Flowrate of the continuous media trickling was varied from 10 mL/min to 200 mL/min. Each setting of the flowrate was maintained for 7 days and the average values of performance parameters measured are given in Table . H 2 conversion reduced with an increase in the trickling flowrate. Taking the 10 mL/min as the base case, the C H 2 increased from an average value of 1.96% at 10 mL/min of trickling flowrate to 15.79% at 200 mL/min of trickling flowrate. Similarly, RE of H 2 reduced from 98.9% to 90.82% and PC reduced from 7.0 Nm 3 /m 3 d to 6.05 Nm 3 /m 3 d. A similar correlation of decrease in PC with an increase in trickling flowrate was reported by . The increased trickling flowrate results in a thicker water film on top of the hydrogenotrophic biofilm. As a result, it increases the resistance to mass transfer for the feed gases H 2 to reach the active hydrogenotrophic methanogens inside the biofilm.