BIOLOGICAL UPFLOW FLUIDIZED-BED DENITRIFICATION REACTOR DEMONSTRATIONPROJECT STAMFORD, CT, USA

The discharge of nitrogen in wastewater treatment plant effluent has b een identified as a receiving water quality issue throughout the Unite d States and in the European Community. Regulatory agencies are evalua ting discharge limits for total nitrogen (TN) as low as 3 to 5 mg/l]. To attain these limits at treatment plants with little or no space for expansion, technologies which can remove large quantities of nitrogen with relatively small space requirements are required. Biological upf low fluidized bed (BFB) technology appears to be well suited to these regions. This paper describes the results of a demonstration project u sing a fluidized bed reactor. The reactor was operated at a flow rate of 15 l/s and an average daily loading of 1843 kg NO3/1000 m(3)/d and maximum loadings of 6407 kg NO3/1000 m(3)/d. At steady-state condition s, effluent total nitrogen concentrations averaged 2.5 mg/l over a tem perature range of 11 to 25 degrees C. At high nitrate loading rates, e ffluent total nitrogen concentrations averaged 4.1 mg/l. Approximately 3 mg of methanol per mg of influent nitrate was used as a carbon sour ce. Reactor empty bed contact time averaged 5.7 minutes. (C) 1997 IAWQ . Published by Elsevier Science Ltd.