In-stream hollow-fiber membrane aeration

Throughout both urban and rural areas across the United States, rivers and streams periodically suffer from low dissolved oxygen concentrations. Current aeration techniques are often expensive or ineffective. Aeration with hollow-fiber membranes has been shown to have the potential to aerate these water courses more cost-effectively than current methods and may be able to provide aeration to locations where traditional technologies are not effective. To optimize mass transfer rates, hollow-fiber membranes in a fiber flag configuration were used. The fiber modules were tested in two different orientations to determine the fiber performance as a function of flow field conditions. The results are compared to more typical fiber configurations. In a second experiment the fiber modules were run continuously in diverted river water for over 1 700 h to determine the long-term performance of the membrane modules in a practical application. The extent of fouling was monitored over the course of the experiment and the fibers were examined to determine if the fouling was biological or chemical in nature. Finally, the previous results were incorporated into a cost comparison between the hollow-fibre membranes and a conventional in-stream aeration technology currently in use.