Bio-ethanol Production and Heavy Metal Lead (Pb) Removal Using Macro Algae Wolffia

Abstract

This study was aimed to evaluate the potential of using macro algae Wolffia for bio-ethanol production and for heavy metal Lead (Pb) biosorption. Macro algae Wolffia was collected locally from a pond. Pretreatment was given by using 1 and 10% sulphuric acid (H₂SO₄) to different batches of Wolffia. Fehling’s test was performed to check the presence of sugar. For the fermentation step Saccharomyces cerevisiae strain was used. Yield obtained using 1% H₂SO₄ pretreated biomass was 0.512 g ethanol/g of biomass, whereas 10% H₂SO₄ pretreated biomass gave 0.784 g ethanol/g of biomass of Wolffia spp. For biosorption of Pb, both suspended cells as well as immobilized bead form prepared using chitosin was used. Various parameters such as effect of pH, effect of contact time, effect of heavy metal concentration and effect of biosorbent doses were checked. Using suspended cells, the maximum Pb reduction reached 98% with 20 g of biosorbent doses and at 60 minutes of contact time. At lower heavy metal concentration of 75 ppm the maximum Pb reduction was seen of about 96%. pH value of 5 was more effective to show a maximum reduction of about 98%. Using the immobilized form of Wolffia as biosorbent, the maximum Pb reduction was 94% at 50 min. At lower heavy metal concentration of 75 ppm, the maximum Pb reduction was seen of about 85%. The pH value of 3 was found to be excellent for 100% reduction of Pb. Therefore, Wolffia proved to be a good adsorbent for heavy metal ion Pb.

Keywords: Wolffia, bio-ethanol, lead, biosorption