Primary Clarifier Odor

Primary clarifiers are often the major odor generation sources in any treatment facility. The main causes of problems occurring in primary clarifiers may be attributed to high BOD concentrations, long detention times, the lack of oxygen transfer across the quiescent surface, anaerobic conditions resulting in hydrogen sulfide accumulation, and efficient stripping of noxious volatiles in the discharge weirs.

Odor prevention in the primary clarifier depends upon a sufficient influent D.O. increase to a concentration in excess of that consumed in passage through the primary clarifier. Provision of 20 to 30 mg/L DO through pure oxygen supplementation will maintain aerobic conditions and preclude hydrogen sulfide generation in the bulk water while allowing bacterial oxidation of hydrogen sulfide flux from the sludge layer into the bulk water. Suspended solids will not be affected as the dissolved oxygen will remain in solution. No effervescence will occur as the amount of D.O. required is well below the saturation concentration of pure oxygen in water.

Adding ECO2 SuperOxygenation to the primaries will either protect existing covers from corrosion or eliminate the need for costly covers and the associated foul air scrubbers altogether.

In addition to odor control, a direct reduction in D.O. consumption will occur in the aeration tank in proportion to the DO consumed in the primary clarifier.

Goals:

• Establish and sustain aerobic conditions
• Prevent odor caused by hydrogen sulfide and other organic compounds
• Prevent corrosion due to sulfuric acid
• Eliminate requirement to cover WWTP headworks and chemically scrub off-gases
• Eliminates confined space maintenance issues
• No impact to settling