Cost analysis of integrated membrane system (IMS)-based industrial wastewater treatment plants (WWTPs)
was carried out in this study. Five plants with different capacities were designed based on MF–RO technology
following a three-stage pretreatment to produce reusable water from industrial oily wastewater. A cost model
was developed to analyze economic impacts of scale-up on different plant sizes and effect of economy on
scale. The cost model provided a useful preview for scale-up purposes by explicating economic behavior of
different cost components with respect to plant size, and presenting the benefits of large scale plants over
small ones. An experimental MF–RO pilot was used to evaluate the applicability of designed IMS-based
WWTPs for treatment of a typical gas refinery wastewater. The proposed process showed significant ability in
the removal of oil and total dissolved solids, in which the high quality of the treated water met international
regulations for a variety of reuse applications.