Strategic Filter Backwashing Techniques and Resulting Particle Passage

The effect of solution chemistry on the behavior of kaolinite in three different situations was investigated: (1) the detachment of kaolinite from glass beads in a fluidized bed, (2) the erosion of kaolinite deposits in a laboratory flume and (3) the determination of the stress-strain rate relationship of concentrated suspensions in a rheometer. The experimental results from these three different approaches could be explained in terms of changes in mode of particle associations which in turn could be characterized in terms of a micromechanical force model which predicts the effect of solution chemistry on the interaction force between adjacent particle surfaces. Understanding the relationship between solution and surface chemistry on the structure, mechanical strength and mechanism of erosion of cohesive sediment deposits is an important step towards developing predictive models of a number of processes including erosion of cohesive sediments in streams and estuaries, and detachment of particles from granular media during filtration and filter backwashing.

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Suspension concentration profiles during rapid gravity filter backwashing

Chemical Engineering Journal ◽

10.1016/s1383-5866(00)00092-7 ◽

2000 ◽

Vol 80 (1-3) ◽

pp. 197-201 ◽

Cited By ~ 2

Author(s):

David Hall ◽

Caroline S.B Fitzpatrick

Keyword(s):

Concentration Profiles ◽

Suspension Concentration ◽

Filter Backwashing

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Optimisation of filter backwashing

Filtration + Separation ◽

10.1016/s0015-1882(01)80418-3 ◽

2001 ◽

Vol 38 (7) ◽

pp. 20

Keyword(s):

Filter Backwashing

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Velocity Gradients in Granular Filter Backwashing

American Water Works Association ◽

10.1002/j.1551-8833.1979.tb04449.x ◽

1979 ◽

Vol 71 (12) ◽

pp. 732-738 ◽

Cited By ~ 5

Author(s):

Jorge Arboleda Valencia ◽

John L. Cleasby

Keyword(s):

Granular Filter ◽

Velocity Gradients ◽

Filter Backwashing

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Development of pre-coagulation and bio-filtration process for advanced treatment of sewage

Water Science & Technology Water Supply ◽

10.2166/ws.2004.0003 ◽

2004 ◽

Vol 4 (1) ◽

pp. 13-22 ◽

Cited By ~ 4

Author(s):

H. Tsuno ◽

T. Hidaka ◽

M. Nakamoto

Keyword(s):

Control Systems ◽

Retention Time ◽

Hydraulic Retention Time ◽

Advanced Treatment ◽

Filtration Process ◽

Automatic Control Systems ◽

Side Stream ◽

Addition Rate ◽

Filtration Unit ◽

Filter Backwashing

A pre-coagulation and bio-filtration process for advanced treatment of sewage is developed and experimentally discussed with a pilot plant. The bio-filtration unit consists of a denitrification filter, a nitrification filter with side stream to the denitrification filter, and a polishing filter with anoxic and aerobic parts. Concentrations of SS, T-CODCr, T-C-BOD, T-N and T-P in the effluent were stably kept at less than mg/L, 20 mg/L, 5 mg/L, 2 mg N/L and 0.2 mg P/L, respectively, and transparency at higher than 100 cm, under total hydraulic retention time (HRT) of 3.2 h in the bio-filtration parts. S-CODCr/NOx−-N ratio of higher than 12 mg COD/mg N is required to keep the remaining NOx−-N concentrations less than 1 mg N/L in the effluent from the denitrification filter. Methanol addition rate of higher than 4.5 mg COD/mg N is necessary to accomplish denitrification with the remaining NOx−-N of less than 0.5 mg N/L in the effluent from the polishing filter. Backwashing in each filter as well as methanol addition and aeration in the polishing filter were able to be operated successfully by the automatic control systems. Therefore this process is proved to be applicable to advanced treatment of sewage with easy maintenance.

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