Handbook of Civil Engineering Calculations

Filtration in a traveling bridge filter is accomplished at a hydraulic loading typically in

the range of 1.5 to 3.0 gal/min per square foot of filter surface (1.02 to 2.04 L/s-m

2

) at av-

erage daily flow. The maximum hydraulic loading used for design is typically 4.0

gal/min/ft

2

(2.72 L/s-m

2

) at peak flow. The peak hydraulic loading is used to size the trav-

eling bridge filter.

The peak flow for this treatment facility is calculated as follows:

Peak flow = (peaking factor)(average daily flow) = (2.5)(4.0 Mgd)

• 10 Mdg = 6944 gal/min (438.2 L/s)

FIGURE 5. Traveling bridge filter.

Rail Filter Cell (typ)

Backwash

Water

Effluent

Effluent Channel

Traveling Bridge

Backwash Pump

Influent'

Washwater

Trough

Washwater Pump

TRAVELING BRIDGE FILTER - PLAN

Washwater Trough Traveling Bridge

Backwash Pump

Backwash Water

Filter Medium

Effluent

Filter Media Support Plate Underdrain Individual Filter Cells

Variable Water Surface.

Influent

Backwash Hood

ILLUSTRATIVE SECTION