Desalination is of growing importance in meeting the needs for greater quantity and improved quality of drinking water, and appropriate concentrate managment can be challenging. A recent report provides useful information on concentrate management.

By Jim Jordahl, Ph.D., P.E., CH2M HILL’s Global Technology Leader for Natural Treatment Systems

Dr. Jordahl was co-principal investigator of a recently published report entitled ‘Development of a Knowledge Base on Desalination Concentrate and Salt Management,’ sponsored by California Department of Water Resources, Bureau of Reclamation and the WateReuse Research Foundation. The WateReuse Research Foundation conducts applied research on the reclamation, recycling, reuse, and desalination of water to advance the science of water reuse.

Desalination is of growing importance in meeting the needs for greater quantity and improved quality of drinking water. Its application is of equal importance in the advanced treatment of wastewater effluent to a quality suitable for potable reuse. In the application of desalination, a byproduct, called concentrate is produced. Concentrate is characterized by high salinity, making disposal in a cost-effective and environmentally safe manner challenging. The result is that the cost and general feasibility of desalination for both municipal and industrial needs are increasingly dependent on appropriate concentrate management (CM).

The same health and environmental concerns that have resulted in the need for higher-quality drinking water have resulted in increased regulations regarding the protection of source waters. As a result, regulations protecting receiving waters (surface and groundwaters) have become more stringent, making their use for concentrate disposal more challenging.

Along with the increasing number and size of desalination plants, the associated volume of concentrate has been increasing. Consequently, concentrate minimization has become a topic of increased interest. With concentrate minimization, the volume of concentrate is reduced, however the salinity and concentration of most constituents present in the concentrate increase, creating different management challenges.

As a result of these and other factors, there is a need for a comprehensive approach to and guidelines for CM. The work funded by WRF and co-sponsors aimed to provide this needed information.

The two project objectives were:

  • To gather, analyze, and synthesize information concerning CM and render it into a form suitable for a background or reference document
  • To recommend an approach and technical content of a guidance manual for CM that built on the results of the informational analysis and synthesis

Several approaches were applied to the information gathering and analysis, including:

  • Survey of municipal desalination facilities
  • Telephone conversations with U.S. EPA and state regulators
  • Participation in various desalination research workshops
  • Review of the desalination and saline management literature
  • An information-gathering workshop with utilities, consultants, and regulators

Information was obtained from municipal and industrial facilities, from both U.S. and international sources. Industrial and international outreach was performed to ensure a broad understanding of technologies, salinity management options and practices, and emerging issues.

The objectives were met using a multifaceted effort involving a survey of more than 150 desalination plants, telephone interviews with regulators, participation in workshops defining CM needs, and a review of global literature.

The resulting report contains a substantial amount of information about CM to be used as a reference or background document to support future development of a guidance manual for CM. The report’s level of detail is useful for a broad audience including utilities, academics, regulators, consultants, and equipment and engineering companies.

The report’s overarching conclusion is that there is a need to better define the issues around CM through the development of a comprehensive information source, such as a knowledge base, that define the issues surrounding CM, and provides support material for understanding the issues. The project’s final report is an effort to meet this need.

The report recommendations are as follows:

  • The report should be used as the basis for the development of a guidance manual, using the draft outline provided to organize the content.
  • The report also should be used as a general reference document for the water industry in educating various groups as to CM issues and practices.
  • The two-phase approach, the initial phase resulting in a background document such as this report, should be considered as an effective strategy for developing guidance manuals on various desalination-related topics.

Dr. Jordahl is a senior soil and environmental scientist and currently serves as CH2M HILL’s global technology leader for natural treatment systems. A recognized salinity management expert, his professional expertise includes management of salt affected soils and waters, soil fertility, treatment wetlands, soil erosion control, greenhouse gas issues for plant/soil systems, alternative landfill covers, land application of wastewaters and solid residuals, and phytoremediation. In addition to project experience across much of the U.S., Dr. Jordahl has worked on projects in Australia, Brazil, Canada, France, Saudi Arabia, South Korea, the United Arab Emirates, and Italy.