The column experiments were performed in a packed bed column of inner diameter 30 mm and length of 500 mm
uniformly packed with 38 g (dry basis) of acid treated biomass operated in a trickle bed regime (see figure 2). During
the column sorption operation, an aqueous solution containing 35 mg/l copper (from CuSO4.5H2O), at pH 4 was
pumped through the column at a constant flowrate (15 ml/min) continuously. At pH 4 it was shown that the rate of
adsorption was high. Experiments were conducted at different pH. The samples were collected from the outlet of the
column at different time intervals and analyzed for the copper effluent concentration by AAS. After the biomass in the
column became saturated, the column was washed at the same flowrate by distilled water for several hours, before a
subsequent copper elution with 0.1N HCl acid. The reason for washing the column for several hours was to ensure that
all solution with Cu ions was removed. This forms first step of biomass regeneration before elution step. The outlet
sample collection and analysis was the same as that used in the biosorption uptake run.