Research Activities of the Desalination Research and Innovation Partnership (DRIP)

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Research Activities of the

Desalination Research and Innovation Partnership (DRIP)

Mark Beuhler, Associate Vice President

Metropolitan Water District of Southern California, Los Angeles, California USA

Introduction

Southern California is a semi-arid area with about 30 centimeters (12 inches) of rainfall annually. Two thirds of the region's water supplies are imported by a system of pumps and aqueducts. Water is imported from the Colorado River on the border with Arizona and the Sacramento River from the northern part of the state. Both water quantity and salinity are major concerns for the region.

Southern California is faced with the challenges of reducing its dependence on imported water from Northern California due to concerns about the environment. It must also reduce its use of the relatively saline Colorado River (Total Dissolved Solids of about 700 parts per million) due to reduced rights to that water. As a result the region is facing projected potable water shortfalls by the year 2020. At the same time, the import of this water consumes over 5 billion kilowatt-hours (kWh) annually, which is the single largest use of electricity in California.

To address these critical water supply and energy issues, water agencies in the region embarked on a multi-year project to develop and demonstrate new and innovative technologies in 1997. The goal of the project is to substantially reduce the cost of desalinating Colorado River water, and to develop new, non-traditional water supplies such as brackish groundwater, municipal wastewater, and agricultural drainage water. This project has been termed the Desalination Research and Innovation Partnership (DRIP).

Unique Features of the DRIP

Research being conducted as part of the DRIP involves a number of unique features, including:

employs a holistic view on the complete desalination treatment process, from pretreatment to brine disposal;

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seeks to demonstrate desalination on a scale beyond current commercial sizes; develops of broad support from numerous water agencies, state agencies, electricity agencies, and others

Sources of Water for Desalination

DRIP is investigating desalination technologies for Colorado River water, municipal wastewater, brackish groundwater, and agricultural drainage water in California. As the DRIP project grows, it will look at several different groundwater sources, reclaimed wastewater sources, and agricultural drainage water sources to further broaden the research scope.

Treatment Processes

Much current research focuses on salinity removal as an isolated process. The DRIP project is investigating the complete water treatment process train to identify process conditions that optimize the entire desalination process.

Pretreatment DRIP is evaluating various pretreatment options to remove suspended solids and to see what impact these processes may have on the effectiveness of desalination technologies. A particular area of interest is whether existing conventional drinking water treatment plants can be used as the pretreatment step for a reverse osmosis treatment plant, saving about 40% of the anticipated capital cost.

Salt Removal DRIP is also investigating multiple salinity removal processes such as new ultra-low pressure reverse osmosis membranes, nanofiltration membranes, electrodialysis reversal, and an innovative capacitive deionization process developed by the Lawrence Livermore National Laboratory.

Brine Handling New brine concentration and disposal options are being tested as well, including methods to concentrate brine to a solid residual. Breakthroughs this area may dramatically improve the viability of desalination in the arid Southwest and other areas because brine handling is often the major technical obstacle for inland areas without ocean disposal options.

Scale-Up

DRIP is the evaluating scale-up issues for desalination and related water treatment technologies. Membrane plants have reached a critical size limit due to manufacturing equipment limitations, typically of about 20 cm in diameter (8 inches). Using current technology, the largest US membrane plant is only 270,000 cubic meters per day (72 million gallons a day) in size and utilizes over 9,000 individual membrane elements.

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reducing the logistical problems associated with using so many individual parts, and improving the economies of scale for these emerging technologies. The goal is to develop prototypes that can be used in plants 570,000 cubic meters per day (150 mgd) or larger. A different set of challenges may be expected when going from small volumes of flow to quite large volumes. DRIP is particularly focused on this scaled-up research because of the availability of excellent large-scale demonstration facilities.

Partners

DRIP consists of a broad and diverse team brought together under its umbrella. The six water agencies conducting the research include the Metropolitan Water District of Southern California (MWDSC), Orange County Water District (OCWD), San Diego County Water Authority (SDCWA), West Basin Municipal Water District (WBMWD), Sonoma County Water Agency, and Santa Clara Valley Water District. In addition, the University of California at Riverside (UC Riverside) will be conducting research on desalinating agricultural drainage water.

DRIP funding partners include Edison Technology Solutions, the Electric Power Research Institute, the American Water Works Association Research Foundation, Lawrence Livermore National Laboratory, California Energy Commission, California Department of Water Resources, U.S. Bureau of Reclamation, U.S. Environmental Protection Agency, and the California Department of Water Resources. These organizations provide funds and technical review but do not conduct the actual research.

Cost and Schedule

The total estimated cost for Metropolitan's portion of the DRIP work is $14.7 million, of which $6.3 million has already been committed to complete work through the year 2002. A total of $10.9 million of outside grant funding has been received from various funding agencies and additional grants are being sought. Partners will also make significant in-kind contributions for their respective DRIP research projects. The ultimate DRIP total cost depends on future work and grants but may range from $25 to $30 million. The DRIP project is expected to be complete in the year 2005.

Growth of DRIP

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alternative brackish source waters from different locations to expand and refine the research.

In addition, high salinity and the high cost of desalination are serious concerns in several other states, including Arizona, Nevada, Texas and Florida. DRIP is currently seeking funding from a number of federal agencies for desalination research and, if received, this funding may allow DRIP to expand beyond California to other states with similar challenges and concerns.

Results to Date

Results of research to date include:

Conducted testing of conventional drinking water treatment alone and conventional treatment combined with ozone and biologically active filters as pretreatment for reverse osmosis membranes (MWDSC)

Conducted testing of a large-scale 41 cm (16 " diameter) RO membrane module for treatment of Colorado River water (MWDSC)

Evaluated a scaled-up of 11,000 cubic meter per day (3 mgd) UV system for disinfection and destruction of micropollutants (MWDSC)

Continued an investigation of new, immersed filtration membranes for pretreatment of municipal wastewater prior to RO (OCWD)

Conducted a study of the performance and economics of an electrodialysis reversal (EDR) process for desalination of municipal wastewater (SDCWA) Initiated pilot testing of a membrane bioreactor as a pretreatment process for municipal wastewater (WBMWD)

Conducted an assessment of agricultural drainage water quality and flows, and conducted pilot testing for desalination of agricultural drainage water (UC Riverside)

Research Planned for Upcoming Year

The DRIP Major planned objectives for the fifth year of DRIP include continuation of the following treatment process evaluations:

Design a 1,900 to 3,800 cubic meter per day (0.5 - 1.0 mgd) reverse osmosis demonstration unit

Demonstrate large-scale desalination and ultraviolet light (UV) technologies for Colorado River water and municipal wastewater

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Conduct pilot testing of new membranes and electrotechnologies for desalination of brackish groundwater, municipal wastewater, and agricultural drainage water

Conduct pilot testing of non-thermal technologies for brine minimization

Summary

The Desalination Research and Innovation Partnership provides an opportunity to advance desalination technology and related processes and produce significant energy savings. A breakthrough has the potential to substantially reduce reliance on imported water, thereby mitigating the adverse environmental and energy impacts associated with water imports.

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