Biofilters:
Biofilters can be used to treat air and water waste from industrial processes that may be contaminated with pollutants. Contaminants in the air stream are passed through a porous media (usually compost or soil) and partitioned out into a thin water film where they can be biodegraded by microorganisms. Scientists using biofilters must cultivate a crop of microorganisms capable of degrading the contaminant. This process is highly dependent on variables such as temperature and humidity conditions, the rate of flow, and the components of the waste stream, which affect the health of the microorganisms. The advantage of using a biofilter is that the hazardous materials are completely destroyed, as opposed to simply separated out. Biofilters have been shown to be effective in removing halogenated organic solvents such as dichloromethane from waste streams.
In situ treatment: Halogenated organic solvents tend to accumulate on fractured bedrock at the bottom of aquifers, which can be a challenging location for removal. Bioremediation is an attractive alternative to removal because of the advantages of low capital costs, no secondary waste, destruction of contaminants, low maintenance, minimal site disturbance, and decreased working hazards. Subsurface anaerobic microbes can use chlorinated solvent as a source of energy with dissolved hydrogen as the electron acceptor. Other microbes can cometabolize compounds when more than one substrate or carbon source is available. Nutrients or fertilizers and additional microorganisms can be added (bioaugmentation) to a site to enhance the rate of biodegradation. Hydrogen Release Compound (HRC, marketed by Regenisis) can be used to promote anaerobic dechlorination at contaminated sites. When injected into the site HRC provides a slow time released amount of dissolved hydrogen, which then serves as the electron donor while the chlorinated solvent is the electron acceptor in the microbe metabolism. The reductive dechlorination process for PCE (tetrachloroethylene):
PCE(C2 Cl4) + H 2 ®TCE(C2 HCl3) + H ++ Cl
TCE(C2 HCl3) + H 2 ®DCE(C2 H 2Cl2) + H ++ Cl
DCE(C2 H 2Cl2) + H 2 ®VC(C2 H 3Cl) + H ++ Cl
VC(C2 H 3Cl) + H 2 ®ethene(C2 H 4) + H ++ Cl
(Borum, 2002)
Ex Situ Treatment:
Ex situ bioremediation involves removing the contaminated soil or water and treating it with microbes and nutrients to mineralize the contaminant. In slurry-phase bioremediation the soils are mixed in water to form a slurry to keep solids suspended and microorganisms in contact with the soil contaminants. In solid-phase bioremediation (land farming, biopiles, and composting) a contained soil is monitored, tilled, and augmented with microbes and nutrients.
Biobarriers:
Biobarriers are essentially biological films designed to contain contaminants like DNAPLs and stop them from leaking into the water supply. The biofilm is a gel layer comprised of exopolymeric substances (EPS) that are excreted by bacteria in order to attach to surfaces. Formation of a biofilm can be induced by injecting a simple carbon source. Porous media field trials found permeability to be reduced by 99%. Ultramicrobacteria with a diameter of less than .3 um have the greatest success in containing DNAPL's due to their ability fo fit in tight spaces. Research trrials are underway in Ontario, Canada with such bacteria cultures to determine if biobarriers will be successful in containing DNAPL's in fractured bedrock
. 
(Sources: Borum, 2002 and Ross, 2002)
Phytoremediation:
The use of plants to remove or sequester contaminants from the environment. See examples.
See more bioremediation technology descriptions from the EPA.