Volatile organic compounds (VOCs) in solid waste landfill cover soil: Chemical and isotopic composition vs. degradation processes

A Randazzo; M Asensio-Ramos; G V Melián; S Venturi; E Padrón; P A Hernández; N M Pérez; F Tassi

doi:10.1016/j.scitotenv.2020.138326

Volatile organic compounds (VOCs) in solid waste landfill cover soil: Chemical and isotopic composition vs. degradation processes

Sci Total Environ. 2020 Jul 15:726:138326. doi: 10.1016/j.scitotenv.2020.138326. Epub 2020 Apr 8.

Authors

A Randazzo¹, M Asensio-Ramos², G V Melián³, S Venturi⁴, E Padrón⁵, P A Hernández⁵, N M Pérez⁵, F Tassi⁴

Affiliations

¹ Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Firenze, Italy. Electronic address: antonio.randazzo@unifi.it.
² Instituto Volcanológico de Canarias (INVOLCAN), 38320 La Laguna, Tenerife, Canary Islands, Spain.
³ Instituto Volcanológico de Canarias (INVOLCAN), 38320 La Laguna, Tenerife, Canary Islands, Spain; Instituto Tecnológico y de Energías Renovables (ITER), 38600 Granadilla de Abona, Tenerife, Canary Islands, Spain.
⁴ Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121 Firenze, Italy; Institute of Geosciences and Earth Resources (IGG), National Research Council of Italy (CNR), Via G. La Pira 4, 50121 Firenze, Italy.
⁵ Instituto Volcanológico de Canarias (INVOLCAN), 38320 La Laguna, Tenerife, Canary Islands, Spain; Instituto Tecnológico y de Energías Renovables (ITER), 38600 Granadilla de Abona, Tenerife, Canary Islands, Spain; Agencia Insular de la Energía de Tenerife (AIET), 38600 Granadilla de Abona, Tenerife, Canary Islands, Spain.

PMID: 32305753
DOI: 10.1016/j.scitotenv.2020.138326

Abstract

Landfills for solid waste disposal release to the atmosphere a large variety of volatile organic compounds (VOCs). Bacterial activity in landfill cover soils can play an important role in mitigating VOC emission. In order to evaluate the effects of degradation processes and characterize VOCs composition in landfill cover soil, gases from 60 sites and along 7 vertical profiles within the cover soil were collected for chemical and isotopic analysis at two undifferentiated urban solid waste disposal sites in Spain: (i) Pinto (Madrid) and (ii) Zurita (Fuerteventura, Canary Islands). The CO₂/CH₄ ratios and δ¹³C-CO₂ and δ¹³C-CH₄ values were controlled by either oxidation or reduction processes of landfill gas (LFG). VOCs were dominated by aromatics, alkanes and O-substituted compounds, with minor cyclics, terpenes, halogenated and S-substituted compounds. Degradation processes, depending on both (i) waste age and (ii) velocity of the uprising biogas through the soil cover, caused (i) an increase of degradation products (e.g., CO₂, O-substituted compounds) and (ii) a decrease of degradable components (e.g., CH₄, alkanes, alkylated aromatics, cyclic and S-substituted compounds). Terpenes, halogenated compounds, phenol and furans were unaffected by degradation processes and only depended on waste composition. These results highlight the fundamental role played by microbial activity in mitigating atmospheric emissions of VOCs from landfills. Nevertheless, the recalcitrant behaviour shown by compounds hazardous for health and environment remarks the importance of a correct landfill management that has to be carried out for years after the waste disposal activity is completed, since LFG emissions can persist for long time.

Keywords: Biogas; Interstitial soil gas; Landfill; VOCs.