Different Carbon Condition Influence The Characteristics Of Aerobic Granular Sludge

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. This paper investigated physical characteristics, COD and ammonia nitrogen removal ability, total nitrogen and phosphorous removal ability and phosphorous removal mechanism of aerobic granular sludge in three internal-circulate sequencing batch airlift reactors (IC-SBARs), the three reactors fed with different substrate including glucose, acetate and ethanol, respectively. The results showed that the morphology and treatment performance of the three reactors could be kept stable in the long-term experiments. The granular sludge fed with acetate and glucose was denser and had better settle ability. The SVI of the three reactors with glucose, acetate and ethanol were 31 mL/g, 29 mL/g and 40 mL/g. The EPS content of the three reactors were keeping increase during the cultivating period. It proved that EPS plays an important role in granulation progress.With the influent of 1000 mg/L COD, 60mg/L NH₃-N and 15 mg/L TP, the COD removal efficiencies of the three reactors with glucose, acetate and ethanol were 96%, 95% and 94%, respectively. Simultaneity the total nitrogen removal efficiencies were 95%, 87% and 55%. The effect of the total nitrogen removal efficiencies was depend on the speed of denitrification, the granular sludge fed with glucose and acetate had a befitting condition for the increase of the denitrification bacteria, so they had a better total nitrogen removal efficiencies than the granular fed with ethanol. Phosphorous removal efficiencies of the three reactors with glucose, acetate and ethanol were 82%, 88% and 52%, respectively. The granular sludge fed with acetate and glucose had excellent phosphorous releasing.