Bioremediation

• enhance the development of indigenous microorganisms to accelerate biodegradation of organic constituents in saturated zone
• effective for full range petroleum hydrocarbon (except MTBE, long chain, high molecular weight and insoluble constituents)
• accepted in combination with other saturated zone remedial technology (e.g. air sparging) and vadose zone remedial operations (e.g. soil vapor extraction, bioventing)
• mechanism criterion: electron acceptor (oxygen, nitrate), nutrients (nitrogen, phosphorus), energy source (carbon)
• treatment modes: aerobic (oxygen respiration), anoxic (nitrate respiration), anaerobic (non-oxygen respiration), co-metabolic

Dual-Phase Extraction

• elimination of every types of contaminants of groundwater, separate-phase of petroleum products, hydrocarbon vapor from subsurface, which are treated and collected for disposal or re-injected to the subsurface
• effective in removal of separate phase products from subsurface, due to great efficiency of extraction rates which increase biodegradation of petroleum constituents by increasing supply of oxygen, similar to bioventing
• mechanism criterion: vacuum, hydraulics and water
• treatment modes
  • subsurface liquid(s) and soil vapor are extracted as a high velocity dual phase stream using a single pump
  • subsurface liquid(s) and soil vapor are extracted separately using 2 or more pumps

Natural Attenuation

• passive remedial approach that depends upon natural processes to degrade and dissipate petroleum constituents
• reduce potential impact of emission of petroleum products by neutralizing the harmful effects or by preventing constituents from being transported to sensitive receptors
• suitable for sites under active remediation which can significantly decrease level of contaminants
• mechanisms:
  • destructive (biological processes): aerobic (oxygen respiration), anaerobic (non-oxygen respiration), hypoxic (low oxygen content)
  • non-destructive (physical phenomena): volatilization, dispersion (mechanical mixing and molecular diffusion) and absorption

Biological Agents

• chemicals or organisms that hasten the rate at which natural biodegradation occurs
• rapid removal of spilled oil from shorelines and wetlands is necessary in order to minimize potential environmental damage to these sensitive habitats
• mechanism criterion: aerobic or anaerobic microorganisms which are decomposers (e.g. bacteria)
• treatment modes:
  • fertilization: nutrient enrichment by addition of phosphorus and nitrogen to a contaminated environment to accelerate the growth of microorganisms for biodegradation
  • seeding: introduction of microorganisms to existing native soil

Dispersing Agents

• chemicals that contain surfactants which catabolyze oil into small droplets which disperse into the water column where they are subjected to natural processes from wind, waves and currents that further accelerate breakdown
• effectiveness of dispersants are influenced by water salinity, temperature and conditions at sea
• frequently used at rough or choppy conditions at sea where mechanical containment and cleanup difficult

Sorbents

• materials that soak up liquid, which is oleophillic (oil attracting) and hydrophobic (water repellent)
• effective in oil spills, depend on:
  • rate of absorption determined by type of sorbents and the type of oil
  • oil retent determined by viscosity of liquid
  • ease of application determined by type of sorbents and the type of oil
• materials or sorbents:
  • natural organic: loose particles such as sawdust which can soak up 3 and 15 times their weight of oil with the help of a flotation device to overcome the sinking problem
  • natural inorganic: clay, perlite, vermiculite, glass wool, sand or volcanic ash which can absorb 4 to 20 times their weight in oil
  • synthetic: polyurethane, polyethylene, nylon fibres which can absorb 70 times their weight in oil where some can be cleaned and reuse while some had to be disposed after first use.

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