Long-term effects of multi-walled carbon nanotubes on the performance and microbial community structures of an anaerobic granular sludge system
Multi-walled carbon nanotubes (MWCNTs) released into the sewage may cause negative and/or positive effects on the treatment system. The objective of this study was to explore over 110 days’ effect of MWCNTs on the performance of anaerobic granular sludge and microbial community structures in an upflow anaerobic sludge blanket (UASB) reactor. The results showed that MWCNTs had no significant effect on the removal of chemical oxidation demand (COD) and ammonia in UASB reactor, but the total phosphorus (TP) removal efficiency increased by 29.34%. The biogas production of the reactor did not change. The anaerobic granular sludge tended to excrete more EPS to resist the effects of MWCNTs during the long-term impact. Illumina MiSeq sequencing of 16S rRNA gene revealed that MWCNTs did not affect the microbial diversity, but altered the composition and structure of microbial community in the reactor. In this process, Saccharibacteria replaced Proteobacteria as the highest abundant bacterial phylum. MWCNTs promoted the differentiation of methanogen structure, resulting in increase of Methanomassiliicoccus, Methanoculleus, and the uncultured WCHA1–57. These results indicated that MWCNTs impacted the performance of UASB reactor and the structures of the microbial community in anaerobic granular sludge.
KeywordsMulti-walled carbon nanotubes Upflow anaerobic sludge blanket Anaerobic granular sludge Microbial community structure Methanogens
This work was supported by the National Key Research and Development Program of China (2016YFC0401105), NSFC (51408020 and 51308319), and the Fundamental Research Funds for the Central Universities (BUCTRC201606).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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