The Efficiency of Lead Biosorption from Industrial Wastewater by Micro-alga Spirulina platensis

Environment contamination by heavy metals is a major issue threatening human health. Adsorption is one of the biological processes for removing toxic metals from wastewater. The aim of this study was to determine the rate of lead biosorption from industrial wastewater by Spirulina platensis. This laboratory scale experimental study was performed during April 2014 to October 2014 in Environmental Health Engineering Research Center, Kerman University of Medical Sciences. In order to determine lead biosorption by Spirulina platensis, different concentrations of biomass (0.1, 0.5, 1, 1.5 and 2 gr) were exposed to different lead concentrations (10, 50, 70, 100 and 150 mg/L) under different conditions including pH (3, 4, 5, 6, 7, 8, 9 and 10) and contact time (5, 15, 30, 60, 120 and 180 min). The rate of residual lead was determined using atomic adsorption instrument. Experiments were also performed in real conditions on battery manufacturing industry wastewater sample. Adsorption isotherms and metal ions kinetic modeling onto the adsorbent were determined based on Langmuir, Freundlich and first and second order kinetic models.Lead adsorption onto Spirulina platensis varied based on the conditions. At constant temperature of 25ºC, optimal pH 7, contact time of 60 minutes and adsorbent concentration of 2g/L, lead adsorption efficiency was 84.32% for real sample and92.13% for synthetic sample. Based on the obtained results, lead adsorption followed Langmuir model and second order kinetic equation. Spirulina platensis, due to its high adsorption potential, can be efficiently used for lead removal from industrial wastewater.