Applying fine bubble aeration to small aeration tanks

Abstract

Because the aeration system in an activated sludge plant typically represents a large part of the total energy requirements, designers and operators need accurate oxygen transfer information to make the aeration system as energy efficient as possible. This paper presents clean water tests performed at 38 wastewater treatment plants. The Specific Aeration Efficiency results (SAE, kgO2/kWh) are reported for: (1) large open channels (volume higher than 1000 m3), (2) small open channels, (3) total floor coverage cylindrical tanks, and (4) cylindrical tanks with a grid arrangement. Some practical guidelines can be drawn, some of them being: (1) high SAE can be achieved at small aeration tanks (< 1000 m3), applying cylindrical tanks with a total floor coverage arrangement of diffusers, volumetric blowers, and moderate air flow rates per diffuser area; (2) the high investment cost of this configuration can be justified with respect to a grid layout characterized by spiral liquid circulation which affects the oxygen transfer; (3) small open channels can meet sufficient SAE values but fail to meet in this range of tank volumes those of total floor coverage cylindrical tanks.

Review of options for creating and maintaining oxygen refuges for fish during destratification-driven hypoxia in rivers

“…They are therefore more efficient at increasing the DO concentration of hypoxic water and do so in a more energy-efficient way (Ovezea 2009). This means ultrafine bubble injection is becoming a more frequently used approach for aerating water in the aquaculture and waste water treatment industries (Duchène et al 2001;Cheng et al 2019). Ultrafine bubble pumps often use pure oxygen, either from compressed liquid gas or generated by a condenser, improving the efficiency with which oxygen is added to the water (Ovezea 2009).…”

Evaluating the performance of fine bubble diffused aeration systems in cylindrical aeration tanks by fuzzy c-means algorithm

“…parallel-lines-type diffuser .cross-type diffuser. The reason is that compared with other layouts of fine-pore aeration tubes, the ring-type diffuser can use the thrust to rotate the water flow in aeration tanks to generate a stable vortex flow field, so that fine bubbles can contact with the water fully and this leads to high overall efficiency of oxygen mass transfer and well uniform distribution of DO concentration in aeration tanks (Duchène et al 2001;Kim & Ra 2005). In the case of the square-type diffuser, it can generate thrust and make a minor horizontal push flow, however, the push flow can not make fine bubbles and water mix well due to lack of turbulent force, and this results in the worse distribution uniformity of DO concentration in aeration tank and lower overall efficiency of oxygen mass transfer than that caused by ring-type diffuser.…”

“…Fine bubble diffused aeration systems equipped with fine-pore aeration tubes have been increasingly used in cylindrical aeration tanks (Duchène et al 2001;Mayer et al 2006;Schierholz et al 2006;Temmerman et al 2015;Wang & Zhang 2017). These aeration systems have several advantages, which have contributed to their extensive development: high oxygenation performances, adaptability to varying oxygen requirements, and a reduction in the production of aerosols (Duchène et al 2001;Gillot et al 2005).…”

Oxygen transfer and power consumption in an aeration system using mist and circulation flow generated by a rotating cone

“…On the studies using air bubbles for aeration, Ashley et al (1992) have studied bench-scale study of oxygen transfer in coarse bubbles, while Duchene et al (2001) have focused on fine bubbles for the aeration. A range of diameter of coarse bubbles is between 6 and 10 mm and one of fine bubbles is between 2 and 5 mm.…”