CADMIUM REMOVAL IN A BIOSORPTION COLUMN

New biosorbent material derived from a ubiquitous brown marine alga As cophyllum nodosum has been examined in packed-bed flow-through sorptio n columns. It effectively removed 10 mg/L of cadmium down to 1.5 ppb l evels in the effluent representing 99.985% removal. The experimental m ethodology used was based on the early Bohart and Adams sorption model , resulting in quantitative determination of the characteristic proces s parameters which can be used for performance comparison and process design. An average metal loading of the biosorbent (N-0) determined wa s 30 mg Cd/g, corresponding closely to that observed for the batch equ ilibrium metal concentration of 10 mg Cd/L. The critical bed depth (D- min) for the potable water effluent quality standard (0.005 mg Cd/L) v aried with the column feed flow rate (2.4 to 9.6 L/h.cm(2)) from 20 to 50 cm. The sorption column mass transfer and dispersion coefficients were determined, which are also required for solving the sorption mode l equations. (C) 1994 John Wiley & Sons, Inc.