Santa Cruz City Wastewater Program Awarded

Tertiary Membrane Pilot Project Wins 2018 Engineering Achievement Award

The City of Santa Cruz Wastewater Treatment Facility was awarded the 2018 Engineering Achievement Award from the California Water Environment Association (Monterey Bay Section) for a pilot project that evaluated tertiary treatment technology in a joint effort with Soquel Creek Water District (District).

Last spring and summer, the SCWWTF and the District collaborated on the pilot project, as part of the District’s proposed Pure Water Soquel project. This small-scale tertiary treatment pilot plant, using ultrafiltration membranes, was in operation for three months on site at the SCWWTF. The pilot plant was partially funded by a U.S. Bureau of Reclamation Title XVI Recycled Water Feasibility Planning Grant for $150,000, which the District received in 2017.

Ultrafiltration membranes are utilized to remove particulates from the City’s secondary-effluent treated water to produce tertiary-treated, recycled water. For the proposed full-scale PWS project, this step would then be followed by reverse osmosis, and advanced oxidation with ultraviolet light. Existing advanced purification facilities including Orange County Water District and West Basin Water District in Southern California, and the Silicon Valley Advanced Water Purification Center and Pure Water Monterey utilize this technology in their water purification processes. This pilot project confirmed and authenticated the technologies involved, and will contribute to the design phase of the PWS project.

“This engineering achievement award acknowledged the high quality of the pilot project, and supports the value and practicality of the data gathered,” said City of Santa Cruz Public Works Director Mark Dettle. “All of the partners involved — the City of Santa Cruz, the Soquel Creek Water District, H20 Innovations and Carollo Engineers — are to be congratulated on this award and on their exemplary, successful work on this project.”

The pilot plant was designed and built by H2O Innovations and was operated by Carollo Engineers Inc. and the District, in collaboration with the SCWWTF staff. The results from the pilot project provided useful data while it was in in operation. Staff were able to evaluate the response of different membranes, develop membrane cleaning strategies, monitor and assess filtered water quality, ascertain maximum sustainable flux/flow rates, determine the size of a plant needed to scale-up the process, and gather other key pieces of information that are crucial as the PWS project moves forward.

The recently approved PWS project involves recycling approximately 25 percent of the secondary treated effluent that is currently being discharged out to the Monterey Bay National Marine Sanctuary from the SCWWTF, purifying it, and then using the purified water to replenish the Santa Cruz Mid-County Groundwater Basin to create a seawater barrier. The basin has been classified by the state as critically over-drafted and is under mandate to be brought into sustainability by 2040.

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The award-winning City of Santa Cruz Wastewater Treatment Facility operates and maintains a regional wastewater treatment and disposal facility. Wastewater treatment is provided for the City of Santa Cruz and the Santa Cruz County Sanitation District including Live Oak, Capitola, Soquel and Aptos. The facility provides quality-of-life service to the community while helping to reduce the City’s carbon footprint and protecting the environment.

The Soquel Creek Water District is a nonprofit, local government agency that provides water resource management within its service area to deliver a safe and reliable supply of high-quality water to meet present and future needs in an environmentally sensitive and economically responsible way.

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For more information: http://www.cityofsantacruz.com