Adsorption of any contaminant is regarded feasible and favorable if RL values fulfill following condition; 0 < RL < 1. Furthermore, RL > 1 (unfavorable), RL = 1 (linear), RL = 0 (irreversible). RL values in this study were found in the range of 0–1 thus showing the feasibility of MB dye biosorption by SBR. A reduction in RL value was also observed with the increase in the initial dye concentration. This observation proposed that the adsorption of MB dye was more favorable at higher initial dye concentration (Ahmad & Rahman, 2011), and the treatment of a wastewater with relatively higher