Copper removal from wastewater using spent-grain as biosorbent

The removal of Cu(II) ions from aqueous solutions using spent-grain was studied. The experimental data fitted the Langmuir isotherm and the maximum adsorption capacity of spent-grain was determined to be 10.47 mg g−1 dry weight (pH 4.2). Kinetic studies showed the adsorption process followed pseudo second-order rate model. Column studies with synthetic Cu(II) solutions were used to investigate the effects of Cu(II) ion concentration, initial pH, flow rate and the presence of EDTA on the Cu(II) removal performance. When treating the spent-lees, the wastewater from the whisky distilling industry, the reduction of Cu(II) uptake capacity to 77.7% (solution pH adjusted to 4.5 with 1 N NaOH) and 31.6% (pH 3.8 without adjustment) was observed compared to Cu(II) uptake capacity when treating synthetic Cu(II) solution. On the basis of the results and that spent-grain is an abundant and by-product from the whisky distilling industry we suggest that it can be economically and effectively applied as a biosorbent for the removal of Cu(II) ions from distilling wastewaters.