Membrane-based hybrid processes for energy-efficient waste-water treatment

Abstract

Membrane-based hybrid processes combine conventional unit operation, such as distillation or solvent extraction, with a membrane-separation process such as reverse osmosis. The rationale for developing such hybrid processes is that the resulting separation process often offers significant advantages over the exclusive use of either of the two component processes. In this paper we discuss two very different membrane-based hybrid applications: the processing of corn steep water, and the recycle of space-station wash waters. Laboratory data used to design the membrane section of each of the hybrid processes is presented. These processes make use of a novel, fouling-resistant reverse-osmosis membrane module being developed at Bend Research. Also included is a discussion of the criteria used for the design of the membrane-based hybrid processes for each application. The corn-steep-water treatment process was optimized using operating costs as the optimization variable. The space-station wash water recycle system, however, was optimized for minimum launch and resupply penalties and for minimum power requirements. The expected performance of each membrane-based hybrid process is compared with the performance of the conventional unit operation.