Technical Service Center
Water Treatment Group
Optimization of Energy Recovery for Seawater RO Desalination Systems
This purpose of this project is to conduct research on seawater reverse osmosis (RO) systems to:
- Decrease the Energy Use
- Demonstrate the Affordability of Seawater RO
Reclamation is a part of the Affordable Desalination Collaboration (ADC) that is funding the project. Half of this $2 million project is funded through California Department of Water Resources Proposition 50 grant.
ADC Press Release
(39 KB, PDF)
Phase 1 Report
(191 KB, PDF)
( 1.77 MB, PDF)
Increasing demand for allocated freshwater resources, declining freshwater quality, drought, and the need for a diverse reliable water supply portfolio are among the many reasons that people across the United States and the world are looking to the sea as a potential supply. However, in the United States, the high cost of desalination has historically hindered interest in seawater as a possible fresh water supply. Sensitive to the issue of cost as a limitation to realizing large scale implementation of seawater desalination, engineers, scientists, and the manufacturing industry have worked over the last fifty years to reduce both the capital and operating cost associated with desalinated water.
The Affordable Desalination Collaboration (ADC) is a California non-profit organization composed of a group of leading companies and agencies in the desalination industry that have agreed to pool their resources and share their expertise in the mission to realize the affordable desalination of seawater. Using a combination of energy efficient, commercially available RO technologies including pumps, membranes and energy recovery equipment, the ADC has demonstrated that seawater reverse osmosis can be used to produce water at an affordable cost and energy consumption rate comparable to other supply alternatives. The research approach and results are made possible through the collaboration of members that include:
The ADC’s demonstration scale seawater reverse osmosis (SWRO) treatment system uses pressure exchanger (PX) technology for energy recovery. The RO array consists of three 8" diameter, 7 element pressure vessels. The flux and recovery can be varied from 6-9 gfd and 35-60% respectively. The overall capacity of the system can be varied from approximately 200-300 m3/day (50,000-80,000 gpd)
The work is divided into two phases. The first phase of testing was completed in March 2006 and took place at the US Navy’s Seawater Desalination Test Facility in Port Hueneme, California. It included testing three membrane sets and varying flux and recovery to seek the most cost effective operating point. The most affordable operating point was estimated by calculating the net present value for each tested condition, accounting for both capital and operating costs.
The second phase, scheduled to start in early 2007, includes testing and demonstrating additional manufacturers’ membranes through a similar protocol as phase I, which involved one membrane manufacturer exclusively. Demonstrating additional manufacturers will validate the results from phase I and show that they can be achieved with several manufacturers’ membranes. It will allow for a direct comparison matrix of performance from four leading membrane manufacturers. A “next generation” hybrid-membrane system involving internally staging membranes of different performance down a single 7-elemenet pressure vessel, will also be tested and demonstrated. In phase II the ADC will also test and demonstrate advanced prefiltration technologies such as ultrafiltration. In general, use of membranes for seawater pretreatment is limited and this work will provide valuable information for the U.S. and around the world. Finally the ADC will develop and test new process designs that are possible as a result of the isobaric energy recovery technologies. As a natural result of PX technology in particular, there are new kinds of flow schemes that can improve the performance of higher recovery seawater and brackish water systems. In phase II, these new flow schemes will be used to demonstrate recoveries of seawater systems above 50%, while still maintaining good water quality and low energy performance.
The ADC is helping to confirm that the industry has made seawater desalination cost competitive and at acceptable levels of energy consumption when compared to traditional sources and processes.