Cultivation And Characteristics Of Aerobic Granular Sludge Under Roomand Low Temperature

Compared with the traditional activated sludge, aerobic granular sludge(AGS) technology, with its advantages of high content of microorganism, rich biological populations, large sludge density, good settleability and less bulking, has become the hotspot in the field of sewage treatment. There are many studies on aerobic granular sludge technology using synthetic wastewater under room temperature, but less focus on municipal domestic sewage treatment and low temperature. In this research, cultivation and characteristics of aerobic granular sludge under room and low temperature is studied experimentally aiming to treat municipal domestic sewage.The aerobic granular sludge is cultivated successfully in two SBR reactors, and is applied to treat municipal domestic sewage through anaerobic- aerobic alternating operation mode under room(R2) and low temperature(R3). The average particle sizes of both R2 and R3 are 160μm and 300μm respectively. Also, the mature AGS cultivated under synthetic wastewater adapts to municipal domestic sewage within 20 days under room temperature, and the average particle size of R3 is 375μm. The AGS system is the co-existences of flocs sludge and granular sludge, and has diverse food chain structure. The bacillus and coccus are the dominant bacterial communities.The granulation of sludge is related to excess extracellular polymeric substances(EPS)of bacterias, for the EPS of AGS is more than that of floc sludge. The chemical functional groups of EPS of both AGS and floc sludge exists a slight differences under FTIR, which shows the different characteristics of sludge. The EPS contains proteinoid, fulvic acid and humic acid, and the major ingredient of EPS is proteinoid.The treatment effect of AGS reactor to municipal domestic sewage is efficient. The concentration of effluent COD and TN of R2 are 44.48 and 21.38mg/L, and the removal are 91.93% and 64.20% respectively. R1 are 44.70 and 20.09mg/L, and the removal are 91.88% and 66.31% respectively. R1 are 54.34 and 19.40mg/L mg/L, and the removal are 85.84% and 67.63% respectively. The effluent N 4-N and PO43--P concentration of three reactors are all below 2.0mg/L and 0.5mg/L, with the removal of 99% and 97% respectively. Meanwhile, all the three reactors have strong tolerance to COD、N 4-N、PO43--P impact load.There is simultaneous nitrification denitrification(SND)denitrification under room temperature and low temperature. The TN removal reaches at 76.5%(R1) and 95.2%(R3)respectively through adding 2 hours anaerobic mixing time. Accumulation of NO2--N is found under low temperature(R3), and the maximum accumulation rate reaches 80%, which provids favorable conditions for the realization of short-cut denitrification.