UNCONFINED MEMBRANES - TRANSFER PERFORMANCE AND MODULE DESIGN

The transfer performance and power requirements of unconfined sealed e nd hollow fiber membranes were studied, Membrane modules, operated in the sealed end mode, were pressurized with oxygen and placed within a submerged rectangular jet discharge. This design is especially well su ited for use in waters containing high solids concentrations. The memb ranes have a greater degree of freedom for movement and are, therefore , less likely to become fouled due to solids being lodged within the f iber bundle. Furthermore, because the membranes are not enclosed withi n a tubular shell, head losses across the membranes are reduced. In a related study, Johnson et al. [1] developed a mass-transfer correlatio n for unconfined membranes similarly situated within a circular jet di scharge. In this study, the mass-transfer correlation developed for ci rcular jets is verified experimentally for larger rectangular module d esigns better suited for use in large scale applications. The headloss es across the modules are characterized in detail as a function of wat er flowrate and membrane spacing. These data are used to estimate the power requirements for different designs under a variety of operating conditions. The mass-transfer rates and corresponding power requiremen ts for the unconfined configuration are compared with other membrane c onfigurations. (C) 1998 Elsevier Science B.V.