Long-term effect of perfluorooctanoic acid on the anammox system based on metagenomics: Performance, sludge characteristic and microbial community dynamic

The effects of PFOA on the nitrogen removal performance, microbial community and functional genes of anaerobic ammonium oxidation (anammox) sludge in an anaerobic baffled reactor (ABR) were investigated. The removal efficiencies of ammonia nitrogen (NH4+-N) and nitrite (NO2--N) decreased from 93.90 +/- 3.64% and 98.6 +/- 1.84% to 77.81 +/- 6.86% and 77.96 & PLUSMN; 1.88% when PFOA increased from 5 mg/L to 50 mg/L, respectively. X-ray photoelectron spectra analysis of the anammox sludge showed the presence of both C-F and CaF2 forms of F. Metagenomics analysis of the anammox sludge in the first compartment illustrated that the relative abundance of Ca.Brocadia and Ca.Kuenenia decreased from 22.21% and 5.61% to 2.11% and 2.84% at 50 mg/L PFOA compared with that without PFOA. In addition, the nitrogen metabolism pathway showed that adding 50 mg/L PFOA decreased the expression of HzsB, HzsC, and Hdh (anammox genes) by 0.096%, 0.05% and 0.062%, respectively.

Automated summary

The effects of PFOA on the nitrogen removal performance, microbial community, and functional genes in an ABR were investigated. The results showed that increasing PFOA concentration decreased the removal efficiencies of NH4+-N and NO2--N, as well as the relative abundance of specific microbial species and the expression of anammox genes in the sludge.