Environmental Engineering Reference
In-Depth Information
2,5
2
1, 5
1
0,5
0
Bf . Modif ication
Af . Modif ication
Fig. 5.3.
Energy distribution in the BioMax ATUs before and after modification
5.4.4 Operational Cost of the BioMax C10 ATUs
The linear compressor of the BioMax C10 system that was used as an aeration de-
vice has the following specifications; power consumption of 0.099 kW, a rated
voltage of 230 V.AC, rated airflow of 80 L/min, rated frequency of 50 Hz and a
duty cycle that is continuous. Using a cost of electricity per unit of 13.94 cents.
The cost of energy used per day if the compressor operates continuously for 24
hours to provide air for the suspended-growth chamber, can be calculated as:
•
per day: 0.099 kW × 24 h × $0.1394 per kW = $0.3312 (5.2)
•
per annum: $ 0.3312 x 365 days = $ 120.89 (5.3)
If the compressor operated for 12 hours a day (50% less energy used) then the cost
of energy used can be calculated as:
•
per day: 0.099 kW × 12 h × $0.1394 per kW = $ 0.1656 (5.4)
•
per annum: $0.1656 × 365 days = $60.45 (5.5)
5.5 Discussion
As evident in
Table 5.2
, the modification experiment yielded better performance
than the existed system. This could be attributed to a number of factors but the
main one been the amount of air introduced into the system by the aeration re-
gime. It could be said that perhaps the aeration period was just enough in the
modification process to provide the necessary conditions for the various biological
activities. Nitrogen removed was higher in the modification experiment than usual
levels in the existed system. The higher percentage removal efficiency could per-
haps be due to higher nitrification and denitrification rate in the aeration chamber.
This is however clear, in support of a report by Wang et al. (2008), that nitrifica-
tion and denitrification occur simultaneously when the dissolved oxygen (DO) in
wastewater treatment plants drops in aeration tanks. It could also be due to the fact
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