Dissolved Oxygen Optimization & Reducing Utility Costs

Supplying dissolved oxygen typically uses between 40 - 60% of the electricity used in waste water treatment. Many facilities have enough aeration capacity for maximum loading design which well above average daily loadings. In the short run managing aeration by optimizing blower or surface aeration operation can cut electricity use. However, in many cases we rely on the diffusers & mechanical aerators for mixing as well as dissolved oxygen. So while we may have enough dissolved oxygen but not have enough mixing to keep biological solids suspended. Optimizing both aeration and mixing can help reduce utility costs. Here is how to optimize aeration:

• Take D.O. readings in the basin at various locations & depths on several days to get a DO profile
• By taking multiple readings in the basin, you can confirm or question the readings on the typical basin side DO meter
• Adjust blowers and aerators to maintain DO of 2.0 at the sampling points in the system. At a DO of 2.0, there is enough oxygen for ammonia removal and the aerobic carbonaceous bacteria (normal COD/BOD removing microbes) are at 90% efficiency. Compare this to a DO of 3.5 which increases utility costs substantially yet only gives a few more % increase in microbial efficiency