The roles of free ammonia (FA) in biological wastewater treatment processes: A review.

Quantify the contribution of anammox for enhanced nitrogen removal through metagenomic analysis and mass balance in an anoxic moving bed biofilm reactor.

Partial denitrification providing nitrite: Opportunities of extending application for anammox

Anammox granular sludge in low-ammonium sewage treatment: Not bigger size driving better performance.

Achieving mainstream nitrogen removal through simultaneous partial nitrification, anammox and denitrification process in an integrated fixed film activated sludge reactor.

Achieving maintream anammox is critical for energy-neutral sewage treatment. This study presents a new way to achieve mainstream anammox, which couples anammox with denitratation (nitrate reduction to nitrite) instead of nitritation (ammonium oxidation to nitrite). An anoxic/oxic (A/O) biofilm system treating systhetic domestic wastewater was used to demonstrate this concept for over 400 days. This A/O biofilm system achieved a total nitrogen (TN) removal efficiency of 80 ± 4% from the influent with a low C/N ratio of 2.6 and a TN concentration of 60.5 mg/L. Nitrogen removal via anammox was found to account for 70% of dinitrogen production in the anoxic reactor. Batch tests confirmed that the anoxic biofilm could oxidize ammonium using nitrite as electron acceptor, and that it had a higher nitrate reduction rate than the nitrite reduction rate, thus producing nitrite for the anammox reaction. Metagenomic analysis showed that Candidatus Jettenia caeni and Candidatus Kuenenia stuttgartiensis were the top two dominant species in anoxic biofilm. Genes involved in the metabolism of the anammox process were detected in anoxic biofilm. The abundance of nitrate reductase (73360 hits) was much higher than nitrite reductase (13114 hits) in anoxic biofilm. This system can be easily integrated with the high-rate activated sludge technology, which produces an effluent with a low C/N ratio. While this new design consumes 21% more oxygen in comparison to the currently studied nitritation/anammox process, the nitrite-producing process appears to be more stable.

Achieving Mainstream Nitrogen Removal through Coupling Anammox with Denitratation

Long-term effect of pH on denitrification: High pH benefits achieving partial-denitrification.

The inhibitory effects of free ammonia on ammonia oxidizing bacteria and nitrite oxidizing bacteria under anaerobic condition.

Achieving nitritation by treating sludge with free nitrous acid: The effect of starvation.

The invention relates to a method for deep denitrification of low carbon source urban sewage and belongs to the technical field of biological sewage treatment. Urban sewage and refluent nitrification liquid enter a short-range denitrification anaerobic ammonium oxidation area of a deep denitrification bioreactor, denitrifying bacteria on a biofilm outer layer reduce nitrate nitrogen in the refluent nitrification liquid into nitrite by utilizing a limited organic carbon source in raw water, and anaerobic ammonium oxidizing bacteria on a biofilm inner layer enable the generated nitrite nitrogen and ammonia nitrogen in part of raw water to react and be converted into nitrogen; the sewage enters an aerobic area to be subject to short-range nitration, so that the remaining part of ammonia nitrogen of the sewage is converted into nitrite nitrogen; then the sewage enters the anaerobic ammonium oxidation area, enters the aerobic area and the anaerobic ammonium oxidation area, and finally enters a nitrification area, so that the nitrate nitrogen and the ammonia nitrogen in the raw water are oxidized to be nitrate nitrogen. According to the method, through the united application of short-range denitrification-anaerobic ammonia oxidation and short-range nitrification-anaerobic ammonia oxidation, the deep denitrification of the low carbon source urban sewage is performed.

Method for deep denitrification of low carbon source urban sewage

Qian Wenting

Papers

Achieving Mainstream Nitrogen Removal through Coupling Anammox with Denitratation

Long-term effect of pH on denitrification: High pH benefits achieving partial-denitrification.

The inhibitory effects of free ammonia on ammonia oxidizing bacteria and nitrite oxidizing bacteria under anaerobic condition.

Achieving nitritation by treating sludge with free nitrous acid: The effect of starvation.

Method for deep denitrification of low carbon source urban sewage