Denitrification in a packed bed biofilm reactor (BIOFOR) - Experiments with different carbon sources.

The objective of this laboratory study was to investigate the efficiency of hydrolysed sludge and solid organic waste as a carbon source for denitrification in a packed bed reactor compared to ethanol and acetic acid. An artificial wastewater with a temperature in the range of 9-11 degrees C was used. The denitrification rate, the COD consumption and utilization efficiency and the pressure drop were response parameters. Under the experimental conditions, a maximum denitrification rate of about 2.5 kg NO3-N/m(3).d was achieved with ethanol, whereas acetic acid gave a lower and more variable rate below 2 kg NO3-N/m(3).d. The required COD/NO3-N ratio with ethanol was close to 4.5 g COD/g NO3-N. A reduced rare was found at effluent concentrations below 15 mg COD/l. Hydrolysate from sludge and solid organic waste gave the same maximum denitrification rate as ethanol, but a ratio of 8-10 g COD/g NO3-N was required. The rate decreased at effluent concentrations below 75 mg COD/l. While close to 69% of the COD in the hydrolysate was removed, only 45% was utilized for denitrification. The removal of phosphorus was found to be three times higher than the theoretical consumption based on growth. (C) 1998 Elsevier Science Ltd. All rights reserved.