Methane concentration and bacterial communities' dynamics during the anoxic desulfurization of landfill biogas under diverse nitrate sources and hydraulic residence times. Issue 2 (April 2023)

• Record Type: Journal Article
• Authors: González-Cortés, J.J.; Quijano, G.; Ramírez, M.; Cantero, D.
• Is Part Of: Journal of environmental chemical engineering. Volume 11:Issue 2(2023)
• Publication Date: 2023-04
• Subjects: Anoxic desulfurization -- Biogas -- Methane -- Renewable energy; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2023.109285
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Landfill biogas contains certain amounts of H2 S that must be removed in order to prevent both equipment corrosion and SO2 emissions to the atmosphere when burnt. Anoxic desulfurization has been proven to be an eco-friendly and cost-efficient method to remove H2 S from biogas. Nevertheless, and despite all the reported benefits, the potential consumption of methane (CH4 ) during the anoxic desulfurization of landfill biogas is a factor that has not yet been thoroughly investigated. The present study evaluates the microbial composition and methane assimilation activity of three microbial samples obtained when feeding different nitrate sources, namely nitrified landfill leachate (M1) or chemical nitrate (M2, M3) with 10 days (M2) and 1.5 days (M3) hydraulic residence times. The samples were characterized by the prevalence of sulfide oxidizing bacteria [ Thiomicrospira (11.4–25.5 %), Family Rhodobacteraceae (9.9–14.3 %), Sulfurimonas (0.34–17.9 %), Thioclava (0–23.5 %) and Arcobacter (0–11.5 %)], as well as the presence of methane oxidizing bacteria [ Halomonas (0.2–16.0 %), Methylophaga (0–0.2 %) and Methylophilacea (0–0.1 %)] and heterotrophic bacteria [ Lentimicrobium (0.1–9.7 %) and Roseovarius (0.1–1.2 %)]. The highest CH4 assimilation levels were reached under anoxic conditions at 34.0 and 50.1 g CH4 m −3 h −1 using nitrate and nitrite, respectively. The oxygen present in the landfill biogas itself had a detrimental effect on the anoxic bioreactor nitrate removal efficiency. The presence of organic matter in the nitrified influent gave rise to CH4 inside the anoxic desulfurization bioreactors, which resulted in the offsetting of the CH4 oxidation caused by methane-oxidizing bacteria (MOB). Graphical Abstract: ga1 Highlights: The anoxic stirred tank bioreactor achieved H2 S removal efficiencies over 95 %. Sulfur oxidizing bacteria dominated the bacterial communities. The presence of methane oxidizing bacteria depended on the HRT and nitrate source. The oxygen present in the landfill biogas itself reduced the nitrate consumption.