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Updated: Feb 7, 2026

Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge
Published on: November 6, 2016
[Nitrogen Removal of Double-bacteria-layer System via PN/A Process]
Jing-Yi Xu1, Jun Du1, Yi-Feng Yang1
1College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
Abstract:
Nitrification and anaerobic ammonia oxidation (ANAMMOX) sludge was acclimated via SBR and MBR reactors respectively, both of which were embedded with microbial immobilization technology and spliced together to construct a PN/A double-bacteria-layer system. A short-term experiment proved that ammonia-oxidizing bacteria (AOB) and ANAMMOX bacteria in the system played dominant roles separately in different stages, which maintained the acid-base balance and achieved efficient removal of NH4+-N (98.8%). A long-term experiment showed that the PN/A double-bacteria-layer system improved the utilization of dissolved oxygen (DO) and enhanced the stability and nitrogen removal efficiency, with limited dissolved oxygen. The nitrogen removal efficiency of the PN/A double-bacteria-layer system remained stable at~80% when the influent NH4+-N was 200 mg·L-1 or 400 mg·L-1 in the presence of 1.0 mg·L-1 DO, whereas those of the control group were only 58.1% and 61.4%, respectively. When influent NH4+-N and DO were 400 mg·L-1 and 3.0 mg·L-1, respectively, the PN/A double-bacteria-layer system achieved a nitrogen removal efficiency, nitrogen loading rate (NLR), and nitrogen removal rate (NRR) of 87.9%, 0.4 kg·(m3·d)-1, and 12.8 mg·(g·h)-1, respectively.
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