Microbial methane oxidation at the Fíflholt landfill in Iceland

• Main Author: Cabral, Alexandre
• Other Authors: Kjeld, Alexandra, Gústafsson, Lúðvík E., Andradóttir, Hrund Ó., Bjarnadóttir, Helga J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Methane oxidation; Landfills in boreal climate; Landfill gas emissions; Oxun metans; Urðunarstaðir í köldu loftslagi; Losun hauggass; Draga; Iceland
• Online Access: http://hdl.handle.net/11143/17089

Abstract: Methane oxidizing biosystems have received wide recognition in recent years as a cost effective and important means to reduce emissions from landfills. However, there is no documentation of the oxidation capacity of Icelandic landfill covers to date and there is limited information on microbial methane oxidation in boreal climates. The present study was carried out to qualitatively assess the oxidation capacity of the current top cover of one of the cells of the Fíflholt landfill, located in West Iceland, using the gas profile method (CO2/CH4 ratio). The landfill has no gas recovery system and the cover is composed of 15-25 cm crushed wood overlain by about 1 m of gravelly sand with 7% (w/w) organic matter content. Sampling probes were installed at two locations on cell 2 at different depths (5 to 120 cm). Several gas concentration measurements were carried out during the autumn and the winter of 2012-2013. It was observed that atmospheric air penetrated deep into the cover and oxidation activity was observed in the gas profiles. The oxidation zone was situated mainly below 40 cm from the surface and went as deep as about 1 m below surface, i.e. to the base of the cover. Oxidation efficiencies ranged from 0 to 99%, reaching maximal values between 30 and 60 cm depth, with mean values 59% and 77% respectively for the two sampling locations for the whole study period. It must be highlighted that relatively high oxidation efficiencies were obtained during winter. This indicates that methane oxidation can occur yearlong in Iceland, although a more thorough field study is needed to verify the extent of this phenomena in Icelandic landfill covers. Such a study would also permit to verify the applicability of the default value of 10% methane oxidation used in biogas generation and emission models. Ágrip: Yfirborðslög sem innihalda lífræn efni og oxa metan hafa hlotið viðurkenningu á undanförnum árum sem hagkvæm og áhrifarík leið til að draga úr losun gróðurhúsalofttegunda frá urðunarstöðum. Oxunarhæfni ...