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.

SUBMITTER: Wang D 

PROVIDER: S-EPMC4858757 | biostudies-other | 2016 May

REPOSITORIES: biostudies-other