Enhancement by leachate with biological additive on methane oxidation in landfill cover soil

• Main Authors: Chung-Hao Lin, 林鍾豪
• Other Authors: 廖文彬
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/83024566569402678837

碩士 === 國立中興大學 === 環境工程學系所 === 94 === The aim of this research was to investigate the potential use of the landfill leachate with biological additive to control the water content of landfill cover soil, and to stimulate the methanotrophic activity at the same time. This approach will enhance the methane oxidation in landfill cover soil. Therefore, the methane emission to atmosphere at landfills will decrease for the mitigation of the greenhouse effects. The experiments conducted in this study included both batch and column tests. The results of the batch experiment show that the methane oxidation was not obvious in the dry soil at a water content of 10%, that methane oxidation was on the low side when the soil was close to the saturation level at 35%, and that the water content most suitable for the methane oxidation should lie in the range of 15%-25%. Besides, the methane oxidation rates under the suitable water content was leachate with bio-additive > leachate> deionized water. At the best water contents of 25%, the maximum methane oxidation rates was 879, 605, and 321 nmole(g of dry soil)-1hr-1, respectively. The continuation of the methane oxidation was leachate with bio-additive > leachate> deionized water. At the best water contents of 25%, the average methane oxidation rates was 629, 375 and156 nmole (g of dry soil) -1 hr-1, respectively. The trends in the change of methane oxidation rates suggest that the role of the bio-agent could have enhanced the mineralization of organic matter in the leachate. That resulted in a shorter period of the time that the organic matter had suppressed the methane oxidation. In this experiment, the ammonium nitrogen in the leachate stimulated the activity of methanotrophs, and improved the rates of methane oxidation. Although the most probable number of methanotrophs increased via incubation, but had not absolute correlation with the oxidative rate of methane. The results of the column experiment shows that after suitable moisture irrigation (water content close to 15%) the methane oxidation rate was higher than before irrigation. Like the results of batch experiment, both the bio-agent and the leachate had the function to enhance methane oxidation. But after excessive moisture irrigation (water content higher than 25%), the methane-oxidation ability of the column decreased; and the bio-agent and leachate had no longer the function to enhance the methane oxidation. Gas concentration profiles indicated that after a period of moisture irrigation, the methane oxidation took place in about 10cm depth, compared with 10-40cm before irrigation. The data of biological parameters indicated that the bio-additive and leachate had the function to enhance methane oxidation which is the same as in the batch experiment. It can be assumed that oxygen is one of the most important limiting factors for the methane oxidation in landfill cover soil. An excessive irrigation caused the blocking of soil pores which limited the influx of oxygen. The shortage of oxygen in soil caused the decline of methane oxidation. It is concluded that both the bio-additive and leachate had the function to enhance methane oxidation when oxygen was not a limiting factor in landfill cover soil.