MgCl2 and KCl Recovery from Brine Wastewater

Abstract

This project’s aim was to design an improved brine wastewater treatment system for desalination facilities. While a multitude of methods exist to do so, General Electric (GE)’s brine concentrator is leading the market by providing a method that not only treats the brine waste, but also recovers anywhere from 60- 94% of the water from the feed. However, their brine concentrator is relatively inefficient from both a financial and energetic perspective; our goal was to develop a system to match their results, while limiting costs and energy usage as best possible. We subsequently designed a system (referred to from here on out as the ‘MgCl2 Separation Unit’) to accomplish the aforementioned objectives. In addition to recovering pure water from concentrated brine, our process also recovers high purity MgCl2 and KCl crystals that are later sold to alleviate the overall process costs. The MgCl2 Separation Unit saw an increased ROI by 22.53% as compared to the GE Brine Concentrator, as well as a surge in NPV of $20,749,200. Additionally, we estimate an aggregate equipment cost of roughly$6,960,000, significantly less than GE’s $8,980,000, and utilities costs of$1,590,000 relative to their $6,920,000. The GE process deals with vapor phase water and thus relies on compressors for pressure changes, which are costly in terms of energy consumption and capital costs, whereas our proposed MgCl2 Separator Unit is limited to liquid/aqueous streams, eliminating the need for costly compressors (from both an energy and economic standpoint). Finally, while both systems are fit to treat 1- 2mgd, the MgCl2 Separation Unit was optimized to recover roughly 84% of feed water, positioning itself in the upper limit of GE’s possible water recovery spectrum