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Remediation Of Metal Contaminated Soil Using A Novel Biotechnological Approach

Asha A.Juwarkar, Prachi Joshi, S.K.Singh, Sadhana Rayalu

The technology applied here aims at bioremediation of metal contaminated soil using heavy metal tolerant strains of Azotobacter in combination with zeolite as a carrier. Azotobacter chroococcum strain HM1, being isolated from the soil near mining area contaminated with heavy metals, is not only heavy metal tolerant and withstand stressed conditions but also fixes atmospheric nitrogen nonsymbiotically. Traditionally this nitrogen biofertilizer is mixed with some carrier like lignite and then it is added to soil. But the novelty of this remediation technology is that, a material called zeolite is proposed to be used as carrier material instead of conventional carriers, because of its physicochemical properties. Zeolite is reported to possess properties like high ion exchange capacity, propensity for modification, potential for regeneration and recycling and soil conditioning. Zeolite when added to metal contaminated soil sorb the metal ions from soil and prevent their leaching to groundwater, also they raise pH of the soil to normal which is lowered due to the presence of heavy metal ions and the nitrogen biofertilizer present on zeolite will fix the atmospheric nitrogen, making it available for plants. In this way a dual purpose of metal removal and soil fertilization will be achieved due to zeolite based biofertilizer. Thus this process of bioremediation offers an effective and ecofriendly approach for soil contaminated with heavy metals such as cadmium, arsenic, chromium etc.