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Table 7.4 Assumptions used for Economic Analysis (continued)<br />

EVALUATED MODIFICATIONS<br />

Assumed Reduction of<br />

,<br />

Effluent Water<br />

Modification Contaminant Consumption<br />

Concentration<br />

[%]<br />

[%]<br />

Replacement of the 600 um screens with 500 ~m 5 0<br />

screens;<br />

Replacement of the 600 pm screens with 150 ~m 20 0<br />

screens;<br />

Installation of DAF (without improved screening); 80 0<br />

In-house modifications without upgrading of the o 50<br />

treatment system;<br />

In-house modifications and replacement of the 5 50<br />

600 pm screens with 500 ~m screens;<br />

In-house modifications and replacement of the 20 50<br />

600 Pm screens with 150 pm screens; and<br />

In-house modifications and installation of DAF 80 50<br />

(without improved screening).<br />

$156,000 to $169,000. Installation of DAF without prior in-house modifications would<br />

result in more than twice the annual expenditures of any of the previously discussed<br />

changes. Due to the smaller equipment requirements, the annual expenditures for DAF<br />

during the amortization period is reduced if in-house modifications are carried out first.<br />

After the amortization period the lowest annual expenditures would be expected for inhouse<br />

modifications and installation of finer screens, followed by in-house modifications<br />

alone. These modifications would result in a reduction of the annual expenditures by a<br />

factor of at least two, compared to the expenditures which would be required if the status’<br />

102<br />

-<br />

—<br />

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