Expert Report

Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

The report reviews the Roadmap developed by the Bureau of Reclamation and Sandia National Laboratories to serve as a strategic research pathway for desalination and water purification technologies to meet future water needs.

Key Messages

  • The Roadmap does not provide an implementation strategy, and current funding levels within the federal government for non-military application of desalination are insufficient to fund research efforts that would trigger a step change in performance and cost reduction for desalination technologies.
  • A research funding program to include alternative desalination technologies also would need to be open to consider new, unforeseen research areas, and all proposals should be subjected to a rigorous review process.
  • Additional geochemical and hydrologic research is needed for further advancement of subsurface concentrate storage.
  • Aside from the desalination of seawater or brackish aquifers, one potential solution to the nation's water supply problem is to utilize increasingly impaired waters, such as municipal wastewaters, by applying desalination treatment technologies for contaminant removal.
  • Cost reductions could also be gained if further research aimed to improve beneficial and sustainable reuse of desalination concentrate.
  • Due to limits in salt concentration tolerated in the root zone and the possibility of leachate degrading ground or surface waters, crop irrigation may not be a viable option in most cases, although research is needed to further examine the limits of this disposal option.
  • Innovative methods are needed for dealing with silica and potentially toxic contaminants, such as arsenic and selenium.
  • More complete identification of the contaminants present in treated wastewaters and lower analytical detection limits for contaminants are needed so that potential associations with observed health effects can be discerned.
  • On-line contaminant monitoring tools, including tools to measure the integrity of membrane systems in real time, are also important research areas.
  • Reducing the costs of concentrate handling would make many sources of water, especially brackish groundwater, available for use.
  • Research should explore the fate of these contaminants and the concentration at which deleterious impacts occur in concentrate management applications.
  • Research to evaluate methods of improving the efficiencies of near-zero liquid discharge (and possibly zero liquid discharge) could increase their areas of applicability.
  • Some important cross-cutting research areas were also not adequately addressed within the Roadmap, including energy use and air emissions from energy intensive desalination technologies.
  • The Roadmap and its underlying process appear to present an appropriate framework for advancing research in several areas of desalination and water purification technology to help address future water needs across the United States, but the Roadmap document lacks an appropriate focus on desalination research and technology needs to meet the identified water supply objectives.
  • The Roadmap does not look at the broader context of energy costs, such as the contribution of fossil fuels to greenhouse gases or the effect of a large-scale desalination on the cost of energy, which could have a substantial influence on wider implementation of desalination. Research is needed to further examine these broad issues, including research on renewable energy sources, energy conservation, methods to reduce energy emissions, and life-cycle analyses for desalination and water reuse.
  • The development of fouling resistant elements and systems, appropriate indicators of fouling, and improved cartridge filter design to reduce replacement rate could lead to reduced operational costs. Large cost savings are also possible through research to reduce the use of pre- and post-treatment chemicals.
  • The five technological areas highlighted in the Roadmap represent appropriate priorities for research and development in the field of desalination and membrane-based water purification, but these technological areas and associated research issues receive only limited attention in the Roadmap.
  • The membrane research areas identified in the Roadmap cover a significant portion of the important research areas, but the committee has identified other key areas that are overlooked in the Roadmap. Research is needed to develop on-line sensors to determine the integrity of the membranes and to detect pathogens and other biological contaminants.
  • To inform the development of analytical surrogates, an improved understanding of structure-activity relationships between organic molecules and reverse osmosis membrane materials are needed.
  • While thermal desalination is not expected to displace membrane-based desalination in the United States, thermal technologies have substantial potential and should be more seriously considered, especially when combined with other industrial applications, such as electric power generating facilities (termed cogeneration), to utilize waste heat and improve flexibility and economics.
  • With additional research and development to support cost reductions, membrane bioreactors could provide a higher level of treatment at comparable costs of traditional treatment .