| Summary: | 碩士 === 國立高雄第一科技大學 === 環境與安全衛生工程研究所 === 101 === Currently, a large number of greenhouse gases in the atmosphere increased, causing global warming and climate changing, and thus lead to disaster. How to reduce emissions of greenhouse gases (especially CO2), is a very important direction which people in all walks of life work hard and research on to. Constructed wetland is one of the main fashion people using in treating waste water. As a result, the constructed wetland’s effectiveness of CO2 reduction is a worth discussion subject. In this research, to establish an assessing model is used to measurs the CO2 emission of the constructed wetland. The model makes use of the state data of the constructed wetland, establishing formula to evaluate the effectiveness of the reduction of CO2 emission.
This study takes 18 constructed wetlands in Taiwan, setting two decades, exploring in three directions:
Firstly, Using the water purification function of the constructed wetland analog design wastewater treatment plant, and then, with point of view of life cycle assessment (LCA), to estimate the CO2 emissions of the wastewater treatment plant, as the CO2 reduction of the constructed wetland functions①.
Secondly, the CO2 emissions of building materials in the initial construction②.
Thirdly, the CO2 sequestration of a quatic plants③.
And then, using Excel spreadsheet to conduct data-estimating, embedded formula, add up (①-②+③) was the constructed wetland total CO2 reduction.
The study first took the constructed wetlands in Pingtung Linluo to establish operational processes, and then calculated the other 17 constructed wetlands, aggregated data to establish the chart. Comparing the average CO2 reduction of the 18 constructed wetlands and the simulated wastewater treatment plant, constructed wetland increased by 485 tons of CO2 emissions in the first year. In the second year, constructed wetlands have not yet reached the effectiveness of reduction, but the CO2 emissions have already lower than the wastewater treatment plant of 24 tons. Until the third years, the CO2 reduction effect of constructed wetlands started generating, however, the wastewater treatment plant continued to discharge CO2, increase with years. In 18 constructed wetlands, the effectiveness of CO2 reduction began to play in an average of a period of one year to four years. Overall, the effect of CO2 reduction can be achieved in three years. The study has shown that, hydraulic loading and artificial wetlands CO2 reduction effectiveness of time, have an obvious logarithmic correlation, that is, the greater the hydraulic loading, the shorter reduction time (years).
To organize the LCA method estimated results by Wen-Sheng Ou, the CO2 emissions of wetland are 36.48 kg/m2. Stock of CO2 absorption on aquatic plants, processing the results of Cui-Huan Chen research institution are approximately 162 ton/ha/year. 18 wetlands in this study, 10 years proper operation can totally reduce about 51,000 metric tons CO2, Average of 11.66 metric tons of CO2 emissions per person per year, can absorb CO2 emissions of some 4,370 persons.
During the operation, we also found that the longer constructed wetland operating time is, the more significant CO2 reduction effect is. As a result, not only continuous artificial wetland management can improve pollution reduction capabilities, but it can also avoid landconducive which caused by poor wetland vegetation. In the long run, elaborating the effective of CO2 reduction. In short, although constructed wetlands need time brewing with proper management, the effectiveness of CO2 reduction is much more promising than the wastewater treatment plant.
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