The extended aeration process and its main advantages and disadvantages

The extended aeration process offers certain benefits that can be combined with conventional processes to obtain a high quality effluent. In this article I provide the main advantages and disadvantages of this process.

The extended aeration process transforms the popularly used fully mixed activated sludge process. This is achieved by a longer hydraulic retention period, as well as a longer solid retention period. Sludge digestion units using an aerobic process are often used when implementing this process. The extended aeration activated sludge process is used where the influent reception rate at the wastewater treatment plant is less than 50,000 gpd or 2 L/s.

Some of the advantages of the extended aeration process are:

This process requires little time to prepare the site as the plants are manufactured as pre-engineered and packaged units. This process is reliable under sufficient supervision. The initial investment and costs are lower. The land area required to install the plant is minimal. This process produces the least amount of sludge among the various processes that use activated sludge. The temperature in the wastewater is around 15 degrees C and this allows for nitrification. Hydraulic head shock at a moderate level can be easily absorbed with a minimum of problems experienced. The resulting effluent is of a higher quality than many other processes.

However, there are also certain disadvantages. These are:

Packaged plants and their prebuilt modules may need some changes to comply with different regional standards for download. At higher temperatures, denitrification occurs which can potentially pave the way for sludge lift. A large variation in the inlet flow can reduce the efficiency of segregation of suspended solids in wastewater and its BOD. Compared to other natural wastewater treatment systems and land-based systems, this process consumes more energy and has a higher cost of power requirements. In colder regions, the process is susceptible to freezing. Certain annoying factors associated with this process are the smell produced when treating the sludge and the noise from the blower. This process requires a higher quality of skill for operational and maintenance functions.