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Polychlorinated Biphenyls: In situ Bioremediation from the Environment
Citation:
Pentyala, S. N., S. Mishrna, A. Rahman, J. Rebecchi, PRASADA RAO S. KODAVANTI, AND R. Stefan. Polychlorinated Biphenyls: In situ Bioremediation from the Environment. Chapter 1, Drs. GR Reddy, SJF Flora, and RM Basha (ed.), Environmental Pollution: Ecology and Human Health. Narosa Pubishing House, New Delhi, India, , 249-262, (2012).
Impact/Purpose:
This chapter addresses the limitations in the current bioremediation technology: a) low bioavailability of PCBs; b) unintentional dispersion of contaminants; and c) failure ofthe PCB degrading bacteria to thrive.
Description:
Polychlorinated biphenyls (PCBs) are a group of hydrophobic and stable organic compounds consisting of 209 possible congeners. Because of their unique physico-chemical properties, PCBs were used in a wide range of industrial applications. The properties that made PCBs useful in industrial applications also made them hazardous for the environment, as they persist, and readily accumulate in the biosphere owing to their hydrophobicity and stability. Due to commercial necessities, many industries have been operating near navigable bodies of water, where historical practices have resulted in substantial PCB contamination of the aquatic environment, particularly lacustrine, riverine and estuarine sediments, creating a reservoir of PCBs with long-term consequences for the environment and human health. This poses a serious risk to humans, animals and even plants living around these installations, since PCBs biomagnify and spread well beyond the primary source. Current PCB remediation practices involve dredging of contaminated sediments, their terrestrial treatment to reduce the contaminant load, and off-site burial. These approaches are expensive and extremely disruptive to the aquatic ecosystems where decades of uniquely constituted sediments that contain thousands of invertebrate and microorganism species that are critical to healthy ecosystems are removed. In situ bioremediation method is one of the novel approaches that presents little disturbance to the contaminated sediments and allow removal of a major fraction of potentially bioavailable PCBs without dredging. This chapter addresses the limitations in the current bioremediation technology: a) low bioavailability of PCBs; b) unintentional dispersion of contaminants; and c) failure of the PCB degrading bacteria to thrive. Several aspects of chemical and bacterial assisted sequestration and destruction of PCBs, along with in situ remediation of PCBs by developing novel biochemical and engineering technologies are discussed.
