Nitrogen removal mechanism of marine anammox bacteria treating nitrogen-laden saline wastewater in response to ultraviolet (UV) irradiation: High UV tolerance and microbial community shift

Abstract

Salt stress can be naturally overcome by marine anammox bacteria (MAB), while their low growth rate and sensitivity to operational conditions are still challenges for the application of anammox. To enhance the enrichment of MAB and decipher the effects of ultraviolet (UV) irradiation on MAB, UV was introduced in the nitrogen removal of MAB treating nitrogen-laden saline wastewater for the first time. The results indicated that MAB were resistant to a fairly high UV-C dose, 12000 mJ/cm2. Their relative abundance was enhanced by 1.2 folds under 12000 mJ/cm2 UV-C. However, the relative abundance of Actinobacteria, Acidobacteria, Chloroflexi and Marinicella were greatly dropped with enhanced UV-C dose. The tolerance mechanism was diversified, e.g. excessive extracellular polymeric substances, special structure of MAB and interspecific competition/cooperation. Although further study was still needed, the findings shed a light on MAB enrichment and exploited great potentials of MAB in nitrogen-laden saline wastewater treatment.