Based on grey entropy analysis,the relational grade of operational parameters with aerobic granular sludge's granulation indicators was studied.The former consisted of settling time(ST),aeration time(AT),superficial gas velocity(SGV),height/diameter(H/D) ratio and organic loading rates(OLR),the latter included sludge volume index(SVI) and set-up time.The calculated result showed that for SVI and set-up time,the influence orders and the corresponding grey entropy relational grades(GERG) were:SGV(0.9935) > AT(0.9921) > OLR(0.9894) > ST(0.9876) > H/D(0.9857) and SGV(0.9928) > H/D(0.9914) > AT(0.9909) > OLR(0.9897) > ST(0.9878).The chosen parameters were all key impact factors as each GERG was larger than 0.98.SGV played an important role in improving SVI transformation and facilitating the set-up process.The influence of ST on SVI and set-up time was relatively low due to its dual functions.SVI transformation and rapid set-up demanded different optimal H/D ratio scopes(10-20 and 16-20).Meanwhile,different functions could be obtained through adjusting certain factors' scope.
