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( Taira Ikeda ),( Yasumasa Tojo ),( Takayuki Matsuo ),( Toshihiko Matsuto ) 한국폐기물자원순환학회(구 한국폐기물학회) 2017 한국폐기물자원순환학회 심포지움 Vol.2017 No.1
Three sanitary landfills have been constructed in the West Bank, Palestine, by international cooperation from several years ago, in order to discontinue the open dumping that had been done up to now. Because of very dry climate feature, management of leachate generated from these landfills mainly relies on evaporation. However, as the side effect, serious odor problem became serious (especially, ammonia odor emitted from leachate pond). Further, because leachate more than the planned amount was generated, it overflows to outside of sites. In order to solve these problems, water treatment facility is needed. However, treated water is going to be used for irrigation because there is no river for discharging effluent. Although the introduction of a reverse osmosis membrane treatment facility (RO) is proposed at the site, leachate generated ate these sites is highly contaminated. Since the sustainability of RO treatment is greatly affected by the quality of the influent, it is necessary to consider pretreatment. Thus, the purpose of this study was set to propose a pretreatment process that can be taken at the site. Because acquisition of the real leachate generated at the site was difficult, artificially simulated leachate was created by using digestion sludge obtained from methane fermentation facility. Some reagents were added to assimilate to inorganic matter concentration of leachate generated at the site. Regarding organic matter concentration, both high BOD/COD and low BOD/COD were confirmed in leachate data of two sites. Artificially simulated leachate which had a high BOD/COD value was created by using some low molecular organic compounds. On the other hand, it was impossible to create simulated leachate which has a low BOD/COD value because high molecular organic compounds used (humic acid, tanic acid) did not dissolve well in digestion sludge. In this study, two physicochemical treatment methods, coagulation sedimentation with polyferric sulfate and fenton treatment were examined, targeted to reduce organic matter concentration. In every experiment, TOC was measured as an index of organic matter concentration. Regarding coagulation sedimentation, TOC removal rate increased to about 25% as the amount of polyferric sulfate added increased, but it did not rise any further. On the other hand, although fenton treatment to simulated leachate caused extremely severe foaming, TOC removal rate was less than 10%. Both results were not effective for pretreatment because organic matter composition of simulated leachate used was mainly composed of low molecular organic compounds. As a consequence, two treatment methods used in this study are ineffective against leachate which has high concentration of low molecular organic compounds. Because local leachate is likely to contain many of these, it is necessary to consider a biological treatment process.
( Junya Machida ),( Toshihiko Matsuto ),( Takayuki Matsuo ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
Even after landfill is closed, biological degradation process and, production of leachate and landfill gas, continues for several decades or longer. In Japan, semi-aerobic structure is recommended for supply air into waste layer by natural convection. The heat generated by aerobic microorganism raise the temperature of waste, then the difference of temperature between waste and the atmosphere drives air to flow into waste layer from the end of leachate collection pipe. In the previous research by authors, there was found the positive correlation between gas velocity and the temperature at exit of gas vent, so the relation can be used to evaluate the soundness of natural aeration function of semi-aerobic landfill. In this study, data of gas velocity and temperature was collected from 26 landfills from which gas flow is detected. Additional measurement was also asked to increase data on the relation between gas velocity and temperature only. As a result, only 7 landfills were considered sound semi-aerobic landfill.
Simulation on the Drying Process of the Waste in Landfill under Arid Climate
( Kanta Okamoto ),( Yasumasa Tojo ),( Takayuki Matsuo ),( Toshihiko Matsuto ) 한국폐기물자원순환학회(구 한국폐기물학회) 2016 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2016 No.-
In arid climate, evaporation from the ground surface is superior to precipitation. Consequently, in landfill under arid climate, the solid waste disposed of is thought to be gradually drying. The drying of waste causes an obstacle in biodegradation of organic matter and results in delay of the stabilization of the waste. Therefore, for the proper landfill management, it is important to clarify how the drying process of the waste progresses; the drying speed of the waste and the reaching depth of the drying in landfill. In this study, long-term drying process of the waste in landfill under arid climate was estimated by simulation with numerical model. The numerical model consists of the coupled equations of mass and energy balance equations for water, water vapor and heat in porous media, and was solved simultaneously using the COMSOL Multiphysics software that is based on the finite element method. Moreover, in order to validate the numerical model, the authors performed column experiments, and then compared their results with the ones in simulation of which condition coincided with experimental condition. Since both results coincided well, full scale simulation was carried out by using the numerical model created. In the simulation, a depth of landfill was set to 10 meters and the simulation was run for 20 years. The simulation results demonstrated that the waste layer in the landfill dried to the total depth of 2.7 meters in 20 years. In the first 1 year, the waste layer dried rapidly from the surface, and then the depth reached to 1.3 meters, which is about 50% of total drying depth. But, the drying speed gradually decreased. During 4 years after the first 1 year, the drying progressed only 0.7 meters, further. It can be concluded that the drying speed of the waste decreases as the drying of the waste layer progresses. Based on the results of this study, it was found that the waste layer close to the surface dries easily, and the waste layer below a certain depth keeps wet condition. This implies that biodegradation of organic matter existing below a certain depth keeps progressing even if the landfill is located in arid area.