Increasing the Top Brine Temperature of Multi-Effects Distillation-MED to Boost Its Performance through Controlling the Formation of Scale by Nanofilteration and Antiscalants

Abstract

Thermal desalination technology especially, multi-effect distillation MED is of great importance to oil producing countries such as those in the gulf region owing to its efficacy in processing seawater with the minimum pre-treatment of the feed and cheap energy input available from waste heat. One of the main drawback of the current MED processes is the susceptibility of scaling when operate above 70 ºC. This limitation deprives the technology to be energy efficient and reduce its optimal productivity. An optimized pre-treatment of the seawater feed by NF membranes can enhance its efficiency significantly. In this work, the possibility of applying a tailored feed quality using thermodynamic speciation chemistry of the feed water and prediction of the scale propensity based on the Saturation Index of the scale minerals was investigated. Different NF membranes with different properties were used and compared experimentally with each other and theoretically with predictions that are based the saturation index. Moreover, new generation of the polymeric antiscalants promoted by the main manufacturers of the inhibitors industry to control scale formation has been investigated. In addition, as part of planned work for future studies, design and construction of a pilot scale based on NF membrane process was carried out and meant to be a potential extension of this work.