NITRIFICATION OF LANDFILL LEACHATE USING SUSPENDED-CARRIER BIOFILM TECHNOLOGY

The possibility of nitrifying municipal landfill leachate using suspen ded-carrier biofilm technology was studied in three laboratory-scale r eactors filled with three different types of carrier media. The effect s of the temperature and the hydraulic retention time (HRT) on the vol umetric nitrification rate were investigated. Steady-state nitrificati on rates were obtained in the processes after approximately 1 month of operation. The nitrification rate showed a rather weak dependence on the temperature, the rate at 5 degrees C being approximately 77% of th e rate at 20 degrees C. The HRT had a more pronounced effect on the ra te of nitrification, shoeing a considerable increase in nitrification rate with a decreased HRT. The highest efficiency was achieved for a c arrier media consisting of small cubes of macroporous cellulose. A max imum nitrification rate of 40 g (NH4+-N)/(m(3) reactor h) was obtained by use of this carrier at 20 degrees C, an HRT of 14 h and a carrier filling degree of 10% of the reactor volume. (C) 1997 Elsevier Science Ltd.