DEVELOPMENT OF A WET WEATHER BNR STRATEGY FOR THE ARLINGTON WATER POLLUTION CONTROL PLANT

The Arlington County Water Pollution Control Plant is undergoing a retrofit to meet a proposed mandatory ammonia and voluntary total nitrogen standard. In conjunction with this upgrade, the County was instructed by the Commonwealth of Virginia to reduce plant bypasses which occur during wet weather conditions. A detailed analysis was undertaken to develop a wet weather management plan which allows increased secondary BNR flows while maintaining nitrification/denitrification in the activated sludge. The main components of the wet weather management plan are the new flow equalization basin, operational flexibility in terms of PE feed to the individual aeration tank passes, flexible aerobic/anoxic swing zones and retrofitting of the secondary clarifiers.