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The State of Maryland, acting to improve the health of Chesapeake Bay under the Chesapeake Bay Program, has initiated the Enhanced Nutrient Removal (ENR) Program to reduce the discharge of nutrients to Chesapeake Bay. The Patapsco Wastewater Treatment Plant (Patapsco), located in the City of Baltimore, Maryland, is currently in the planning and design stages of a nutrient removal project that includes the upgrade of the facility from secondary treatment limits with no nitrogen removal technology to ENR levels (3 mg/L total nitrogen and 0.3 mg/L total phosphorus, annual average). However, previous work at the facility indicated that a portion of the influent is frequently inhibitory to nitrification, causing complete failure in the previous attempts to nitrify the wastewater.

At the initiation of the project, it was thought that a pretreatment system to reduce this inhibition would be necessary prior to implementing a nutrient removal project. However, bench-, pilot-, and full-scale testing indicated that the existing high purity oxygen process was able to reduce the inhibition significantly. This allowed the use of a two-stage treatment approach in which the existing plant would be left in place to provide secondary treatment and remove the nitrification inhibition and a tertiary treatment system would be added for nitrification and denitrification.

Document Type: Research Article


Publication date: 2005-01-01

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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 These proceedings are not peer reviewed.

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