Study On Formation And Characteristics Of Aerobic Granular Sludge Under The Enhancing Granulation Conditions

Aerobic granular sludge has the advantages of compact structure, excellentsettleability and degradation. The aerobic granular sludge is hard to be practicalapplication, because its formation time is too long. In order to shorten the formationtime of aerobic granular sludge, we study the formation process and characteristicsunder the strengthening granulation conditions by putting coagulant into the SBR at thepreliminary stage of the formation.The results of the study shows that, granular sludge appears on the8thd in thereactor with coagulant, which is2days earlier than the process without coagulant, andrealizes complete granulation on the25thd, which is10days earlier than the processwithout coagulant. The stable stage of the aerobic granular sludge under the enhancinggranulation conditions is longer than the aerobic granular sludge without coagulant.After the addition of PAC, there are40days and44days between the completegranulation and granules broken with stirring and without stirring. It is17days and21days longer than the SBR without PAC. After the addition of PAC, the re-granulationtime is13days with stirring and9days without stirring, it is7days and11days shorterthan the SBR without PAC.The aerobic granular sludge under the enhancing granulation conditions has highergranule strength, specific gravity and lower water content. Under the PAC and stirringcondition, the granule strength, specific gravity and water content of aerobic granularsludge is99.03%,1.189,94.85%respectively; Under the PAC condition, the granulestrength, specific gravity and water content of aerobic granular sludge is98.96%, 1.092,95.03%respectively; compare with the SBR without PAC, granule strength is3.28%and3.21%higher respectively; specific gravity is14.9%and5.5%higherrespectively; water content is0.9%and0.72%lower respectively.At the preliminary stage of the formation, after the addition of PAC, the removalrate of NH4+-N in the SBR with stirring and without stirring is55.6%and55.8%, it is10.5%and10.3%lower than the SBR without PAC. But after the complete granulation,the removal rate of NH4+-N in the SBR with PAC and stirring is73.4%; the removal rateof NH4+-N in the SBR with PAC is72.9%.It is3.7%and3.2%higher than the SBRwithout PAC.