In this study, we grasped the transition of the properties of the treated products in the manufacturing process of organic fertilizers by fermentation treatment mainly using wastewater treatment sludge as a raw material.

We also tried to propose a maturity index that can be reflected in the processing operation.

In addition to the previously reported data, we grasped the change in the degree of maturity by the fluorescence pattern by three-dimensional fluorescence measurement called fluorescence fingerprint.

As a result, it was considered that the determination of the degree of maturity based on the fluorescence pattern could be an index of the degree of maturity that can be used for on-site fermentation process management because the analysis time is completed in about several minutes.

On the other hand, in order to standardize this method, it was necessary to optimize the water extraction conditions.

Methane fermentation is a method of decomposing sewage sludge, livestock waste, and industrial wastewater by methane-producing bacteria under anaerobic conditions to produce biogas, and to stabilize and reduce the volume of waste. In Japan, methane fermentation systems have not been widely used yet due to the high cost associated with the large size of methane fermentation systems and the difficulty of collecting, transporting, and managing biomass. In order to solve the problems of large scale methane fermentation systems, small scale methane fermentation systems have been developing. The systems are affordable so the installation is relatively easy. The problems of collection, transportation, and management by collaborating with livestock farmers who discharge livestock-based circulating resources have also been solved these years. However, since the methane fermentation system for small-scale is affordable system, the methane fermentation must improve the efficiency. Therefore, in this study, we aimed to increase the biogas production amount by adding activated carbon to the methane fermenter.

In order to perform effective bio-drying, multi layer static pile forced aration reactor is introduced. Simulation program to simulate bio-drying process using this reactor was developed. Results of simulation showed that this reactor with periodical layer change, can give more effective drying performance than traditional static pile forced aeration reactor without layer change.

Outline of simulation program for bio-drying using static pile forced aeration reactor is introduced. Results of simulation with this program are compared with the results of bio-drying experiments under ambient temperature. Validity of this simulation is discussed.

Various samples of food wastes as carbon sources for mesophilic methane fermentation were examined. The concentration of methane in formation gas was in the range of 50 – 70 %. On the other hand, the concentration of hydrogen sulfide formation varied greatly depending on the type of food waste. According to the results of microbial flora analyses and pH measurements, the compositions of the digestive liquids were stable for the changes of the carbon sources.

We investigated the causes of inhibition events in the biogas plant receiving household and commercial food wastes. The data on daily input waste information (product name, volume, etc.) and biogas generation for about 7 years, and analytical values (pH, etc.) for each tank for 5 years were obtained. We analyzed one of the inhibition events as an example. First, the three months prior to the event was divided into two periods: the two weeks immediately prior to the inhibition (Period II) and the rest of Period I. Then, the amount of input waste and the amount of input COD for both periods were compared statistically to find which wastes were put to the fermenter significantly during Period II. As a result, the three types of wastes, such as the powdered soup, the gummies, and the cheese, were extracted as inhibitor candidates. The analytical values showed pH decrease in the fermenter for the six days centered at the inhibition. From these findings, it seems that the three types of wastes that were uniquely added during Period II caused fermentation inhibition.

Electrostatic separation, which is a step used in plastic sorting, is a sorting method that utilizes the difference in charge polarity as generated when different types of plastic are rub together or touch each other. In the electrostatic separation, the charged state of plastic fluctuates according to various conditions such as the temperature and humidity, the magnitude of the applied voltage, and the input material composition ratio, which affects recovery rate. In this work, we investigated the method to observe the fall distribution of triboelectric plastics in real time. As a method, the state of the plastic falling was photographed with high-speed camera, and the fall distribution was quantified by image processing. As a result of the experiment, we clarified that the fall distribution created by image processing has a high accuracy of 1.5 pt compared to the actual measurement. By applying this method to electrostatic separation, we expect to rase recovery rate.

Most of MSW incineration ash has been disposed of in landfills in Japan although valuable metals, such as Au, Ag, and Cu are contained in the ash. In particular, grate sifting ash (GA), which is dropped into a gap of a grate in a stoker-type of incinerator, has been reported as remarkable metal resource. However, few facilities separately collect GA from bottom ash (BA) as well as few studies reported the variation of elemental contents in GA. This study investigated annual variation of elemental contents in GA and BA to evaluate separation effect of GA. GA and BA were collected once a month for one year, and each sample was sorted into metal particles and ash powder after milling and sieving. To identify twenty-five elemental contents by ICP-OES/MS metal particles and ash powder were subject to digestion with aquq regia; additionally, alkali fusion was applied to ash powder. As a result, a large proportion of metal particles was found in GA and the annual Cu contents of GA were in the range of ores or higher than that. So, GA would be utilized as a metal resources.

Survey results of waste sampling from waste bunkers regularly conducted in MSW incinerators include unavoidable fluctuations due to various difficulties encountered in combustible waste sampling and analyzing processes.

This study examined annual representative eight constituent mass percentages and LCVs of fed-waste from waste sample surveys mainly conducted during FY2012-19 in MSW incinerators in Tokyo Special Ward District, quantifying the sizes of two kinds of deviations contained in their values by using estimated annual mean LCVs and referential LCVs.

Solid waste is pyrolyzed and pyrolyzed residue is combusted completely in the waste layer formed on the bottom of Vertical combustor. The layer helps waste to combust and protect the grate from overheat, and furthermore it works to disperse the primary air uniformly. We tried to measure the residence time of two kinds of cylindrical tracers with different thickness. As a result, we found that the residence time was 16 to 21hours and its of lighter tracers was longer. It is considered that the powder and granular residue will stay more than 21hours. By this investigation we confirmed the residence time of waste is sufficient to combust completely.

Clinical waste discharged from medical institutions is put into incinerator while staying sealed combustible container (without opening), due to its hazardousness (e.g. infectiousness.) Therefore, it is difficult to obtain the properties (e.g. heating value and elemental composition) of the clinical waste. In this study, the properties of the clinical waste were estimated by considering the mass balance in a waste incineration plant. The lower heating value (LHV) of clinical waste was estimated to 28000 kJ/kg-wet by subtracting the heating value derived from industrial waste from the total heating value generated by the incinerator that co-burns clinical waste and industrial waste. The composition of chlorine and ash of clinical waste were estimated by the same method; by subtracting chlorine and ash derived from industrial waste from the total amount of those released from the incinerator. To obtain the properties of clinical waste itself (not including the container), the contribution of the containers (plastic containers and cardboard boxes) were estimated. The LHV of clinical waste itself (not including the container) was estimated to 29600 kJ/kg-wet.

At the Kitanagoya Plant in Nagoya City, which introduced a shaft-furnace type gasification and melting system for municipal solid waste treatment, we worked to reduce CO₂ emissions by using biomass fuel produced from sewage sludge. A part of the sewage sludge fuel is put into the melting furnace in a granular state, and the remaining part is crushed by a crusher and then blown into the combustion chamber. As a result, we were able to reduce the amount of coke used by about 0.10 kg and the amount of city gas used by about 0.011 Nm³ and improve the amount of power generated by about 1.28 kWh per kg of sewage sludge fuel. Although the hydrogen chloride concentration of the combustion exhaust gas increased, the exhaust gas composition at the stack was well below the regulation value. The total amount of CO₂ emission reduction per ton of sewage sludge fuel used was -1.11t, and when 50kg of sewage sludge fuel was used per ton of waste, the amount of CO₂ emission reduction per ton of waste incineration was estimated to be -55.4kg.

In recent years, as the operation of Waste to Energy plants has been facing a chronic shortage of human resources and stricter environmental regulations, the need for advanced operations and maintenance has been increasing. NIPPON STEEL ENGINEERING CO., LTD. (NSE) is working toward the realization of "Think Plant^®", a self-sustaining Waste to Energy plant that can detect abnormalities and make optimal operational decisions on its own by utilizing big data and AI with our proprietary real-time on-site support system "PlantPAD^®" and cloud-based operation support system "DS Cloud^®". NSE has already achieved results such as "upgrading Advanced Shaft Furnace operation" and "next-generation predictive maintenance”. PlantPAD^® has three functions: (1) remote monitoring, (2) maintenance support, and (3) plant-wide operation monitoring. These functions contribute greatly to remote support of operations and reduction of inspection workload on sites. NSE has already implemented remote support for four commissioning projects in Japan, and planning to apply the system to commissioning and operation support not only in Japan but also overseas.

In the effective control of biomass-burning power generation plant, understanding the combustion behavior of the inputted biomass is important. It is particularly desired to prevent or at least reduce the risk of melting and clogging of ash within the furnace to minimize their effect on the plant's operation under such troubles. Major type of furnaces employed in the woody biomass burning power generation is fluidized bed combustor, and travelling stoker furnace is also employed in some cases. For the future demands which may require to use not commonly-used biomasses as raw materials for co-combustion of woody biomass power generation, it is necessary to have a laboratory-scale incinerator to grasp the effect of co-combustion of different types of biomasses to find the conditions in which the stable, clogging-free combustion can be achieved. We therefore designed and prepared a laboratory-scale incinerator simulating a stoker incinerator using tubular reactor and applied it to biomass burning tests. This paper presents the details of newly prepared apparatus and the results of the burning test.

To achieve carbon neutrality in 2050, CO₂ reduction technology by fixing (CCS) and using (CCU) CO₂ is drawing attention. At our company, we focused on the property that heavy metals are fixed to fly ash, adsorbed and insolubilized by the carbonization reaction in which fly ash absorbs / immobilizes CO₂. A demonstration test of carbonation technology was conducted on an actual scale plant to investigate absorption / immobilization CO₂ generated at the plant. In the demonstration test, (1) promotion of effective use of CO₂ by carbonation and (2) reduction effect of heavy metals treatment chemical usage were verified. Lab-scale carbonation tests were also conducted at multiple facilities to clarify the effects of furnace type and ash composition on carbonation.We report the test results on these different scales.

In recent years, the demands for the stable operation and the cost reduction related to the CO₂ emission control in the incineration facilities were increased. On the other hand, there was a serious shortage of the highly experienced operators in the facilities. This made the remote monitoring support system has become more indispensable than ever.Based on this situation, we put the effort by constructing the centralized management system of the operating status of the multiple incinerators. The remote monitoring /operation support systems utilizing the cloud system were built, the operation data was collected and processed altogether, and finally the obtained know-how was expanded and utilized for optimizing of the other incineration facilities. This effort was made by a joint research with Yokohama City. The proposed operating guidance involving the machine learning were tested and the stability of steam generation, one of the evaluation criteria, was confirmed. The operating guidance may be able to demonstrate performance equal to or better than normal operating by verification of guidance operating using machine learning. In the future, the prediction technique involving the control system will be performed to improve the highly automated operation which can be the solution for the shortage of human resource and improvement of the operation quality.

Higher efficiency in waste to energy plants, as decentralized power suppliers, has been required. A waste to energy plant, Hatsukaichi energy clean center, has been operated with 450 C× 6MPa boiler and heat supplying to a local industry since April 2019. This plant was designed based on our previous corrosion test of SUS310S tubes. In this study, corrosion speed of super-heated tubes after 19 months and energy efficiency are reported.

This study focuses on the partitioning of heavy metals (Pb, Cd, Cr, As, Cu) between bottom ash and fly ash in a waste incineration plant. For the plant that incinerate clinical waste and industrial waste (incineration amount is about 50 tons per day), the heavy metal content in the bottom ash and the fly ash were measured. Then the partitioning ratio was calculated from the heavy metal content and the amount of the ashes generated. The result showed that 2.1 kg of Pb was discharged per day, and about 50% of the Pb was partitioned into fly ash. Nearly 90% of Cd was partitioned into fly ash (although its concentration is low and uncertainty is high). Almost all part of Cr (2.6 kg per day) and Cu (39 kg per day) remained in the bottom ash. Although the content of As was too low to consider the partitioning ratio, most of As seemed to remain in the bottom ash. A weak correlation was found between the contents of Pb and Cu in fly ash, suggesting that the origins of the two may be the same.

From March 2020, incineration residue which is redioactively contaminated by the accident of Fukushima DAiichi has been treated in thermal treatment facilities. Its main product is molten slag and is planned to be reuse, while its by-product is highly radioactive fly ash and its treatment is the subject of various studies. In the previous report, mass balance of some cases of trestment was calculated and compared. In this report, unit trestment cost of treatment and unit disposal cost of products were assumed and their cost was calculated.

As a result, the total trestment and disposal cost of volume reduction process for incineration residue including thermal treatmet was around 310 billion yen and the treatment and disposal cost for fly ash was 50 to 80 billion yen.