Treating Municipal Wastewater With Aerobic Granules

Aerobic granule is granular microbial self-aggregate cultivated in aerobic waste water treating system. Compared with conventional activated sludge system, the aerobic granule has strong and compact microbial structure, improved stability and higher biomass retention, the process of effluent separating is simple, the structure of the reactor is compact, which can leave out the second settling and refluence device, the occupied area is small; the system can withstand the unfavorable hydraulic effect and toxic substances; compared with anaerobic granules, the aerobic granules are more stable when used to treat the organic wastewater of low concentration, and the start-up period is much shorter than that of the anaerobic granules.Based on cultivating mature aerobic granular in SBAR, aerobic granule is applied to treat municipal wastewater. The ratio supplied by real municipal wastewater in influent COD is increased gradually by every 5 percents. finally, the reactor is supplied exclusively with municipal wastewater. This study investigates the removal of COD and NH3-N by aerobic granule sludge, which is nearly 70% and 90% in average respectively. The biomass MLSS in the reactor is changed in the range of 2000~3500mg/L in different stages of the experiment. The settling ability of the granule is kept high, the Sludge Volume Index (SVI) is 35~50ml/g-MLSS.The author also discusses the Simultaneous Nitrification and Denitrification (SND) in the process of treating municipal wastewater with aerobic granules.In order to investigate the stability of the aerobic granules, based on cultivating mature aerobic granular in SBAR ,aerobic granules are applied to treat municipal wastewater by inoculating the activated sludge of the traditional wastewater plant. After completing the process of making actual municipal wastewater as the sole organic source, the stability of the aerobic granular is investigated by increasing the organic loading rate. The author also investigates and compares the difference of the granule formation process and the treating ability to organic substances and the nutriment under different HRT.