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This poster presentation highlights the quality assurance and quality control programs currentlyimplemented at Passaic Valley Water Commission in Totowa, New Jersey to ensurecontinued optimal performance of dissolved ozone monitors. The monitors are used todetermine the primary disinfectant residuals at the Little Falls Water Treatment Plant. Thereare a total of four ozone contactors at the facility with four monitors installed in multiple cells ofeach contactor. The program success requires the efforts of the Laboratory, Operations andMaintenance Departments and is the primary focus of a designated online water qualityInstrument Team at the facility.In order to comply with 40 CFR 141.74, the PVWC Laboratory holds state certification forStandard Method 4500-Osub3/sub B Ozone Residual, Indigo Colorimetric Method, where this methodis used to verify the calibration of all of the continuously monitoring ozone sensors that are inservice at a required frequency of twice per week.The PVWC Laboratory staff also incorporate an additional step in the method to determine theamount of interference resulting from the oxidation of existing manganese in the water. Theamount of interference can than be accounted for and corrected, ultimately increasing theaccuracy of the method. This is of particular importance since many systems have convertedfrom pre-chlorination to ozone and do not necessarily remove manganese before the ozoneprocess. The presence of manganese would give a false positive ozone residual using theIndigo Colorimetric Method.The Operations Department has been trained by the Laboratory to perform daily ozoneresidual checks using the Hach AccuVac method. The spectrophotometer used for thisprocedure is performance checked weekly by the laboratory. The operation department'sresults are reviewed by the instrument team daily to determine if there is an issue. Theinstrument team is responsible for troubleshooting. The Maintenance Department corrects anyflow-related problems resulting from sample line clogging. The Instrument Team hasimplemented a preventive maintenance program for the dissolved ozone sensors that isdesigned to avoid sensor failure. Quarterly, each sensor is refurbished and zeroed accordingto the manufacturer's procedures. Includes tables, figures.

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Edition: Vol. - No. Published: 11/01/2007 Number of Pages: 14File Size: 1 file , 600 KB