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Bioremediation, Reuse-recycling - Tertiary Treatment of Metal containing Wastewaters using Aquatic microphyte Azolla

Mr. Anju Arora
Senior Scientist - Centre for Conservation and Utilisation of Blue Green Algae, Division of Microbiology, Indian Agricultural Research Institute, N. Delhi. India.110012.
Ph. 91-11-25848431, Fax 91-11-25741648. email: anjudev[at]yahoo.com
 

On our planet, water is finite but renewable resource. With demographic changes and changing lifestyles, there is enhanced need for water. We use water for domestic, agricultural and industrial operations and Wastewaters originate from domestic as well as industrial sources. To have sustainable water supply it has become imperative to reuse what is termed as wastewaters. Experts predict that we can no longer have the luxury of using water once and sustainability in waters can only be achieved through wastewaters.

Safe use of treated wastewaters for irrigation purposes, gardening, landscaping and non residential purposes is being encouraged. However, the quality of wastewaters to be reused, has to be assured. Besides physical and chemical technologies for improving the quality of wastewaters, the biological processes offer much superior alternatives. The aerobic and anaerobic biological treatment processes have been efficient in bringing down the pollutant loads in wastewaters to acceptable levels. However, certain pollutants like heavy metals have to be removed during tertiary treatment. Wetland processes using natural plants and microorganisms offer most suitable alternatives for polishing of primary/secondary treated wastewaters.

Azolla, an aquatic fern has been studied extensively for its metal accumulating potential and its role in remediation of metal contaminated wastewaters. It removes heavy metals both by active and passive processes. The presentation will be made of studies on Chromium removal by aquatic fern Azolla. Chromium is toxic metal pollutant in wastewaters coming from tanneries. Potential of Azolla to remove Cr from its growth environment by active and passive processes was evaluated. Azolla was able to tolerate Cr stress and grow in presence of 10ppm Cr. It was able to remove Cr and accumulate it in its biomass in a batch process. However, under semicontinuous process simulating stabilization ponds/ wetlands the removal was not as efficient. The results of studies on removal of Cr by Azolla from contaminated wastewaters will be presented and possibility of Azolla to be employed in wetlands and for tertiary treatment of wastewaters for Cr removal will be discussed.

 

Application for Participation (PDF)