tertiary treatment, not only in removal of BOD, COD, TSS, and coliforms, but also
in land space requirement and consequently in capital cost required to be invested for
reusing the treated effluent in snow making machines.
8 Treatment of Trickling Filter Effluent
The effectiveness of the FF-Cell in treating the secondary trickling filter [40] effluent
at the Norwalk Wastewater Treatment Plant in Ohio, USA was investigated in this
part of the applications. Norwalk is located in northern Ohio, approximately 50 miles
southwest of Cleveland and supports a population of 14,500 people. The plant treats
combined domestic sewage and food processing waste [18].
Secondary trickling filter effluent was pumped to the FF-Cell with a submersible
sump pump at 164 m
3 /d. Treatment chemicals were added directly to the feed line
using masterflex variable speed peristaltic dosing pumps. Alum was added approximately 12 m ahead of the FF-Cell to allow for thorough mixing. Anionic polymer
(Nalco 7769) was added in line just prior to the FF-Cell inlet compartment. TSS,
BOD, and phosphate-P tests were all performed on daily composite samples collected from the influent and effluent of the FF-Cell. Experimental results are
summarized in Table 2.6. It can be seen that on the average, the FF-Cell met the
tertiary effluent standards (TSS ¼ 10 mg/L, BOD ¼ 10 mg/L and P ¼ 1 mg/L) with
removals above 90%. Considering the final three testing periods (# 6, 7 and 8 in
Table 2.6) when chemical dosages, 120 mg/L of alum and 0.25 mg/L of polymer,
were optimized, the FF-Cell effluent met the above-mentioned effluent standards all
Table 2.6 Tertiary treatment of trickling filter effluent by FF-Cell at Norwalk, OH, USA [18]
Period
TSS, mg/L
BOD
mg/L
Phosphates-P, mg/L
In
Out
In
Out
In
Out
1
104
11
54
5
8.8
0.8
2
136
6
51
3
9.2
0.4
3
122
12
–
–
9.6
1.1
4
106
1
45
2
–
0.3
5
72
4
43
3
6.7
0.3
6
a
28
9
20
4
7.0
0.7
7
a
132
7
32
4
4.5
0.2
8
a
103
8
39
4
7.8
0.6
Range:
min.
28
1
20
2
4.5
0.2
max.
136
12
54
5
9.6
1.1
Average
100
7.2
41
3.6
7.7
0.6
Removal, %
93
91
92
a Optimized chemistry: Alum ¼ 120 mg/L as alum and anionic polymer Nalco 7769 ¼ 0.25 mg/L
All tests were done on daily composite samples
66
N. K. Shammas et al.
in land space requirement and consequently in capital cost required to be invested for
reusing the treated effluent in snow making machines.
8 Treatment of Trickling Filter Effluent
The effectiveness of the FF-Cell in treating the secondary trickling filter [40] effluent
at the Norwalk Wastewater Treatment Plant in Ohio, USA was investigated in this
part of the applications. Norwalk is located in northern Ohio, approximately 50 miles
southwest of Cleveland and supports a population of 14,500 people. The plant treats
combined domestic sewage and food processing waste [18].
Secondary trickling filter effluent was pumped to the FF-Cell with a submersible
sump pump at 164 m
3 /d. Treatment chemicals were added directly to the feed line
using masterflex variable speed peristaltic dosing pumps. Alum was added approximately 12 m ahead of the FF-Cell to allow for thorough mixing. Anionic polymer
(Nalco 7769) was added in line just prior to the FF-Cell inlet compartment. TSS,
BOD, and phosphate-P tests were all performed on daily composite samples collected from the influent and effluent of the FF-Cell. Experimental results are
summarized in Table 2.6. It can be seen that on the average, the FF-Cell met the
tertiary effluent standards (TSS ¼ 10 mg/L, BOD ¼ 10 mg/L and P ¼ 1 mg/L) with
removals above 90%. Considering the final three testing periods (# 6, 7 and 8 in
Table 2.6) when chemical dosages, 120 mg/L of alum and 0.25 mg/L of polymer,
were optimized, the FF-Cell effluent met the above-mentioned effluent standards all
Table 2.6 Tertiary treatment of trickling filter effluent by FF-Cell at Norwalk, OH, USA [18]
Period
TSS, mg/L
BOD
mg/L
Phosphates-P, mg/L
In
Out
In
Out
In
Out
1
104
11
54
5
8.8
0.8
2
136
6
51
3
9.2
0.4
3
122
12
–
–
9.6
1.1
4
106
1
45
2
–
0.3
5
72
4
43
3
6.7
0.3
6
a
28
9
20
4
7.0
0.7
7
a
132
7
32
4
4.5
0.2
8
a
103
8
39
4
7.8
0.6
Range:
min.
28
1
20
2
4.5
0.2
max.
136
12
54
5
9.6
1.1
Average
100
7.2
41
3.6
7.7
0.6
Removal, %
93
91
92
a Optimized chemistry: Alum ¼ 120 mg/L as alum and anionic polymer Nalco 7769 ¼ 0.25 mg/L
All tests were done on daily composite samples
66
N. K. Shammas et al.