| |
|---|---|
 (341Kb)
|
28,770,000 Yen (for FY1997;9,331,000 Yen)
The study was done to develop the control technologies of the emission of methane(CH4) and nitrous(N2O) oxide from a wastewater treatment plant. Beneficial use of sludge digestion gas was also studied. The emission of methane and nitrous oxide through the wastewater treatment processes was observed. The control measures to reduce the emission, however, could not be fully developed. The annual methane emission from the whole wastewater treatment plants in Japan was estimated as around 7,500 tons.
The incineration of sludge by a fluidized method brought relatively high emission rate of nitrous oxide. The increase in combusting temperature to up around 800¡Á850¡î was found to reduce about 30 % of the nitrous oxide emission from the sludge incineration compared to the emission under the current operational condition. The effects of the higher temperature operation on The green-house effect as well as the cost and durability of an incinerator were investigated and it was concluded that the global warming potential(GWP) could be towed and the durability and construction cost would be little affected.
A simulation model to predict the excess digestion gas was developed. According to the model, the seasonal variation of the excess gas could be predicted as a function of the site parameters. The storage and transport methods of the excess gas was studied, and the adsorbing method was found effective and applicable to small wastewater treatment plants.
Green-House Effect, Methane, Nitrous Oxide, Wastewater Treatment, Sludge Incineration, Sludge Digestion