The purpose of this experimental research was focused to improve the quality of the effluent and the yielded sludge when the papermill wastewater was treated by the indirect aerated submerged biofilter as a second treatment method of papermill wastewater. Changing the various experimental factors (Nutrient additions or not, HRT, F/M ratio, recirculation ratio, etc) with indirect aerated submerged biofilter, the results are as follows. 1) Because of the microbes concentration could be sustained to 9,000 ㎎/l in submerged biofilter and then the volumetric organic loads could be increased to 2.7 ㎏-BOD/㎥/day, the reactor volume can be reduced. 2) Because of the yield coefficient(Y) and the endogenous decay coefficient(kd) were revealed 0.4 and 0.07/d, the yielded sludge volume was reduced. 3) The concentration of the sloughed sludge in the reactor was 2.62-4.01 %, so the thickener could be omited in the papermill wastewater sludge treatment process. 4) When the operating was conducted at HRT of 4hrs, the treatment efficiencies of BOD and COD were obtained 80% and 70%. 5) The range of the theoretical recirculation ratios of this reactor was 14-26. According to those ratios, at the low loads ( BOD volumetric loads is less than 0.79㎏-BOD/㎥/day, F/M ratio is less than 2.0/d) the results were fitted to the theoretical recirculation ratios (14∼26) and at the high loads the efficiency were increased to the rise of recirculation ratios.

• 원찬희 | Chan Hee Won