Incinerator Ash Research Articles

Heavy metal removal using an advanced removal method to obtain recyclable paper incineration ash

Various agents, including ethylenediaminetetraacetic acid, oxalic acid, citric acid, and HCl, were applied to remove heavy metals from raw paper incineration ash and render the ash recyclable. Among these prepared agent solutions, ethylenediaminetetraacetic acid showed the highest efficiency for Pb removal, while oxalic acid showed the highest efficiencies for Cu, Cd, and As removal. Additionally, three modes of an advanced removal method, which involved the use of both ethylenediaminetetraacetic acid and oxalic acid, were considered for use at the end of the rendering process. Among these three modes of the advanced removal method, that which involved the simultaneous use of ethylenediaminetetraacetic acid and oxalic acid, i.e., a mixture of both solutions, showed the best heavy metal removal efficiencies. In detail, 11.9% of Cd, 10% of Hg, 28.42% of As, 31.29% of Cu, and 49.19% of Pb were removed when this method was used. Furthermore, the application of these three modes of the advanced removal method resulted in a decrease in the amounts of heavy metals eluted and brought about an increase in the CaO content of the treated incineration ash, while decreasing its Cl content. These combined results enhanced the solidification effect of the treated incineration ash. Thus, it was confirmed that the advanced removal method is a promising strategy by which recyclable paper incineration ash can be obtained.

Incorporation of potential toxic elements adsorbents incinerator ash into mortar: a sustainable approach

Incorporation of potential toxic elements adsorbents incinerator ash into mortar: a sustainable approach

Structural parts based on Municipal-Solid-Waste incineration ashes

We investigated a novel processing technique of municipal solid waste incineration (MSWI) ashes. By using two thermodynamic driving forces – a strong alkaline activator and a compaction pressure, the otherwise relatively nonreactive MSWI ashes could form strong solids, with relatively high flexural and compressive strengths. The produced material was dense, with a low defect density. The effects of the compaction pressure range, the alkaline activator amount, and the MSWI fly ash to bottom ash ratio were examined. We also used 5 wt% class-C fly ash, 5 wt% class-F fly ash, and/or 1 wt% epoxy as additives. This study may open a door to advanced MSWI ash upcycling approaches, useful to environmental preservation and sustainability.

Creating coagulants through the combined use of ash and brine

Sludge incineration and seawater desalination are two approaches that can be used in the disposal of waste activated sludge (WAS) and for obtaining fresh water. As resource recovery from wastewater treatment and water purification is a topic of particular interest in these times, “water mining” has become a focus of research, with phosphate/P-recovery from WAS incineration ash, and extraction of useful elements from the brine of desalination being important steps in the pursuit of a circular/blue economy. However, P-recovery from ash involves removing metals, which need to be disposed of carefully, as does the brine collected. If cations in the ash and anions in the brine could be combined in order to produce coagulants/flocculants, a new circular model would be established. A preliminary experiment for this purpose has demonstrated that a liquid poly‑aluminum chloride (PAC) could be synthesized from the aluminum ion/Al3+ removed from the ash and the original brine. With this work, we synthesized the liquid PAC by a hydrothermal method, and the results from infrared spectrometer demonstrated that the synthesized PAC was similar to a commercial PAC. Moreover, the synthesized PAC was able to efficiently reduce the effluent turbidity of wastewater treatment plants (WWTPs), especially when compared with the commercial PAC. It is therefore important that research in this area be continued in order to improve the quality of synthesized coagulants and to produce different coagulants based on cations and anions in ash and brine.

A REVIEW OF RECENT TRENDS TO INCREASE THE SHARE OF POST-CONSUMER PACKAGING WASTE TO RECYCLING IN EUROPE

Through the Circular Economy Package, the EU aims to reduce material imports and environmental impacts of waste management. Ambitious recycling targets should help to achieve these objectives. As a response, the waste industry developed technical and organizational solutions that can intervene at different stages of a waste management system in order to increase the recovery of recycling materials, starting with improved separate collection over the use of modern material recovery facilities up to the enhanced treatment of waste incineration ashes. The large question is how each of these options can contribute to increase recycling rates to achieve a circular economy. By reviewing case studies as presented in the most recent literature published since the year 2010 from European countries on the recycling of post-consumer packaging waste of glass, metals, paper, and plastics, this study contributes to answer this question. In the first stage, the review found 644 articles matching with the search terms and published since the year 2010. Of these, 46 remained for an in-depth analysis, since 319 did not present case studies as defined in the scope of this article. The articles reviewed provide a good overview on the state of knowledge on increasing recycling of post-consumer packaging waste by improved separate collection, material recovery facilities, and waste incineration bottom ash treatment. Additional information and case studies, however, are required, particularly large-scale experiments to test new separate collection systems, large-scale with different feedstock material at the most-modern material recovery facilities and waste incineration bottom ash treatment plants.

The Effect of Municipal Solid Waste Incineration Ash on the Properties and Durability of Cement Concrete.

The aim of this study is to investigate the effect of municipal solid waste incineration bottom ash from a cogeneration plant on the physical and mechanical properties and durability of cement concrete. Part of the cement in concrete mixtures tested was replaced with 0%, 3%, 6%, 9%, and 12% by weight of municipal solid waste incineration bottom ash. Concrete modified with 6% of bottom ash had a higher density (2323 kg/m3), compressive strength at 28 days (36.1 MPa), ultrasonic pulse velocity (3980 m/s), and lower water absorption rate (3.93%). The tests revealed that frost resistance, determined in all-sided testing directions, of concrete modified with 6%, 9%, and 12% of bottom ash added by weight of cement corresponds to strength grade F100. Such concrete can be used in construction works.

Biochar as carbon sequestration material combines with sewage sludge incineration ash to prepare lightweight concrete

Sewage sludge incineration ash (SSIA) is a solid waste containing heavy metal pollutants, which could be recovered as construction material via cement solidification. Biochar, as a carbon sequestration material, has properties of water absorption, metals immobilization, electron donor, etc. This study produced lightweight concrete (LC) with the ratio of SSIA to Portland cement being 1:1 (w/w), and incorporated peanut shell biochar produced at 500℃ and 700℃ pyrolysis (BC500, BC700) with addition rates of 1–5 %. Both BC500 and BC700 increased the mechanical properties of the LC at their optimal addition rates, i.e., 5 % BC500 and 3 % BC700 respectively, achieved 10.8 MPa and 11.1 MPa compressive strength, 2.1 MPa and 2.8 MPa flexural strength, being much higher than the control (6.2 MPa compressive strength and 1.35 MPa flexural strength). Biochar also significantly enhanced the water resistance of LC by 56.3 % (BC500) and 60.4 % (BC700). Instrumental analysis (TGA, XRD, SEM-EDS and heat flow) revealed that the alkaline and porous biochar promoted and prolonged the hydration reactions with forming more cementitious materials such as calcium silicate hydrate and ettringite. Biochar simultaneously strengthened the metals immobilization in LC including Cr, Cu, Zn, Mn, As and Cd, especially it acted as electron donor to reduce Cr(VI) into Cr(III) with less toxicity and mobility. Based on leaching test, it was confirmed that converting 1-ton biomass into biochar and incorporating into SSIA-based FC could achieve 541 and 980 kg CO2eq carbon sequestration for BC500 and BC700 respectively.

Hierarchically porous glass–ceramics by alkaline activation and crystallization from municipal solid waste incineration ashes

As a hazardous waste, municipal solid waste incineration (MSWI) fly ash poses a serious threat to the environment, and considerable efforts have been made to achieve its harmless treatment. Herein, a novel approach for handling MSWI fly ash has been proposed to prepare porous glass–ceramics by alkali activation–crystallization, which overcomes the difficulty of controlling air bubbles under high temperatures. MSWI bottom ash rich in Al2O3 and SiO2 are co-treating as raw material to develop glass framework structure. The alkali activation mechanism shows that the development of MSWI ashes based basic glass from monomer to silica–aluminate gel under alkaline condition. The influence of H2O2 addition on the morphology and physical properties of porous glass–ceramics were evaluated. Porous glass–ceramics with uniform hierarchical pore structure have been fabricated at 3 mol/L NaOH, a solid loading of 55 wt%, and 1–4 wt.% H2O2, then crystallization treatment at 1150 °C for 2 h, the porosity and the bulk density of which varies from 77.22 to 82.94% and 0.68–0.91 g/cm3 respectively, while their relatively high compressive strength ranges from 1.62 MPa to 3.85 MPa. Attributed to the hierarchical porous structure, uniform distribution of pores and excellent physical properties, porous glass–ceramics has potential applications in construction, filtration, and adsorption materials, providing a convenient and feasible method for the efficient and comprehensive utilization of MSWI ashes.

Fresh, Mechanical, and Microstructural Properties Investigation on the Combined Effect of Biomedical Waste Incinerator Ash and Bagasse Ash for High-Strength Concrete

The combination effect of supplementary cementitious materials in the production of high-strength concrete production is an effective way to reduce the amount of cement required while contributing to environmental sustainability and cost. This study aims to assess the microstructural investigation on the combined effect of biomedical waste incinerator ash (BWIA) and bagasse ash (BA) as a partial replacement of cement in high-strength concrete production. The cement was partially replaced with BA (0%, 2.5%, 5%, and 7.5%) and BWIA (0%, 2.5%, 5%, and 7.5%). The mix design was done as per the ACI 211-4R-93 mix design standard. Slump, slump flowability, density, and compaction factor tests were conducted for freshly mixed concrete. Mechanical properties of the hardened concrete from four different mixes were also determined for the 7- and 28-day cured specimens. The microstructural properties of the hardened concrete for all mixes were also investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Based on the experimental results, the compressive strength of high-strength concrete at every 2.5% BA and 2.5% BWIA replacement of cement in the concrete mix at 7 days of curing was slightly decreased, while at 28 days of curing, the compressive strength of the control mix (51.8 MPa) decreased as compared to the mix codes' compressive strength of the BWIA and BA5 and BWIA and BA10 mix codes, at 54.8 MPa and 52.5 MPa, respectively. The SEM micrographs showed that the partial replacement of cement by the BWIA and BA leads to a decrease in the pore proportion in the enlarged interfacial transition zone (ITZ), reduced CH crystals, and a denser C–S–H gel as compared to the control specimen. The XRD pattern showed the existence of portlandite, ettringite, okenite, quartz, and calcite in the cement and aggregate phases. As a result, the usage of BWIA and BA has a significant impact on the properties of high-strength concrete in fresh, hardened, and microstructure high-strength concrete.

Effect of Municipal Solid Waste Incineration Ash on Microstructure and Hydration Mechanism of Geopolymer Composites

The geopolymerization process is an appropriate way of disposing of municipal solid waste incineration fly ash (MSWIFA), and possesses the advantages of immobilizing the heavy metals and making full use of its pozzolanic properties in manufacturing green, cementitious materials. In this study, coal fly ash (FA) and metakaolin (MK) were used to prepare a geopolymer composite, with MK partially replaced by different proportions of MSWIFA through the alkali-activation method. The microstructure and hydration mechanism of the geopolymer composites containing MSWIFA were investigated through mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and Fourier transform-infrared spectroscopy (FT-IR) tests; and the immobilization effect of the geopolymer paste on heavy metal ions was explored through inductively coupled plasma-atomic emission spectrometry (ICP-AES). The MIP analysis showed that the addition of MFARR had an overall degrading effect on the pore structure of the matrix. When the content of MSWIFA reached the maximum of 35%, the porosity and average pore diameter increased by 25% and 16%, respectively, corresponding to the case without MSWIFA. However, the pore size distribution exhibited an improving trend when the MFARR was increased from 15% to 25%. The SEM images revealed that the integrity of the micromorphology of the geopolymer mortar became weaker after adding MSWIFA. When the MSWIFA content was increased to 35%, the microstructural compactness decreased and more pores and microcracks appeared in the matrix. The FT-IR pattern study suggested that all the geopolymer composites had a similar internal structure, consisting of O-H, C-O, Si-O-Si, and Si-O-Al. The main component of the geopolymer paste hydrated at 28 d remained dominated by calcium silica-aluminate (C-A-S-H), when the MSWIFA ranged from 0% to 35%. Finally, the ICP-AES results showed that the leaching concentrations of the geopolymer paste of J-40 at 28 d for Cd, Cr, Cu, Pb, and Zn met the requirements of Chinese standards.

Potential Use of Municipal Waste Incineration Ash as a Hardening Slurry Ingredient

In recent years, there has been a marked increase in the amount of municipal waste generated in Poland. In the context of circular economy assumptions, the key is the availability of technologies that would make it possible to safely process and reuse waste, especially when it is difficult to manage. One such direction is thermal waste treatment. In 2020, 21.6% of all municipal waste was subjected to this process. Consequently, the amount of ash generated is significant (approximately 2,823,000 tons annually). One of the uses of waste materials is the sealing of earth hydrotechnical facilities, such as flood embankments, water dams, and embankments of waste landfills. For this purpose, cut-off screens made of hardening slurries are used. In order to improve the tightness and corrosion resistance of hardening suspensions, combustion by-products are added to their composition. The article presents an assessment of the possibility of using ashes from municipal waste incineration as an additive to hardening slurries. It also discusses the technological and operational parameters of hardening slurries with the addition of the ashes in question. Binding requirements for hardening slurries used for the construction of cut-off walls is also defined. The experiment showed that the tested hardening slurries meet most of the suitability criteria. Further research directions are proposed to fully identify other properties of hardening slurries in terms of their environmental impact.

A new direction for tackling phosphorus inefficiency in the UK food system

The UK food system is reliant on imported phosphorus (P) to meet food production demand, though inefficient use and poor stewardship means P is currently accumulating in agricultural soils, wasted or lost with detrimental impacts on aquatic environments. This study presents the results of a detailed P Substance Flow Analysis for the UK food system in 2018, developed in collaboration with industry and government, with the key objective of highlighting priority areas for system interventions to improve the sustainability and resilience of P use in the UK food system. In 2018 the UK food system imported 174.6 Gg P, producing food and exportable commodities containing 74.3 Gg P, a P efficiency of only 43%. Three key system hotspots for P inefficiency were identified: Agricultural soil surplus and accumulation (89.2 Gg P), loss to aquatic environments (26.2 Gg P), and waste disposal to landfill and construction (21.8 Gg P). Greatest soil P accumulation occurred in grassland agriculture (85% of total accumulation), driven by loadings of livestock manures. Waste water treatment (12.5 Gg P) and agriculture (8.38 Gg P) account for most P lost to water, and incineration ashes from food system waste (20.3 Gg P) accounted for nearly all P lost to landfill and construction. New strategies and policy to improve the handling and recovery of P from manures, biosolids and food system waste are therefore necessary to improve system P efficiency and reduce P accumulation and losses, though critically, only if they effectively replace imported mineral P fertilisers.

Screening dilute sources of rare earth elements for their circular recovery

Metals, including rare earth elements (REE), are the cornerstone of our current and future low-carbon urban infrastructure. This study looks at different waste resources and contaminated materials present in the urban setting as REE sources. Wastes and other dilute sources such as incineration ashes, sediments, and mine tailings are not only essential sources of REE in achieving a circular, carbon-neutral economy but may be the most realistic one. E-waste, being the most REE concentrated waste, faces serious reservations regarding handling in large-scale facilities, and this waste is generally landfilled. In this study, we analyzed REE total concentrations and pH desorption curves in ten dilute sources of REE: Ferrochrome slag from a mine in South Africa, sediments retrieved form stormwater ponds in Denmark, coal fly ashes, municipal solid waste (MSW) fly ashes, wood fly and bottom ashes and sewage sludge fly ashes (ashes from different sources). After analyzing different residues, we found that coal fly ashes and stormwater retention pond sediments present the most promising ones. While coal fly ashes have the highest critical REE contents from the studied wastes, the sediments collected from a stormwater retention pond showed the highest REE leachability. We can find Nd, Dy, and Er – all critical REE – in sediments/soils near highways, coal ashes, and bauxite residue. Overall, coal fly ashes contain the highest critical REE contents found in the studied wastes but sediments collected from stormwater water ponds present the highest leachable REE. In fact, up to 100% of total REE found in these sediments are leachable at room temperature and low pH. Future REE resource extraction efforts should account for REE speciation in wastes and not only total contents.

Chemical activation of pozzolanic activity of sludge incineration ash and application as row bonding materials for pervious ecological brick

Some incineration ashes, such as fly ash, blast furnace slag etc., have emerged as eco-friendly alternatives to ordinary Portland cement in order to reduce the environmental impacts. However, it is still unclear that the sludge incineration ash (SIA) which comes from lake or river sludge after incineration can also be used as that or not. In this paper, the pozzolanic activity and chemical excitation assay of SIA were experimentally studied in order to be used as a raw bonding material, and the performances of pervious ecological brick prepared with SIA were investigated. The results showed that the activity index of SIA was similar as that of FA, and it can be used as auxiliary cementing material in concrete instead of part of cement. The hydration process of incineration ash in cement-SIA composite cementitious system can be promoted by chemical activators such as NaOH, Na2SO4, Na2SiO3 and NaAlO2. The activation effect on SIA of multi-component exactor combination which optimized by orthogonal experimental methods was better than that of a single component exactor. It is a new green disposal path of sludge from lake or river which contains humus and pollutants. The permeability, water conservation and freezing resistance of pervious ecological brick which prepared with the SIA-cement paste can meet the engineering application requirements.

Municipal solid waste incineration (MSWI) ash co-disposal: Influence on per- and polyfluoroalkyl substances (PFAS) concentration in landfill leachate

Municipal solid waste incineration (MSWI) ash is often managed through co-disposal with unburned wastes in landfills, a practice previously reported to result in enhanced leaching of pollutants (e.g., heavy metals) in landfill leachate. The objective of this study was to evaluate the effect of co-disposed unburned wastes on per- and polyfluoroalkyl substances (PFAS) in MSWI ash landfill leachate. Leachate was collected from four landfills containing MSWI ash, either as a sole waste stream or co-disposed of with sewage sludge and MSW screenings. Samples of ash and unburned materials were collected and assessed separately for leachable PFAS in the laboratory. All samples were analyzed for 26 PFAS. Results showed that greater ash content was associated with lower leachate PFAS concentrations. The pure ash monofill exhibited the lowest PFAS in landfill leachate (290 ng L−1) while the landfill contained a large amount of unburned waste had the highest PFAS (11,000 ng L−1). For laboratory leaching tests, average ∑26PFAS concentration in lab ash leachate (310 ng L−1) was 10 and 24 times lower than observed in lab sewage sludge leachate (3,200 ng L−1) and lab MSW screenings leachate (7,500 ng L−1), respectively. Leachate from the ash-only landfill had ∑26PFAS concentration similar to what was measured in the ash itself. On the contrary, ∑26PFAS concentration in co-disposal landfill leachates were similar to those in PFAS-rich unburned waste itself, regardless of the percentages of landfilled unburned wastes. We hypothesize that leachate generated in co-disposal scenarios preferentially flows through PFAS-rich unburned materials and that biotransformation of precursors enhanced by unburned waste degradation further contributes to higher concentrations of terminal PFAS in ash co-disposal sites. Landfill operators should expect PFAS in leachates to be higher when PFAS-rich unburned wastes are disposed of alongside MSWI ash, even if the unburned fraction is small.

Desulphurization of FGD wastewater through bacterial sulfate reduction process with agricultural incineration bottom ash as an amendment

Coal-fired power plants produce a large amount of sulfate-laden flue gas desulphurization (FGD) wastewater, while a sustainable amount of incineration ash was produced as solid waste in biomass power plants. Both FGD wastewater and incineration ash led to serious environmental problems without proper treatment. Sulfate reduction was an efficient technology for FGD wastewater treatment, however, the carbon source was insufficient for reducing sulfate in FGD wastewater which needed to be replenished. In this study, pyrolyzed incineration bottom ash (PIA) was introduced to sulfate reducers for FGD wastewater treatment. Sulfate-reducing activity increased (up to 2.9-fold) with PIA300 (incineration ash pyrolyzed under 300 °C) addition. Remarkably increasing abundance of Clostridium (12-fold) and Paraclostridium sp. (79-fold) bacteria were observed in sulfate-reducing sludge with PIA300 addition. Pyrolyzed incineration ash not only acted as a carrier for sulfate reducers, but also provided additional carbon, alkalinity and trace elements (Fe, K, Ca, etc.) for sulfate reduction. Incineration ash was partially degraded by sulfate-reducing bacteria (up to 39.4%), meanwhile, heavy metals (Mg, Al, Cr, Co, Ni, Cu, Zn, etc.) leached from ash and existed in FGD wastewater were efficiently co-removed (95–100%). Addition of PIA to sulfate reducers led to increased formation of extracellular polymeric substances, which might enhance the biotransformation and degradation of organic matters in both ash and FGD wastewater. Thus, a promising FGD wastewater treatment technology was established in this study, to achieve simultaneous FGD wastewater reclaim and solid waste utilization.

The Impact of Bio-Based Fertilizer Integration Into Conventional Grassland Fertilization Programmes on Soil Bacterial, Fungal, and Nematode Communities

Phosphorus (P) is an essential plant macro-nutrient applied to soil in agriculture, mainly sourced from non-renewable mined phosphate-rock, of which readily accessible reserves are currently under pressure, while global food demand continues to grow. Meanwhile, an abundance of P is lost in waste-streams. Hence, bio-based fertilizers are increasingly produced using nutrient-recovery technologies and evaluated as a sustainable fertilizer alternative. However, there is little knowledge of how these products affect soil microorganisms. In this study, four new phosphate bio-based fertilizers (two struvite and two incinerator ashes) were assessed in permanent grassland-plots to understand their impact on soil bacterial, fungal, and nematode community responses. The experiment consisted of 40 plots (each 6 × 2 m2) of 8 treatments (2 struvite, 2 ash, cattle slurry, 100% mineral fertilizer, zero P fertilizer, and a control without fertilization) with 5 replications arranged in a randomized complete block design. Community data were obtained by amplicon sequencing of DNA extracted from soil samples and subsequent analysis of community composition, diversity, structure and influencing environmental variables. Diversity of the soil microorganisms was maintained by all bio-based fertilizer treatments. Results showed that soil bacterial, fungal, and nematode communities of the struvite-treatments were similar to those in 100% mineral treatment. Communities in ash-treatments were more disturbed in their compositions, abundances and structures, possibly due to their high pH and heavy metal content. From canonical correspondence analysis, available P, K, and Mg, as well as plant P uptake and biomass yield, were identified as factors significantly influencing bacterial and nematode communities across different treatment groups. In particular, the abundance of environmental disturbance sensitive nematodes (e.g., Dorylaimida) was significantly reduced by one of the ash products. Overall, results indicate that both struvites are benign to soil bacterial, fungal, and nematode communities and can be safely applied as a source of renewable P to meet crop nutrition requirement. The ash products require further investigations before recommending their regular application as fertilizer. As the application of novel bio-based fertilizers will increase in the foreseeable future, the findings of this study would be valuable to feed into developing environmental risk assessment protocols.

Sustainable alkali-activated binders with municipal solid waste incineration ashes as sand or fly ash replacement

The present study investigates the feasibility of using two types of municipality solid wastes incineration ashes, namely, fly ash and bottom ash in the production of sustainable alkali-activated binder. The ashes are collected from the incineration plant and characterized to determine their particle size distribution, specific gravity, chemical composition, and heavy metals content. The ashes are then used as either fly ash or sand replacement with five replacement ratios 0%, 5%, 10%, 15%, and 20% to produce the binder. The produced binder are characterized in terms of strength, workability, density, water absorption, thermal conductivity and stability, chemical composition, and heavy metals content. The results reflect the ability of producing sustainable alkali-activated binder with small dosage of MSWI ashes as either fly ash or sand replacement without negatively affecting its strength, workability, density, and water absorption. The ashes enhance the thermal insulation capability of the binder.

Leaching of Titanium Dioxide Nanomaterials from Agricultural Soil Amended with Sewage Sludge Incineration Ash: Comparison of a Pilot Scale Simulation with Standard Laboratory Column Elution Experiments.

Nanoscale titanium dioxide (nTiO2 (Hombikat UV 100 WP)) was applied to sewage sludge that was incinerated in a large-scale waste treatment plant. The incineration ash produced was applied to soil as fertilizer at a realistic rate of 5% and investigated in pilot plant simulations regarding its leaching behavior for nTiO2. In parallel, the applied soil material was subject to standard column leaching (DIN 19528) in order to test the suitability of the standard to predict the leaching of nanoscale contaminants from treated soil material. Relative to the reference material (similar composition but without nTiO2 application before incineration) the test material had a total TiO2 concentration, increased by a factor of two or 3.8 g/kg, respectively. In contrast, the TiO2 concentration in the respective leachates of the simulation experiment differed by a factor of around 25 (maximum 91.24 mg), indicating that the added nTiO2 might be significantly mobilisable. Nanoparticle specific analysis of the leachates (spICP-MS) confirmed this finding. In the standard column elution experiment the released amount of TiO2 in the percolates between test and reference material differed by a factor of 4 to 6. This was also confirmed for the nTiO2 concentrations in the percolates. Results demonstrate that the standard column leaching, developed and validated for leaching prediction of dissolved contaminants, might be also capable to indicate increased mobility of nTiO2 in soil materials. However, experiments with further soils are needed to verify those findings.

Estimation of the Amount of Recovery of Valuable Resources according to the Renovation of a Circular Landfill

To change from a linear economy to a circular economy, the necessity of recycling scarce resources through recycling waste is emerging. In South Korea, the concept of landfill mining has been introduced as a way to convert landfills into resources, and recycling-type landfills are being created. In this study, the operation status of domestic municipal waste landfills was identified, and the amount of resource recovery according to the renovation of a circular landfill was calculated. Of 215 public landfill sites, 67 landfill sites that have been used or have a residual landfill rate of less than 40% were investigated, and the total amount of waste landfills here was confirmed to be 68,509 thousand m3. Among landfill wastes, the energy production potential from combustible wastes was calculated to be 55,835,540 Gcal when energy was recovered through stocker-type incineration. The amount of recovered valuable resources among landfill wastes was estimated to be 1,065 thousand tons. As a result of evaluating the potential for recycling of major metals, trace metals, and rare earth elements contained in incineration ash, the content of Fe among major metals such as Fe, Al, Cu, and Zn was in the range of 27,280 to 245,517 tons, which is the national integrated resource management system. The possibility of circular use was confirmed as the range of the mass flow analysis statistic was similar. In the case of trace metals, the content ranges of Cr, Pb, and Co were 162 to 1,716 tons, 99 to 875 tons, and 35 to 64 tons, respectively, similar to the statistics. In the case of rare earth elements with high potential value as future resources, national statistics were absent or recent data were insufficient, but in the case of Dy, a similar content could be confirmed. 70% of the total landfill capacity can be used for the recycling landfill capacity according to the composition of the recycling landfill, and when the municipal waste is finally disposed of after resource recovery in the recycling landfill, the lifespan of the existing landfill can be extended by more than 5.4 times.