Use of Sequencing Batch Reactor for Biological Denitrification of High Nitrate-Containing Water

Abstract

The efficiency of a sequencing batch reactor in denitrification of drinking water with relatively high nitrate concentrations (40–250 mg/L as N) was evaluated. Ethanol at a COD/N of 2.00 was found sufficient to reduce nitrate concentrations to acceptable levels (<10 mg/L as N). Within the first 6 min of reaction, nitrite accumulation in the range of 0.03–3.5 mg/L as N was observed increasing with the increase of initial nitrate concentrations. In the first hour, nitrate removal was significantly high in the range of 85.7–91.5%. Anoxic reaction times of 3, 5, and 7 h were required for nitrate concentrations of 40–160, 200, and 250 mg/L (as N) to achieve acceptable levels of nitrate and nitrite. Alkalinity of the denitrified water increased on average by 3.53 mg as CaCO