Effects of orifice size and surface conditions on oxygen transfer in a bench scale diffused aeration system

Abstract Non‐steady state gas transfer methodology was used to examine the effect of orifice size and surface conditions on the rate of oxygen transfer in a 239 L bench scale tank. Each orifice size tested (40 μ, 397 μ and 1588 μ) increased the overall oxygen transfer coefficient (KLa20, hr−1) ; standard oxygen transfer rate (OTs, g O2/hr) ; transfer efficiency (Eo, %) and energy efficiency (Ep/ g O2/kW‐hr) as orifice diameter decreased. The three surface conditions examined exerted a minor effect on oxygen transfer.