Factors Affecting the Performance of Diffused-Air Aeration Systems for Aquaculture

A diffused-air aeration system which operated at low gauge pressure (1.1 to 4.3 m H20) was operated with six or twelve diffusers at five depths between 0.91 and 3.35 m and six air flow rates between 28 and 255 l/minute. The standard oxygen transfer rate (SOTR) or amount of oxygen transferred per hour increased markedly with increasing diffuser depth and air flow rate, but the power required to deliver air to the diffusers also increased as air flow rates and diffuser depths increased. Best standard aeration efficiency (SAE) values (2.0 to 2.5 kg O2/kW·hr) were obtained at air flow rates of 28 and 57 1/minute. With six diffusers and 28 and 57 air/minute, peak SAE occurred at 2.13 and 2.74 m, respectively. With twelve diffusers, peak SAE was achieved at 0.91 m for 28 1 air/minute and at 2.74 m for 57 1 air/minute. In order to efficiently deliver air into water at a high rate, a large number of diffusers is needed.