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Many utilities considering indirect potable reuse want to know if ultraviolet (UV) peroxide treatment for NDMAwill remove other xenobiotic contaminants. Endocrine disrupting compounds (EDCs),pharmaceuticals and personal care products (PPCPs) are presently unregulated contaminants withpoorly understood human health and ecological effects that occur with great consistency inwastewater effluents. This study evaluated the ability of UV peroxide to reduce EDCs and PPCPswhen applied at the dose needed to control NDMA. Pilot testing occurred at the City of San Diego's 30-MGD North City Water Reclamation Plant(NCWRP) located in San Diego, California. The NCWRP consists of bar screening, grit removal,primary clarification, aeration, secondary clarification, filtration, demineralization withelectrodialysis reversal (EDR), and disinfection. A process flow diagram of NCWRP showing themajor unit operations is provided.A side stream of filtered effluent was fed to a pilot consisting of a Zenon ZeeWeed 500 UFmembrane system, a dual stage RO membrane system, and a Trojan Technologies Inc.UVLogic8AL30 low pressure high output (LPHO) UV lamp system. Hydrogen peroxide was addedwith a static mixer at the inlet pipe to the UV reactor. An overall schematic of the pilot train is provided, along with a picture of the UV reactor and the specifications forthe Trojan UV system. NDMA as well as EDC and PPCP compounds were spiked into the UV reactor influent during thepilot study. The specific EDC and PPCP compounds selected for spiking were chosen based on thefollowing criteria: high likelihood of occurrence in prior monitoring results; provision of abroad range of physical and chemical properties; and, amenability to a single solid-phaseextraction LC/MS/MS analysis (Vanderford, 2003). A brief description of the target chemicalsutilized in the study is provided. NDMA was spiked to approximate 800 ng/L andEDC/PPCP compounds were spiked between 280 and 990 ng/L. Positive and negative controlsamples were associated with each experiment. The bench-scale UV collimated beam apparatus, consisting of a low-pressure UVlamp housed within a 6.6 cm diameter collimating tube, was used to characterize the delivered doseof the pilot-scale system. An International Light calibrated radiometer (IL1400) was used tomeasure the UV intensity at the surface of 150-mL water samples contained within a petri dish anduniformly placed below the collimator. These water samples were collected from the pilot facilityand fortified with NDMA to achieve a uniform high initial concentration of approximately 1000ng/L. Analysis of the NDMA concentration of these samples after different UV exposure periodswas used to generate a dose-response curve. This curve is then utilized to characterize the delivereddose of the pilot system by comparing the log reduction achieved with the pilot facility to thecorresponding dose of the collimated beam curve. Includes 5 references, tables, figures.

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Edition: Vol. - No. Published: 06/01/2006 Number of Pages: 7File Size: 1 file , 420 KB