2003 年 36 巻 4 号 p. 449-457
Recently, the control of non-CO2 greenhouse gases has attracted interest as a way to prevent global warming. Several research studies on the development and assessment of technologies to control CH4 and N2O emissions by human activities are under way. In the wastewater treatment field, the development of anoxic/oxic processes and the introduction of bacteria that effectively prevent N2O emission have been studied. Moreover, it has been clarified that eco engineering technologies such as artificial wetlands and soil trench systems are very effective, especially in developing countries. As for landfill disposal, CH4 oxidation by cover soil and the use of CH4 gas as a source of energy have very effectively reduced the emission of CH4. In the combustion field, it was clarified that N2O emissions vary according to the structure of each combustor and its operational conditions. And research and development concerning combustors and their optimum operational conditions are under way. Concerning automobile sources, characteristics of N2O emission from gasoline fueled vehicles installed with a catalyst were examined. Three way catalysts and so on are now being developed. Chemical industries, especially adipic acid production are another non-negligible N2O source, and cracking process related countermeasures have been applied. CH4 and N2O emissions from agricultural land are strongly dependent on the oxidation-reduction environment of soil and on fertilization, so they must be suitably managed. The development and management of ruminants feeding and suitable treatment of animal waste are very important ways to control CH4 and N2O from livestock. Research projects to improve the CH4 and N2O emission-absorption inventory, and to estimate the suitable technologies to control CH4 and N2O emission are now in progress. Combining these projects appropriately will develop technologies and systems and will make great contributions to the control of the emission of GHGs and to global warming.
