Environmental Engineering Reference
In-Depth Information
10.4.7 sludge Production in Pounds per Million gallons
A common method of expressing sludge production is in pounds of
sludge per million gallons of wastewater treated:
TotalSludgeProduction(lb)
(10.8)
Sludge (lb/MG)
=
TotalWastewater Flow (MG)
Example 10.8
Problem: Records show that the plant has produced 85,000 gal of sludge
during the past 30 days. The average daily flow for this period was 1.2
MGD. What was the plant's sludge production in pounds per million
gallons?
Solution:
85,000 gal
×
×
8.34 lb/gal
Sludge
=
=
19,692 lb/MG
1.2MGD
30 day
s
10.4.8 sludge Production in Wet Tons per year
Sludge production can also be expressed in terms of the amount of
sludge (water and solids) produced per year. This is normally expressed
in wet tons per year:
ction (lb/MG)
Avg. Daily Flow (MGD)
Sludge Produ
(10.9)
×
×
365 da
ys/yr
Sludge Production
(wet tons/yr)
=
2000 lb/ton
Example 10.9
Problem: The plant is currently producing sludge at the rate of 16,500 lb/
MG. The current average daily wastewater flow rate is 1.5 MGD. What will
be the total amount of sludge produced in wet tons per year?
Solution:
Sludge
Production
16,500 lb/MG1.5 MGD365 d
×
×
ays/yr
=
=
4517 wettons/yr
2000 lb/ton
10.5 sludge ThiCKening
The solids content of primary, activated, trickling-filter, or even
mixed sludge (i.e., primary plus activated sludge) varies considerably,
depending on the characteristics of the sludge. Note that the sludge
removal and pumping facilities and the method of operation also affect
the solids content. Sludge thickening (or concentration ) is a unit process
 
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