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Angels Camp, CA, United States

The City of Oxnard in California is implementing a strategic water resources program known as the Groundwater Recovery Enhancement and Treatment (GREAT) program, which includes an Advanced Water Purification Facility (AWPF) that will use a major portion of the secondary effluent from the City's existing Water Pollution Control Facility to produce high-quality treated water to be used for irrigation of edible food crops, landscape irrigation, injection into the groundwater basin to form a barrier to seawater intrusion, and other industrial uses. The AWPF, currently under design by CH2M HILL, will employ a multiple-barrier treatment train consisting of microfiltration, reverse osmosis, and ultravioletlightbased advanced oxidation processes to purify the secondary effluent to conform to California Department of Public Health Title 22 Recycled Water Criteria for groundwater recharge. The AWPF, which will have initial and build-out capacities of ca. 24,000 and ca 95,000m3/day, respectively, was limited to a 1.8-hectare site, with 0.4 hectares dedicated to a Visitor's Center and administration building. Further, the depth below grade and height of the AWPF's structures were constrained because of the high groundwater table at the site, the high cost of excavation and dewatering, and local codes. To accommodate these various restrictions, an innovative design approach has been developed. This paper summarizes the design constraints and innovative solutions for the design of the AWPF. © IWA Publishing 2010. Source

Franks R.N.,Hydranautics Nitto Denko | Bartels C.R.,Hydranautics Nitto Denko | Birch D.,City of Oxnard
AWWA/AMTA Membrane Technology Conference and Exposition 2012 | Year: 2012

In November 2008, the City of Oxnard, located sixty miles northwest of Los Angeles, commissioned its first, large scale, brackish water reverse osmosis (BWRO) desalination water treatment facility as part of its comprehensive regional water resources development program. The uniquely designed RO uses energy saving technologies in a hybrid configuration to minimize power consumption. The 7.5 MGD (28,400 m3/day) RO has been operating stably for three years and affords the opportunity to compare the tradeoff between its original capital cost and its operating cost based on actual performance data. Downstream cartridge filtration, the two stage BWRO system treats ground water with an average salinity expressed in TDS of 1,500 mg/l and a temperature ranging between 18°C and 25°C. The plant employs a hybrid design by using two different RO membranes with differing permeabilities and rejections in each of the two stages. Contrary to a typical hybrid design, the Oxnard inverts the membrane installation by placing the higher permeability membranes in the first stage while higher rejecting membranes improve the permeate quality coming from the second stage. The flux imbalance that would normally occur in such an reversed hybrid is offset by the presence of an Energy Recovery Device (ERD) between the two stages. This leads to a more equitable flux throughout the system. The selection of an ERD increased the capital cost of the plant. However, the use of a hybrid design in combination with the ERD, offers operational cost savings relative to a more conventional, lower capital, system. Placing the higher rejecting membranes in the second stage where they are needed most means that the overall permeability of the plant is lower than if the higher rejecting membranes had been located in the first stage. The operational savings associated with this unique membrane combination offsets the higher capital cost of the ERD which makes the design preferable both economically and technically. This paper evaluates the capital and operating cost associated with the reversed hybrid design and compares the Oxnard design to other Brackish RO designs including a similar design that takes advantages of the latest RO membrane chemistry as well as manufacturing developments that were not available when Oxnard was commissioned in 2008. The evaluation is based on actual operating data spanning the past three years, including actual feed and permeates water ion analysis. The difference in operating cost will be compared to the differences in capital cost, and a 2 year return on investment will be shown. The technical and economic evaluation of the system, based on three years of operating data, illustrates the use of an innovative design employing the latest energy saving technologies to reduce energy consumption and operating costs. This evaluation can be used to design an RO system and evaluate the tradeoff between capital cost and operating cost, while seeking to tailor the element selection to meet specific permeate quality targets. © 2012 American Water Works Association. Source

Chakraborti R.K.,CH2M | Bays J.S.,CH2M | Ng T.,City of Oxnard | Balderrama L.,City of Oxnard | Kirsch T.,City of Oxnard
Water Science and Technology | Year: 2015

A pilot study was conducted for 7 months for the City of Oxnard, California, on the use of constructed wetlands to treat concentrate produced by microfiltration and reverse osmosis (RO) of reclaimed wastewater. The treatment performance of a transportable subsurface-flow wetland was investigated by monitoring various forms of nitrogen, orthophosphate, oxygen demand, organic carbon, and selenium. Significant mass removal of constituents was measured under two hydraulic residence times (HRTs) (2.5 and 5 days). Inflow and outflow concentrations of nitrate-N and ammonia-N were significantly different for both HRTs, whereas nitrite-N and total organic carbon (TOC) were significantly different during HRT2. Mass removal by the constructed wetland averaged 61% of nitrate-N, 32% of nitrite-N, 42% of ammonia-N, 43% of biochemical oxygen demand, 19% of orthophosphate as P, 18% of TOC and 61% of selenium. Mass removal exceeded concentration reductions through water volume loss through evapotranspiration. Calibrated first-order area-based removal rates were consistent with literature ranges, and were greater during HRT1 consistent with greater mass loads, higher hydraulic loading and shorter HRTs. The rate constants may provide a basis for sizing a full-scale wetland receiving a similar quality of water. The results indicated that engineered wetlands can be useful in the management of RO membrane concentrate for reclaimed water reuse. © IWA Publishing 2015 Water. Source

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