Talking the Talk of Bioremediation

Necessity is clearly the mother of invention, especially when it comes to language. As each new event causes a civilization to be at a loss for words to describe it, the civilization invents the words it needs. Hazardous waste management has certainly contributed its share of new words. Take, for example, the term “bioremediation.” This is the processof using microorganisms or their enzymes to return an environment that has been by polluted by contaminants to its original state. Bioremediation can be used alone to attack specific contaminants that can be degraded by bacteria, or it can be one step in a multi-pronged approach.

The first words in the lexicon associated with bioremediation that you need to be aware of are “in situ” and “ex situ.”  These are not strictly new words; they are actually Latin phrases dating back to the Romans, but they have taken on a new usage in the 21st century world of hazardous waste management. In situ, or literally “in place” means treating the contaminated material on site while ex situ, or “away from the place” means  the contaminated material is removed and treated elsewhere.

Biomremediation can often be accomplished by biostimulation. This means that the contaminated environment is altered to stimulate the growth of  bacteria that already exist there that are capable of degrading those contaminants. This is usually accomplished by adding various forms of nutrients, such as phosphorus, nitrogen, or carbon. However, the problem with this process is that while the good bacteria is growing, so is the undesirable bacteria. These bad bacteria can cause what is known as biofouling. This can result in the clogging of pumps, which are used to remove the contaminants.

Another process that is sometimes confused with biostimulation is bioaugmentation. This usually involves studying the types of bacteria present in the area to determine if they are capable of degrading the contaminants. If there is no indigenous variety of bacteria that is capable of performing the job, then a new bacteria is introduced into the area that can do the degrading. In this process a sufficiently high dose of the desired bacteria is introduced into an area so they become dominant. There is no fouling; and when the job is done, the bacteria die and turn into carbon dioxide and water, which can be pumped out and removed.

Some other types of bioremediation include bioventing and biosparging. Bioventing is a technology that provides oxygen to existing soil microorganisms that have been deprived of oxygen in order to stimulate them to degrade any aerobically degradable compounds in the soil. Aerobically degradable means they can be degraded by the use of oxygen. The oxygen is introduced as part of the air that is directly injected into the contamination in dry soil. Bioventing uses low airflow rates to provide only enough oxygen to sustain the microorganisms’ activity.

Biosparging is a remediation process that also uses microorganisms that already exist in a contaminated area to degrade the contaminants. In biosparging, air and sometimes nutrients are injected into saturated or wet soil to increase the microorganisms’ activity. In addition, biosparging can be used to reduce concentrations of contaminants that are dissolved in groundwater, or adsorbed in the soil below the water table.

As industrial chemical processes become more sophisticated, the contaminants that are released from these processes will become more complex requiring more innovative ways of removing them from the environment. The technologies mentioned in this article are the beginning of the movement toward righting the wrongs done to the environment. Understanding what they are can help business owners look for the right kind of products and services that can keep them in compliance with the regulations established to maintain a green America.

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