In this study, to secure remaining volume in landfill site and establish cycle of useful metal, the iron waste contained in municipal solid waste incineration bottom ash was subdivided by its origin. Municipal solid waste incineration bottom ash contained about 10%-20% iron waste. Iron waste was classified to 83 types of origin, and the top 11 types in weight accounted for over 90% of the total weight. It is possible to collect the iron waste before incineration by the separate waste collection system. Many screws were observed in 2055 per ton bottom ash. It accounted for 59.7% of the total quantity. But screws are used for connecting parts of things, so it is difficult to separate them before incineration. Although the iron concentration depended on each type, most of them were around 40-50%. For recycling, the type of rod has a high Cu content which is harm to the property of steel. It is necessary to consider another recycling way.

Stabilization through insolubilization treatment using chelates, etc . is mandatory for the landfill disposal of incinerated fly ash, but it has been pointed out that organic chelates can have effects on water treatment, such as nitrification inhibition, and the amount added is sometimes excessive as well. Therefore, we focused on the insolubilization of heavy metals through carbonation treatment to reduce the amount of chemicals added. Targeting fly ash from industrial waste collected multiple times from the same facility on different collection dates, we investigated changes in its elemental composition and the insolubilization of Pb through carbonation.

Regarding elemental composition, there was little variation in Na, K, Cl, or Ca content depending on the sampling date. The Pb content, however, varied greatly, suggesting that the fluctuation of the Pb content in the received waste had an effect. From the results of carbonation treatment, it was inferred that the decrease in the pH of the fly ash was affected by the amount of Ca reacting with CO2 in the fly ash. The elution concentration of Pb varied greatly within the collected fly ash, but the elution of Pb after carbonation was reduced to 80 to 99.7% compared to untreated cases.

Bar screens are seen at canals in tropical Asian urban cities, which are installed to collect solid wastes in canals. During heavy rainfall, solid wastes are transported to bar screens and accumulated there and clog it. This cause reduction of drainage function of canals and results in flooding. However, no sufficient budget for periodical cleaning of canals is expected. Then, it is important to maintain drainage function with least cost by finding common characteristics of solid wastes that is trapped at bar screen at the very beginning and/or cause large reduction of drainage function. We represented the generation of clogging at a bar screen in a canal by accumulated solid wastes by using Smoothed Particle Hydrodynamics method and Bullet Physics. We found that solid wastes with larger dimensions than opening of the bar screen and larger density than that of water tend to be the cause of clogging. On the other hand, solid wastes which tend to rotate easily passed through the bar screen.

In order to identify metal-enriched zone in landfills and utilize valuable metals as urban mining, the resistivity and induced polarization measurements have been carried out as a nondestructive three-dimensional prospecting. The authors conducted some experiments for further improvement of the induced polarization measurement. In the experiments, we measured resistivity and IP parameters in the samples: samples consisting of a mixture of iron sulfide and sand. The measurements were conducted in the cases of samples with different iron sulfide ratio (0%,5%,10%,15%), different water content (8%,12%,16%,20%,24%), different salt concentrations in pore water (0.05,0.1,0.2,0.3,0.5 mol/L). The results show there can be specific effects of water content and salt concentrations on the electrical parameters: resistivity and IP parameters.

The PRB method is implemented as one of the measures to prevent groundwater pollution, and the results of water quality surveys at observation wells are often used to confirm the purification effect. However, it is difficult to know the effect of the adsorption layer in a wide range only with a well. For that reason, in this study, we considered the application of resistivity monitoring to study the effect of the adsorption layer. It is considered that the change in resistivity can be used to easily and non-destructively grasp the outline of the change in underground properties, and further the effect of the purification layer can be known.

First, in a column experiment, while flowing the contaminated solution in the column, the specific resistance of the column and the electric conductivity of the outflow solution were measured and examined. As a result, it is considered that Cd adsorption by the adsorption layer (activated carbon) was confirmed, the specific resistance of the column increased, and the electrical conductivity of the effluent solution decreased.

Next, in the soil tank experiment, the PRB layer was created and simulated groundwater was reproduced to monitor the effect of the adsorption layer by resistivity.

As operation period of landfill sites is long, renewal or improvement of strogate structure, liner systems and leachate treatment facility is necessary. However, actual situation on aging of facilities is not clear. Rencent precipitation has been changed, which results in increase of inner storage of leachate within waste layers. This study conducted a questionnaire survey for landfill sites for MSW to clarify problems

around the long-term operation of landfill sites and countermeasures. Results sugested that proper stock management of landfill sites, such as periodical checking and improvement, is important, and that countermeasures for recent change in precipitation are required.

In TAISEICORPORATION,We pushed forward technology development for the efficiency of construction management duties about Waterproof in the disposal site construction. We report the summary, the inspection situation and the result about "the construction management tool which I applied ICT" that inspection by the true construction was completed and "the Waterproof sheet thermal adhesion region simple detachment testing equipment" which inspected the effectiveness in an indoor examination.

There continue to be reports of unpleasant odor and death due to the generation of hydrogen sulfide resulting from waste disposal in landfills. A potential solution was examined in which industrial waste could be used as an inhibitor of hydrogen sulfide generation in landfills. Fundamental experiments were conducted on about 5000 tons of iron oxide sludge produced as industrial waste by companies in the prefecture in order to determine whether iron oxide sludge has an inhibiting effect on hydrogen sulfide. Hydrogen sulfide generation was reduced to less than the detection limit (0.05 ppm) when 10 g or more of iron oxide sludge was added to a solution of 50 g of plaster powder, 200 ml of demineralized water, and 1.0 ml of liquid preculture, which together meet the conditions for hydrogen sulfide generation. In addition, when hydrogen sulfide moved through iron oxide sludge with a packing density of 1.09 g/cm³, adsorption of over 50% of the hydrogen sulfide was observed. Through these fundamental experiments, iron oxide sludge was found to have potential applications as an inhibitor of hydrogen sulfide generation.

Nitrogen removal by anaerobic ammonia oxidation has been developed for leachate treatment because it is energy saving and low-cost technology for low BOD/N wastewater rather than conventional recycling nitification-denitrification process. In this report, the operational report of new nitrogen removal process “DENIMOX®” which has been in operation form August 2018 at final treatment site for industrial waste in Japan are shown. DENIMOX® is consists of partial nitritation process and anaerobic ammonia oxidation process.

The operational report from August 2018 to June 2020 shows that the process has been stable to the change of operational condition such as change of NH₄-N concentration or increase of quantity of leachate. This result shows that anaerobic ammonia oxidation can remove nitrogen stably in the case of leachate treatment.

In recent years, Vietnam has become one of the most developed countries in Southeast Asia. Although the volume of construction and demolition waste (CDW) is also increasing rapidly with the rapid development of the economy and industry and its recycling rate is only 1-2%.Promoting proper treatment and disposal has become one of the most critical issues. Currently, most of the CDWs are sludge and construction residues. Not only soil but also general waste is dumped in the landfill. The landfill site does not have a good management system for receiving waste.Therefore, there is a risk of receiving hazardous waste. Therefore, by appropriate standard operating procedures (SOP), the CDW landfill.It is essential to understand the environmental pollution potential of the site and the surrounding environment. It is also essential to understand the potential for CDW to be used as a recycled material.In order to use these products, quality-controlled and safe products are required, and the safety of these products must be confirmed. It is necessary.The purpose of this paper is to confirm the environmental impact study for the vicinity of the construction waste landfill and to prepare an appropriate SOP.

Constructed wetlands are widely known to save energy, to be low cost, to have environmental friendliness and to provide sustainability for the wastewater treatment system. They have been used for treating various types of wastewater around the world including domestic, agricultural, industrial wastewaters and various runoff waters. There is little information concerning the treatment of high salinity landfill leachate with constructed wetlands. We studied the treating performance in the treatment of high salinity of landfill leachate and the effect of the evapotranspiration (ET) on the treating performance using the two stage of hybrid constructed wetland. The obtained results from this study were as follows:The average of the treating efficiencies in BOD, COD, TN and NH4-N were in 93.8, 59.8, 35.1 and 45.7%, respectively The constructed wetlands had a high ET rate.The load reduction rates calculated from water budget were 5 to 7% higher than the removal rates calculated from the concentration between inflow and outflow. The ET provided a large influence on the treating performance.

It has been reported that carbonation with CO₂ has the effect of reducing the Pb elution of the bottom ash of general waste in stabilization treatment. Also, the recovery of valuable metals by physical separation via air tables, etc., is performed as well, mainly in Europe. In this study, we investigated the influence of the combined treatment of carbonation and separation (air tables and eddy currents) on the elution characteristics of heavy metals for the purpose of recycling the bottom ash into civil engineering materials. For each sample of treated ash, we measured the Pb, Cr(Ⅵ), and B concentrations of the test solutions obtained by elution testing and testing in a small indoor lysimeter. As a result, the reduction of Pb elution and the increase of Cr(Ⅵ) elution through carbonation were confirmed, but no clear difference was observed in the elution of Pb or Cr(Ⅵ) through separation. On the other hand, it was clarified that the concentrations of B elution in the solution and in the leachate were lower in carbonation after separation than in the reverse order. Also, no clear difference was found in Pb, Cr(Ⅵ), or B elution in either due to the difference in the separation method.

The hazardous waste landfill site is required to appropriately store the harmful substances contained in the hazardous waste and prevent the discharge of them to the outside, semipermanently. From a long-term perspective, the risk of structural deterioration and disasters can be considered, but in such an event, the release of harmful substances must be avoided. A previous study investigating the waste actually accepted at the hazardous waste landfill site found that refractory bricks used in the melting furnace was major waste accepted. This is because the leaching concentration of hexavalent chromium exceeds the criterion. Therefore, in this study, we conducted a weathering acceleration experiment on refractory bricks from which hexavalent chromium leaches out, and examined the effect of environmental conditions in the hazardous waste landfill site on the dissolution behavior of chromium. As a result, it was confirmed that under humid conditions, the leaching of hexavalent chromium was significantly reduced.

Since fly ash is a specially controlled general waste, it is insolubilized mainly to treat organic chelating agents to prevent the elution of Pb, etc. However, when fly ash stabilized by an organic chelating agent is landfilled, the residual chelate increases the nitrogen and COD concentrations in the leachate, which interferes with the leachate treatment. Therefore, a new fly ash stabilization method that replaces the organic chelate is required. So far, we have proposed that the environmental load can be reduced by changing to an inorganic stabilizer. However, as compared with the organic chelating agent, the inorganic stabilizer is added in a large amount, which may be economically disadvantageous. In order to reduce the amount of inorganic phosphorus-based drug added, we have conducted research and development to reduce the addition rate by adjusting pH and CaCO3 using commercial hydrochloric acid. We will report the results of a scaled up simulated landfill experiment.

Microplastics (MPs) are those that have a size of 5 mm or less, and their existence has been confirmed in sea areas around the world. It is known that fine plastics called microplastic fibers (MFs) are generated from chemical fiber products, and it is also reported that more than 80% of MPs found on the coast were MFs. MFs have been detected in benthic organisms, shellfish, fish, etc., and there is concern that organisms ingesting MFs that have adsorbed harmful substances may affect higher consumers through the food chain.

Looking at the field of civil engineering, the non-woven fabrics that are used in large quantities in weed-proof sheets, light-shielding protective mats, etc. are made of chemical fibers and are often installed outdoors. It is considered that the non-woven fabric installed outdoors is deteriorated by ultraviolet rays and MFs fall out and flow into rivers and oceans due to rainfall. Since the research on the evaluation of the generation potential of MFs is not sufficient, in this research, the quantification method of the MFs which slipped out due to the deterioration of the nonwoven fabric was examined.

Chlorine in waste combustion has been studied in the fields of HCl generation, metal chlorides formation, and synthesis of organic chlorinated compounds, i.e. dioxins. Those chemical reactions are likely governed by reactive Cl₂; however, Cl₂ occurence in flue gas had hardly been reported, because of the difficulty of Cl₂ quantification. An new practical method to determine HCl and Cl₂ separately was proposed. Based on US EPA Method 26A which collected HCl in a acidic solution and Cl₂ in alkaline solution, the new method empolyed a wet coiled tube for acidic HCl trapping; afterwards, Cl₂ was reduced with H₂O₂ solution in a large vessel. The large volume brought a prolonge retention time(several decades seconds) for reaction of Cl₂ dissolution and reduction; moreover, both gas and mist after Cl₂ trapping are colleted in glass fiber filter. HCl was completely partitioned to the wet coiled tube without leaking to the vessel. 10% of Cl₂ was captured at the coiled tube and the rest was evenly partitioned to vessel and filter. The results suggests Cl₂ collection needs a certain prolonged retention time; in addition, the mist involves considerable chloride ion generated from Cl₂.