Using anammox biofilms for rapid start-up of partial nitritation-anammox in integrated fixed-film activated sludge for autotrophic nitrogen removal

Ying yu Li, Xiao wu Huang, Xiao yan Li*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Integrated fixed-film activated sludge (IFAS) reactors are suitable for partial nitritation-anammox (PNA) for autotrophic nitrogen removal; however, its start-up and biofilm formation are slow and difficult. In this study, a new sludge seeding strategy was developed for the start-up of PNA-IFAS by using the pre-cultivated anammox biofilms. Two bioreactors were used in the experimental study, including a reactor that was started conventionally with the pre-acclimated suspended PNA sludge and bare biocarriers (PA-S) and a reactor that used the new seeding method with anammox biofilms pre-acclimated on biocarriers and ammonia-oxidizing bacteria (AOB) sludge in the suspension (PA-B). The use of anammox biofilms as the seed biomass greatly shortened the start-up period of the PNA-IFAS reactor to 1 month or so. Moreover, reactor PA-B achieved a higher nitrogen removal rate (707.3 mg N/(L·d)), better nitrogen removal efficiency (86.8 ± 2.8%), and lower nitrate yield (9.4%) than reactor PA-S. The biofilm development in PA-B was accelerated and its biofilm content was nearly 10 times higher than that of PA-S. The initial segregation of anammox in the biofilm and AOB in the suspended sludge provided an environment that not only accelerated the start-up of PNA-IFAS but also helped suppress the enrichment of unwanted nitrite-oxidizing bacteria (NOB) in the bioreactor, as evidenced by the lower NOB abundance in PA-B (<0.5%) than in PA-S (>2.2%) according to microbial community analysis.

Original languageEnglish
Article number148314
JournalScience of the Total Environment
Volume791
DOIs
StatePublished - 15 Oct 2021
Externally publishedYes

Keywords

  • Autotrophic nitrogen removal
  • Biofilm formation
  • Integrated fixed-film activated sludge
  • Partial nitritation-anammox
  • Start-up
  • Wastewater treatment

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