Journal
JOURNAL OF CLEANER PRODUCTION
Volume 336, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.jclepro.2022.130486
Keywords
Anaerobic ammonia oxidation; Bioelectrochemical system; Biofilm spatial structure; Nitrogen removal; Weak electrical stimulation
Categories
Funding
- National Natural Science Foundation of China [51808226, 51908217]
- Science & Technology Innovation Action Plan of Shanghai [20230742100, 21230714000]
- Fundamental Research Funds for the Central Universities [TP2017041]
- Shanghai Engineering Research Center of Biotransformation of Organic Solid Waste [SERC2020A02]
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A study was conducted on the effect of weak electrical stimulation on biofilms in a bioelectrochemical anammox system. Continuous stimulation was found to enhance the electron transfer system activity and nitrogen removal, while also facilitating the secretion of extracellular polymer substances and promoting the formation of compact biofilms. Microbial analysis showed an increase in specific microorganisms, indicating the importance of weak electrical stimulation in diversifying the microbial community and creating a robust nitrogen metabolic pathway.
A bioelectrochemical anammox system (BEAnS) was constructed , operated at low temperature to investigate the effect of weak electrical stimulation (continuous or intermittent) on metabolism behaviors, electrochemical activity, nitrogen removal , spatial distribution of anammox biofilms. Results showed that the continuously stimulated biocathode exhibited the highest electron transfer system activity (34.2 & PLUSMN; 6.9 mu g mg(-1) h(-1)), the fastest electron transfer coefficient (0.0412 s(-1)), the largest current density (0.25 A cm(-2)), and the smallest polarization resistance (~4 omega). This led to an enhanced nitrogen removal of 60.6 & PLUSMN; 5.6% and energy recovery of 289.1 mW m(-3) , compared with that of the control. Confocal laser scanning microscopy and fluorescence in situ hybridization analysis confirmed that continuous weak electrical stimulation could accelerate the secretion of extracellular polymer substances, which facilitated the aggregation/adhesion of single cell and subsequent development of compact and stratified co-existing biofilms on cathode. Microbial analysis further demonstrated the proliferation of electrotrophic denitrifying microorganisms (i.e., Thauera , Hydrogenophaga , Ignavibacterium), nitrifier (Candidatus_Nitrotoga), and denitrifier (Denitratisoma), except for anammox bacteria (i.e., Candidatus_Brocadia , and Candidatus_Jettenia), implying the critical role of weak electrical stimulation in diversifying N-degrading microbial community and creating a more robust nitrogen metabolic pathway. These findings can provide a novel insight into autotrophic electroactive anammox biofilm enrichment and their activity enhancement by weak electrical stimulation.
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