Simultaneous nitrogen and phosphorus removal from municipal wastewater by Fe(III)/Fe(II) cycling mediated partial-denitrification/anammox

The efficient removal of nitrogen and phosphorus remains challenging for traditional wastewater treatment. In this study, the feasibility for enhancing the partial-denitrification and anammox process by Fe (III) reduction coupled to anammox and nitrate-dependent Fe (II) oxidation was explored using municipal wastewater. The nitrogen removal efficiency increased from 75.5 % to 83.0 % by adding Fe (III). Batch tests showed that NH4+-N was first oxidized to N-2 or NO2--N by Fe (III), then NO3--N was reduced to NO2--N and N(2 )by Fe (II), and finally, NO2--N was utilized by anammox. Furthermore, the performance of phosphorus removal improved by Fe addition and the removal efficiency increased to 78.7 %. High-throughput sequencing showed that the Fe-reducing bacteria Pseudomonas and Thiobacillus were successfully enriched. The abundance of anammox bacterial increased from 0.03 % to 0.22 % by multiple nitrite supply pathways. Fe addition presents a promising pathway for application in the anammox process.

Automated summary

This study explored the feasibility of enhancing nitrogen and phosphorus removal in wastewater treatment through Fe (III) reduction coupled to anammox and nitrate-dependent Fe (II) oxidation. The results showed that the addition of Fe improved the removal efficiency of nitrogen and phosphorus and successfully enriched key bacteria.