7.1 National Research Council Models
The National Research Council (NRC) compiled data for 34 operating rock trickling
filters over an 8-month period during World War II [80]. The range of BOD removal
in the field operations was between 75% and 95%. These field data are presented
graphically in Fig. 3.20. The average performance of a single-stage rock trickling
filter based on these field data can be expressed by the empirical models proposed by
the NRC in 1946.
E 1 ¼
100
1 þ K nrc W=VF
ð
Þ
0:5
¼ L 0 À L e =L 0
ð3:33Þ
F ¼
1 þ R
1 þ 0:1R
ð
Þ
2
ð3:34Þ
W ¼ L 0 Q
ð3:35Þ
R ¼ Q r =Q
ð3:36Þ
in which:
K nrc ¼ 0.0085
E 1 ¼ % efficiency of BOD removal for process, including recirculation and
sedimentation
L 0 ¼ BOD of influent, mass/volume, lb/MG
L e ¼ BOD of effluent, mass/volume, lb/MG
W ¼ BOD loading to filter, mass/time, lb/d
Fig. 3.20 Comparison of trickling filter operating data with NRC equation. (Source: US EPA)
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L. K. Wang et al.
The National Research Council (NRC) compiled data for 34 operating rock trickling
filters over an 8-month period during World War II [80]. The range of BOD removal
in the field operations was between 75% and 95%. These field data are presented
graphically in Fig. 3.20. The average performance of a single-stage rock trickling
filter based on these field data can be expressed by the empirical models proposed by
the NRC in 1946.
E 1 ¼
100
1 þ K nrc W=VF
ð
Þ
0:5
¼ L 0 À L e =L 0
ð3:33Þ
F ¼
1 þ R
1 þ 0:1R
ð
Þ
2
ð3:34Þ
W ¼ L 0 Q
ð3:35Þ
R ¼ Q r =Q
ð3:36Þ
in which:
K nrc ¼ 0.0085
E 1 ¼ % efficiency of BOD removal for process, including recirculation and
sedimentation
L 0 ¼ BOD of influent, mass/volume, lb/MG
L e ¼ BOD of effluent, mass/volume, lb/MG
W ¼ BOD loading to filter, mass/time, lb/d
Fig. 3.20 Comparison of trickling filter operating data with NRC equation. (Source: US EPA)
126
L. K. Wang et al.