(Credit: Pixabay)Paso Robles, California, recently announced the completion of the new Tertiary Treatment Facilities at its wastewater treatment plant (WWTP), augmenting the roughly 30,000-resident city’s water stewardship in a state dealing with water scarcity.
Black & Veatch served as designer and engineer of record for both the secondary treatment project and the tertiary treatment project heralded as one of the largest, most complex infrastructure projects in the history of the 130-year-old city known for its hot springs.
The Paso Robles WWTP project comes amidst California’s growing focus on sustainable, resilient and reliable water solutions. Like many other cities in California, water is at a premium, and Paso Robles has a master plan that involves producing quality recycled water to irrigate public areas such as city parks and golf courses. By reducing the need to pump groundwater from the Paso Robles Groundwater Basin, the WWTP project helps build sustainability while strengthening the city’s water supply, according to town officials.
The Tertiary Treatment Facilities project involved multiple components, including an Aqua-Aerobic cloth disc filtration process and in-channel Trojan ultraviolet (UV) light disinfection. UV disinfection was selected in lieu of the more cost-effective chemical disinfection to remove potential for formation of disinfection byproducts to the recycled water distribution system. The existing secondary clarifiers were repurposed and converted to an equalization basin upstream of the new filtration process. The project also entailed converting one of the onsite ponds to store the recycled water.
The facilities also feature an advanced nutrient harvesting system that removes ammonia, nitrate and phosphorus from the filtrate that comes from the digested sludge dewatering system. The filtrate, without being treated, was causing buildup of struvite in the pipes and inhibiting treatment processes. The nutrient harvesting system is used to remove the nuisance struvite and to create commercial-grade fertilizer. In addition to plant maintenance purposes, the city is marketing the fertilizer to offset the cost of building the facility. This nutrient harvesting system is the first of its kind in the State of California.
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