Greenhouse gas emissions trend in old landfill, Malaysia

Abstract

According to Malaysia National Greenhouse Gas Inventory report, a total of 67,532 Gg CO2eq of methane was emitted in year 2011. The highest methane emission was from the solid waste disposal sites, which accounted for about 46 % from the total which remained the largest source throughout the time series period. Proper gas monitoring was not done in most landfills which the emission trend, pattern and impact remains untold. Understanding methane and carbon dioxide concentration trends will positively help in spatial variation of landfill emissions in Malaysia. Therefore, this research highlighted two objectives. First, to test feasibility of prototype sampling tube to collect gas samples. Second, to analyze gas samples using micro gas chromatography and evaluate emission trend in Taman Beringin Closed Landfill. Using proper technique, the sampling tube was employed manually at the gas well which located at the highest point of the hill. Three samples collected everyday between 12 to 2 p.m. for 1 mth. Result shows an interesting trend recorded for methane and carbon dioxide. Though the concentrations vary for each day, it highlighted certain range in the graph. Methane ranging between 550,000 ppm to 850,000 ppm and carbon dioxide ranging between 400,000 ppm to 620,000 ppm. It is high concentration emitted everyday considering maximum recommended safe methane concentration for workers during an 8-h period is 1,000 ppm (0.1 %) as stated by National Institute for Occupational Safety and Health's (NIOSH) and Occupational Safety and Health Administration (OSHA) has set a Permissible Exposure Limit (PEL) for carbon dioxide of 5,000 ppm by volume (0.5 % concentration). In addition, T-test was done to statistically shows the significant different between samples collected and the permissible standard. Result shows significant high concentration emitted compared to the safe level allowable in ambient air. This study helps addressing gap in landfills greenhouse emission monitoring in Malaysia.