Development of a Knowledge Base on Desalination Concentrate and Salt Management
Year Released: 2013
Funding Partners: Bureau of Reclamation, California Department of Water Resources, Water Research Foundation
Total Investment: $354,734 (Cash: $200,000, In-Kind: $154,734)
Principal Investigator: Mike Mickley, P.E., Ph.D., Mickley & Associates
A critical issue for the estimated 320 U.S. municipal desalination facilities (96% of which are inland brackish water plants) is that few, if any, cost-effective environmentally sustainable concentrate management (CM) options exist for inland desalination facilities. In the past decade, increasing CM challenges have led to some plants not being built. The challenges continue to increase resulting in the need for a comprehensive knowledge base to define and characterize CM issues. This reference and a future CM guidance manual will support utility decision making relative to desalination (and more specifically CM) planning.
Goals and Objectives
The project gathers, analyzes, and synthesizes information that will support the objectives of:
- identifying and defining issues that can affect municipal desalination facility decision-making needs—in regard to concentrate management,
- providing an up-to-date information base supporting the understanding of concentrate management, and
- defining a recommended approach for preparing a concentrate management guidance manual to be generated in a future project.
This report is as a knowledge base that may be useful to regulators, consultants, and engineering companies involved in municipal desalination concentrate management. Several approaches were applied for gathering and analysis of information, including:
- a survey of municipal desalination facilities
- telephone conversations with U.S. EPA and state regulators
- participation in various desalination research workshops
- a review of the desalination and saline management literature
- an information-gathering workshop with utilities, consultants, and regulators
Information was obtained from municipal and non-municipal industries, including international as well as U.S. sources. Other industries and countries were included to ensure a broad understanding of technologies, salinity management options and practices, and emerging issues.
Findings and Conclusions
The information obtained was used to develop a characterization of concentrate management options, practices, trends, and needs and to define present and future issues related to concentrate management. The report is an examination of this information and a concise description of concentrate management issues, along with detailed supportive information.
Findings from the survey and other information gathering project efforts include:
- An increased number of plants are treating source water for removal of contaminants as well as for salinity reduction.
- An increased number of plants have concentrate containing contaminants that restrict CM options or require treatment to remove the contaminants prior to disposal.
- Some desalination plants have not been built due to CM issues.
- CM is increasingly being considered in the context of integrated watershed water resource management.
- Discharge/disposal regulations are likely to become more stringent due to numeric nutrient standards, emerging contaminants, and other contaminants being considered for regulation.
- Desalination treatment processing will become more complex and will produce concentrate that will require additional treatment prior to using some CM options.
- There has been increased interest in high recovery processing usually under the labels of volume reduction or concentrate/brine minimization.
- Similarly, there has been increased interest in salt recovery from concentrate as a means of reducing waste and providing a product of value whose sale can offset operating costs. The most frequently mentioned CM issues of existing desalination plants are:
- the time, effort, and thus cost of obtaining the concentrate disposal permit
- the time, effort, and thus cost of monitoring concentrate characteristics for permit compliance.