A novel multi-stage external loop airlift reactor (MS-ELALR) has been designed to remove phenol and Cr(VI) from wastewater by means of their adsorption onto the surface of activated carbons. The multi-staging has been achieved by hydrodynamically induced continuous bubble generation, breakup and regeneration. The typical values of gas holdup, liquid circulation velocity, interfacial area and volumetric mass transfer coefficient of the MS-ELALR were found to be 0.42-0.66, 0.04-0.13 m/s, 70-300 m2/m3 and 0.01-0.5 s-1 respectively. Powdered activated carbons were prepared from four different...