Energy recovery devices are employed in nearly all seawater reverse osmosis (SWRO) desalination plants to recover pressure from the membrane reject stream and return it to the process. Because of the high pressures and low membrane permeate recovery rates common in these systems, the membrane reject stream contains a considerable amount of energy However, the application of energy recovery is much less common in brackish water RO systems, primarily because of the relatively low feed pressure and low flow rate of the membrane reject stream. The fear is that energy recovery devices can also potentially limit the flexibility of a brackish RO process because of efficiency losses or flow-rate constraints encountered during off-peak operation. The results of the study indicate that energy recovery devices would be conomically beneficial in most brackish systems. As indicated in the study results, a feed pressure of greater than 150 psi is approximately the point where energy recovery devices start to have a payback of less than 5 years. In addition to retrofit applications, isobaric ERDs can enable a plant to be expanded by the reject ratio without replacing the high pressure feed pump or ignificantly increasing energy consumption.
This presentation is available to AMTA Members only.
- Jeremy Martin
- Energy Recovery, Inc.
- AMTA Annual Meeting, San Diego, CA
- San Diego Biennial
- Energy Recovery Device, Seawater Reverse Osmosis, brackish