EFFECT OF C N RATIO ON THE BIOREGENERATION OF BIOLOGICAL ACTIVATED CARBON/

To obtain insight into the role of biological activated carbon (BAG) i n the operation of the denitrification process using external carbon s ource, the effect of C/N ratio on bioregeneration of BAC was investiga ted using a fluidized bed reactor. The CM ratio was controlled by the semi-continuous mode in which NO3-N was continuously supplied to each column. The supply of sucrose as a sole organic carbon was controlled during the experimental period. The BAC under steady state of the cont inuous experiments was supplied to the semi-continuous experiment. The organic carbon was supplied to each column for 20 minutes in all semi batch experiments, but the intervals were varied from 8 to 24 hours. T he influent organic carbon concentrations were controlled to maintain the average CM ratio at 7.06 for all semi-batch experiments. In the se mi-continuous experiment, the five columns have achieved an average de nitrification efficiency ranging from 71% to 99%, though the influent C/N ratios were varied from 0 to 508. This is due to the adsorption an d desorption capacities of BAG. BAC plays a role as a storage tank for the residual sucrose using its micropore during the time when sucrose was supplied, and BAC supplied the sucrose to the denitrifying bacter ia as a carbon source so as to keep high nitrogen removal rate when su crose was not fed to the columns. These results suggest that bioregene ration may be influenced by the C/N ratio in the environment around BA G. (C) 1997 IAWQ.