This European chemical company’s propylene oxide/tertiary butyl alcohol plant decided to expand its activated sludge system. The existing 1.58 MG (6,000 m 3) concrete basin had reached capacity. Also, three 60 hp (45 kW) surface splasher aerators negatively impacted winter treatment due to heat loss from evaporative cooling. The flow had to be heated to maintain treatment efficiency. That was expensive. And, the aerosols from the surface splasher aerators also caused odor problems.
A new parallel activated sludge system was put online in 1990, doubling capacity. The AIRE-O2® aspirator aeration system was chosen for the new basin, after receiving good engineering recommendations. Sixteen (16) x 25 hp (18.5 kW) units were bridge-mounted in four rows of four aerators each. The project engineer said, 'To compare the two systems, all you have to do is look at them. You can see the difference. The AIRE-O2® system basin is far more superior in terms of aerosols, odors, and its overall appearance.'
The 0.265 MGD (1,000 m 3/day) flow has a chemical oxygen demand (C.O.D.) of 7,000 mg/l and achieves a 90% removal rate. The engineer reports, 'The AIRE-O2® aerators offered more operational flexibility. The units offered turndown capability to match the flow. Our maintenance people are very happy with them. Maintenance is much easier with their light weight and compact size.'