Nitrogen Removal Properties And Process Of Aerobic Granular Sludge

Aerobic granulation was a process in which suspended biomass aggregate and form discrete well-defined granules spontaneously in aerobic systems. Aerobic granular sludge has been investigated since last century. As self-aggregated bio-particles by microorganisms under certain conditions, it has compact structure and good settling ability. Because of the mass transfer limit, there could be different kinds of oxygen and substrate conditions in the granules, which could be propitious to the proliferation of various microorganisms. Based on the successful cultivation of aerobic heterotrophic granular sludge, granules with well nitrogen removal were cultivated by adjusting the ammonium loading rate, aeration rate and hydraulic retention time, and the properties and mechanisms of nitrogen removal were investigated in this work. The main projects were focused on the cultivation of nitrogen removal granules, nitrogen removal process, optimization of the reaction process, mass transfer characteristics, reaction kinetics and microbiological components and structure.The main experimental results were listed as follows: According to the prophase work on the heterotrophic aerobic granules, activated sludge (AS), nitrified sludge (NS) and aerobic heterotrophic granular sludge (GS) were used as the inoculum respectively, and the adjustment of ammonium loading rate, aeration rate and hydraulic retention time were used to promote the accumulation of nitrifier-denitrifier bacteria. After 120 days operation, granules with well COD and nitrogen removal activity were successfully cultivated in all the three types of systems. The COD removal efficiencies of the three systems were 95.70,96.04,96.55% and the ammonium nitrogen removal efficiencies were 90.67,94.51,97.29% respectively, under the operation conditions of cycle period being 4h, organic loading rate being 1.6g/L·d and ammonium-nitrogen loading rate being 0.53g/L·d.IA results showed that mature granules in three systems had mean diameter being 1.88, 2.37 and 2.26mm respectively, and the maximum settling velocity of which were 104.22, 120.89 and 135.00m/h. The corresponding wet sludge density was 1.0156, 1.0187 and 1.0262g/cm~3, and the MLSS were 7.25, 9.81 and...