The immobilization of Arthrospira platensis biomass in different matrices--a practical application for lead biosorption.

The biosorption of lead by cyanobacteria (Arthrospira platensis) immobilized in different matrices was studied. This was the first time that sodium alginate, silica gel and agarose beads have been used for the removal of lead from solutions of the metal in concentrations ranging from 50 to 500 mg/L. The effect of pH in the range 4.0 to 5.5 on lead removal was also investigated. For the best biosorbent chosen from those mentioned above, lead biosorption in samples of real wastewater was examined. The maximum biosorption capacities (q) for cells immobilized in alginate, agarose and silica gel were 424.99 ± 16.73, 272.66 ± 7.54 and 2.68 ± 0.25 mg Pb/g dry matter of biosorbent, respectively. The initial pH of the solution as well as initial Pb(II) concentration had an influence on metal uptake. The highest lead sorption by alginate and agarose immobilized cells was reported at pH 5 and at initial lead concentration of 500 mg/L, while sorption by silica immobilized cells was the most effective at pH 4 and initial concentration of 100 mg Pb(II)/L. The reported lead uptake (about 165 mg/g dry weight) by cyanobacterial cells entrapped in sodium alginate was higher in real wastewater than in simulated wastewater of the same initial lead concentration. The results revealed that this new biosorbent system can be a promising candidate for eliminating Pb(II) from wastewater, and more detailed research should be carried out.