UFC 3-280-03
23 JULY 2003
2-3.2
Comparison with other Dewatering Processes. Table 2-1compares
mechanical dewatering devices used for various sludge applications. Mechanical
dewatering devices include the centrifuge, vacuum filter, belt, and pressure filter (i.e.,
fixed-volume and variable-volume press) presses. The following trends were noted from
this information:
The solid bowl centrifuge and vacuum filter presses generate similar results.
The belt filter press results are better than those for centrifuge and vacuum
filter presses, but are not as good as the plate filter press results.
The fixed-volume plate filter presses will produce 6 to 10% drier cake than the
continuously fed systems (i.e., centrifuges, vacuum, and belt presses).
The variable-volume filter press can increase cake solids by an additional 3 to
5% over the fixed-volume filter press.
Table 2-1. Comparison of mechanical sludge dewatering processes
for various sludge applications.
Percent Total Dewatered Cake Solids
Variable
Solid Bowl
Vacuum
Belt
Fixed
Type of Sludge
Volume
Centrifuge
Filter
Press
Volume
Filter Press
Filter
Press
Metal Finishing Waste
1525
1525
NR
4055
NR
Municipal:Primary (P)
2935
2532
3238
4046
4450
Municipal:Raw Waste Activated
1420
1218
1319
2733
3036
Sludge (WAS)
Municipal:Digested P
2732
2229
2933
4046
4350
Municipal:Digested P&WAS
2024
1621
1621
3339
3642
Municipal:Digested WAS
1216
914
1116
2532
3035
Municipal:Thermally Conditioned P
2935
3036
3036
4651
4954
and WAS
Municipal:Raw Trickling Filter (TF)
1420
1318
1320
2632
2933
Municipal:Digested TF
1620
1319
1420
NR
NR
Municipal:Raw P and TF
2126
1823
2126
3136
3440
Municipal:Digested P and TF
2025
1723
2025
2934
3338
Municipal:Water Alum Treatment
1215
1520
NR
4050
NR
Petroleum Industry
1015
1520
1520
3550
NR
Pulp and Paper Industry
2535
2030
NR
3540
NR
NR
Not Reported
P
Primary Sludge
WAS Waste Activated Sludge
TF
Trickling Filter Sludge
Source: EPA (1982b and 1987), Eckenfelder (1981).
Overall, these results demonstrate that higher cake solids may be obtained by use of
the plate and frame filter presses.
2-12
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