Aeration in Wastewater Treatment

Wastewater aeration is the addition of air to the treatment process to allow the bio-degradation of pollutants and forms an integral part of the process. Unlike chemical treatments, such as disinfection, this process relies on microorganisms already present in the wastewater to break down and digest pollutants for subsequent settling/removal.

In municipal wastewater treatment, aeration is part of the stage known as secondary treatment. The activated sludge process is the most commonly used system within this stage of wastewater treatment. This involves blowing air into a tank (or series of tanks, depending on hydraulic throughput required) containing the wastewater to be treated. By adding air through specially designed nozzles that control bubble size, air flow rate, etc this promotes microbial growth within the wastewater which in turn generates activated sludge "flocks", which can be easily settled out later in the treatment process. Some recirculation of these flocks is also carried out within the process, to encourage further flocculation and removal of contaminants.

I visited one such wastewater plant recently and was interested to learn more about the design of the plant and how IPS Flow Systems have assisted with the piping systems required to deliver air and recirculated "flocculated" wastewater to various basins within this particular plant. I was fortunate enough to see inside one drained down tank and exactly how the air and water is delivered to the process compared to an in-service tank. Our solvent welded PVCu piping systems are currently being used to refurbish the plant for this very purpose. Some of this pipework can be seen in the pictures above.

This plant in question receives and processes close to 350 litres per second of wastewater with a variety of contaminants.