REMOVAL OF DICHLOROMETHANE FROM WASTE GASSTREAMS USING A HYBRID BUBBLE COLUMN/BIOFILTER BIOREACTOR: EFFECT OF EMPTY BED RETENTION TIME ANDKINETIC OF BIOFILTRATION

Introduction: Dichloromethane (DCM) is an air pollutant emitted mainly through industrial application. In this study, removal of DCM from waste gas streams using a pilot-scale hybrid bubble column/biofilter (HBCB) bioreactor was studied in steady state. Materials and methods: The hybrid bioreactor had two compartments: bubble column bioreactor and biofilter.The experiments were carried out with relatively constant concentration of DCM (approximately 240 ppm) and variable empty bed residence time (EBRT) of 50, 100, 150 and 200 s in steady state. Results: The average DCM removal efficiency of the HBCB bioreactor at EBRT of 200 and 150 s were 79 and 71%, respectively, but further reduction of EBRT significantly decreased the DCM removal efficiency. DCM removal rate was determined to be in the range of 12.1 g/m3.h to 19.6 g/m3.h. The first order rate equation best described the kinetic data of biofiltration (R2>0.99) with kinetic constant of 0.0114 1/s. The mixed liquor characterization indicated that the daily adjustment of pH and EC was sufficient to prevent any limitation in the performance of the HBCB bioreactor. Conclusions: This study showed that the HBCB bioreactor could be an efficient, economical and flexible option for DCM removal from waste gas streams.