Bioremediation

Bioremediation

This site was prepared for a basic introduction to the area of bioremediation of hazardous material cleanup sites.

For more information

please go to the links near the bottom of this page.

What is Bioremediation?

Bioremediation is the process of using biological products to help cleanup (remediate) areas that contain environmentally hazardous products, such as:

· Industrial, Commercial, & Municipal waste and spills

· Petrochemical spills and leaks

· Heavy metal contamination

What is the “Bio” in Bioremediation?

The Bio of this remediation technology (and natural occurring) is typically a variety of natural occurring microbes and introduced plant life (phytoremediation) such as grasses, trees, sunflowers, Indian mustards, geraniums and other varieties that are being tested and utilized.

Why Bioremediation, aren’t there other ways to cleanup these sites?

Yes, there are other methods to cleanup hazardous material (hazmat) sites and some of these methods are still necessary, but sometimes they are:

· Several times more expensive than bio methods

· Very disturbing to the environment

· Only move the contaminated material to another site

· Produce large amounts of material to be disposed of (low efficiency)

· Take a long time to implement

· Marginal outcomes of cleanup

· May not be technologically feasible w/o bio methods (subsurface features & aquifers)

· May spread the contamination

o Spills during cleanup and transportation

o Continued spread of the original problem before it can be cleaned up

o Methods of disposal (some methods re-release the contaminates back into the atmosphere)

How does it work?

The remediation can be implemented in several different ways depending upon the process that is being used and the targeted material for cleanup. Some examples are:

· Introducing microbes into the contamination zone that digest and breakdown the chemicals into smaller and more environmentally friendly products

· Introducing a bio-stimulant that encourages the natural occurring indigenous microbes to digest and breakdown the chemicals into smaller and more environmentally friendly products

· Mineralization of the contamination by the microbes

· Introduction and cultivation of plants and/or trees that take up the contamination along with other nutrients and either breakdown these chemicals or store them within the plant tissues where it is more concentrated and easily harvested

· Combinations of the above

Is it safe?

Yes, the plants and microbes that are being used are naturally occurring. We are just encouraging them to help us cleanup these areas.

Are these processes being used today?

Yes, they are in several different areas:

· Salem, New Hampshire – A decommissioned wastewater treatment plant was found to have soil and groundwater contamination from chlorinated solvents. A bio-stimulant containing yeast and lactose (a recycled solid waste from a dairy product manufacturer) was injected at the site to stimulate a naturally occurring microbe to anaerobically digest the chlorinated solvents. 3

· Idaho Falls, Idaho – An injection well installed in the Snake River Aquifer during the early 1950’s contained organic sludge, treated sanitary sewage, and industrial process wastewater. It was estimated to have up to 35,000 gallons of trichloroethene (TCE) deposited into it. During testing, It was found that the indigenous subsurface bacteria were breaking down the TCE into smaller components on their own, but slowly. After the injection of sodium lactate (electron donor) the breakdown process accelerated, resulting in a significant reduction of the TCE concentrations. 13

· Massachusetts – The Massachusetts Department of Environmental Protection revised its Massachusetts Contingency Plan to provide licensed site professionals the regulatory ability to apply bioaugmentation at cleanup sites without prior approval. This change was made due the success of pilot projects and the need for further cleanup of sites to meet closure requirements (state standards) after mechanical methods where exhausted. These methods of bioaugmentation have expedited cleanups and reduced budgets allowing more sites to be cleaned. 5

· Winter Park, Florida – A leaking underground storage tank at a Florida resort property contaminated the groundwater with hydrocarbons at a concentration of 300,000ppb. After the injection of non-pathogenic, naturally occurring bacterial strains, the groundwater contaminants were reduced to Florida’s standards within one month. 1

· Maryland - At the Aberdeen Proving Ground, waste pits containing toxic residues threatened the wildlife and water supply in a nearby wetland area. A field-scale pilot project at this site uses poplar trees to contain the toxic materials in a limited area and possibly degrade these materials into nontoxic byproducts. 17

· Trenton, New Jersey - At a former battery manufacturing facility, a field of lead-tolerant plants is removing lead from the soil around the outside of the factory building. 17

· Hartford, Connecticut – A city lot that is contaminated with lead that is being remediated with phytoremediation techniques. Plant species being utilized are: Sudan grass, Sunflower, and Indian mustard. 16 http://www.trincoll.edu/prog/soilanalysis/

What does the future have in store?

There are several processes that under investigation at this time. Here are but a very few:

· Fort Worth, Texas – At the Naval Air Station, a phytoremediation demonstration plot was developed to remediate shallow ground water contaminated with chlorinated ethenes by the transpiration and degradation by mature cottonwood trees to reduce the oxygen levels and encourage an anaerobic microbial ecosystem to remediate the contamination of TCE. 11

· Northern California – Experimental plots at a petroleum refinery site were established to determine the effect of established vegetation on the quality and quantity of Rhizosphere microorganisms. The results were that the presence and type of plants and the levels of contamination greatly influence the microbial communities. 6

· Arkansas – A phytoremediation plot to determine the effectiveness of various grass covers and root movement and its affect on the microorganisms in the remediation of weathered petroleum contaminated sites. Below are two graphs of soil samples taken in test plots testing for weathered Diesel Range Organics (DRO). 15

· Michigan – At Michigan State University, microbiologists have isolated a bacterium from sediment samples in the Upper Hudson River that lives exclusively on trichloroethane (TCA), a widely used and environmentally prevalent solvent commonly found in the soil and groundwater at Superfund sites. 12

· Shiprock, New Mexico – Nitrates are being studied as to how it is involved in the bioreduction process of uranium. The results of the test show that the addition of nitrates (electron acceptor) to anaerobically oxidize insoluble U(IV) precipitates to soluble U(VI) may be used to help extraction methods of the U(IV) from the subsurface. After extraction the nitrates must be depleted to reduce the uranium back to U(IV). 10

· India – A study is being conducted in the ability of microbes to decompose and mineralize Monocrotophos (MCP), an organophosphorus pesticide used in the agriculture community of India to protect crops such as: cotton, sugarcane, groundnut, tobacco, maize, rice, soybean, vegetables, etc. 7

· Madrid, Spain – A study is underway to investigate the tolerance, uptake, and accumulation of various heavy metals (Pb(II), Cd(II), Cr(III), Cr(IV), CH3Hg+, and Hg(II)) in lupin plants. Preliminary results show the plants are tolerant to the Cd(II), Pb(II), Cr(III), and Hg(II) and upon harvesting they showed accumulations mainly in the roots for all four and also translocation to the shoots for Hg(II). Accumulation amounts were affected by chemical form and the co-presence of other metals. The plants showed severe signs of toxicity upon exposure to Cr(IV) and CH3Hg+. 18

· New Jersey – Investigation of a phased approach of the restoration of petroleum contaminated sites using bioremediation and soil tillage in combination with revegetation cover using native plants at later steps of remediation when the total petroleum hydrocarbons (TPH) has reached a level of 1% or lower. Below is a flowchart of a typical decision pathway for this approach. 9