The overall volumetric mass transfer coefficient (KLa) and the overall gas holdup (ε) were measured in a jet loop reactor (JLR) used for the intensive aerobic biological treatment of waste water. The process parameters and their ranges were: inlet water flow rate: 30 &#le; QL &#le; 70 l/min, inlet air flow rate: 4 &#le; Qg &#le; 36 l/min. The ratio of water flow rates from the bottom of the reactor (QB) and the inlet water flow rate (QL) varied in the range 0.0 &#le; QB/QL &#le; 0.92. It was found that, both KLa, and ε increased with increasing Qg. Up to a critical Qg value, neither KLa nor ε varied with energy dissipation rate per unit volume, E/V, but beyond these Qg values, KLa decreased while ε increased with increasing E/V. Water withdrawal from the bottom of the reactor in addition to that from the top, increased KLa up to 30% depending on the process conditions. Use of pure oxygen instead of air could also lead to increases in KLa up to 19%.
Keywords: gas hold-up, jet loop reactor, mass transfer, oxygen transfer, process intensification, wastewater treatment, water treatment, water quality