Wool textile waste is composed mainly of protein that can be hydrolyzed to generate amino acids. For the purpose of recycling, wool waste is subjected to pressurized hot water treatment to convert the protein to water-soluble protein, followed by hydrolysis of the water-soluble protein using cation exchange resins as catalysts. However, the wool proteins often undergo excessive decomposition during the pressurized hot water treatment. The present study examined methods for suppressing the excessive decomposition and optimizing conditions for hydrolysis of the water-soluble proteins. The results indicate that the excessive decomposition can be suppressed by shortening the retention time using a semi-flow reactor. In addition, a high ion-exchange capacity and an increase in the resin density in the reaction vessel effectively promoted hydrolysis.
Using a laser exhaust gas analyzer installed at an incinerator outlet, the authors measured O2, H2O, and CO2 concentrations in exhaust gases. The amounts of oxidation reactions of C and H in the waste and the H2O evaporation amount were calculated from the measurement results. The amount of heat generated by the waste combustion was calculated. Furthermore, the heating value of the waste was calculated. The generated calorific value showed good agreement with the estimate based on the heat balance around the incinerator, indicating high estimation accuracy. Moreover, comparison with the analysis result showing a lower measured heating value of waste, revealing large error in conventional heating value estimation. Furthermore, because the measured heat generated by exhaust gas components can be predicted in advance of the boiler evaporation amount, combustion can be stabilized when applied to combustion control. Benefits such as increased electrical generation were confirmed from reduced fluctuation of boiler evaporation.
This paper estimates the effects of unit-based pricing on municipal solid waste in Japan from data generated by a municipal-level panel created to examine the municipal mergers known as “the big merger of Heisei.” Previous studies had used data from a pre-merger panel due to the fact that data regarding the merged municipalities had been lost following the finalization of the mergers. In order to observe the current effects of unit-based pricing on municipal solid waste after the period of the mergers, this study has created panel data using hypothetical data from merged municipalities. It was created in order to incorporate certain data that was generated before the mergers took place. Considering the effects of municipal mergers, empirical results from the created panel data show that both simple unit-pricing and two-tiered pricing programs decreased the amount of municipal solid waste after being introduced. Moreover, the restraining effects continued over a long period of time. The restraining effects are being underestimated because the effects of these municipal mergers are not being fully taken into consideration. Results also show the mergers that were a part of ‘the big merger of Heisei’ have increased the amount of municipal solid waste.
The prevention of damage to super-heater tubes due to high-temperature corrosion caused by various components in MSW is a key to the wider dissemination of waste power generation. To suppress corrosion by using additives is one type of effective method. In these methods, however, it is important to minimize the amounts of additives used, because of increasing additive costs and ash treatment amounts. In this study, for the purpose of selecting additives with high capabilities, several additives were compared and evaluated using laboratory tests that simulated the environment of an actual stoker-type waste incinerator boiler. As a result, the suppression effect of natural zeolite was found to be the highest among the tested samples. Natural zeolite was mixed in deposit ash collected from an actual plant and tested, and the suppression effect was observed to be between 5 and 25 mass-%. It was also found that zeolite captures gaseous corrosive components and acid gases. The former suggests the possibility of an even greater suppression effect when used in actual plants. The latter shows the possibility of being applicable as an acid gas treatment agent.
Reverse logistics (RL) is an important component of both corporate strategies and social systems. Corporations are expected to get more deeply involved in RL as their environmental responsibilities increase. In this paper, we review previous studies from Japan and other countries to uncover the fact that research on Japanese reverse logistics (JRL) has been inadequate, quantitatively and qualitatively, when compared with RL studies around the world. Through our study, we also found out some of the reasons behind this deficiency in accumulatedresearch : a practical need appears to be lacking, which stems from Japan′s institutional historical perspectives, the difficulties in conducting seeds study due to its unique legalities related to waste and recycling among other issues. Moreover, we generated suggestions for developing the Japanese RL (JRL) system and related research fields. One such example is to embrace the management concept to the same extent as RL systems in other countries have, as a means of expanding its scope and establishing an international RL system based on Japanese geographical characteristics. We also extracted core publications to be followed in order to build up more efficient RL research that will require the application of social network analysis in Japan for the future.
This study focuses on the location decisions of private disposal sites for industrial waste. Using a unique dataset of industrial waste disposal sites from 1977 to 2012 in Japan and an econometric approach, we investigate trends in site selection for private industrial waste disposal locations. We also investigate the characteristics of communities that tend to locate disposal sites. Our results show that the number of disposal sites being constructed decreased after the Japanese waste disposal law revision was implemented in 1997 and 1998. In addition, we found that the introduction of an industrial waste tax and trade restrictions on industrial waste shipments tend to decrease the number construction of sites for industrial disposal.
Generally, bio-wastes have high moisture. However, they have high caloric values if they are dried. Composting is one of the traditional recycling methods for them. It uses aerobic biological reactions. The high temperature that results from self-heat generation and the aeration for oxygen supply make the product dryer than the original. This phenomenon shows that effective drying can be achieved if this process is controlled well. However, it is not easy to find optimum operational conditions, because this process is very complicated with many environmental and operational factors. In this research, a simulation program that describes this process was developed. By comparing simulated results with the results of drying experiments, the validity of the simulation program is discussed.
A numerical simulation including a municipal solid waste (MSW) combustion model and an NOX prediction model with a detailed chemical kinetics mechanism for a stoker-type MSW incinerator was developed. In this model, the waste bed layer on stoker grates was expressed as groups of waste particles using the Euler-Lagrange approach. In order to reduce the computational load, the NOX concentration was calculated using a decoupled detailed chemical (DDC) model. The model was validated by comparison with a combustion test in a small-scale incinerator. The calculation results could express the distribution of temperature, the flow pattern in the incinerator and the CO concentration at the outlet. In order to conduct NOX prediction, at least 8 species should be selected as pollutant species in the DDC model. Furthermore, accounting for 13 pollutant species gave better accuracy. These results showed the usefulness of the model.