Oxygen transfer characteristics of hydrophilic treated polypropylene hollow fiber membranes for bubbleless aeration

Bubbleless membrane aeration is a promising method for water oxygenation. In this work, the oxygen transfer characteristics of hydrophilic treated polypropylene (PP) microporous hollow fiber membranes were studied. Both cross flow and parallel flow modules were used for the bubbleless aeration of water with operating pressures up to 100 kPa. An intermittent degassing process was used in the aeration operation to maintain high oxygen transfer. A correlation was developed to evaluate the membrane resistance at different pressures. It was found that with an increase in operating pressure from 20 to 100 kPa, the membrane resistance decreased almost linearly from 8.8 × 104 to 4.6 × 104 s/m and from 4.0 × 104 to 2.1 × 104 s/m in cross flow and parallel flow, respectively. At appropriate operating pressures, the membrane resistance for hydrophilic treated PP membranes was similar to dense and composite membranes, while only one-third of the resistance of hydrophilic polysulfone membranes. Mass transfer was correlated with the Reynolds number over the range of operating pressures. The correlations obtained in this study are in agreement with previously reported correlations at a low Reynolds number.