Pilot plant studies were conducted to evaluate the use of pre-denitrification for nitrogen removal at low-rate biological filter works. The plant was operated over a range of recycle ratios to determine the optimum operating conditions. It was possible to meet a total nitrogen limit of 15 mg TN/l with a 2:1 ratio of recycled filter effluent to settled sewage. Following the studies, an economic comparison was made to compare the costs of pre-denite plant with post-denitrification in tertiary sand filters. The cost-effectiveness of the pre-denite process depended on the price of the external carbon source used in post-denite plant. Biological fluidised beds were shown to be the most cost-effective type of pre-denite plant.
Pre- or post-denitrification at biological filter works? A case study
A. Dee, N. James, I. Jones, J. Strickland, J. Upton, P. Cooper; Pre- or post-denitrification at biological filter works? A case study. Water Sci Technol 1 October 1994; 29 (10-11): 145–155. doi: https://doi.org/10.2166/wst.1994.0756
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