A battery manufacturing plant has been ordered to cease discharging acidic waste liquids containing mercury into the city sewer system. As a result, the firm must now adjust the pH and remove the mercury from its waste liquids. Three firms have provided quotations on the necessary equipment. An analysis of the quotations provided the following table of costs.

Bidder	Installed Cost	Annual Operating Cost	Annual Income from Mercury Recovery	Salvage Value
Foxhill Instrument	$35,000	$8,000	$2,000	$20,000
Quicksilver	40,000	7,000	2,200	0
Almaden	100,000	2,000	3,500	0

If the installation can be expected to last 20 years and MARR is 8%, which equipment should be purchased based on Present Worth Analysis? (Justify answer)