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The behaviour of carbon dioxide (CO2) and methane (CH4) emissions at the surface and below the soil cover in an industrial waste landfill under anaerobic operating conditions was evaluated for six years. This landfill contained gypsum board waste and incineration ash – a practice currently allowed because of a change in Japanese regulations. The CO2 and CH4 fluxes decreased throughout the six years of the survey. Almost all of the survey points exhibited fractions of CH4 in landfill gas emissions of <0.5 (mean values: 0.0–0.1 [surface], 0.0–0.3 [subsurface]) under anaerobic conditions. In addition, a relatively high first-order reaction rate constant for the landfill gas emissions (0.3 year−1) was observed. The landfill leachate showed a relatively high sulphate ion (SO42–) concentration, although other environmental conditions, such as the pH, oxidation–reduction potential and ammonium concentration, were not at levels that could have inhibited CH4 production. These findings suggest that the low fractions could have been related to the lower amounts of CH4 generation caused by competition between methanogens and sulphate-reducing bacteria (SRB). Therefore, SRB could play a major role in the degradation of organic carbon in the landfill. [ABSTRACT FROM AUTHOR]

Adsorption parameters such as the distribution coefficient are required to predict the release behavior of contaminants using advection-dispersion models. However, for potentially contaminant-releasing materials (PCMs) such as dredged sludge and coal ash, these parameters cannot be obtained by conventional adsorption tests. This study developed a method to determine adsorption parameters for PCMs from a set of batch tests conducted in parallel as a function of the liquid-solid ratio (LS-parallel test). This LS-parallel test was performed on sandy soil derived from marine sediment using liquid-solid ratios from 1 to 300 L/kg. The water-contact time was also changed from 10 min to 28 d to elucidate the kinetics or equilibrium of contaminants released from the sample. Adsorption parameters were successfully obtained if the substance was under adsorption control. A column percolation test was performed to confirm the effectiveness of the obtained parameters. Good agreements were observed for SO42− and B, but discrepancies remained for other substances such as F− and As suggesting that improvements are necessary in both the LS-parallel test procedure and the advection-dispersion model. [ABSTRACT FROM AUTHOR]