BBC : What is Bioremediation?
 
Groundwater Reliance Statistics
Bedrock Aquifer Contamination Statistics
Advantages of Bioremediation
Site/Treatment Assessment
Research Directions
 

Bioremediation is a clean-up technology that uses naturally occurring microorganisms to degrade hazardous substances into less toxic or nontoxic compounds.

These microorganisms may:

  1. Ingest and degrade organic substances as their food and energy source,
     
  2. Degrade organic substances, such as chlorinated solvents or petroleum products, that are hazardous to living organisms, including humans, anddegrade the organic contaminants into inert products.

Because the microorganisms already occur naturally in the environment they pose no contamination risk.
 

Groundwater Reliance Statistics:

In New Hampshire, approximately 60% of the state's population rely upon groundwater as a source for drinking water. Approximately 25% of the state's population uses private wells, most of which are drilled into bedrock. Of the approximately 2,200 public water supplies in New Hampshire, it is estimated that at least 85% rely upon groundwater from fractured bedrock as a source. Similar trends are seen throughout New England. In general, bedrock aquifers are heavily relied upon as domestic and small public drinking water sources in much of the United States.
 

Bedrock Aquifer Contamination Statistics:

   
Of the 18 Federal Superfund sites located in New Hampshire, 15 have bedrock contamination.
 
     
       

In New Hampshire, there are approximately 400 hazardous waste sites, 3,000 petroleum sites, and 197 unlined solid waste landfill, some of which are impacting or have the potential to impact bedrock aquifers. Of the 18 Federal Superfund sites located in New Hampshire, 15 have bedrock contamination.
 

Advantages of Bioremediation:

The remediation of bedrock aquifer contamination is extremely difficult with existing technologies, such as pump and treat. This is due to the expense and uncertainty in locating and removing contamination from fractured bedrock to the degree necessary to restore groundwater. Therefore, an in situ remediation mechanism such as biological degradation could be an essential component to restoring an aquifer to drinking water quality.

The high costs and sometimes limited effectiveness of conventional remediation technologies have stimulated interest in bioremediation as an alternative clean-up method. Bioremediation can be performed directly in the subsurface by using naturally occurring microorganisms to degrade the contaminants. Bioremediation has been used to clean-up many groundwater and soil contamination sites. Keys to the success of bioremediation include insuring that:

  1. The microorganisms actually degrade the contaminants to acceptable (less harmful) by-products
     
  2. They perform the degradation in an acceptable time frame, and
     
  3. They have adequate supplies of substances they need to degrade the contaminants.
       
bioremediation can be accelerated by supplying substances to the microorganisms that will stimulate them.

 
 
       

Finally, the microorganisms must be exposed to favorable physical and chemical conditions in the subsurface. Biodegradation of contaminants may occur naturally in the subsurface at fairly slow rates. These natural processes may be too slow to insure adequate treatment in an acceptable time frame. However, bioremediation can be accelerated by supplying substances to the microorganisms that will stimulate them.
 

Site/Treatment Assessment:

Bioremediation must be carefully evaluated before it is considered acceptable as a treatment alternative at a specific contaminated site.

Typically, three steps must be taken to assess whether bioremediation will work:

  1. Field monitoring must show that the contaminant concentrations are decreasing.
     
  2. Laboratory studies must also corroborate that the subsurface microorganisms are capable of degrading the contaminants.
     
  3. Data must show that the microorganisms are actually degrading the contaminants in the subsurface at the waste site.

Until recently, there was little evidence that microorganisms existed in bedrock. Now studies have shown that bacteria exist in uncontaminated bedrock, living along the fractures that permeate the rock and in the water that flows through them. Very little data are available on the implementation or success of this technique.
 

Research Directions:

In order to assess whether bioremediation can be used to clean-up contaminated bedrock:

  • Regulatory agencies must have a better understanding of the microorganisms that live in the bedrock and their ability to degrade contaminants.
     
  • Protocols must be developed to evaluate whether bioremediation is an adequate clean-up method.
     
  • Finally, methods to accelerate bioremediation in the bedrock fractures must be developed.

 

 

 
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