The Extended Aeration (EA) system is one of common Biological system used to treat domestic wastewater due to its functionality and simplicity.
The treatment plant provides the proper environment, sufficient oxygen and other elements which allow the bacteria to consume the organic matter and to live and multiply within the treatment plant. In this way the aerobic bacteria and microbes decompose the sewage and waste to a stable form – odor and nuisance free.
This process operates under the following theory:
Raw domestic wastewater from last manhole is channeled into the primary screen where mechanical coarse screen was installed to remove coarse solid materials. The screened sewage inside wet well will then be lifted up to the secondary screen by a set of raw sewage pumps. A duty mechanical fine screen was also installed at the secondary screen chamber to remove finer solid materials in the sewage. Two aerated grit chambers are proposed subsequent to fine screen chamber for removing inert materials such as fine sand, gravel etc. Last but not least for the pre-treatment system, a grease/oil removal system is used to remove the potential oil in sewage to ensure good performance of the extended aeration system.
Advantages of Extended Aeration System:
- Easily maintained mechanical work.
- Extended aeration processes are often better at handling organic loading and flow fluctuations, as there is a greater detention time for the nutrients to be assimilated by microbes.
- Systems are odor free, can be installed in most locations, have a relatively small footprint, and can be landscaped to match the surrounding area.
- Extended aeration systems have a relatively low sludge yield due to long sludge ages, can be designed to provide nitrification, and do not require a primary clarifier.