HIGH LOADING DENITRIFICATION BY BIOLOGICAL ACTIVATED CARBON PROCESS

High loading denitrification was studied using granular activated carb on (Calgon Filtrasorb 400, size: 0.8-1.4 mm) column with injecting car bon source (sucrose) only once a day. Under the condition of EBCT (emp ty bed contact time) = 80 min, C:N ratio = 1.88, once per day injectio n mode of organic supply was able to sustain an average denitrificatio n efficiency of 84 to 89% even with influent NO3-N concentration of 80 mgl(-1). With an influent NO3-N of 20 mgl(-1) and C:N ratio of 1.88, however, reduction of EBCT to 20 min resulted in very poor denitrifica tion. In the latter case, 46% of the added carbon was lost in the effl uent immediately after the injection. Short EBCT critically affected t he process mainly due to insufficient adsorption rate. Microbial denit rification capability and fermentation might also limit the process. E xtended organic injection is a possible option to improve the process efficiency. Occurrence of the sulfate reduction was limited in early p hase of the cycle.