Conventional methods of remediation Conventional methods of remediation Dig up and remove it to a landfill Cap and contain Risk of excavation, handling and transport of hazardous material Very expensive to find another land to finally dispose these materials Maintain it in the same land but isolate it
Only an interim solution Requires monitoring and maintenance of isolation barriers for a long timeIs there a better approach?Products are not converted into harmless products. Stay as a threat!
Better approaches :Destroy them completely, if possible Transform them in to harmless substances High temperature incinerationChemical decomposition like dechlorination, UV oxidation Methods already in use
Bioremediation makes effective better approach possible. Either by destroying or render them harmless using natural biological activity.
Relatively low cost Low technology techniques Generally has general public acceptance Can often be carried out on site – no excavation, no transport Drawbacks May not be effective on all contaminants Time duration – relatively long Expertise required to design and implement – although not technically complex
Bioremediation :is defined as the process whereby organic wastes are biologically degraded under controlled conditions to an innocuous state, or to levels below concentration limits established by regulatory authorities
Types of Bioremediation : Engineered Bioremediation Intrinsic Bioremediation
Qualities of : Qualities of Microorganisms Environment Able to degrade hydrocarbons Able to fix nitrogen No secondary/side effects Presence of accessory nutrients (N P K Fe) Absence of heavy metals Adequate O2, Temperature, pH
Sources of microorganisms : From contaminated field sites (with varying environmental conditions - subzero temperatures or extreme heat, desert conditions or in water, with excess of oxygen or in anaerobic conditions, with presence of hazardous compounds or on any waste stream) From culture collections Genetically Engineered Microorganisms (GEMs) Sources of microorganisms
Bioremediation Strategies :Bioremediation Strategies In situ Bioremediation (at the site)Ex situ Bioremediation (away from the site)
Bioaugmentation involves practice of adding specialized microbes or their enzyme preparation to polluted matrices to accumulate transformation or stabilization of specific pollutants
Ex situ bioremediation types :Ex situ bioremediation types Landfarming involves a simple technique in which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded.
Phytoextraction :Phytoextraction Also called PhytoaccumulationA process used by the plants to accumulate contaminants into the roots and shoots or leaves.
Phytotransformation :Phytotransformation also called Phytodegradation refers to the uptake of organic contaminants from soil, sediments, or water and, subsequently, their transformation to more stable, less toxic, or less mobile form. Metal chromium can be reduced from hexavalent to trivalent chromium, which is a less mobile and non-carcinogenic form.
Phytostabilization :Phytostabilization Leachable (permeate gradually) constituents are adsorbed and bound into the plant structure so that they form a stable mass of plant from which the contaminants will not reenter the environment
Phytodegradation : Phytodegradation also called rhizodegradation is the breakdown of contaminants through the activity existing in the rhizosphere. Due to the presence of proteins and enzymes produced by the plants or by soil organisms such as bacteria, yeast, and fungi. a symbiotic relationship that has evolved between plants and microbes Plants provide nutrients necessary for the microbes to thrive, while microbes provide a healthier soil environment.
Rhizofiltration :Rhizofiltration is a water remediation technique that involves the uptake of contaminants by plant roots used to reduce contamination in natural wetlands and estuary areas The wide part of a river where it nears the sea; fresh and salt water mix
Phytoremediation is well suitedfor : Phytoremediation is well suited for use at very large field sites where other methods of remediation are not cost effective or practicable use at sites with a low concentration of contaminants where only polish treatment is required over long periods of time in conjunction with other technologies where vegetation is used as a final cap and closure of the site