Sodium molybdate is widely used as a corrosion inhibitor in recirculating cooling water systems. Molybdate exhibits comparatively low aquatic toxicity and was therefore apart of the EPA's rationale for limiting chromate use in comfort cooling towers. The EPA's recent final ruling on molybdenum in sludge (40CFR, 503.13, 2/19/93) is unnecessarily stringent and in conflict with previous EPA rulings. This paper will examine specific concerns over molybdate discharge, the EPA's justification for these new limits and future prospects for the use of molybdate as well as end-user impact.

94-06: Molybdate Use in Cooling Towers: Impact of the New EPA Sludge Rule and