Saving Silicon Valley: How A Reuse Project Became Its Own Tech Breakthrough
By Sanjay Reddy, Jim Fiedler, Hossein Ashktorab, and Jim Clark
The Silicon Valley Advanced Water Purification Center project provides expanded reuse opportunities, increased sustainability, and promise for the future.
Long before Governor Jerry Brown declared a drought state of emergency in January, water managers throughout California had gone to impressive lengths to stretch existing supplies and prepare for continued water shortages. Last year, the WateReuse Association recognized the inspirational Silicon Valley Advanced Water Purification Center (SVAWPC) project with its (Large) Project of the Year Award, and this year the project became Global Water Awards’ 2015 Wastewater Reuse Project of the Year. The SVAWPC has produced highly purified water for a drought-proof recycled supply for over a year.
A collaborative effort between the Santa Clara Valley Water District (SCVWD), which owns and operates the facility, and the city of San Jose, which operates South Bay Water Recycling (SBWR), the SVAWPC is the largest project of its kind in Northern California and the first in the San Francisco Bay Area. It transforms treated wastewater that would otherwise be discharged into San Francisco Bay into 8 MGD of sustainable supply, which meets California’s primary drinking water standards for applications including industrial processes, cooling water, landscaping, irrigation, and recreation. The facility uses a trio of tertiary treatment technologies to add a local, safe, reliable resource to Silicon Valley’s supply portfolio.
Transforming Water
Water reuse requires not only motivation and technology but also a market that values the product. An earlier study revealed that salinity was a concern in the existing recycled supply for a region where consistent quality was crucial in industrial user operations. A feasibility study confirmed that development of an advanced recycled water treatment facility with a high-quality water product that could be blended with existing recycled water would provide more consistent recycled water quality. Evaluation of options ensued, and approximately $5.5 million in state grants from the California Department of Water Resources and $8.25 million in federal funding through the American Recovery and Reinvestment Act helped fund the resulting $72 million project.
The state-of-the art SVAWPC purifies nitrified secondary effluent from the neighboring San Jose-Santa Clara Regional Wastewater Facility using an integrated membrane system consisting of 38 million liters/day (ML/d, or 10 MGD) microfiltration (MF) and 30.3 ML/d (8 MGD) reverse osmosis (RO) followed by a 38 ML/d (10 MGD) UV disinfection process. The purified water is then blended with existing recycled water produced at the regional facility to enhance quality and expand reuse.
The backwash from the MF units and neutralized products from the MF and RO chemical cleaning are returned to the regional facility for treatment. The brine from the RO system is returned to the regional facility’s chlorine contract basin for blending with the plant’s effluent prior to the discharge into San Francisco Bay. Using advanced treatment processes to further remove pollutants and other potentially harmful constituents, such as salt, from the recycled water opens up additional potential uses for the recycled water. The higher-quality recycled water could be used in the future to improve groundwater quality, which would further reduce the demand on potable water supplies.
The new water supply is distributed via the regional purple-pipe recycled water system. More than 700 SBWR customers now use the enhanced recycled water. With total dissolved solids levels of approximately 500 mg/L, the blended water reduces chemical use and maintenance costs for industrial users and is easier to use in some irrigation and agricultural applications because of reduced salt buildup.
Demonstrated Success
A 30-day performance acceptance test demonstrated that equipment could operate continuously for 24 hours a day under design conditions with no major interruptions and still meet permitted water quality requirements. The test also demonstrated successful integration of the product water into the existing recycled water system under various operating modes.
Black & Veatch served as the prime consultant for the project, providing design, membrane procurement, and construction and operations support. JR Filanc served as the general construction contractor. The SVAWPC began operations in March 2014, followed by a grand opening ceremony in July.
In addition to increasing recycled water treatment capacity and quality for the region and allowing more versatile uses, the expandable SVAWPC is helping raise awareness and support for advanced processes that render water of such high quality capable of more versatile uses. Today, recycled water meets about 5 percent of the county’s total water demand; by 2025, the SCVWD plans to double that number. The district is using the facility to evaluate the possibility of using highly purified water for potable reuse.
Value Beyond Dollars
The value of the SVAWPC exceeds the price retailers and end users pay for the purified water. It helps facilitate a shift away from imported water supplies. It decreases the region’s dependence on the Sacramento- San Joaquin Delta, improving the resiliency of the region’s water system. And it helps motivate water users to switch their industrial, landscaping, and agricultural demands from potable to recycled water. The expandable facility also lessens discharges of treated effluent into San Francisco Bay, which helps preserve the tidal habitat.
In its first year of operation, the facility has consistently met and exceeded the design goals for finished water quality. Changes in the influent water quality required adoption of additional operational strategies to minimize impacts to the treatment process and finished water-quality goals. The discharge of the brine from the RO system to the regional facility’s chlorine-contact basin has been optimized for improved performance of the treatment process. The SVAWPC provides broad reuse opportunities that add resiliency to a system impacted by severe drought.
About The Authors
Sanjay Reddy is a project director in the Walnut Creek, CA, office of Black & Veatch. Jim Fiedler is chief operating officer, and Hossein Ashktorab is recycled water unit manager for the Santa Clara Valley Water District in San Jose, CA. Jim Clark is a senior vice president for Black & Veatch based in Los Angeles. All authors have extensive experience with water management, especially water resource recovery and reuse.