The HEED® design is an emerging technology that is finding applicability over a wide range of desalting applications and feed types, including in areas where ion exchange (IE) and reverse osmosis (RO) were once thought to be the only viable options. In addition, HEED® often compliments and improves the efficiency of IE and RO when used as a roughing demineralizer (initial desalination step) in integrated hybrid process treatment arrangements. Hybrid processes consisting of HEED®, RO, and/or distillation also offers a solution to an increasingly important issue: disposal of concentrate generated by RO.
This highly concentrated brine can be difficult to dispose, especially at inland desalination plants. For some applications, combined HEED® and RO hybrid systems would result in more efficient operation since electrodialysis efficiency decreases with decreasing diluate (product) concentration; the HEED® process would only be utilized to partially reduce the concentration of the feed rather than produce a very low concentration finished product, with the RO providing the finished product.
This configuration also allows higher overall recovery, single pass RO system operation since the RO feed (electrodialysis diluate) concentration would already be reduced by the HEED® process. It also allows blending of HEED® and RO product waters to produce the final water quality desired, minimizing membrane area required for both HEED® system and RO.
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HEED® is a registered trademark of EET Corporation