title: Achieving Stable Nitritation for Mainstream Deammonification by Combining Free Nitrous Acid-Based Sludge Treatment and Oxygen Limitation.
abstract: Stable nitritation is a critical bottleneck for achieving autotrophic nitrogen removal using the energy-saving mainstream deammonification process. Herein we report a new strategy to wash out both the Nitrospira sp. and Nitrobacter sp. from the treatment of domestic-strength wastewater. The strategy combines sludge treatment using free nitrous acid (FNA) with dissolved oxygen (DO) control in the nitritation reactor. Initially, the nitrifying reactor achieved full conversion of NH4(+) to NO3(-). Then, nitrite accumulation at ~60% was achieved in the reactor when 1/4 of the sludge was treated daily with FNA at 1.82 mg N/L in a side-stream unit for 24 h. Fluorescence in-situ hybridization (FISH) revealed FNA treatment substantially reduced the abundance of nitrite oxidizing bacteria (NOB) (from 23.0 ± 4.3 to 5.3 ± 1.9%), especially that of Nitrospira sp. (from 15.7 ± 3.9 to 0.4 ± 0.1%). Nitrite accumulation increased to ~80% when the DO concentration in the mainstream reactor was reduced from 2.5-3.0 to 0.3-0.8 mg/L. FISH revealed the DO limitation further reduced the abundance of NOB (to 2.1 ± 1.0%), especially that of Nitrobacter sp. (from 4.9 ± 1.2 to 1.8 ± 0.8%). The strategy developed removes a major barrier for deammonification in low-strength domestic wastewater.
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, QLD 4072, Australia.
authors.forename: Dongbo
authors.initials: D
authors.lastname: Wang
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, QLD 4072, Australia.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, QLD 4072, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Laloo
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, QLD 4072, Australia.
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, QLD 4072, Australia.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Bond
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, QLD 4072, Australia.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D001419:Bacteria / Q000145:classification / Q000254:growth & development / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D058448:Biota; D017404:In Situ Hybridization, Fluorescence; D009608:Nitrous Acid / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology*; D018508:Water Purification
chemical_list: D012722:Sewage; D010100:Oxygen; D009608:Nitrous Acid