Large hidden costs and relatively low energy efficiency of FBD Aeration under field conditions became a major component of Aeration OpEx.

Clean-In-Place : Every 4 months to 2 years; Requires Aeration Tank emptying for 10-15 days; Aeration tank operation recovery –up to 2 months;
Energy Consumption rises due to FBD performance deterioration due to fouling and accelerated aging:

-  at first 12 months energy consumption rises by 30% above that of new diffusers;
- energy Consumption rises every year by additional 20% even if diffusers cleaned
Diffusers Replacement: complete replacement - every 5 years ( even if Manufacturer state different); Partial replacement - up to 15% /year (Aeration Tank emptying required); Replacement cost is up to 3 times more expensive than new diffusers;
Fine pore diffusers always require cleaning. If cleaning is not possible, fine poor diffusers are a very poor choice. ( M. K. Stenstrom, D. Rosso; University of California )