Landfill gas (LFG) emissions, consisting mainly of CO2 and CH4, include low amounts of non-methane volatile organic compounds (VOCs), having a significant impact on air quality. Despite most of LFG is generally recovered by the implemented gas collection and extraction systems, a relevant amount remains uncollected and escapes to the atmosphere. Landfill cover soils act as full-scale bioreactors able to reduce diffuse CH4 emissions, while their effective role in mitigating VOCs emissions is still debated. In this study, a simulated landfill experiment was conducted to investigate the degradation processes affecting VOCs. A handmade LFG, generated by the anaerobic digestion process of food waste in a dedicated labscale digester, was forced to flow up through a typical section of a final landfill cover soil (H = 60 cm, d = 15 cm) consisting of silty sand. The experiment lasted for 23 days. Series of gas samples were periodically collected each 10 cm along the soil column and from the digester, and were consequently analyzed in terms of VOCs, main components, and 13C/12C ratios of CH4 and CO2. Overall, LFGrelated components (CO2, CH4, and H2) and VOC concentrations decreased over time and toward the upper part of the soil column due to the progressive exhaustion of anaerobic digestion process and air dilution, respectively. CH4 was efficiently degraded at oxidizing conditions as also confirmed by the distribution of δ13C-CH4 and δ13C-CO2 values along the soil profile. Alkanes resulted more recalcitrant than aromatics, terpenes, and Osubstituted compounds. Alkylated aromatic and branched alkane compounds were the most degraded among those of their respective organic groups. Cyclics, alkenes, and halogenated compounds were mainly found in the headspace of the digester. These preliminary data showed that this kind of labscale experiments could represent a reliable approach to deeply investigate the behavior of VOCs in landfill cover soils under controlled conditions.
Attenuation of Volatile Organic Compounds (VOCs) in a simulated landfill cover soil system / Antonio Randazzo, Stefania Venturi, Francesca Zorzi, Gabriele Bicocchi, Fabio Tatàno, Franco Tassi. - ELETTRONICO. - (2022), pp. 0-0. (Intervento presentato al convegno 1st Congress of Società Geochimica Italiana “From theoretical to applied geochemistry”).
Attenuation of Volatile Organic Compounds (VOCs) in a simulated landfill cover soil system
Antonio Randazzo;Stefania Venturi;Francesca Zorzi;Franco Tassi
2022
Abstract
Landfill gas (LFG) emissions, consisting mainly of CO2 and CH4, include low amounts of non-methane volatile organic compounds (VOCs), having a significant impact on air quality. Despite most of LFG is generally recovered by the implemented gas collection and extraction systems, a relevant amount remains uncollected and escapes to the atmosphere. Landfill cover soils act as full-scale bioreactors able to reduce diffuse CH4 emissions, while their effective role in mitigating VOCs emissions is still debated. In this study, a simulated landfill experiment was conducted to investigate the degradation processes affecting VOCs. A handmade LFG, generated by the anaerobic digestion process of food waste in a dedicated labscale digester, was forced to flow up through a typical section of a final landfill cover soil (H = 60 cm, d = 15 cm) consisting of silty sand. The experiment lasted for 23 days. Series of gas samples were periodically collected each 10 cm along the soil column and from the digester, and were consequently analyzed in terms of VOCs, main components, and 13C/12C ratios of CH4 and CO2. Overall, LFGrelated components (CO2, CH4, and H2) and VOC concentrations decreased over time and toward the upper part of the soil column due to the progressive exhaustion of anaerobic digestion process and air dilution, respectively. CH4 was efficiently degraded at oxidizing conditions as also confirmed by the distribution of δ13C-CH4 and δ13C-CO2 values along the soil profile. Alkanes resulted more recalcitrant than aromatics, terpenes, and Osubstituted compounds. Alkylated aromatic and branched alkane compounds were the most degraded among those of their respective organic groups. Cyclics, alkenes, and halogenated compounds were mainly found in the headspace of the digester. These preliminary data showed that this kind of labscale experiments could represent a reliable approach to deeply investigate the behavior of VOCs in landfill cover soils under controlled conditions.
I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
