Frequently Asked Questions

Read answers to frequently asked questions.  Contact us for additional information.

  • 1. What is the Regional Recycled Water Advanced Purification Center?

    The Regional Recycled Water Advanced Purification Center (Center) is a 500,000 gallon-per-day demonstration facility, currently under construction, designed to test an innovative water purification process for potential groundwater replenishment.  Cleaned wastewater from the Sanitation Districts’ Joint Water Pollution Control Plant (JWPCP) in Carson is sent to the Center, where it is further purified using a unique application of membrane bioreactors followed by reverse osmosis and an ultraviolet light/advanced oxidation process. Scientists and engineers will test this advanced purification process to demonstrate that the resulting purified water meets all health and water quality requirements and is safe to replenish groundwater basins used as a drinking water supply.  As it is a testing facility, the water purified at the Center will go back to the start of the JWPCP to be re-treated and eventually sent to the ocean.

  • 2. Why are you constructing the Advanced Purification Center?

    The Center is being constructed to test the purification process, ensure it produces water safe for groundwater replenishment and reuse, and obtain regulatory approval for the purification technology being used. It also will allow Metropolitan, in collaboration with the Sanitation Districts, to optimize operations and identify costs, gather operational data, and develop design parameters needed for a future full-scale facility. In addition, the Center will be used to showcase the project to the public. Visitors will have an opportunity to tour the facility and learn more about the purification process.

  • 3. When will construction be complete?

    Construction is expected to be complete by the end of 2018. Equipment testing and start-up activities will begin in 2019 and the Center is anticipated to be online in mid-2019.

  • 4. Is the water produced at the Advanced Purification Center the same as used in purple pipe recycled water systems that irrigate landscaping?

    No. While recycled water in purple pipe systems undergoes an extensive treatment process and can be used for irrigation and industrial purposes, the water is not intended for human consumption.  The Center uses advanced water treatment technologies such as reverse osmosis and ultraviolet disinfection, which have been used in Southern California and elsewhere for decades to produce water that safely replenishes groundwater basins for use as a drinking water supply.

  • 5. Is this the same technology as ocean desalination?

    Ocean desalination also uses reverse osmosis technology. However, because ocean water is about 25 times saltier than wastewater, desalination requires much more energy, additional membranes, and higher operational and maintenance costs compared to purifying wastewater.

  • 6. Does the purification process take out any pharmaceuticals and any other particles that may remain in the cleaned wastewater?

    Yes, all three technologies in the purification process at the Center remove pharmaceuticals and other microscopic materials. This has been verified in previous pilot studies conducted by Metropolitan and the Sanitation Districts as well as by water agencies operating purification facilities that use some of the same advanced technological processes. The purified water will be monitored and tested by scientists and engineers for hundreds of compounds, including pharmaceuticals, to ensure the water meets water quality requirements to replenish groundwater basins.

  • 7. What is a membrane bioreactor?

    MBRs are often used in wastewater treatment plants, where it removes organic materials and nitrogen compounds from water.  At the Center, the membrane bioreactors (MBR) will use both biological treatment and membrane technology to clean the water before it is sent on the reverse osmosis process.  The Center’s MBRs will serve two purposes. First, they will remove nitrogen compounds from the water through biological treatment. Second, they will filter particles – many smaller than 1/100th of a grain of sand – using membrane technology.  The MBR process will ensure that the reverse osmosis units operate successfully without fouling, or prematurely downgrading, them.

  • 8. Why are you testing a unique application of membrane bioreactors at the Advanced Purification Center rather than using microfiltration processes used in some existing water purification facilities?

    The JWPCP is an ocean discharge facility and is not designed to remove nitrogen compounds such as ammonia, nitrates and nitrites from wastewater. The Center’s purification process must remove these and other compounds to ensure the water is safe to replenish groundwater basins. MBRs are not only effective at removing nitrogen compounds, but also are able to remove organics and other microscopic materials, including microorganisms such as Cryptosporidium and Giardia. In addition, they help minimize the fouling and downgrading of reverse osmosis membranes. Microfiltration alone cannot perform this important two-step treatment process of removing nitrogen and removing particulates from the water prior to reverse osmosis treatment. While MBRs have been extensively used in wastewater treatment, they have not yet been tested and approved for groundwater replenishment projects in California. If the MBR technology, in combination with reverse osmosis and an ultraviolet light/advanced oxidation process (UV/AOP), is able to achieve the same level of performance as using microfiltration with reverse osmosis and UV/AOP, it could result in increased efficiency and significant cost savings for water reuse projects.

  • 9. What is potable reuse?

    Potable water is drinkable. Potable reuse refers to highly purified water that meets or exceeds federal and state drinking water standards and is safe to reuse for drinking. The Center is currently focused on producing purified water for indirect potable reuse, i.e. water that doesn’t flow directly to a user. With indirect potable reuse, purified water would first replenish groundwater basins, where it would undergo additional, natural filtration and blend with other water supplies. Water from the underground basin would eventually be pumped up, treated, and reused again. Direct potable reuse refers to purified water that water flows directly into the drinking water treatment and distribution system, skipping the groundwater basin step.

  • 10. How will this unique application of membrane bioreactors be tested?

    The testing period involves three stages: (1) initial testing of equipment and developing laboratory methods; (2) testing each technology and the overall purification process for performance during normal, baseline conditions; and (3) testing each technology and the overall purification process for performance during compromised or challenged conditions. The testing period will span at least one year, during which time scientists and engineers will evaluate and monitor the purification process for hundreds of water quality parameters to determine  its ability to produce water that complies  with all water quality and regulatory requirements associated with groundwater replenishment and reuse.

  • 11. How will this new purification process be approved?

    After the testing period is complete, Metropolitan will prepare a detailed report on the demonstration project, including water quality data and test results and submit it to the State Water Resources Control Board’s Division of Drinking Water (Division) for review. The Division will determine if the proposed purification process, including application of the MBR technology, meets all water quality and public health standards. The report also will be submitted to the Los Angeles and Santa Ana Regional Water Quality Control Boards to ensure all water reuse requirements are met. Once the purification process is approved, it may be used for a future full-scale facility. This efficient, cost-effective advanced treatment process also may be used by other water utilities, further expanding water reuse in California.

  • 12. What happens if the purification process is not approved?

    Extensive testing will be conducted at the Center to demonstrate the proposed purification process using MBR technology will meet regulatory requirements. Ultimately, if the purification process is not approved, other alternatives will be considered. One option would be to be to use MBRs or potentially another nitrogen removal technology in addition to the purification process used at existing facilities (microfiltration, reverse osmosis, UV/AOP). Other options also would be researched and reviewed as needed.

  • 13. What will happen to the Advanced Purification Center after testing is complete?

    Once testing is complete, the Center may be used to conduct additional studies and research on the water purification process. These studies will provide information needed to develop design criteria and optimize operation of a full-scale advanced water treatment facility.  Additional research and treatment evaluations also may be conducted in the future for other types of reuse, such as direct potable reuse, in which the purified water flows directly into one of Metropolitan’s  water treatment plants and then into the distribution system instead of to a groundwater basin.  New regulations will need to be developed by the State before this type of process can be utilized by Metropolitan.

  • 14. Will it be possible to visit the Advanced Purification Center?

    Yes, tours will be offered once the Center is fully operational. Please check our website in mid-2019 or sign up for our e-mail updates for more information.

  • 15. Can we taste the purified water?

    During the testing period, no tasting will take place as the Center’s purification process has not yet approved by regulators. After the process is approved, there may be opportunities to taste the purified water at the Center.

  • 16. What will happen to the water after it is purified?

    During the testing period, the purified water from the facility will return to the start of the JWPCP where it will be re-treated and eventually flow to the ocean. If a full-scale program moves forward, the purified water could recharge groundwater basins in Southern California, be used by industries, and potentially could provide another source of water to two of Metropolitan’s water treatment plants.

  • 17. How is the facility funded?

    Metropolitan’s budget includes both capital and operations and maintenance costs for the Center. The Sanitation Districts, partners in the demonstration project, have provided critical infrastructure to the Center during construction including: the project site, electrical and communications equipment, process water piping and discharge lines, and inspection staff.  Once the Center is operating, the Sanitation Districts will contribute staff time and various resources to perform laboratory analyses. They will also provide the Center with cleaned wastewater, electrical power and other services associated with testing.

  • 18. Are grant funds available and being used?

    Metropolitan is researching grant and other funding opportunities at the State and Federal levels for both the demonstration facility and a full-scale program. Metropolitan plans to apply for both grant funds and low-interest loans.

  • 19. When and how will you decide to go to a full-scale program?

    The boards of directors for both Metropolitan and the Sanitation Districts will ultimately decide whether a full-scale program will be pursued. It is anticipated that Metropolitan’s board will consider whether to move forward with the next steps for a full-scale project in mid- to late- 2019, including environmental review and preliminary design. At the same time, it is expected that the Sanitation Districts’ board will decide whether to support the project hosted at their facility.  At that time, the both boards will have been provided with extensive information on a full-scale program including a feasibility study, conceptual report, institutional and financial assessments, expert panel and other technical reports, and initial demonstration project results.  This information will allow both boards to make an informed decision on the program.

  • 20. What is the cost of a full-scale program?

    Currently, a full-scale program producing up to 150 million gallons of water each day is estimated to cost $3.4 billion to build and $129 million each year to operate and maintain, resulting in a total cost of about $1,830 per acre-foot of purified water.

  • 21. Why do we need to consider this program?

    The full-scale Regional Recycled Water Program would produce a drought-proof local source of water, readily available rain or shine, for the Metropolitan’s service area.  It would help free up imported water for other uses. The water would help replenish Southern California’s groundwater basins, which provide 30 percent of the region’s water supply and have seen levels drop to historic lows in recent years. The program also would help diversify the region’s water sources to meet the needs of the growing economy at a cost comparable to other local water resources.

  • 22. Which areas would get this water?

    If a full-scale program is implemented, the water could be used to refill up to four groundwater basins in Los Angeles and Orange counties. These basins supply water to 7.2 million people throughout these counties. The water could also be used by industries in the harbor area. In addition, if regulations are developed allowing for it, the water could provide an additional source of water for Metropolitan’s Weymouth and Diemer water treatment plants, eventually delivering the water to much of Metropolitan’s service area. Other opportunities for use of the purified water may also be developed in the future.

  • 23. Where can I get more information?

    Please visit our website, for more information. You may also sign up for e-mail updates from Metropolitan about current programs and projects, including the Center.

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