Wastewater Calculations - Mathematics and Statistics for the Environment - page 732

Polymer

Sludge

Disposal

Water

Return for
treatment

FIGURE 24.9 Belt filter press.

■ EXAMPLE 24.117
Problem: A belt filter press 5 ft wide receives a primary biosolids flow of 150 gpm. What is the
hydraulic loading rate in gpm/ft 2 ?

Solution:

Flow (gpm)
B

150 gpm
5ft

Hydraulic loadingrate(gpm/ft) = = = 30 gpm/ft

eltwidth (ft)

24.14.2.2.2 Biosolids Feed Rate
The biosolids feed rate to the belt filter press depends on several factors, including the biosolids (lb/
day) that must be dewatered, the maximum solids feed rate (lb/hr) that will produce an acceptable
cake dryness, and the number of hours per day the belt press is in operation. The equation used in
calculating biosolids feed rate is

Dewateredbioso lids (lb/day)

Operatingtime(hr/day)

Biosolidsfeed rate (lb/hr) = (2 4.151)

■ EXAMPLE 24.118
Problem: The amount of biosolids to be dewatered by the belt filter press is 20,600 lb/day. If the
belt filter press is to be operated 10 hr each day, what should the biosolids feed rate in lb/hr be to
the press?

Solution:

Dewateredbioso lids (lb/day)

Operatingtime(hr/day)

20,60 00lb/day

10 hr/day

Biosolidsfeed rate (lb/hr) = = = 2060 lb/hr

24.14.2.2.3 Solids Loading Rate
The solids loading rate may be expressed as lb/hr or as tons/hr. In either case, the calculation is
based on biosolids flow (or feed) to the belt filter press and percent of mg/L concentration of total
suspended solids (TSS) in the biosolids. The equation used in calculating solids loading rate is

Solids loading rate (lb/hr) = Feed (gpm) × 60 (min/hr) × 8.34 lb/gal × (%TSS/10 0) (24.152)