Using algae to treat industrial effluents containing heavy metals presents an alternative to the current practice of using other biosorbents and physical and chemical methods. In this study, effluent from a leather-processing chemical industry in Ranipet, Tamil Nadu, India, was treated for the removal of heavy metals using the microalga, Chlorella vulgaris, which was isolated from the effluent itself. The objectives of this study were to (1) assess the mass balance of a model parameter, lead, in laboratory conditions and estimate the lead adsorption capabilities of the microalga and (2) conduct pilot-scale studies for the removal of heavy metals, using the microalga, from the effluent and the solid waste accumulated over the years generated by conventional treatment methods. The results of the study show that after 8 hours, Chlorella vulgaris exhibited a better adsorption capacity under sunlight compared to laboratory conditions (i.e., 30.6 mg/g dry weight vs 10.5 mg/g dry weight, respectively). Similarly, reduction of heavy metals and mass balance in pilot-scale field studies conducted in a high-rate algal pond showed that the microalga, apart from adsorption, complexation, and entrapment mechanisms, is likely to possess phycovolatilization capability probably via biotransformation processes.

In the present project, the green microalga, Chlorella vulgariswas used to remove heavy metals from the effluent of a leatherprocessing chemical industry (a multi-national company), located in Ranipet, Tamil Nadu, India. The industry is one of the world’s leading suppliers of leather-processing products and also has strong market niche in many proprietary products. Some of the products from the industry include polyurethane and acrylic resins, lacquers and lacquer emulsions, pigment dispersions, protein binders, wax emulsions and fillers, shoe finishes, and dye formulations. The average total effluent generated per day by the factory amounts to approximately 25 to 30 kL and the effluent contains heavy metals, namely lead, chromium, cadmium, copper, zinc, and nickel. An already-existing effluent treatment plant (ETP) functioning inside the factory premises converts the pollutants into solid waste by polyelectrolyte precipitation and pressure filtration. However, as a result of this treatment, tons ETP solid waste separated from the effluent have been accumulated over the years. The industry, therefore, has the
problem of heavy metals in their effluent and in the accumulated ETP solid. Therefore, the authors designed the study to (1) assess the mass balance of a model parameter, lead, in laboratory conditions and estimate the lead adsorption capabilities of the microalga and (2) conduct pilot-scale studies for the removal heavy metals from the effluent and from the ETP solid waste using C. vulgaris.


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World's First Phycoremediation plant: Dr V Sivasubramanian, has set up the First Phycoremediation plant at SNAP Industry. Algal remediation technology helps in pH correction of the acidic effluent and complete reduction of sludge formation. SNAP is now a zero disposal company. The phycoremediation plant has been in operation from September 2006. The effluent generated by the industry is highly acidic and of very high TDS (40000 mg/L). The entire effluent is evaporated using slope tank with zero sludge formation. The algal biomass produced is used in Biofertilizer preparation and sold by the Company. .......(.more )


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