Removal and recovery of copper (II) ions by bacterial biosorption

Studies were conducted to investigate the removal and recovery of copper (I I) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated sludge process. The equilibrium of copper biosorption fol lowed the Langmuir isotherm model very well with a maximum biosorption capa city (q(max)) of 36.5 mg of Cu2+/g of dry cell at pH 5.0 and 52.1 mg of Cu2 +/g of dry cell at pH 6.0. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Cop per uptake by cells was negligible at FH 2.0 and then increased rapidly wit h increasing pH until 6.0. In multimetal systems, Micrococcus sp. exhibited a preferential biosorption order: Cu similar to Pb > Ni similar to Zn. The re is virtually no interference with copper uptake by Micrococcus sp. from solutions bearing high concentrations of Cl-, SO42-, and NO3- (0-500 mg/L). Sulfuric acid (0.05 M) was the most efficient desorption medium, recoverin g > 90% of the initial copper sorbed. The copper capacity oi Micrococcus sp . remained unchanged after five successive sorption and desorption cycles. Immobilization of Micrococcus sp. in 2% calcium alginate and 10% polyacryla mide gel beads increased copper uptake by 61%. Biomass of Micrococcus sp. m ay be applicable to the development of potentially cost-effective biosorben t for removing and recovering copper from effluents.