Environmental Engineering Reference
In-Depth Information
During all periods of this experiment a high degree of the BOD removal was
noted. The effect of BOD removal as a function of the decrease in the aeration
time was evident in this experiment.
Table 5.2
shows BOD removal from a mean
value of 77.2 to 12.6 mg/l, indicating about 83.7% removal efficiency of the influ-
ent quality. Nitrate nitrogen concentrations showed in
Table 5.2
, indicates an ap-
preciable decrease from 36.3 to 18.7 mg/l. This represents about 48.5% removal
efficiency. Ammonia nitrogen (NH
3
-N) concentration showed an increase in con-
centration from 8.5 to 12.4 mg/l after modification, whereas in the existed system,
it increased to 14.6 mg/l. Due to the low concentration of nitrate and ammonia af-
ter the modification it could be assumed that some amount of nitrification and de-
nitrification occurred. Phosphorus removal efficiency was very high. It can be in-
ferred that a decrease in the influent concentration was from 5.9 to 3.6 mg/l
indicating removal efficiency of 40% (
Table 5.2
). Suspended solids (SS) were
found to decrease in both effluents. However, the decrease was very pronounced
after the modification.
Table 5.2
indicates a decrease in SS concentration from
39.2 to 9.4 mg/l. This represents about 76.4%.
90
80
70
60
50
Bf.project
Af.project
40
30
20
10
0
Nit-N
Phos
Susp solids
BOD5
Fig. 5.2.
Performance of the BioMax ATUs at the two different energy levels
On the whole, the general performance of the BioMaX ATUs (
Fig. 5.2
) was better
after the modification in the aeration regime.
5.4.3 Argument for Energy Conservation
Figure 5.3
shows the energy distribution before and after modification of aeration
period of the BioMax system. It was observed that 50% energy conservation was
made when the system operated for 12 hours/day. This is also reflected in a 50%
reduction in the operational cost. This means that 50% energy conservation re-
duced the operational cost also by 50%.
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