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Comparative Study of On-line Instruments for Monitoring Low Nutrient Concentrations

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As many facilities in the Chesapeake Bay and beyond plan Enhanced Nutrient Removal (ENR) capital improvements / upgrades to achieve stringent effluent TN limits of less than 3 mg/l and TP<0.18 mg/l, concern is growing about the operational complexities of monitoring and responding rapidly to changes in the biological processes. To effectively manage the ENR process one requires accurate real time data to monitor or control critical parameters such as DO, Phosphorus, Nitrate, Nitrite and Ammonia. This study was conducted at DCWASA's Blue Plains Advanced WWTP from January to June 2008. It was a part of a pilot study for Moving Bed Bioreactor (MBBR) technology. Three different online analyzers were installed at the MBBR pilot: (i) ChemScan (ii) Hach's Nitratax™ plus sc, and (iii) Endress+ Hauser's nitrate analyzer. They were used to monitor the following nitrogen species, NOx-N, NO2-N, NH3-N, and orthophosphate (PO4-P). The analyzers were installed at seven different locations and grab-samples were collected from all seven of those locations for comparison using laboratory analysis. The online readings and lab results were compared for each analyzer. This study was conducted over a six-month period but not all of the analyzers were in service at all times during this period.

This paper presents a comparison of lab and online data and offers some insights as to the accuracy of the various units. In addition, specific maintenance requirements for each type of analyzer were identified and are discussed in this paper.

Keywords: Enhanced Nutrient Removal; Online Analyzers; Online Nutrient Monitoring; Process Instrumentation

Document Type: Research Article


Publication date: 2009-01-01

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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