Characteristics Of Simultaneous Biological Nitrogen And Phosphorus Removal In A Single Sequencing Batch Hybrid Reactor

To control the eutrophication, researches on economical and effective nitrogen (N) and phosphorus (P) removal from wastewater are concerned deeply in the field of wastewater treatment all over the world. In the traditional single biological nitrogen and phosphorus removal process, effective nitrogen removal amd phosphorus removal could not be reached, because of the different sludge retention time (SRT) among phosphorus-accumulating organisms (PAOs), denitrification organisms and nitrification organisms, and the competition for the carbon source between denitrification organisms and the PAOs.Based on the latest researches on the biological nitrogen and phosphorus removal, a sequencing batch hybrid reactor (SBHR) system was explored in this paper. The study includs three parts: (1) cultivating hybrid sludge for biological nitrogen and phosphorus removal and characterizing sludge in the process; (2) analyzing influence factors on the nitrogen and phosphorus removal and optimizing operation parameters; (3) the mechanism of nitrogen and phosphorus removal in the SBHR system, including microorganism characteristics, flow pattern characteristics and mass transfer characteristics. A new thought was provided for solving the conflict of simultaneous biological nitrogen and phosphorus removal in single system.The experimental results show that C/N, COD loading and shear force are important for cultivating hybrid sludge. The PAOs and denitrifying PAOs in hybrid sludge were formed and accumulated rapidly when the transfer of organic substrates was improved by increasing the COD loading and augmenting the shear force in the SBHR system operated in the periods of anaerobic/aerobic/anoxic. At the end of the cultivating, 100% of NH4+-N is almostly removed, the average removal of TP and COD is over 90% and 85%, respectively; and the suspended activated sludge in the SBHR system has good settling ability (the Sludge Volumetric Index (SVI) and the Mixed Liquid Suspended Solid (MLSS) are 60.0 ml/g and 3000~4200 mg/L, respectively). The attached biofilm in SBHR system exist at a very dense and irregular structure, and its color is brown yellow. Coccus, bacillus, as well as protest, animalcule were observed in the attached biofilm by microscope, and they all show good activity.By adjusting C/N, COD loading and period of the different stage, the optimum...