Optimal Aerations in the Inverse Fluidized Bed Biofilm Reactor When Used in Treatment of Industrial Wastewaters of Various Strength

Abstract

The aim of this work was the determination of the optimal aerations, and more specifically the corresponding optimal air velocities u opt , at which the largest COD removals were achieved in treatment of industrial wastewaters of various strength conducted in the inverse fluidized bed biofilm reactor. The largest COD removals were achieved at the following air velocities u opt and retention times t s , and (V b /V R ) = 0.55: i) for COD o = 72,780 mg/l at u opt = 0.052 m/s and t s = 80 h ; ii) for COD o = 62,070 mg/l at u opt = 0.042 m/s and t s = 65 h; iii) for COD o = 49,130 mg/l at u opt = 0.033 m/s and t s = 55 h ; iv) for COD o = 41,170 mg/l at u opt = 0.028 m/s and t s = 45 h; v) for COD o = 35,460 mg/l at u opt = 0.025 m/s and t s = 27.5 h; and vi) for COD o = 26,470 mg/l at u opt = 0.014 m/s and t s = 22.5 h. In the treatment operation conducted in a reactor optimally controlled at the above values of u opt , t s and (V b /V R ), the following decreases in COD were obtained: i) from 72,780 to 5410 mg/l; ii) from 62,070 to 3730 mg/l; iii) from 49,130 to 2820 mg/l; iv) from 41,170 to 1820 mg/l; v) from 35,460 to 1600 mg/l; and vi) from 26,470 to 1180 mg/l, that is, approximately a 93%, 94%, 95%, 96%, 95% and 96% COD reduction was attained, respectively.