COMPREHENSIVE ASSESSMENT OF PERFORMANCE CAPABILITIES OF BIOLOGICAL NUTRIENT REMOVAL PLANTS OPERATING IN THE CHESAPEAKE BAY REGION

BACKGROUND AND INTRODUCTION Nutrient removal from bodies of water is fast becoming a highly scrutinized and significant objective of governing agencies across the country. In the Mid Atlantic region, the new commitments under the 2000 Chesapeake Bay Agreement requires optimization of existing nutrient removal processes and upgrades of the major wastewater treatment plants to allow for additional nutrient reductions that approach the limits of conventional treatment technologies.A number of nutrient removal plants have been constructed and recently commissioned and are now fully operational in the Chesapeake Bay. The primary goal of this study is to review the performance of six biological nutrient removal (BNR) plants ranging in size from 5 mgd to 273 mgd, with effluent total nitrogen (TN) limits of 8 mg/L to 3 mg/L annual average. The plants employ treatment processes that include the Modified Ludzak Ettinger (MLE), step-feed nitrification/denitrification with and without carbon addition, four-stage Bardenpho and a two-stage activated sludge process with post-denitrification and carbon addition. The results of this review will be useful to others as they seek to optimize existing facilities to maximize the removal of nutrients.