This research delves into the implementation of homogenization techniques through crane operations over an extended period in waste pits at general waste incineration facilities. It focuses on utilization of the stoker method for this scenario. Homogenization, achieved through the agitation or scattering of waste materials within the pits, has emerged as a pivotal factor for ensuring the stabilization of the combustion processes within the furnace. The resultant combustion stability plays a dual role: facilitating a steady flow of main steam for power generation and curbing maintenance expenses.
　Given the intricate challenges associated with conducting prolonged real-world validations within general waste incineration facilities, we opted for a discrete-event system simulation as a substitute for using tangible equipment. This approach serves to confirm the efficacy of homogenization effects.
　The procedures of waste agitation and scattering were meticulously simulated and scrutinized over a 31-day span. The findings unveiled that scattering enabled the controlled introduction of homogenized waste into the furnace, yielding results closely aligned with the established Target calorific value. In contrast, when we compared the crane operations, scattering demanded a greater number of tasks tied to homogenization and waste transfer, aiming to mitigate disparities in elevation. This comparative analysis offered valuable insights into optimizing crane operational efficiency.

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Since the mid-2010s, plastic resource circulation has entered a new phase due to the increase in marine plastics and other factors, with many countries now taking actions to address this issue. In this paper, we compare the responses of two non-EU developed countries, the UK and Japan, from the perspective of EPR (Extended Producer Responsibility). We also discuss the differences and meanings surrounding both of their responses. The research method used classifies the changes seen after the introduction of new policies in both countries, looking into three aspects: physical, financial, and informational. Each of these is then analyzed in four stages: collection, recycling, appropriate treatment, and product design. The results show clear differences between the two countries: The UK has been strengthening producer responsibility through a combination of physical, financial, and informational policy measures. By contrast, Japan has not adopted a financial approach, but focuses on voluntary efforts, with the goal that each actor in the product chain (production, distribution/sales, use, and recycling) will work together to fulfill their respective roles. Future studies are needed to examine the causes behind the different responses between the two, as well as to demonstrate the policy effects.

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This study surveyed collection performances for PET bottles, cans, and other wastes using smart recycling bins (SmaGO^® FORCETECH Co.). 13 recycling bins were positioned along Route 423 from Harajuku Station to Omotesando Station. Waste collection performances for these bins were recorded during the period from July 7 to August 5, 2022. According to pedestrian flow data near the recycling bins (KDDI Location analyzer^®, KDDI Co.), per capita wastes collected in a day were measured and used for waste collection modeling. Waste collection data shows log-normality for PET bottles, cans, and other wastes, which was significantly influenced by factors such as weather, temperature, and specific day. Although a model based on log-normal distribution including distance to recycling bins as the model variable failed to predict waste collection performances, a modified model that includes logarithmic distance and effects of weather, temperature, and day was found to appropriately predict PET bottle and can collection performances. Even the modified model, however, failed to make appropriate predictions for other types of waste collections. This suggests that psychological behavior mechanisms regarding waste drop-off at recycling bins is clearly different in comparison to PET bottles, cans, and other wastes.

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This study examines the impact of a household waste fee policy for general waste which has been implemented in Akita City since July 2012. Results of the SDID (Synthetic Difference-in-differences) alone confirmed that the introduction of this fee-based waste management policy reduced per-capita waste emissions by approximately 35 kg. This is equivalent to a reduction of approximately 12.4 %, suggesting the effectiveness of Akita City’s policy of charging for household waste.  Furthermore, it was also shown that implementation of this policy reduced household waste emissions by approximately 4.3 g per each 1 yen owed on waste fees in Akita City.

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Mercury emissions from municipal waste incinerators necessitate mitigation measures in accordance with the Minamata Convention on mercury.
 A dedicated experimental apparatus was devised to continuously measure gaseous mercury concentrations, specifically modeling the filtration process within municipal waste incinerators using a bag filter with sprayed activated carbon (AC). This apparatus was used to assess the efficiency of main AC formulations in the market for gaseous mercury removal by comparing concentrations at the front and back of the adsorbent column. We confirmed the increased effectiveness and stability of AC impregnated with calcium chloride and iron (III) chloride, particularly under high temperatures (200 ℃).
 Subsequent, investigations focused on evaluating the impact of three coexistent gases (hydrogen chloride, sulfur dioxide, and water vapor) in exhaust emissions on gaseous mercury removal. We confirmed hydrogen chloride as the most influential factor among these gases. Finally, we fabricated six types of powdered AC, each impregnated with distinct agents (three chloride compounds, hydrogen chloride, sulfuric acid, and phosphoric acid), and systematically assessed their efficiency in gaseous mercury removal. The result unequivocally demonstrates the superior efficacy of hydrogen chloride as the most effective impregnating agent among the six formulations.

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Focusing on the influence of waste activated sludge ozonation, batch and continuous experiments were conducted to verify the synergistic effects of the anaerobic co-digestion of sewage sludge and food waste (FW). The results of the batch experiments confirmed that biogas production exceeded the predicted value by co-digestion. In the continuous experiments, 10%, 20%, and 30% of FW by weight were added to untreated and ozonated systems. In all cases, the biogas production increased efficiently. The net biogas production of FW was calculated to be higher than 918 NmL/g-VS for the 10% and 20% feedings. On the other hand, with 30% FW feeding, the net biogas production of FW in the untreated system dropped significantly to 665 NmL/g-VS, while that in the ozonated system remained as high as 1036 NmL/g-VS. Therefore, it was clear that the ozonated system was superior to the untreated system under high organic loadings. Furthermore, the dewatering test results suggested that ozonated system are less likely to increase the weight of dewatered sludge even when FW is added.

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This study uses panel data taken from Japanese prefectures over a period of 21 years (2000−2020) to analyze the impact of industrial waste taxation on the amount of industrial waste being generated and its final disposal. Looking at the types of taxation, the study takes into consideration points such as economic situation, regulations on transporting industrial waste originating in other prefectures, and the effects over time. Results showed that no significant reduction effect was observed in the amount of industrial waste generated, for all taxation types. As for final disposal, not considering the effect of time, the reduction effect was observed for all taxation types when only industrial waste generated in the prefecture was targeted. Reduction effects were also observed in the special levy by final disposal contractors and intermediate disposal with incinerators and final disposal contractors when waste originating from other prefectures was included. In contrast, considering the effect of time, these reduction effects were canceled out by the effect of time in all taxation types. In addition, the results of staggered DID analysis, which can remove possible biases due to multiple intervention timing, showed that continuously significant reduction effects during some periods were observed only in prefectures where taxation of the special levy had been introduced by final disposal contractors in 2003.

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The authors aim to develop a numerical analysis method that can appropriately assess the impact on the surrounding environment when designing disposal sites for excavated rock that contains naturally occurring arsenic. We investigated the elution behavior of arsenic in embankments made using tunnel excavation rock, and we confirmed the permeability characteristics of the embankments and the elution characteristics of the excavated rock. In addition, we conducted unsaturated column tests using excavated rock taken from this embankment, and, by formulating the elution rate of the advection-dispersion equation based on the results, the amount of arsenic elution was reproduced with a certain degree of accuracy. This time, we conducted unsaturated column tests under multiple conditions with different particle sizes and water spray rates, narrowed down the parameters related to arsenic elution, and improved the elution model. In addition, the environment within the embankment may change to a reducing environment over time, and the amount of arsenic eluted may increase. Therefore, we conducted unsaturated column tests using a reducing agent solution to confirm the effect on arsenic elution characteristics and considered incorporating this into the elution model.

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In 2019, the Japanese government established The Resource Circulation Strategy for Plastics, which set multiple numerical targets relating to the reduction and recycling of plastic waste. In order to implement policies to effectively achieve the goals outlined in the Strategy, the actual situation of plastic waste generation needed to first be clarified. In Japan, however, there has not been sufficient research done to estimate the amounts of plastic waste being generated at regional levels. This study estimates the total generation of plastic waste for all municipalities in Japan based on the results of waste composition surveys in incineration facilities and amounts of recycled plastics. Based on data from this estimation, we analyze the regional factors that influence per capita generation amounts. As a result, significant relations were found between household expenditures on processed food and the value added in the accommodation and food service industries. This suggests that overall emissions may be higher than previously estimated based on material flow analysis.

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In the Japanese market, green-branded toothbrushes are less common compared to Europe, where various types are readily available. Therefore, this study aimed to investigate differences in exposure to and purchase of green-branded toothbrushes among consumers and in environmental consciousness and behavior across Japan, Bulgaria, and France. The study was conducted through a questionnaire survey which revealed that in Japan, points such as daily use; prior experience; and exposure to green-branded toothbrushes all scored lower than that of Bulgaria and France. Moreover, Japanese consumers tended to prioritize price when choosing a toothbrush, showing less consideration for sustainability. Results suggested that greater efforts, aimed specifically at the character of Japanese consumers should be made in Japan in order to promote environmental marketing initiatives and give rise to heightend eco-friendly changes in consumer behavior.

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