effective in the reduction of both suspended solids (92% removal) and turbidity
(91% removal). The secondary treatment plant effluent had a total suspended solids
content in the range of 6–39 mg/L, which was reduced to an average value of below
2 mg/L. In a similar performance, the treatment plant effluent had turbidities in the
range of 2.6–14 NTU, while the FF-Cell was able to attain an average effluent
turbidity of 0.5 NTU. The BOD values were consistently at or below 1.0 mg/L.
Another application of flotation to tertiary treatment has been reported by Kiuru [36].
7 Treatment of RBC Effluent
An FF-Cell unit was installed at the Jimmy Peak Wastewater Treatment Plant in
Hancock, Massachusetts, USA. (Fig. 2.5). The 400 m
3 /d resort area domestic
wastewater flows through an aerated equalization tank, two rotating biological
contactors (RBCs) [37, 38], one circular secondary sedimentation clarifier (3.6 m
diameter), one rectangular tertiary sand filter (3.1 m
2 area), and finally two ultraviolet disinfection units [39] before being discharged to a leaching field. The FF-Cell
was fed from the RBC’s effluent just before the flow enters the secondary sedimentation clarifier (see Fig. 2.5).
Table 2.5 documents the chemical dosages applied to the FF-Cell influent, as well
as the performance data for both the FF-Cell and the conventional combination of
secondary clarifier and sand filter as they were run in parallel. The results demonstrate that with optimization of chemical dosages, it is possible to produce effluents
that can satisfy the most strict standards or guidelines with BOD & TSS
Table 2.4 Tertiary treatment of activated sludge effluent by FF-Cell at Oak Meadows STP,
Licking County, OH, USA [18]
Chemical Addition
Suspended Solids
Turbidity
Period
a
mg/L
NTU
Chemical
mg/L
In
Out
In
Out
1
Alum (as Al 2 O 3 )
3.6
23
1.0
2.6
0.95
2
Alum (as Al 2 O 3 )
4.3
39
2.6
4.3
0.50
Polymer: 1849A
0.4
3
Alum (as Al 2 O 3 )
4.9
5.9
1.0
4.2
0.29
Polymer: 1849A
0.4
4
Alum (as Al 2 O 3 )
5.3
24
2.6
14
0.46
Polymer:
Percol LT-25
0.3
5
Alum (as Al 2 O 3 )
5.6
–
–
3.7
0.34
Polymer:
Percol LT-25
0.5
Average
23
1.8
5.8
0.50
Removal %
92
91
a All tests were done an daily composite samples
2 Water Reclamation
63
(91% removal). The secondary treatment plant effluent had a total suspended solids
content in the range of 6–39 mg/L, which was reduced to an average value of below
2 mg/L. In a similar performance, the treatment plant effluent had turbidities in the
range of 2.6–14 NTU, while the FF-Cell was able to attain an average effluent
turbidity of 0.5 NTU. The BOD values were consistently at or below 1.0 mg/L.
Another application of flotation to tertiary treatment has been reported by Kiuru [36].
7 Treatment of RBC Effluent
An FF-Cell unit was installed at the Jimmy Peak Wastewater Treatment Plant in
Hancock, Massachusetts, USA. (Fig. 2.5). The 400 m
3 /d resort area domestic
wastewater flows through an aerated equalization tank, two rotating biological
contactors (RBCs) [37, 38], one circular secondary sedimentation clarifier (3.6 m
diameter), one rectangular tertiary sand filter (3.1 m
2 area), and finally two ultraviolet disinfection units [39] before being discharged to a leaching field. The FF-Cell
was fed from the RBC’s effluent just before the flow enters the secondary sedimentation clarifier (see Fig. 2.5).
Table 2.5 documents the chemical dosages applied to the FF-Cell influent, as well
as the performance data for both the FF-Cell and the conventional combination of
secondary clarifier and sand filter as they were run in parallel. The results demonstrate that with optimization of chemical dosages, it is possible to produce effluents
that can satisfy the most strict standards or guidelines with BOD & TSS
Table 2.4 Tertiary treatment of activated sludge effluent by FF-Cell at Oak Meadows STP,
Licking County, OH, USA [18]
Chemical Addition
Suspended Solids
Turbidity
Period
a
mg/L
NTU
Chemical
mg/L
In
Out
In
Out
1
Alum (as Al 2 O 3 )
3.6
23
1.0
2.6
0.95
2
Alum (as Al 2 O 3 )
4.3
39
2.6
4.3
0.50
Polymer: 1849A
0.4
3
Alum (as Al 2 O 3 )
4.9
5.9
1.0
4.2
0.29
Polymer: 1849A
0.4
4
Alum (as Al 2 O 3 )
5.3
24
2.6
14
0.46
Polymer:
Percol LT-25
0.3
5
Alum (as Al 2 O 3 )
5.6
–
–
3.7
0.34
Polymer:
Percol LT-25
0.5
Average
23
1.8
5.8
0.50
Removal %
92
91
a All tests were done an daily composite samples
2 Water Reclamation
63