Bioremediation Dr. Bhavesh Patel (M.Sc., Ph.D.) Principal V.P. and R.P.T.P. Science College, Vallabh Vidyanagar Email- bhavesh1968@rediffmail.com

What is Bioremediation? “ It is a pollution treatment technology that uses biological systems to catalyze the destruction or transformation of various chemicals to less harmful forms.”

Key words Assimilation: Incorporation of elements in to biomass. Dissimilation: Release of elements from biomass. Recalcitrant: Nondegradable (difficult to degrade). Xenobiotics: Compounds foreign to biological systems. Often refers to human made compounds that are resistant to biodegradation.

Bioremediation : Concept Human interference – 18th Century Synthesis of complex compounds like: Pesticides, Solvents,Fertilizers, Nitroaeromatics, Plastic etc. Recalcitrant (xenobiotic) Bioremediation Mineralization or less harmful forms

Why Bioremediation? Conventional technology involves moving large quantities of toxic waste, contaminated soil to incinerators, thus costly. Bioremediation can be performed on site, thus economic. In Bioremediation the end products are generally nontoxic. (if complete mineralization occurs) Other activity at the contaminated site is relatively undisturbed. Requires simple equipments. ECOFRIENDLY

Limitations Bioremediation is not the solution for all the environmental pollution problems. It may take long time, if the conditions are not favorable.

Approaches to Bioremediation Intrinsic Bioremediation >Monitoring the natural biodegradation process. Biostimulation >Carry out environmental modification i.e. pH, temp., aeration, nutrients etc. Bioaugmentation >Seeding with pollutant degrading bacteria. >Creating microbial consortia (co-metabolism). >Molecular breading.

Targets Aerobic Aerobic cometabolic Anaerobic Aromatic compounds Chlorinated solvent Chlorinated solvent BTEX TCE Perchloroethylene Phenol DCE TCE Styrene Vinyl chloride DCE Chlorobenzene Bromoform Nitro aromatics Aniline MTBE TNT Nitrobenzene HCFCs PCBs Naphthalene PAHs Solvents Chlorinated solvents Sulfur compounds Fertilizers BTEX-benzene,toluene,ethylbenzene,xylenes; DCE-dichloroethene; HCFC-hydrochlorofluorocarbon; MTBE- methyltertiarybutylether; PAH- poly aromatic hydrocarbon;PCB- poly chlorinated biphenyl; TCE- trichloroethene

The masters - Organisms The white rot fungus Phanerochaete has extensive biodegradative capabilities. It is successfully used for : Pesticides – DDT Munitions – TNT High MW polynuclear aromatics – Benzopyrene Plastics – Polyethylene

Cont… Bacteria Pseudomonas have also been widely used as seed culture for Trichloroethene (TCE), PCBs etc. Microbial consortium can be used that include : >Sulfate reducing bacteria >Methanogenic bacteria >Pseudomonas >Alkaligens >Acinetobacter

Cont… Genetically modified organisms : Chakrabarty was the first to create a hydrocarbon degrading Pseudomonas putida by recombinant DNA technology that has ability to degrade over 100 different hydrocarbons. Bacterium Deinococcus radiodurans has been modified to consume and digest toluene and ionic mercury from highly radioactive nuclear waste.

PCBs – Hard to treat Poly Chlorinated Biphenyl has a pair of benzene ring in which Cl is substituted at H. 209 different kinds of PCBs are possible. First made in 1881, Commercially available 1920, Monsanto sold it by trade name Aroclor. PCB has high BP, low water solubility, low conductivity, hard to burn, acid-alkali resistant. It is used in making adhesive, carbonless copy paper, insulators, lubricants, plasticizer, varnishes, epoxy paints etc. 1944 – PCB enters the food chain. Fortunately Bioremediation is possible (Anaerobic-dehalogenation)

Worst oil spill Exxon supertanker – March 1989 11 million gallons of crude oil was spreaded over Alaska. 1000 miles of Alaskan shorelines were contaminated with oil. This affect birds, aquatic ecosystem, plants. Over 1 million $ spent per day. Fertilizer were applied – Biostimulation. Took 2-3 years – Bioremediation.

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