Nitrification of industrial waste-waters with high nitrogen concentration in aerated packed-bed reactors

The use of a two-step aerated packed-bed reactor yielded 99% nitrification of inorganic nitrogenous wastes carrying 800 to 1,300 mg N/l (COD of the wastes 55 mg O2/1). The beds were aerated with air enriched in CO2 pH values between the units were routinely adjusted. The efficiency of nitrification was 33 mg N/l/h. A change of the composition of the wastes to nitrogenous-organic (COD 1,200 mg O2/l) caused a drop in the efficiency of nitrification to 24 mg N/l/h and the subsequent introduction of a three-step system. Concomitant COD reduction was 85% with 73% reduction occurring in the first bed. The number of auto- and heterotropic bacteria in the nitrogenous-organic wastes and effluents from the separate beds were determined.