title: Methanogenic population dynamics during startup of a full-scale anaerobic sequencing batch reactor treating swine waste.
abstract: Changes in methanogenic population levels were followed during startup of a full-scale, farm-based anaerobic sequencing batch reactor (ASBR) and these changes were linked to operational and performance data. The ASBR was inoculated with anaerobic digester sludge from a municipal wastewater treatment facility. During an acclimation period of approximately 3 months, the ASBR content was diluted to maintain a total ammonia-N level of approximately 2000mg l(-1). After this acclimation period, the volatile solids loading rate was increased to its design value of 1.7g l(-1) day(-1) with a 15-day hydraulic retention time, which increased the total ammonia-N level in the ASBR to approximately 3,600 mg l(-1). The 16S ribosomal RNA (rRNA) levels of the acetate-utilizing methanogens of the genus Methanosarcina decreased from 3.8% to 1.2% (expressed as a percentage of the total 16S rRNA levels) during this period, while the 16S rRNA levels of Methanosaeta concilii remained low (below 2.2%). Methane production and reactor performance were not affected as the 16S rRNA levels of the hydrogen-utilizing methanogens of the order Methanomicrobiales increased from 2.3% to 7.0%. Hence, it is likely that during operation with high ammonia levels, the major route of methane production is through a syntrophic relationship between acetate-oxidizing bacteria and hydrogen-utilizing methanogens. Anaerobic digestion at total ammonia-N levels exceeding 3500mg l(-1) was sustainable apparently due to the acclimation of hydrogen-utilizing methanogens to high ammonia levels.
authors.affiliation: Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana 61801, USA
authors.forename: Largus T
authors.initials: LT
authors.lastname: Angenent
authors.forename: Shihwu
authors.initials: S
authors.lastname: Sung
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Raskin
mesh_terms: D000641:Ammonia / Q000032:analysis; D000818:Animals; D019149:Bioreactors; D004269:DNA, Bacterial / Q000032:analysis; D019605:Euryarchaeota; D009584:Nitrogen / Q000378:metabolism; D011157:Population Dynamics; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012037:Refuse Disposal; D013552:Swine
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D000641:Ammonia; D009584:Nitrogen