EMISSION CHARACTERISTICS OF GREENHOUSE GASES (CH4·N2O) CONSIDERING SEASONAL FLUCTUATIONS FROM JOHKASOU

The emissions of greenhouse gases (CH4, N2O) from Johkasou were monitored at three sites for over a year, and the seasonal variabilities were analyzed. Based on the annual average emissions, about 90% of CH4 was emitted from the anaerobic tank and about 80% of N2O was emitted from the aerobic tank. CH4 emissions increased when the amount of influent DO into the anaerobic tank decreased. It is caused that the amount of CH4 production increases due to the progress of anaerobic treatment at the bottom of the anaerobic treatment tank. On the other hand, N2O emissions increased when BOD and NH4-N in the tank increased as the water temperature rise period. It is caused that nitrification reaction (nitrite oxidation) in the aerobic tank does not proceed promptly due to elution of BOD and NH4-N from the stored sludge in the Johkasou.