Comparative biosorption of Pb2+ by live algal consortium and immobilized dead biomass from aqueous solution

The percent removal and uptake of Pb2+ by algal-consortium (CP1) developed from wastewater of biological oxidation pond (Wazirabad, New Delhi, India) was studied under batch conditions with live biomass compared with continuous system using dried biomass immobilized on silica under laboratory conditions. In batch study, algal consortium (CP1) consisting of a mixed culture of Chlorella > Chlamydomonas > Lyngbya sp. was found to remove 17% of Pb2+ after 15 days of incubation from culture media containing 10 mg/L Pb2+, which decreased by increasing metal concentration from 20-50 mg/L. This reduction in removal efficiency was co-related with direct toxic effect of Pb2+ on live consortium as indicated by drastic inhibition in growth. A maximum lead uptake capacity (q(max)) of 33.31 mg/g showed good accumulation potential of live consortium. Bioresin derived from the biomass of dried algal consortium immobilized on silica gel and packed in column exhibited 92.5% removal of Pb2+ with inlet Pb2+ concentration of 33.90 mg/L was brought down to minimum 0.375 mg/L of Pb2+ in outlet stream. The plot of outlet concentration to volume exhibited the typical 'S' shape curve with Pb2+ uptake capacity of 15.95 mg/g. Efficient recovery of 86.16% of Pb2+ was achieved by elution with dilute HCl which indicated multiple usability of immobilized biomass.