BIOLOGICAL DENITRIFICATION OF DRINKING-WATER USING AUTOTROPHIC ORGANISMS WITH H-2 IN A FLUIDIZED-BED BIOFILM REACTOR

Biological denitrification of drinking water was studied in a fluidized sand bed reactor using a mixed culture. Hydrogen gas was used as the reaction partner. The reaction kinetics were calculated with a double Monod saturation function. The K//S value for hydrogen was below 0. 1% of saturation. No appreciable biofilm diffusion effects were detected. Reactor performance was a function of the culture's past history. Batch experiments always exhibited an accumulation of NO//2** minus , but continuous experiments with a sufficiently long residence time always resulted in complete nitrogen removal. Rates of up to 23 mg N/L h, 25 mg N/g DW h, and 7. 9 mg H//2/L h were achieved. Residence times of 4. 5 h would be required for complete denitrification of water containing 25 mg NO//3** minus -N/L or approximately 1 h for every 5 mg/L.