Variation of biological and hydrological parameters and nitrogen removal optimization of modified Carrousel oxidation ditch process

To enhance the nitrogen removal, a systemic monitoring of the biological and hydrological parameters of Carrousel oxidation ditch in Chongqing Jingkou Wastewater Treatment Plant was carried out to study the feasibility of simultaneous nitrification and denitrification (SND). The variation and distribution of parameters such as flow velocity, concentration of dissolved oxygen (DO) and mixed liquor suspended solids (MLSS) in oxidation ditch were monitored and analyzed, which were major control factors for SND. The results showed that, the dimensional distribution of flow velocity, DO and MLSS were affected significantly by the operation condition of the aeration wheels. With all the four aeration wheels being in operation, DO and flow velocity were higher and the mixing of MLSS was sufficient. With three aeration wheels being in operation, the flow velocity in most of the bottom areas was enough to meet the basic requirements of no deposition, and the anaerobic region and aerobic region could exist simultaneously in one oxidation ditch, which was helpful to the process of SND. According to spatial distribution characteristics of the flow velocity, DO and soluble components under optimized condition, different functional zones of biochemical reaction in the Carrousel oxidation ditch system were defined, which might contribute to the optimization control and SND of Carrousel oxidation ditch.