PHOTO 1
The stainless steel air manifold connects to each MF membrane module with a flexible hose. During the MF backwash operation, air is forced through holes in the bottom of the membrane modules, gently agitating or "scouring" the surface of the membranes to remove debris.

PHOTO 2
Orange County Water District's new $480 Groundwater Replenishment (GWR) System, which will provide indirect reuse potable water from treated effluent to more than 144,000 households in Orange County, California.

PHOTO 3
During the final phases of disinfection, UV light combines with hydrogen peroxide to create an advanced oxidation reaction that breaks down any organic compounds.

---

Project Description

Facing extended droughts and continued population growth, the Orange County Water District (OCWD) and Orange County Sanitation District (OCSD) implemented an innovative solution for providing safe drinking water to the citizens and businesses in Orange County. Designed by CDM, the Groundwater Replenishment (GWR) System-the largest water purification project of its kind in the world- produces potable water from highly treated wastewater. A model of sustainability, the project conserves and recovers limited water resources, reduces energy consumption compared to imported water transport, and supports economic vitality.

This $480 million project purifies clarified secondary-treated wastewater effluent beyond drinking water standards using advanced membrane purification. The treated water is then injected into an underground seawater barrier or percolated into aquifers, providing a new water source for about 500,000 people.

Integrated Approach

Sustainable water-cycle project solves regional needs and protects aquifer: By treating effluent to high standards, OCWD is not only creating a reliable water supply from a previously wasted local resource and reducing reliance on costly imported water, it is ensuring demands are met even during drought periods. The purified water percolates into the ground, replenishing the aquifer and reducing total dissolved solids. The injected water blends with existing groundwater, forming a barrier against seawater intrusion.

Use of a local water source conserves energy: Less power is required to purify wastewater than to import a similar amount of water from Northern California or the Colorado River, reducing the regional power demand.

New system produces cleaner, higher-quality water: The purified water is near distilled quality, requiring that minerals be added back in for stability. The resulting water is superior in quality than water available for recharge from imported water or stormwater.

Efficient process maximizes land use: The new, streamlined facility can produce 70 million gallons per day (mgd) of purified water in about the same spatial footprint that housed Water Factory 21 (WF21), which treated 5 mgd.

Quality

Advanced treatment ensures public safety: The GWR System uses the best technologies available-microfiltration (MF) for pretreatment, reverse osmosis (RO) for purification, and ultraviolet light (UV) for disinfection. OCWD chose the multi-barrier approach of MF and RO followed by UV disinfection to remove bacteria, emerging contaminants, and viruses, ensuring public health and safety. This efficient plant is highly automated, reducing the number of required operators.

Extensive testing proved water quality, provided training: Extensive pilot and demonstration testing determined design criteria and operating costs. Sharing space with WF21 to keep it online during construction, a Phase I facility using 6 mgd of MF and 5 mgd of UV replaced the outdated lime and chlorine systems prior to demolition. This enabled operators to gain 2.5 years of experience running the advanced system prior to operating the complex 70-mgd plant, which incorporated the original Phase I facility, saving money for Orange County.

High standards protect public health: The Phase I facility demonstrated the effectiveness of the actual MF/RO/UV treatment system and met the stringent criteria of the California Department of Public Health prior to completion of the facility. As required by the state, OCWD appointed an independent advisory panel comprising public health, medicine, environmental engineering, and biology experts for independent oversight.

Originality

Innovative process converts waste into resource: With the GWR System, treated wastewater-previously discharged to the Pacific Ocean-becomes a drinking water source for 144,000 households.

Revolutionary approach changes the water industry: OCWD is moving beyond treating water for more common agriculture applications and purifying it to drinking water quality. In doing so, the GWR System is setting the standard for recycled water projects-it has been visited by industry professionals from Singapore, Australia, and China, and similar plants are underway in Singapore, Australia, and Miami.

Complexity

Flagship facility for the world: Expandable to 130 mgd, the GWR System is one of the largest plants in the world using MF/RO/UV to purify treated wastewater into drinking water. Scaling up the innovative technology from pilot to full size required a significant increase in the membrane area, pump capacity, ancillary facilities, and the number of trains, as well as heavier equipment, a larger building, and multiple chemical deliveries per day.

Distributed control system enhances efficiency: A sophisticated distributed control system guides accurate and efficient process management-facilitating local computations, simplifying code maintenance, and enabling rapid adjustments. The system is easily expandable and enables the thousands of input and output connections required for this instrument-intensive plant.

Social or Economic Advancement

Project preserves the area's natural resources: The environment-friendly plant reduces the amount of treated wastewater released into the ocean. By operating in "storm flow mode" and bypassing the ocean outfall during major storms, the plant treats secondary effluent with MF and UV, ensuring that it does not exceed capacity and delaying the need for another ocean outfall. Reusing the water maximizes a reliable source and expands the seawater intrusion barrier to protect groundwater.

Outreach gains widespread community support: OCWD gained community support through public education in the 20 cities and water agencies within the service area of 2.3 million people. Outreach to citizens; businesses; local officials; state legislators; medical and science experts; and environmental groups, including Surfrider Foundation, Orange County Coastkeeper, the Sierra Club, and many others, garnered support with no organized opposition. Recently, the project has received favorable mainstream media coverage including The New York Times, NBC Nightly News, CNN, and National Public Radio.

A financially viable solution: The GWR System produces water that is cost competitive with other sources, such as imported water from the Metropolitan Water District. And, recycled water provides economic benefits to the area residents by reducing salinity of the water in the groundwater basins. The lower mineral content groundwater pumped from the basin helps the community by reducing detergent and cleaning costs and extending the life of water heaters, boilers, and plumbing fixtures.

Meeting a community's needs: The pioneering advanced water treatment facility helps drought-proof Orange County while providing safe, potable water to a growing population in an environmentally friendly and energy efficient way.


Click here to return to the full list of this year's winning entries.
Click here to return to the E3 Competition home page.