[Nitrogen Removal Effect and Conversion Characteristics of Nitrous Oxide in Single-stage and Multi-stage A/O Processes].

The single-stage A/O and multi-stage A/O processes were simulated by sequencing batch reactors (SBRs) with alternate stirring and aeration. The removal efficiency of nitrogen and the release mechanism of NO were studied under the identical conditions of influent quality, hydraulic retention time (HRT), sludge retention time(SRT), temperature and anoxic/oxic (A/O) retention time ratio. Experimental results showed that COD or ammonia-nitrogen removal had no significant difference between the single-stage and the multi-stage A/O processes for the influent quality equivalent to municipal wastewater.

Nitrogen-removal performance and community structure of nitrifying bacteria under different aeration modes in an oxidation ditch.

Oxidation-ditch operation modes were simulated using sequencing batch reactors (SBRs) with alternate stirring and aerating. The nitrogen-removal efficiencies and nitrifying characteristics of two aeration modes, point aeration and step aeration, were investigated. Under the same air-supply capacity, oxygen dissolved more efficiently in the system with point aeration, forming a larger aerobic zone.

[Optimization and comparison of nitrogen and phosphorus removal by different aeration modes in oxidation ditch].

The oxidation ditch operation mode was simulated by sequencing batch reactor (SBR) system with alternate stirring and aeration. The nitrogen and phosphorus removal efficiencies were investigated in two different aeration modes: point aeration and step aeration. Experimental results show that oxygen is dissolved more efficiently in point aeration mode with a longer aerobic region in the same air supply capacity, but dissolved oxygen (DO) utilization efficiency for nitrogen and phosphorus removal is high in step aeration mode.