In Japan, thermal treatments such as incineration and melting are applied to a significant amount of waste, resulting in thermal treatment residues (incineration ash, slag, metal, etc.) that contain elements originally present in the waste. The most fundamental issue in this context is establishing methods for quantifying the content of valuable metals and harmful elements in these thermal treatment residues. This study compared two types of acid solutions to investigate the appropriate digestion methods for 44 elements in various thermal treatment residues: (1) the AR method, a decomposition method using aqua regia (a mixture of nitric acid and hydrochloric acid), and (2) the FB method, a method involving decomposition with a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, followed by reheating after adding boric acid. The results showed that for the acid decomposition of thermal treatment residues, it is desirable to apply both the AR method and the FB method when the target elements are Mo, Pd, and In, or when metals are the samples to be analyzed. When the target elements are valuable elements such as Pt and Au or harmful elements such as Cd, As, and Pb, the application of the FB method is recommended.

78% of the landfilled at MSW landfill sites is incineration residue. (excluding covering soil) In the Sea Surface Landfill, the waste is immersed, and the percolating water remains mostly immobile. The high pH due to lime used in incineration flue gas treatment, and high COD and T-N concentrations caused by residual chelates, lead to delays in stabilization. In particular, pH reduction takes a long period of time. Against this background, an airlift pump was introduced to move percolating water within the landfill layer and to bring the waste into contact with air. Experiments were conducted to reduce pH by mixing and circulating percolating water and surplus water to achieve uniformity and improve water quality. Additionally, the pH was reduced through neutralization with CO₂ in the air during the airlift. This study, We report the results of a simulated landfill experiment using incineration residue with Ca(OH)₂) and NaHCO₃ as desalination agents, organic chelates and inorganic phosphorus agents as fly ash stabilizers.

The problem that the nitrification process does not proceed at sea-based landfill sites has been identified. The suspected cause is the organic chelate agents which are used for the treatment of heavy metals in incineration fly ash. It has been found that these organic chelate agents decompose near neutral pH, but the decomposition process and the resulting products are not well understood. In this study, we hypothesized that the organic chelate agent DEA decomposes to produce allylthiourea. We conducted experiments to determine whether allylthiourea is produced during the DEA decomposition process and to understand changes in nitrification inhibitory properties during this process. While the concentration of DEA decreased due to decomposition, the TOC value remained nearly constant, indicating that it did not fully decompose to carbon dioxide and intermediate products are present. However, the production of allylthiourea during the decomposition process was not identified. Results from the nitrification inhibitory properties experiments suggest that the intermediate products have nitrification inhibitory properties and that these intermediates may further decompose into other intermediate products during the decomposition process.

In waste disposal sites, gas vent pipes are installed to release generated gas from underground and introduce new air for the purpose of stabilizing landfills. When investigating the blockage of gas vent pipes at actual land-fill sites, the pipes were found to be deformed in a manner that caused them to buckle, and it is unclear what loading conditions cause the deformation conditions at the site. Therefore, in order to explore the factors that cause the buckling of gas vent pipes, indoor compression tests were conducted using high-density polyethylene pipes used at actual land-fill sites. In this paper, we summarize the test results for each high-density polyethylene pipe material and report on their deformation characteristics and deformation conditions.

In many controlled landfills, leachate collection pipes penetrate the impermeable barrier at the toe of the reservoir dam in the downstream section of the landfill. Inspection of the joints between leachate collection pipes and water-impermeable sheets is crucial to prevent leachate leakage, as poor joint quality can lead to increased leakage risks. Heat fusion of polyethylene water-impermeable sheets, which are the same material as the leachate collection pipes, is possible, but self-propelled heat fusion machines are not suitable for complex joint geometries. Indoor integrated molding is increasingly being adopted to improve workability, but there was no high-precision inspection method for joints between leachate collection pipes and water-impermeable sheets. This paper reports the development and evaluation of a high-precision inspection method for joints between leachate collection pipes and water-impermeable sheets for indoor integrated molding.

A survey was conducted at the Kinuura Port No. 3 Area Final Disposal Site to identify the causative substances of persistent COD contained in the leachate from the controlled landfil site, and to consider stable and effective treatment methods.

A questionnaire survey revealed that chelating agents, which have been identified as a source of persistent COD, are used in the waste brought to the disposal site to suppress the leaching of heavy metals.

A water quality analysis using GC/MS confirmed that N,N-diethyldithiocarbamate (DDTC), a type of chelating agent, remains in the leachate for a long period of time without being decomposed.

Since the loss of DDTC during the pre-analytical treatment process and the presence of other COD sources have not understood, future challenges in order to take measures to treat persistent COD is to establish a method for quantifying DDTC in the leachate and to calculate the contribution of DDTC to total COD from the correlation between DDTC and COD.

A bentonite-sand mixtures soil layer as clay liners for MSW final disposal landfill is constructed using a compaction method by road roller in situ.We have studied the construction method of clay liners by block placement made the bentonite-sand mixtures.We will report the result of permeability test with different gap space between blocks.As the result, the gap space between blocks is sealed by bentonite swelling.

The clay liners made the bentonite-sand mixtures, which is constructed as a part of the water-shielding layer of the final disposal landfill is basically based on construction by spreading and rolling in situ. However, bentonite swells due to rainfall during construction, making it difficult to compact at the target density, and it is inevitable to suspend construction during rainfall, and improvements are desired from the viewpoint of quality assurance and process management. Therefore, we proposed a construction method of making the bentonite-sand mixtures into blocks in advance at a factory and placing those blocks on site. As a result of conducting a block placement test using a forklift equipped with a push-pull attachment, it was possible to place the blocks with a gap equal to or less than the allowable gap, and it was possible to confirm the applicability of the block placement method.

Stabilization was evaluated using water quality and ionic ratios of leachate and stagnant water in venting tubes in a general waste landfill site. The slight differences in the progress of stabilization could be evaluated by water temperature, ORP, and Organic matter indicators between each location of venting tubes. Most of ionic ratios patterns were matched with characteristics of either the methanogenic stationary phase or the final stage of methane fermentation. Water quality of leachate has been shown to be a representative indicator of landfill condition. On the other hand, a specific pattern of ionic ratios was shown in one stagnant water, the reason for this was thought that chemical properties of the reclamation waste which had been filled near this venting tube affected leaching of salts.

In May 2024, the Genkai Town mayor (Saga Prefecture) accepted a literature survey. Most of Genkai Town, however, is classified as unsuitable in the scientific characteristic map.

Although the Government supports restarting and promoting nuclear power plants, the radioactive waste emitted from nuclear power plants is seldom discussed.

This presentation will discuss the cases of Germany and Switzerland, two countries that have taken a different approach to Japan by adopting a screening method that prioritises safety and fairness and by attempting to provide a new perspective on selection criteria, public participation and grants.

The gas emission and composition at difference depths were observed in the gas ventilation pipe with diameter 200 mm installed additionally at a controlled waste landfill site. The amount of gas emission, determined from the sum of methane and carbon dioxide concentrations in the gas at depth with minimal air infiltration and gas flow velocity measured at 10-second intervals using a hot-wire anemometer, showed that the variation trends of gas emission generally corresponded with changes in atmospheric pressure at the investigation site. On the other hand, because a difference of 0.01 m/s in gas flow velocity with large-diameter gas ventilation pipe significantly affects the gas emission, it seems preferable to reduce the diameter to measure the gas flow velocity more accurately. Furthermore, when comparing the "standard method" for collecting gas from different depths within the gas ventilation pipe to the "BaAP method" which uses a balloon-type sealing device designed for large-diameter gas ventilation pipes to sample gas from the surrounding waste layer, it was found that the BaAP method could investigate the actual gas in the waste layer, whereas the standard method investigated gas that had been mixed and homogenized within the gas ventilation pipe.

A rapid and low-cost method for measuring chloride ions by silver nitrate titration (Fajans method) using an adsorptive indicator. Eosin at pH 8 is used as the indicatorent indicator. Since the coloration needs a certain amount of chloride ion, a known amount of chloride ion was added to the sample prior to the titration and subtracted from the measured value, resulting in a good agreement with the ion chromatography method. Although the application of eosin to chloride ions has been denied for more than 50 years, the above improvement enabled eosin to chloride ion; moreover, the application level was in range of mg/L, which is 1/100 of the conventional method.

It is useful to understand changes in the distribution of water content in waste landfill site in order to explore the water channel and to evaluate the water flowin the site. The authors have previously demonstrated that changes in water distribution in a repository can be visualized by water injection tests and high-density electrical resistivity tomography monitoring. In this paper, we report the results of a similar study conducted in a municipal solid waste landfill site to evaluate the differences from the previous studies.

While serious concerns have been raised about the marine plastic pollution, it has been pointed out that waste management, especially landfills, is an important source of plastic release into the environment. On the other hand, while the impact of waste management in Japan on environmental release is considered to be relatively small, quantitative analysis on release pathways and amounts is considered necessary to promote recycling and resource management of plastics and to verify the effectiveness of measures to control the release. In order to contribute to the estimation of the amount of plastic released into the environment due to waste management in Japan and to verify the effectiveness of reduction measures, We are developing an assessment model of plstic release from waste manageemt that takes into account the plastic degradation and decomposition. In this report, we present the results of our evaluation of the amount of microplastics by polymer types released into the environment through municipal waste management processes.

Currently, MSW landfill sites are mainly composed of incineration residue and incombustible shredded waste, although some incombustible shredded waste-based landfill sites are also beginning to exist. However, few studies have been conducted on the early stabilization of landfills with mainly incombustible shredded waste. In our previous studies, leaching tests of incombustible shredded waste have frequently detected leaching values of lead and mercury that exceed landfill standards. Therefore, we obtained samples from a MSW landfill sites that had introduced a pretreatment of incombustible shredded waste for immersion washing, and conducted simulated landfill experiments to confirm the effectiveness of the pretreatment. The results of this study have confirmed that the quality of leachate is quickly reduced by the pretreatment, and that it is possible to avoid exceeding the effluent standard, especially for mercury. This time, we dismantled a simulated landfill tank and conducted elution tests on the filling material, and confirmed that the pre-treatment for immersion washing contributes to early stabilization and that the leachate may meet the decommissioning conditions within two years after the end of landfill operation.

Bharali, n.d, defines the mass curve analysis as a cumulative plotting of net reservoir inflow, where the maximum difference between the supply peaks and the demand curve is taken n as the required storage capacity of a reservoir. Many existing methods are used to determine the capacity of leachate ponds, however; in this study, the mass balance method and the mass curve method were applied to calculate the leachate pond’s capacity. The major influencing parameters observed in this study were rainfall and evapotranspiration and the meteorological data was sourced from the meteorological bureau in Port Moresby the capital city of Papua New Guinea where the Baruni landfill is located. Port Moresby experiences a tropical climatic condition however, its rainfall pattern is lesser than other townships as it is located in a rain shadow area. The Baruni Landfill is a semi-aerobic landfill rehabilitated in 2014. For a closed system of leachate to be feasible, leachate generation has to be lower than leachate consumption. Leachate is reduced through evapotranspiration during the dry season when the leachate stock is recycled back to the disposal surface to enhance evapotranspiration. Semi-arid areas can utilize the mass curve method to design their leachate pond.

Leachate from the final disposal site must be continuously treated until the site is closed, even after the landfill operation has ended. As a result, it is necessary to operate the leachate treatment facility for a long period, leading to maintenance and management costs that become an economic burden. Therefore, it is essential to reduce leachate until the final disposal site is closed.

To reduce the volume of leachate, it is most effective to discharge rainwater as surface runoff as much as possible. Previous studies have confirmed that by applying a 15% diluted cover soil substitute to compacted cover soil, the surface runoff rate is higher compared to using only cover soil (indoor artificial rainfall experiment)1).

This report presents the results of experiments conducted to confirm the rainwater infiltration suppression effect of the cover soil substitute by performing outdoor natural rainfall experiments and verifying the surface runoff function through the application of the cover soil substitute at an actual final disposal site.

In Japan, the number of sea surface landfill sites accounts for 0.62% of the total number, but their landfill capacity accounts for 27.69% of the total capacity. This is approximately 24.1 times the size of inland landfills. In addition, the sea surface landfill is an important facility for accepting disaster waste in the wake of recent disasters. We believe that sea surface landfill facilities will be an important part of Japan's future waste treatment and landfill and waste management. We have confirmed that it is possible to electrically decompose and remove residual chelates, chelate-derived COD and nitrogen, and non-chelate-derived COD and nitrogen. We will confirm the same electrolytic decomposition of chelate- and chelating agent-derived COD and nitrogen in residual water discharged from sea surface landfill sites.

The development of a horizontal permeable reactive barriers (HPRB) technology has been carried out to control the quality of inner water in landfill. In a pilot-scale experiments (test cell) at a landfill, this technology has demonstrated effective capture and purification of numerous contaminants, including heavy metals and organic chemicals. In this study, we proposed a method to estimate adsorption parameters through soil column experiments using high-performance liquid chromatography (HPLC) and mathematical analysis for design HPRB as cover soil in landfill. We constructed a model of the transport and adsorption of heavy metals flowing through a layer filled with HPRB in the soil column and performed numerical simulation. Subsequently, using the data obtained from these numerical calculations and column adsorption experiments, we estimated the adsorption parameters by the Simplex method as the optimization technique.

The environment surrounding final disposal sites has changed significantly over the past few years. As a result of the upgrading of incineration facilities, incineration residues account for more than 78% of the landfill volume, resulting in a highly saline and highly alkaline environment. For this reason, physical-chemical rather than biological treatment has become the main leachate treatment method. However, there are also problems with the treatment of persistent organic matter and nitrogen derived from organic chelates used in fly ash stabilisers. Against this background, the authors have focused on the possibility of decomposing persistent organic matter by electrolysis and have conducted empirical studies. In this study, it was found that the introduction of an electrical treatment system centred on electrolysis and electrodialysis membranes, instead of the current leachate treatment system, can significantly shorten the treatment process and reduce electricity costs.

Detection of organic fluorine compounds such as PFOA in leachate from landfill sites has been reported. PFOA is difficult to decompose, and it is difficult to remove it by conventional leachate treatment processes such as coagulation precipitation and biological treatment. In this study, we focused on the electrochemical oxidation method, which generates a strong oxidizing agent electrochemically to decompose the target substance. Tests were conducted on leachate from a waste disposal site to evaluate the relationship between the wastewater treatment process of the leachate and the PFOA treatment performance by electrochemical oxidation. Electrochemical oxidation reduced the concentration of PFOA in the leachate and leachate well water treatment water to below the detection limit as the amount of electricity input increased. It was suggested that efficient PFOA decomposition could be achieved by introducing an electrochemical oxidation process after the removal of organic matter.

This study investigated the pore structure and water infiltration behavior of samples taken from landfills where incombustible residues or incinerator ash are landfilled using a combination of X-ray CT analysis and FEM fluid analysis. The study results confirm the formation of ‘water channels’ in incombustible residue landfill layers, where water moves through specific and limited pore spaces. It is important to understand how much water channels exist within the landfill layer (effective porosity) for future predictions. On the other hand, it was shown that water infiltration is homogenous in the incinerated ash landfill layer and that leachate concentrations may be higher because water is in contact with all wastes.Different types of landfill waste cause significant differences in infiltration behavior and the resulting water quality. This has a direct impact on the maintenance of landfill sites. Knowledge of the difference in the mass transfer depending on types of landfill waste could contribute to improved design and management strategies for landfill sites.

The objective was to predict changes in Ca concentration in leachate over time based on the amount of Ca leached from incineration residue and the volume of leachate. Different leaching tests were performed on bottom ash and chelate-treated fly ash. Scenarios for predicting changes in Ca concentration in leachate over time were developed using data from existing final disposal sites. The results showed that the measured and calculated Ca concentrations in the leachate from 2005 to 2022 showed relatively good agreement (R², 0.731). The leaching scenarios developed in this study would have the possibility to predict Ca concentrations in leachate. Assuming that the landfill is completed in the year 2023, the Ca concentration in the leachate was calculated using this leaching scenario, and the obtained result showed that it would take 35 years until the Ca concentration in the leachate reached the level where no Ca removal treatment was required.

The relationship between landfill gas concentration and landfill gas generation was clarified by measuring the landfill gas concentration (sum of methane and bicarbonate concentrations) and landfill gas velocity at the vent pipe in a final waste disposal site where landfill has been completed. It was found that the methane concentration at the outlet air vent of the gas discharge pipe tended to be higher in plots with a shorter period of time since the end of the landfill. The percentage of methane concentration by level at the ventilation pipe outlet showed that the number of ventilation pipes with a methane concentration of less than 5% increased by 50%, from 29% in 2006 to 79% in 2023, indicating that stabilization is progressing. The distribution of carbon dioxide concentration in the gas extraction pipes was classified as flat or curved, with the flat type having the largest amount of landfill gas generation and the curved type having the smallest amount.Furthermore, it was found that the landfill gas concentration must be at least less than 1% in order to satisfy the abolition criterion of less than 1L/min for landfill gas generation.

The main landfill material in MSW landfill sites is incineration residue in Japan. Incineration residue contains a large amount of alkaline materials. The authors have recently tested a slow neutralization technique for landfill incineration ash layers using a highly dissolved carbon dioxide solution by UFB generating nozzle. In this report, the authors present the results of a test in which the incinerated ash layer was drained with a highly dissolved carbon dioxide solution (CO₂-UFB water) and the results of SEM observation and SEM-EDX elemental composition of the incinerated ash particles after the test. Following the previous report, we confirmed that neutralization of the incinerator ash layer interstitial spaces progressed, the effluent (leachate) pH decreased, and the inorganic carbon IC concentration increased. SEM images confirmed the formation of non dense (sparse) crystals on the surface and SEM-EDX confirmed CaCO₃ formation.

Environmental pollution from plastic waste, despite recycling efforts, remains critical, with only 7% recycled and 85% ending in landfills. This leads to microplastics dispersal through air and leachate. Bioplastics, derived from renewable sources and potentially biodegradable, offer a solution but their degradation behavior in landfill is poorly understood. This study reviews landfill environments and bioplastic biodegradation mechanisms. In landfills, waste undergoes aerobic and anaerobic decomposition, generating leachate and greenhouse gases (GHG). Bioplastic biodegradation depends on polymer properties and environmental factors like temperature, moisture, and microbial activity. Studies using lysimeters and small-scale reactors simulate landfill conditions, assessing bioplastic degradation through weight loss and gas emissions. ASTM D5526 outlines procedures for measuring ultimate biodegradation, but challenges like waste heterogeneity and reactor handling persist. Future research should focus on lab-scale experiments, the impact of varying landfill conditions on bioplastics, and accurate GHG emission estimates to better understand bioplastic degradation in landfills.

Landfills are significant sources of greenhouse gases (GHG), including methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). Traditionally, N2O emissions have been disregarded due to assumed negligible levels. This study investigates N2O generation in simulated landfills under anaerobic and passive aeration conditions. Laboratory columns were filled with a mixture of simulated waste, mimicking real waste composition in Thailand. The experiment ran for 60 days. The results revealed a positive correlation between N2O and CH4 fluxes in the anaerobic column, suggesting N2O production might occur even without oxygen. This challenges the current understanding and necessitates including N2O in future assessments of GHG emissions from anaerobic landfills. However, the findings require further validation through extended experiments with more data collection. The contrasting negative correlation observed in the passive column highlights the complexity of factors influencing N2O production. Further investigation into microniche formation and methane flux analysis is recommended. Additionally, identifying the microbial communities and nitrogen losses within the system is crucial for a comprehensive understanding of N2O generation. This study provides preliminary insights into N2O emissions from landfills and emphasizes the need for further research to refine our understanding and improve the accuracy of landfill-related GHG emission estimations.

Among the PFAS that have been attracting increasing social concern in recent years, PFCAs and PFSAs have been confirmed to be detected in leachate from final disposal sites. It is thought that PFCAs and PFSAs eluted from waste are adsorbed to waste in the disposal site, so it is necessary to understand the adsorption behavior of PFCAs and PFSAs to waste and predict their movement in the disposal site. In this study, we conducted a batch test of PFCAs and PFSAs using incinerated fly ash, evaluated the amount of adsorption to incinerated fly ash considering adsorption to centrifuge tubes, and calculated the distribution coefficient Kd, which represents adsorption characteristics.

Perfluoroalkyl carboxylic acids(PFCAs) and Perfluoroalkyl sulfonic acids(PFSAs) are detected in leachate from landfills in Japan. It is suspected that these come from incineration residues, but it is not clear to how much they are actually contained in PFCAs and PFSAs. In this study, we conducted content tests of PFCAs and PFSAs in various types of incineration fly ashes, including thermal recycle residues, based on the content test procedures established in a previous study. The content tests were conducted on a total of 15 types of ashes. The total content ranged from 0.01 to 1.21 ng/g for industrial waste incineration fly ash and 0.18 to 0.77 ng/g for municipal solid waste incineration fly ash, in order to discuss the trends by waste type, it is necessary to increase the number of samples. In addition, there were no clear differences among furnace types, acidic flue gas treatment methods, and thermal recycle residues in municipal solid waste.

Some heavy metals in the leachate of municipal solid waste can change their toxicity because of redox reactions, so it is important to comprehend the oxidation-reduction conduction of the leachate. We can see them by measuring the pH and Eh of the leachate. Eh is the electrode potential based on hydrogen and calculated by converting ORP. but there are considerable variations of Eh for each measurement. Therefore, we evaluated whether we can use Eh as an indicator of oxidation-reduction state. The value of Eh was corrected to account for the effect of variability in pH measurements. At first, the variation value of corrected Eh was 70 mV maximum. However, by improving the methods of experiments to control the oxidation, the variation value of the three measurements was less than 20 mV. Then, we can use Eh as the indicator of the oxidation-reduction condition of the leachate.

The Minamata Convention on Mercury has come into effect in August 2017. As a result, intermediate treatment of waste mercury and waste mercury compounds is obligatory for "purification, sulfurization, and solidification," and it is essential to evaluate the long-term stability of waste mercury in final disposal facilities. In this resarch, we conducted a series of leaching tests to clarify the pH dependence of mercury leaching from mercury sulfide (HgS) and sulfurized and solidified waste mercury under alkaline conditions. It was indicated that the mercury leaching characteristics of HgS differed depending on the degree of sulfurization. The mercury containment effect of the solidification treatment with modified sulfur was demonstrated up to around pH 13 for waste mercury. It was suggested that the modified sulfur solidification can be suppressed.

Heavy metals contained in waste are landfilled after stabilization and insolubilization treatment, but there is concern that they may leach out depending on the environmental conditions. On the other hand, it has been revealed that some of the heavy metals leached from landfill waste are co-precipitated in calcium scale that is formed near the leachate collection drainage pipes where air can easily enter, and are difficult to flow out of the landfill layer with the leachate. However, since calcium scale is a substance that dissolves in acid, there is concern that it will dissolve when it comes into contact with acid rain, and the coprecipitated heavy metals will flow out. Therefore, in this study, we conducted an acid rain exposure test on the scale, examined the possibility of heavy metals flowing out. From the results of this study, it was clarified that there is almost no leachig that exceeds the effluent standard.

Treating incineration ash with carbonation reduces pH, forms carbonates, and insolubilizes heavy metals (such as lead) by reacting with CO₂. It is considered effective to use carbonation in combination with adding chelating agents to incineration fly ash with high concentrations of eluted heavy metals.On the other hand, there is concern that organic chelating agents may increase the load on leachate treatment due to increased T-N and COD, and that thiourea-like substances may inhibit nitrification, so there is a demand to reduce the amount of chelating agents added.The purpose of this study was to verify the effect of treating incineration fly ash with carbonation and chelating agents to suppress lead leaching, and to examine the effect of carbonation in reducing the amount of chelating agents.In the test, industrial waste incineration fly ash was treated with carbonation and the addition of a chelating agent, and the elution characteristics were evaluated.As a result, it was shown that by treating the incineration fly ash with carbonation before adding the chelating agent, it is possible to obtain the lead leaching inhibition effect with a smaller amount of chelating agent added, thus reducing the T-N leaching load derived from the chelating agent.

Incineration is a common treatment method of waste, and the incineration residuals are mainly treated with chemicals using chelating agents, but in recent years the stability of chelating agents has been questioned. In order to evaluate the stability of heavy metals in landfill waste, we conducted an availability test of scales to determine the maximum possible elution amount of heavy metals, and evaluated the elution period of heavy metals based on the buffering capacity of scale against acid rain (pH 4.8). The results showed that most heavy metals are likely to be difficult to dissolve even under acidic conditions, although the amount of heavy metal dissolution is affected by their morphology as compounds and their state of existence. It was also found that it takes a long years for all of the dissolvable metal amounts to leach from the scale, indicating that the leaching of heavy metals is controlled in the landfill site.

Mg-based and Ca-based adsorbents are used to remove arsenic (As) from As-contaminated water or to immobilize As in As-contaminated soil, but there are concerns on the deterioration of the adsorbent due to the leaching of base material components. On the other hand, previous studies have reported that the combined addition of Mg-based and Ca-based adsorbents has improved As removal performance and inhibited the leaching of base material components, and an adsorption behavior of arsenate As(V) was evaluated using adsorption isotherm models. However, no similar studies have been conducted on arsenite As(III), which is more toxic than As(V). Therefore, in this study, the adsorption behavior of As(III) in the combined addition of Mg-based and Ca-based adsorbents was examined based on verification of suitability with the adsorption isotherm models and results in XRD analysis.

At illegal waste dumping sites and improper disposal sites, leachate containing various hazardous substances originating from landfill waste leaks into the surrounding environment, causing environmental pollution such as groundwater contamination and surface water pollution. In such waste-derived environmental pollution cases, the methods used to identify the source of the pollution and to determine the extent of the impact of leachate leakage are mainly chemical investigation methods such as analysis of pollutants (e.g., heavy metals, VOCs, DXNs, PFAS, etc.) and tracer substances, and major dissolved ions, Geophysical investigation methods such as electrical conductivity measurement, electrical prospecting, magnetic prospecting, etc. have been used.

In this study, as a complementary method to the above investigation methods, a basic study based on actual field data was conducted on a method for evaluating the water quality of waste-derived leachate using bacterial flora analysis, one of the biological investigation methods.

The surface of the waste building material was stained with two different dyes. After staining, they were observed under a stereomicroscope (x50). When methylene blue (MB) erythrosine (RED-3) was added to the building material sequentially, the asbestos was colored from light blue to reddish purple or pink. Based on the coloration and shape, the material was determined to be chrysotile. Since some fibrous material was not stained, the surface of the building material was modified with a cationic polymer; drops of MB and RED-3 resulted in red staining. The colored material was confirmed to be amosite by XRD, EDX, and microscopic Raman spectra. The dye staining method was compared to XRD and official analytical methods. All samples in which asbestos was detected by the official analysis method were detected by the dye staining method. There were no false positives or false negatives. The staining method provided a clearer image than the official analysis method. Detection of asbestos in building materials by this method is simple, rapid, and sensitive. This method is suitable for testing for the presence of asbestos in building materials discarded at disaster or demolition sites, or even in buildings prior to demolition.

Zinc in melting fly ash inhibits cement hydration and makes cement solidification difficult, but the addition of sodium aluminate in equal molar amounts with zinc can accelerate hardening. The mechanism of this phenomenon was analyzed by X-ray diffraction. Zinc exists as zincate in the alkaline atmosphere created by cement, and when mixed with cement, calcium zincate is formed. This reaction is thought to remove calcium from the liquid phase, thereby inhibiting the hydration of calcium silicate, the main component of cement hardening. Normal hydration began after all the zincate had combined with calcium. Sodium aluminate, a cement rapid hardening agent, produced hydrates that incorporated the zincate. Accelerating hardening by sodium aluminate was thought to be due to the formation of hydrocalumite, unlike the normal cement hardening reaction. Hydrocalumite is considered to incorporate zincate, and in the long term, the strength increase due to normal hydration of cement can be expected.

At Clean Center Futaba, the final disposal site for specific waste generated at the specific reconstruction and revitalization base, fly ash generated during the incineration of specific waste is solidified in cement since November 2023 in order to prevent radioactive cesium leaching. The properties of fly ash, such as its constituent components, change depending on the incineration method and the origin of the incinerated waste, and these properties affect its strength and the effectiveness of suppressing the leaching of radioactive cesium. Since it is necessary to take such diverse fly ash conditions into consideration, a mix design has not been established. A mix test was conducted using the fly ash to be used, while referring to existing research results. This report provides an overview of the pre-mix test conducted before the actual construction of the cement solidification.

Japanese government policy mandates that decontamination waste, mainly contaminated by ¹³⁷Cs, will undergo final disposal outside of Fukushima prefecture. Post-incineration fly ash, heat-treated with calcium chloride, concentrates Cs as cesium chloride (CsCl) in melting fly ash (MFA). Washing MFA dissolves CsCl, but the solution contains interfering ions like Na, K, and Rb. This study focused on estimating the saturation adsorption amount of copper ferrocyanide (CFC) using ion exchange theory on batch test and column tests with a model solution of MFA washing solution. The model solution was prepared with initial [K]₀ = 3.0 mol/L and [K/Cs]₀ = 1,000. batch tests were conducted in varying L/S ratios, Column tests were carried out using controlled flow rates, measuring Cs in the filtrates. Results showed that the saturation adsorption amount varied with the L/S ratio and salt concentration ratios on batch tests. These findings highlight the need for careful consideration of MFA composition and flow rates to optimize volume reduction. Column tests indicated higher adsorption was achieved at lower flow rates, estimation based on ion exchange theory indicated that the K'Cs/K ratio on the low adsorption rate side was the dominant factor.

This study aimed to measure the airborne PCB concentrations during on-site dismantling work in storage facilities for PCB-containing waste and evaluate the effectiveness of negative pressure management measures using a protective sheet, referred to as a greenhouse, and an activated carbon exhaust pump installed within the sheet. The study focused on the cutting and surface scraping of concrete containers for PCB waste, and measured airborne PCB concentrations inside and outside the greenhouse, as well as at the exhaust outlet. The results showed that the PCB concentration inside the greenhouse during the work was up to ten times higher than before the work, but the concentration at the exhaust outlet was low, and the outdoor concentration was comparable to that in the general atmospheric environment. Additionally, the PCB concentration inside the storage facility showed a decreasing trend over approximately two years after the work was completed. These results indicate that the management measures were effective.

Cs leaching was evaluated by a long-term leaching test on cement-geopolymer (GP) solidified Cs adsorbed zeolite (natural mordenite), a candidate for final disposal of fly ash generated from thermal treatment of decontaminated waste. The leaching tests were conducted in accordance with the ANSI 16.1 method, replacing the solvent in appropriate interval. In addition, changes in Cs leaching behavior due to freezing and thawing of the specimens and immersion in seawater were evaluated, assuming specimen degradation and contact with high-salinity solution, which are expected in an actual disposal environment. As a result, it was clarified that Cs leaching from the cement/GP solidified Cs adsorbed zeolite is determined by diffusion in the solid phase. Freeze-thawing did not affect the Cs leaching rate, but when the specimen was immersed in sea water Cs leaching was accelerated. When the cement solidified body was immersed in seawater, Cs leaching was suppressed by surface precipitates. The cumulative Cs elution rate was below 0.6% even after 100 days of immersion in seawater, and the incremental Cs concentrations in leachant were within the order of concentration standards in environmental water. The results indicate that zeolites can be promising candidate as a final disposal form that retains Cs for a long period of time.

When waste is burned, organic chlorine such as HCl is generated. However, there have been no reports to date that Cl₂ has been detected in these gases. Therefore, the purpose of this study was to separately quantify HCl and Cl₂. As for the details of the experiment, HCl or Cl₂ was generated by mixing chemicals, and then the gas was collected in a collection liquid of H₂O, HNO₃, or H₂O₂ placed in a three-stage collection device. The collected liquid was analyzed by the fayance method, and the amount of HCl and Cl₂ collected was measured. As a result, there was a tendency that the amount of HCl collected was the largest in the first stage, and the amount of Cl₂ collected increased only when H₂O₂ was used as the collection liquid. Based on these results, it was found that HCl and Cl₂ could be efficiently separated and collected by using HNO₃ as the collection liquid in the first stage and H₂O₂ in the second and third stages.

Kureha Ecology Management Co., Ltd. processes a variety of industrial waste, including waste containing selenium (Se). After incineration, the discharge of Se is subject to standard values, requiring appropriate measures. Of particular concern is the presence of hexavalent selenic acid SeO₄^2- (referred to as Se(VI)) and tetravalent selenous acid SeO₃^2- (referred to as Se(IV)) in the drainage, necessitating measurement techniques for each valence state. While our company measures total Se using ICP/MS, we lack the capability for valence-specific measurements. Therefore, we have launched an IC-ICP/MS system capable of simultaneously separating and measuring elements, to assess the practicality of valence-specific analysis of Se. This method has been confirmed to clearly separate and quantify Se(IV) and Se(VI). Furthermore, it is anticipated that this approach, which allows valence-specific measurements for other elements such as arsenic, boron compounds, and hexavalent chromium, will contribute to the maintenance and management of waste treatment facilities and the establishment of drainage treatment technologies.

In this study, the effects of the leaching conditions of the Environment Agency Notification No.13 test on the test results were examined for general waste incineration ash. Three container placement conditions (setting upright-horizontal shaking, setting sideways-widthwise direction shaking, setting sideways-lengthwise direction shaking) were examined. The average concentration of zinc leached was highest (21.1 mg/L) in the sideways setting with shaking in the widthwise direction, whereas the average concentration leached in the sideways setting with shaking in the lengthwise direction was 20.0 mg/L. The lowest leach concentration (13.1 mg/L) was observed in the upright setting with horizontal shaking. Additionally, four container volume conditions (250, 500, 1000, and 2000 mL) were examined. The highest concentration of zinc leached (average 20.1 mg/L) was observed in the 500 mL container, whereas the average leach concentrations in the 250 and 100 mL containers were 18.5 and 18.4 mg/L, respectively. The leach concentration was the lowest (17.0 mg/L) in the 2500 mL container.

Per/polyfluoroalkyl Substances (PFAS) have water and oil repellent properties and are also utilized in familiar products. However, since they are chemically stable, they hardly undergo degradation in the environment, and environmental persistence, bioconcentration, and toxic properties are concerned.PFOS/PFOA which is a kind of PFAS has been detected in some rivers and groundwater in Japan. The purification of PFAS contaminated environmental water has been studied by adsorption treatment using activated carbon. After the adsorption treatment, waste activated carbon is generated, but it is considered that this waste activated carbon contained PFAS needs to be appropriately and reliably degraded treatment.In order to appropriately evaluate the degradation treatment of PFAS, it is required to accurately understand PFAS content containing in waste activated carbon. It is also essential in analysis to establish an optimum pretreatment method of reliably extraction PFAS from waste activated carbon and recovering the total amount of PFAS.Therefore, in this study, 40 PFAS compounds listed in UE EPA Method 1633 were used to adsorption test for powdered activated carbon. After that 40 PFAS compounds adsorbed powdered activated carbon were extracted by ultrasonic extraction, and then PFAS recovery rate was evaluated.

Combustion gas generated by incineration of municipal solid waste is sprayed with slaked lime to remove HCl and SOx. Municipal solid waste incineration (MSWI) fly ash is produced by collecting gas neutralized and excess slaked lime using a dust collector. Harmful components including chlorine and water-soluble crystalline phases might be released into the environment through contact with environmental water. In this study, the leaching behavior of crystalline phases from MSWI fly ash at different leaching test times was quantitatively evaluated by crystal phase analysis. The crystalline phases in the residues after the leaching tests with different test times were quantified by powder X-ray diffractometry/Rietveld refinement. The formation of crystalline calcium carbonate and the leaching of water-soluble salts were observed from the quantitative results of the crystalline phases.

Municipal Solid Waste Incineration fly ash is collected from incineration gas generated by an incineration process of municipal solid waste. Heavy metals are concentrated in fly ash and might be released into the environment through contact with environmental water. Leaching tests are performed in individual countries to evaluate leaching quantities of heavy metals in waste. In this study, the relationship between the leaching behavior of heavy metals and the chemical state of the crystalline phase was evaluated by two kinds of pH dependency tests. The results of pH dependency tests indicated that the pH of the eluate and mixing method was related to the leaching behavior of heavy metals.

The application of microwave plasma atomic emission spectroscopy (MP-AES) for quantitative analysis of lead (Pb) in incineration ash has been discussed. Leaching solutions were prepared according to the method outlined by Environmental Agency Notification No. 13. The solutions were spiked with Pb. External calibration and automatic standard addition were utilized to determine the concentration of Pb via MP-AES. The quantitative results obtained from MP-AES were compared to the lead concentrations in the spiked leaching solutions. These concentrations were determined using quantitative results obtained from inductively coupled plasma mass spectrometry and the quantity of Pb added to the solutions. The external calibration method yielded satisfactory results at 368.347 nm, but interference effects were observed at 405.782 nm. However, the automatic standard addition method suppressed these interference effects, even at 405.782 nm. These findings confirm that using the standard addition method with automatic addition effectively mitigated interference, making MP-AES a reliable method for quantifying Pb in waste incineration ash.

There are more than 1,000 large apartment buildings in the Tokyo metropolitan area, and in the event of a disaster, the disposal of human waste, household waste, and disaster waste generated from these buildings is likely to be a major issue, but there has not been much substantive discussion on this issue to date.Assuming a disaster in central Tokyo (especially an earthquake directly beneath the capital), this study will consider the amount and state of disaster waste generated, taking into account the expected damage and the period of outage of infrastructure such as electricity and water, and will consider the issues and measures for the disposal of disaster waste in large apartment buildings.