Estimating the porosity of a full-scale anthracite filter bed

The weight of media per unit of filter area cannot be directly measured in a full-scale filter bed as it can be in a pilot-scale filter column. Thus the porosity of a full-scale bed of filter media cannot be readily calculated, and determinations of the porosity in full-scale filters are rarely repo...

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Bibliographic Details
Published in:Journal - American Water Works Association 1999-12, Vol.91 (12), p.54-63
Main Authors: Trussell, R. Rhodes, Chang, Melissa M., Lang, John S., Hodges, Willie E.
Format: Article
Language:English
Subjects:
Accuracy
Anthracite
Applied sciences
Backwash
Benchmarks
Coal
Design engineering
Drinking water and swimming-pool water. Desalination
Estimate reliability
Exact sciences and technology
Filters
Flow
Flow control
Gravel
Head Loss
Manometers
Pilot projects
Pollution
Porosity
Tape measures
Underestimates
Water filtration
Water treatment and pollution
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Summary:The weight of media per unit of filter area cannot be directly measured in a full-scale filter bed as it can be in a pilot-scale filter column. Thus the porosity of a full-scale bed of filter media cannot be readily calculated, and determinations of the porosity in full-scale filters are rarely reported. In this study the porosity of one full-scale monomedia filter bed was estimated by comparing the head loss in a full-scale filter with the head loss in a pilot-scale filter, when both used the same anthracite media. The full-scale filter contained uniform anthracite media with an effective size of 1.5 mm loaded to a depth of 6 ft (1.8 m). The gradual termination of the backwash flow produced more consistent porosities in pilot-scale filter beds. The porosity of the full-scale filter bed was about 48 percent, somewhat lower than that expected in pilot-scale columns. Thus, full-scale designs based on pilot data may underestimate clean-bed head loss.
ISSN:0003-150X
1551-8833
DOI:10.1002/j.1551-8833.1999.tb08750.x