Cultivation of denitrifying anaerobic methane-oxidizing microorganisms in a continuous-flow sponge bioreactor

Abstract

Anaerobic treatment of sewage has many advantages; however, the effluent contains high levels of dissolved methane. In this study, we investigated the use of a closed-type downflow hanging sponge (DHS) reactor for application of the denitrifying anaerobic methane oxidation (DAMO) reaction for nitrogen and dissolved methane removal. When using nitrate, the DAMO reaction achieved a denitrification rate of 84.4 g N m day, which is close to that required for practical application of denitrification to anaerobic sewage treatment. The microbial community that developed in the DHS was investigated using16S rRNA, and novel species of DAMO bacteria affiliated with Group b of NC10 phylum were enriched. This contrasted with the results of previous studies in which the Candidatus Methylomirabilis oxyfera affiliated with Group a was enriched. The results obtained herein suggest that a post-treatment system for anaerobically treated sewage using a closed-type DHS reactor may become practical in the near future.

Significance of anaerobic oxidation of methane (AOM) in mitigating methane emission from major natural and anthropogenic sources: a review of AOM rates in recent publications

“…3), with the caveat that these high rates may not exist in nature. Specically, nitrite-based DAMO in bioreactors usually shows methane oxidation at 0.00004-22.31 mmol CH 4 cm À3 d À1 , 22,49,53,62,63,98,110,[224][225][226][227][228][229] oen higher than nitrite-DAMO observed in terrestrial and marine environments. Besides, unlike sulfate-AOM, it seems that the nitrite-DAMO is not limited by methane.…”

Denitrifying anaerobic methane-oxidizing bacteria in river networks of the Taihu Basin: Community dynamics and assembly process

“…Previous studies have confirmed that Group A had the ability to oxidize methane by enrichment culture and genomic analysis ( Ettwig et al, 2009 ; He et al, 2015 ; Wang et al, 2016 ; Xu et al, 2018 ). Recent studies have also enriched Group B, indicating that it may also have the ability to oxidize methane ( Hatamoto et al, 2017 ; Ma et al, 2017 ). These results implied that the DAMO process may play an important role in reducing methane emissions in the river ecosystem, while its in-situ activity needs to be further explored.…”

A novel identified Pseudomonas aeruginosa, which exhibited nitrate‐ and nitrite‐dependent methane oxidation abilities, could alleviate the disadvantages caused by nitrate supplementation in rumen fluid fermentation

“…Previous research has found that the ruminal nitrogen increased significantly following dietary nitrate supplementation (Guo et al ., 2009), and it indicated that other pathway is also involved in ruminal nitrate metabolism. The DAMO process, which has been widely detected in different environments where nitrate is available (Ettwig et al ., 2009; Shen et al ., 2014; Wang et al ., 2017) and was accelerated by the addition of nitrate (Hatamoto et al ., 2017), uses / as the electron receptor to oxidize CH 4 . In this process, both and can be reduced to N 2 .…”