete phase model (DPM) were used to study the waste recovery efficiency at different pressure outlet conditions and outlet pipe locations. The validity of the model was verified by velocity tests at the outlet and inlet compared with simulations. The effect of particle size and particle generation rate on solid particle recovery efficiency was further investigated by analyzing the flow field distribution of the recovery unit. The results show that the maximum velocity of the gas phase in the recovery device increases with the increase of the absolute value of the outlet pressure, when the outlet pressure is -6500 Pa, the maximum velocity is 67.59 m/s. When the absolute value of the outlet pressure is greater than 6000 Pa, a small amount of steel shot particles is discharged from the recovery bin under the action of the outlet pressure, resulting in the loss of steel shot particles. After the outlet pipe position optimization, the steel shot particle recovery efficiency increased by 10% and the waste particle recovery efficiency increased by 18.9%.

Physical and Mechanical Properties of Cementitious PVC Composites

This research studies the physical and mechanical properties of mortar composed of PVC plastic waste particles used as fine aggregate replacement material. PVC particles in quantities of 5%, 10%, 15%, 20%, 25%, and 30% by volume were used for sand fraction substitution. This quantity of PVC was used to formulate seven mixes with a cement content of 525 kg/m3 and a water-to-cement ratio (w/c) of 0.45. At 7 and 28 days, the compressive and splitting tensile strengths of the mortar's mechanical characteristics were evaluated. Additionally, the physical characteristics of density and absorption were investigated. The findings demonstrated that the mechanical properties and density of mortar containing PVC powder were minimized.

Mechanical and acoustic properties of alkali treated agricultural waste reinforced sustainable polyurethane composites

In this research, polyurethane (PU) foam composites were prepared by using various agricultural waste (rice husk, corn silk, artichoke stem) particles. In order to enhance the compatibility and adhesion between the waste particle and PU matrix, alkali treatment was employed. The alkali treated particles were chemically and morphologically characterized by Fourier transform infrared (FTIR) spectroscopy, cellulose determination instrument, and scanning electron microscopy (SEM), respectively. The effects of the alkali treatment on the structural, morphological, mechanical, and acoustic properties of the overall PU foam composites were all examined. Due to the differences in chemical compositions of the agricultural wastes, the alkali treatment affected the acoustic and mechanical properties of the PU foam composites in varying ratios. The PU foam composite reinforced with alkali treated artichoke stem waste particles showed the highest tensile strength value of 265 kPa, whereas the highest sound absorption value of 40.5% as an enhancement on the acoustic properties compared to the blank PU foam composite was recorded in corn silk waste particle loaded sample.

Upcycling tea waste particles into magnetic adsorbent materials for removal of Cr(VI) from aqueous solutions

In this work, locally available tea wastes were used as precursors for the development of cost-effective bio-sorbent materials for heavy metal removal from wastewater. Chemical and thermal treatments to prepare magnetic/non-magnetic tea waste-based adsorbents were discussed and correlated their properties with corresponding Cr(VI) adsorption capacity. These bio-sorbents were thoroughly characterized by FT-IR, PXRD, N2 adsorption-desorption surface area techniques and Cr adsorption performance was investigated in batch reactor under different conditions such as adsorbent dosage, initial Cr concentration, solution pH and contact time. Careful bleaching steps, incorporation of magnetic iron nanoparticles and judicious temperature treatments of tea wastes resulted in high performing biosorbents with a complete removal of Cr at a dosage of 0.25 g/mL of the solution. Cr adsorption on these tea waste-based bio-sorbents were found to be fitting to a pseudo 2nd order kinetics.