The influences of flow patterns(mixed-flow and plug-flow)and fermentation pretreatment on aerobic granular sludge(AGS)formation with various substrate availability levels were investigated by running four identical la...The influences of flow patterns(mixed-flow and plug-flow)and fermentation pretreatment on aerobic granular sludge(AGS)formation with various substrate availability levels were investigated by running four identical laboratory-scale sequencing batch reactors(R1-R4),comparing two anaerobic feeding strategies and three kinds of substrates.R1 achieved faster granulation with a fast influent fill step followed by a modified anaerobic mixed-flow phase,but the AGS showed poorer stability with a cracked structure and a high suspended solids concentration in the effluent.The anaerobic plug-flow feeding mode(with influent fed slowly from the bottom)in R2 provided deeper penetration depth for the substance to reach the core of A G S and accordingly strengthen A G S stability.An acidogenic upflow sludge bed reactor was introduced as a pretreatment to improve the AGS performance by enhancing glucose pre-fermentation(R4).AGS fed with mixed volatile fatty acids(VFA)after glucose fermentation showed similar performance compared with the reactor fed with acetate in the aspects of stability,structure,size distribution and nitrogen removal efficiency,and 74%similarity in the microbial community.For actual wastewater with low VFA concentrations,fermentation treatment was suggested as a promising pretreatment for stable AGS granulation and operation.展开更多
An analytical approach is described for the axisymmetric flow through a permeable near-sphere with a modification to boundary conditions in order to account permeability. The Stokes equation was solved by a regular pe...An analytical approach is described for the axisymmetric flow through a permeable near-sphere with a modification to boundary conditions in order to account permeability. The Stokes equation was solved by a regular perturbation technique up to the second order correction in epsilon representing the deviation from the radius of nondeformed sphere. The drag and the flow rate were calculated and the results were evaluated from the point of geometry and the permeability of the surface. An attempt also was made to apply the theory to the filter feeding problem. The filter appendages of small ecologically important aquatic organisms were modeled as axisymmetric permeable bodies, therefore a rough model for this problem was considered here as an oblate spheroid or near-sphere.展开更多
基金This work was supported by Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2017ZX07102-003 and 2017ZX07103)National Natural Science Foundation of China(Grant No.51608298).
文摘The influences of flow patterns(mixed-flow and plug-flow)and fermentation pretreatment on aerobic granular sludge(AGS)formation with various substrate availability levels were investigated by running four identical laboratory-scale sequencing batch reactors(R1-R4),comparing two anaerobic feeding strategies and three kinds of substrates.R1 achieved faster granulation with a fast influent fill step followed by a modified anaerobic mixed-flow phase,but the AGS showed poorer stability with a cracked structure and a high suspended solids concentration in the effluent.The anaerobic plug-flow feeding mode(with influent fed slowly from the bottom)in R2 provided deeper penetration depth for the substance to reach the core of A G S and accordingly strengthen A G S stability.An acidogenic upflow sludge bed reactor was introduced as a pretreatment to improve the AGS performance by enhancing glucose pre-fermentation(R4).AGS fed with mixed volatile fatty acids(VFA)after glucose fermentation showed similar performance compared with the reactor fed with acetate in the aspects of stability,structure,size distribution and nitrogen removal efficiency,and 74%similarity in the microbial community.For actual wastewater with low VFA concentrations,fermentation treatment was suggested as a promising pretreatment for stable AGS granulation and operation.
文摘An analytical approach is described for the axisymmetric flow through a permeable near-sphere with a modification to boundary conditions in order to account permeability. The Stokes equation was solved by a regular perturbation technique up to the second order correction in epsilon representing the deviation from the radius of nondeformed sphere. The drag and the flow rate were calculated and the results were evaluated from the point of geometry and the permeability of the surface. An attempt also was made to apply the theory to the filter feeding problem. The filter appendages of small ecologically important aquatic organisms were modeled as axisymmetric permeable bodies, therefore a rough model for this problem was considered here as an oblate spheroid or near-sphere.
