Characteristics of landfill gas components

Due to the high moisture content of the waste and the temperature inside the bed reaching up to 50°C, the landfill gas is characterized by high water vapor saturation. Relative humidity of landfill gas is usually near the saturation point. 

Among aromatic compounds, the ones that appear in the highest concentrations are benzene and its derivatives, toluene and xylenes. The presence of toluene was found in biogas immediately after the deposit of waste, due to high volatility of this compound. The aromatics content in biogas increases with the intensification of anaerobic conditions (Parker et al. 2002). According to Allen et al. (1997), the concentrations of aromatic compounds in landfill gas range from 94 to 1906 mg m .  

Cyclic organic compounds alicychc cycloalkanes and cycloalkenes and aromatic hydrocarbons constitute a group of gases which are very toxic. Cycloalkenes (e.g. limonene, a—pinene) predominate the concentration of cycloalkanes (e.g. cyclobutane, cyclohexane). The concentration of the cycloalkanes in the gas formed in landfills in the United Kingdom ranged from 80 to 487 mg m (Allen et al. 1997). 

The highest concentration of hydrogen sulphide in biogas is noted in the early stages of waste decomposition. The decrease in the concentration of H S is most likely caused by the precipitation of the sulphides in the reaction with heavy metals (such as Cu and Fe) or their oxides, which are present in the deposited material. Sulphides as water insoluble compounds remain in the mass of waste (Parker et al. 2002). The organic sulfur compounds in the greatest concentrations in landfill gas are dimethyl sulphide (DMS), carbon disulphide, methyl mercaptan, dimethyl disulphide (DMDS) at the concentrations of 0.007-180 mg m 0.09-61.6 mg m 0.084-17.94 mg m 0.0124-0.942 mg m respectively (Kim et al. 2005, Shin et al. 2002). 

The range of concentrations of selected volatile organic compounds found in landfill gas are presented in Table 2.3. 

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