Abstract: The key to managing the city's black odorous water is to increase its oxygen content. Low-pressure and bubble-free characteristics of a membrane aeration biofilm reactor (MABR) often lead to an uneven distribution of dissolved oxygen (DO) over the treated water body, thereby reducing its overall performance of oxygenation and lowing its treatment effect. In this study, a MABR system is modified by installing special hollow fiber membrane filaments inside it so that the improved system can produce bubble plumes to stir the water and improve its oxygen transfer. An experiment is conducted to simulate this modified system and test its oxygenation effect and the uniformity of dissolved oxygen in treating artificial black odorous water. The results show that the bubble plume stirring can both raise the oxygenation efficiency and improve the uniformity of dissolved oxygen, thus improving the water treatment effect. And for the improved system, its oxygenation effect is increased with aeration pressure. Compared with the cases of no aeration (0 kPa), its average DO saturation rates of river water over 24 h under aeration pressures of 10, 20 and 30 kPa is increased by -2.8%, 17.7% and 29.4% respectively in our horizontal tests, and by 13.6%, 6.6% and 32.1% respectively in our depth tests. In these two types of tests, increasing aeration pressure leads to more uniform distributions of the saturation rate (its mean variances are 1.7 and 13.5 respectively). Under aeration pressures of 10, 20 and 30 kPa, the mean deviations in the saturation rate are 0.3, 3.9 and 0.4 respectively in the horizontal tests, and 9.8, 18.4 and 3.4 in the depth tests. Thus, the improved MABR system can achieve better oxygenation effect and better oxygen content uniformity, helping solve the urban river problem of black odorous water.

Key words: membrane aeration biofilm reactor (MABR), aeration effect, uniformity, DO saturation rate