Effect Of Granule Age On Characteristics And Mathematic Modeling Of Aerobic Granules

Aerobic granular sludge is a type of microbial aggregate through self-immobilizationand granulation of the microorganisms in activated sludge. Aerobic granule has beenregarded as a novel and promising wastewater treatment system due to its specialcharacteristics, such as regular and compact physical structure, diverse microbial species,good settle ability, and high biomass retention.The research is including three parts. The first part was the research of aerobicgranule characteristics with different granule age. The different morphology,physicochemical characteristic, pollutants removal and microbial activity between theshort age and long age aerobic granule, were investigated respectively in the SBR reactors,.The short age aerobic granule was cultivated from activated floccules sludge and the otherwas gotten from aerobic granular sludge which was operated stably more than one year.The results indicated that the wet density, the specific gravity and integrated coefficient（IC） of the short age aerobic granule were1.066g/cm³,1.013g/cm³and98.7%,respectively, and that of long age were1.026g/cm³,1.010g/cm³and98.4%, respectively.All of them were higher than the long age aerobic granule. The mean diameters of themwere1.9mm and2.2mm, respectively. SVI and the settling velocity of short age aerobicgranular sludge showed better settle ability. The results of the removal rate of COD,NH₃-N and TP indicated that the short age aerobic granular sludge has better contaminantremoval efficiency during the stage of stable operation. The TN removal rates of themwere about80%. The SOUR_H, SOURNH4and SOUR_NO2of the short age aerobic granulewere26.4,14.8and11.2mg/（h·g）, respectively. And that of long age were25.2,14.4and8.4mg/（h·g）, respectively.The second part was the study on the measurements and analyses of CODcomponents in the activated sludge models. The batch OUR respirometric experiment andflocculation-0.45μm filtration method were used to measure readily biodegrable substrate（SS）. The results indicated that flocculation-0.45μm filtration method own much higherveracity than batch OUR respirometric experiment to measure SSin wastewater. There aresome subjectivity results explained with batch OUR respirometric experiment and it also needmore advance technology and better exact accuracy. We measured soluble unbiodegradable component （S_I） with0.45μm filtration method. The results indicated that0.45μmfiltration method was easy to operate, showing a good reproducibility and practicality.The third part was the simulation of the SBR process of aerobic granules usingmodified ASM3model. The modified ASM3entails the introduction of the simultaneousstorage and growth concept and the nitrification and denitrification in both nitrite andnitrate. The sensitivities of COD, NH₃-N, and TN toward the stoichiometric and kineticcoefficients were analyzed. Eleven parameters(Y_H,O2, K_S, μ_H,STO, μ_H, b_STO,O2, μ_AOB,KAOB,O2, η_NO3, η_NO2, b_NOB,å'ŒK_NOB,O2)were varied in the analysis. The experimentalresults from the concentration profiles of COD, NH₃-N, and TN during each cycle wereused to verify the model. Model verification yielded good agreement between theexperimental and simulated results. In contrast to the original version of ASM3, themodified ASM3model was shown to have the capacity to describe the substrate removalmechanisms.