A mass production test of tsukuritake mushrooms (Agaricus bisporus) that can be cultivated in compost was conducted to develop a new utilization method for sewage sludge compost. The fruit body yield was 1350 ± 230 g / container in the test plots using sewage sludge compost/cow manure, which was comparable to the control plot using horse manure compost. In the test plots using sewage sludge compost, the amount of free amino acids in fruit bodies increased by 50-70 % compared to the control plots. Furthermore, heavy metal analysis of fruiting bodies showed the detection of Cd and T-Hg in fruit bodies in the test plots using sewage sludge compost. Judging from the acceptable values for agricultural products and the content of heavy metals in domestically grown mushrooms, however, the values of the fruit bodies cultivated in this test were judged to have no effect on health. The waste fungus bed was subjected to a cultivation test of komatsuna (Brassica rapa var. perviridis), and it was found that the mushroom waste bed containing sewage sludge compost and cow dung compost especially grew more than the section with chemical fertilizer application and could be used as a partial substitute for fertilizer.

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In order to recover valuable metals and harmful metals from municipal solid waste incineration bottom ash with air table sorting, the sorting characteristics were investigated. As a result of applying crushing, aqua regia decomposition, and alkali fusion to each fraction before sorting, it was found that Pb, Fe, and Ca had a high proportion of morphologies that were easily crushed and dissolved in aqua regia, while Cu, Zn, and Al had a high proportion of metal morphologies that were difficult to crush. For the 0.5-2.0 mm fraction, it was confirmed that the Newton’s separation efficiency of Pb, Cu, and Zn tends to improve as the difference in particle density increases between high-density particles and low-density particles. Metal particles contained in Pb, Cu, Zn can be efficiently sorted by the density difference with surrounding particles, while particles incorporated into compounds such as aluminosilicate are less likely to have density differences with surrounding particles, making sorting difficult. Correlation analysis of 0.5-2.0 mm high-density particles showed that Pb, Cu, and Zn had correlation coefficient of more than 0.9, and that these elements were concomitantly recovered by air table sorting.

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In this study, for the purpose of recycling ceramic siding waste powder emitted in the cutting process, the decomposition behavior during heat treatment and the hydraulic property of heat treated ceramic siding waste powder were evaluated. The organic mixture could be removed by heating at 530 °C. Then, as determined from the result of XRD analysis, cement hydrate (CSH) could be changed to larnite (2CaO・SiO₂) by heating at 530 °C and wollastonite (CaO・SiO₂) by heating at 700 °C. In addition, when ceramic siding waste powder was molded by adding water after heating at 530 °C for various times, three-point bending stress became approximately constant by heating at 530 °C over 30 minutes. These results suggested that ceramic siding obtained a hydraulic property by heating at 530 °C over 30 minutes. Finally, it was conjectured that the ceramic siding waste powder could be reused as not only recycled aggregate but also recycled cement by heat treatment at 530 °C.

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Accelerated carbonation treatment for recycling MSW incineration bottom ash can simultaneously reduce CO₂ emissions. In this study, we designed a public implementation of this technology and conducted a test at the Saga City Incineration Plant, which has CO₂ separation and capture facilities. Two types of gas-exhaust gas from the same incineration plant and CO₂ separated and recovered from such exhaust gas-were ventilated through the bottom ash and used to investigate the elution characteristics of heavy metals (through (1) elution testing and (2) lysimeter testing) and the effects of carbonation treatment on their mechanical characteristics as civil engineering materials. Carbonation significantly reduced the Pb elution concentration in both (1) and (2), but the concentrations of Cr(VI) increased in both (1) and (2). There was no difference for B between untreated and treated bottom ash in (1), but in (2) the concentration was lower than that of untreated. Regarding mechanical characteristics, we confirmed that while carbonation reduced the modified CBR value and cone index, strength was satisfied as a material for roadbeds and embankments. For the gas types, there were differences in the carbonation reaction status and B concentration behavior.

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In recent years, the amount of waste gypsum board disposed of in managed landfill sites has been increasing, and the generation of H₂S gas from waste gypsum board has become a problem even in this kind of landfill site.
　As a countermeasure against H₂S gas generation, we confirmed the effect of ventilation that makes a tank aerobic in our previous studies, but we had not investigated the effect of layer thickness. Moreover, it is difficult to sustain ventilation during and after disposal in landfill because of the cost. Therefore, we investigated whether it is possible to reduce the concentration of H₂S by reducing the concentration of organic matter sources by improving the washout function through ventilation and the limitation of layer thickness. As a result, we confirmed that the landfill tank layer could be improved to an aerobic state by setting the layer thickness to about 1 m. However, even if the concentration of the organic matter source is low as a factor in H₂S gas generation, generation will continue when the tank is anaerobic, and a certain concentration of sulfate remains.

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Leachate contains a wide variety of chemical substances. Therefore, evaluating the combined effects of chemical substances in leachate by only Ministerial Ordinance control values is not sufficient. So, a leachate evaluation method that can complement chemical analysis is needed. An additional problem is that the stabilization of leachate generally takes a long time after the closure of a landfill. The purpose of this study was to determine a leachate management method for evaluating the stabilization of landfill by applying a bioassay that can comprehensively evaluate the leachate. We have developed a bioassay using Tanichthys albonubes and Daphnia magna that can easily obtain results with a small amount of water and a short evaluation time of 24 hours, and we have defined a landfill stabilization index. We found that evaluations by this method using bioassay could be used for monitoring landfill leachate as one landfill stabilization indicator.

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Not much research has been reported about the influence of heavy metals and organic matter leaching out of landfill with incineration residue over a long period. The effects of cover soil and the characteristics of landfill with incineration residue were considered in a long term experiment of 15 years with large-scale lysimeters. Examining the leachate quality over a long period, the leaching of organic matter and heavy metals from landfill with incineration residue was observed during the initial period of the experiment. Though the incineration residue contains a small amount of organic matter, the possibility of leaching higher concentration of BOD₅, COD_Mn and other compounds during the initial period of the experiment was confirmed. Although the incineration residue contains high amounts of heavy metals, the concentrations did not exceed regulation standards over a long period. The majority of the heavy metals remained in the incineration residue (in the lysimeter). In addition, part of the heavy metal was trapped and accumulated in the scale that formed in the lysimeters. The proper treatment and controlling of leachate during the initial period is important for landfills with incineration residue.

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CaCl₂, NaCl, and other byproducts generated by waste treatment are landfilled as fly ash. Cl⁻ dissolved in leachate is discharged to public water, which has an impact on agriculture and marine resources. Therefore, concentrate and dry salt (hereafter referred to as by-product salt) are generated by desalting treatment facilities. This study was conducted on the possibility of recycling by-product salt as a disinfection material for wastewater treatment by generating NaClO and other compounds from it by electrolysis. As a result, a mixture liquid (hereafter referred to as eco hypochlorite) of NaClO and KClO with an effective chlorine concentration of above 5,000 mg / L was generated by a diaphragm-free electrolysis method with the concentration of salt water at 3 % and Ca²^＋ at 30 mg / L. In the sterilization capacity test of eco hypochlorite, it was confirmed that its capacity is equal to or greater than that of industrial NaClO. According to the feasibility study, when the amount of dried by-product salt is more than 0.5 t / day (equivalent to the amount of by-product salt generated from a city of 100,000 people) and recycled as disinfection material in a sewage treatment facility, it will provide economic merits to both the source (final disposal site) and the user (sewage).

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Recently, woody biomass power generation in Japan has been increasing under a feed-in tariff (FIT) scheme in Japan. Knowing the amount of woody biomass ash generated during power generation is increasing in importance, considering both proper waste treatment and effective resource use. In this study, the amount of woody biomass ash was estimated through a literature survey of 6 kinds of woody biomass fuels and various information on 191 power generation facilities burning woody biomass and palm kernel shell (PKS) that are registered under the FIT scheme. By this estimation, 26 million to 30 million tons of woody biomass will be burned to produce 35 million MWh of electricity, and 170 thousand to 810 thousand tons of woody biomass ash will be generated in fiscal 2023. 63% of the ash will be from PKS. The maximum estimated amount is almost 20% of that of municipal solid waste incineration residue. Therefore, the establishment of effective recycling and proper treatment methods for woody biomass ash is needed as soon as possible.

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Coastal landfill site stabilization is expected to be accelerated by the removal of the finer particle fraction (d<0.425 mm), which contains a large amount of pollutants and lowers the permeability of landfilled solid waste layers, from municipal solid waste incineration bottom ash. This study focused on a method of removing the finer particle fraction by putting incineration bottom ash into an open channel (open channel classification) and a verification test was conducted. In addition, development of a numerical model that can reproduce the motion of incineration bottom ash particles in an open channel was attempted. As a result, it was clarified that about 60% of the finer particle fraction could be removed by open channel classification. It was also made clear that the settling velocity of incineration bottom ash is slower than the theoretical settling velocity assuming a sphere; the settling velocity of incineration bottom ash of 0.425mm particle size is about 80% of the theoretical value. Moreover, it was demonstrated that the motion of incineration bottom ash particles can be reproduced by a numerical model using a Reynolds-averaged Navier-Stokes equation and an equation of motion by appropriately setting the degree of sphere for each particle size in incineration bottom ash.

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The RoHS Directive was established in the EU in 2002 to restrict the use of certain hazardous substances in electrical and electronic equipment as a means of promoting more effective management. It strongly encourages measures to be put in place at the production stage, with focusing on risks at the disposal stage in the presence of various chemical substances. With regard to environmental impact of waste treatment, the directive is expected to contribute to reducing the impact in developing countries and other countries and ultimately to reduce the harm caused in the recycling process by preventing the diffusion of hazardous substances contained within the product.
　The Japan Chemical Substances Control Law takes into account the lifecycle of chemical substances. The Law regulates the use of targeted chemicals which are selected under a prioritization process according to their toxicity and the amounts they emit into the environment with consideration of degradability. The promotion of more effective management is expected as substances that hold greater risk to the environment and disposal workers in the waste management field are also given priority like the RoHS directive.

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Shaking of cultures was carried out to examine the maximum P elution concentration of night soil sludge incineration ash and the effective factor for concentration using the technique of bacterial leaching (BL) with sulfur-oxidizing bacteria. The highest P elution concentration in incineration ashes from 14 facilities was 5,700 mg-P L⁻¹ with an addition rate of 6 %. The incineration ashes with high P elution concentrations had high addition rates, P elution yields and P concentrations. The ashes with low P elution concentrations had extremely low values. In the ashes with high elution yields, instead of Fe-based flocculant, Al-based was used, and it was thought that phosphate was contained more as Al(PO₄) than Ca₉Al(PO₄)₇. Discriminant analysis to distinguish high-concentration elutions (≧3000 mg-P L⁻¹) from low-concentrated elutions (<3000 mg-P L^-1) was carried out. The significant discriminant function was obtained with a 92.6 % discriminant rate for high-concentration elutions. It was revealed that the higher the P in the elution from ash samples, the less Ca, K and Al they contained. The phosphorus elution unit cost of BL elution, calculated from use agent cost, was from 1/4 to 1/3 that of chemical elution by sulfuric acid.

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This study focuses on the consumer experience of e-commerce reuse, a concept which has become popular in recent years. The paper analyzes the influence of the e-commerce reuse experience on clothing disposal behaviors by consumers. The results/analysis of an online survey targeting females aged 15-49 revealed that consumers prefer e-commerce reuse to conventional reuse routes, such as second-hand stores, if they have the opportunity to experience sales using e-commerce reuse. Even if a consumer does not currently use e-commerce reuse modes, wasteful behavior surrounding unnecessary clothing disposal can be prevented. At the same time, reuse behavior using a second-hand store gets promoted if a consumer has taken up e-commerce reuse in the past. These results indicate that through the experience of e-commerce reuse, consumers are learning about this re-use method and better recognize the reusability of clothing they no longer need.

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In order to improve the recovery rate of potassium (K) from swine wastewater in the simultaneous recovery of nitrogen (N), phosphorus (P) and potassium, a recovery experiment was carried out with a pH range from 10 to 11. Further, to evaluate biological treatment of the solution after recovery, semi-batch treatment with activated sludge was investigated. It was found that with the conditions of pH 10.5, P/(N＋K) of 1.3, and Mg/P of 1.2 in molar ratio, N and K could be recovered at a rate of over 80 % and P concentration could be kept under the discharge standard. With these conditions, an N recovery rate of 81 % was reached, much higher than the previous recovery rate of 67 % and indicating improvement of the K recovery rate. An N recovery rate of 89 % was reached, so a high recovery rate was maintained. Furthermore, the net P recovery rate was 39-79 %, indicating that more P could be recovered than was added. TOC could be removed from the solution after recovery at a pH of 10.5, the same as from swine wastewater, without neutralizing the solution. No biological denitrification was required to meet the discharge standard for nitrogen.

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This nationwide investigation aimed to collect data through surveys conducted by local governments on food loss from garbage composition and to discern general trends and behaviors relating to food waste using comparison analyses. To verify results, a waste composition survey was also carried out to inspect and clarify certain qualifying points. Findings show that in the case of avoidable food waste from daily households, the direct disposal rate decreases according to population density while as for leftovers, there was little correlation with population density. On the other hand, in the case of direct disposal from commercial activities, results suggested waste proportions decrease in urban areas of higher population density but such a correlation is lessened in the case of households. The composition survey data also revealed that data availability on the quantity of leftovers is limited and that expansion of the survey ― for commercial systems in particular ― is necessary. Lastly, the paper gives indications of certain problems found in the operation of waste composition surveys for food loss, namely the separation method of leftovers and preparation residues, weighing of the packaging, and treatment of “excessive removal”.

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Material recycling is a meaningful way to reduce environmental impacts and costs simultaneously. Mitsubishi Electric Corporation has realized “closed-loop recycling from household appliances to household appliances” in which polypropylene (PP), polystyrene (PS) and acrylonitrile-butadiene-styrene (ABS) are collected from a mixture of residual plastics contained in discarded household appliances and sorted for recycling.
　In this research, the dark-colored recycled PP and the light-colored recycled PP were separated from the mixed-colored recycled PP using a color sorter, and the recycled PP was polished using a plastic polisher to remove surface contamination. As the number of surface polishings of the recycled PP increased, the heat life became longer, so a clear correlation was seen between the heat life and the amount of contamination. From the relationship between the amount of residual copper in the recycled PP and the heat life, it is necessary to set the amount of residual copper in light-colored recycled PP to less than 3 ppm in order to obtain a heat resistance comparable to that of virgin PP without adding a metal deactivator.

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In order to enforce sustainable waste management, it is crucial to grasp the actual cost impacts of waste collection, transportation, and disposal methods. In much of the literature analyzing waste management costs, the use of econometric analysis is not sufficient to understand each sector of waste collection, transport, intermediate disposal, and final disposal, nor to compare the differences between municipalities that independently conduct waste management and inter-municipalities that cooperate with other municipalities in them. This paper analyzes management costs for municipal solid waste, considering each sector of waste management and the differences between municipalities and inter-municipalities. The results of the study show that economies of scale are observed in all sectors of waste collection, transport, intermediate disposal, and final disposal. This was found particularly remarkable in intermediate disposal and final disposal. The paper also clarifies that the average cost of waste collection and transport is lower in inter-municipalities, and the economies of scale are larger in inter-municipalities than in municipalities that collect independently. In addition, it points out the possibility of reducing outsource costs as a means of reducing costs in inter-municipalities.

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Cardboard box composting has been widely recommended by many local governments and practiced by many citizens to reduce household solid waste disposal and to make organic fertilizers from kitchen food waste in Japan. However, little scientific information is available on box compost. In this study, we evaluated the quality of box compost by measuring the changes in compost temperature during composting and determining the mass balance, physicochemical properties, and biological aspects, including the germination index and hygiene-indicator bacteria. During composting for 90 days, 61.6kg of kitchen food waste and 11.0 kg of rice bran were added to a box. The temperature of the compost was in a range of 36.8 - 67.1 °C (55.3 ℃ on average). On a raw weight basis, 66.6 % of the total load (returned compost as basal material, kitchen food waste, and rice bran) was reduced by decomposition and evaporation. On a dry weight basis, 46.2 % of the total input was decomposed. The cation exchange capacity of the product was 69.8 cmolckg⁻¹. Plant germination and bacterial examinations showed the products were free of harmful germs and plant growth inhibitors. These results indicate that box composting can significantly reduce the amount of household waste and produce sanitary organic fertilizer.

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Many local governments in Japan are known to hold public idea competitions as a means of raising awareness about the issue of waste reduction. The study outlined in this paper tests whether the public majority opinion can be effectively determined by text-mining all submissions of a competition sponsored by Gunma Prefecture, rather than focusing only on the winning submissions. The analysis focuses on elementary school students who comprised over 80% of the applicants. Results indicate that nouns such as ‘paper’, ‘cloth’, ‘PET bottles’, and ‘skin (vegetable peelings)’ appeared frequently in the submissions among this age group. This suggests there is a strong awareness about garbage and which of the 3Rs (reduce, reuse, recycling) should be promoted with regard to each different waste group. Furthermore, the mined text revealed that the judging system was likely to award a high score to the minority of submissions that were linguistically more original than others. The methodology used in this study to demonstrate that it is possible to understand and analyze majority public opinion on an issue may offer a way to add value to the conventional ideas behind holding such competitions.

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