BIOREMEDIATION

BIOREMEDIATION

• Bioremediation is a process that uses naturally occurring or genetically engineered microorganisms such as yeast, fungi, and bacteria to transform harmful substances into less toxic or non-toxic compounds.
• Bioremediation has been used since the late 1970s to degrade Petroleum product and Hydrocarbons.
• During Bioremediation, microorganisms break down a variety of organic compounds in nature to obtain nutrients, carbon, and energy for growth and survival.
• Bioremediation promotes the growth of microorganisms to degrade contaminants by utilizing those contaminants as carbon and energy sources.

Forms of Bioremediation

• There are two basic forms of Bioremediation currently practiced. They are

1. Bioaugmentation (microbiological approach) - Biological augmentation is the “Addition of Archaea or Bacterial cultures” required to speed up the rate of degradation of a contaminant. Organisms that originate from contaminated areas may already be able to break down waste, but perhaps inefficiently and slowly.
2. Biostimulation (microbial ecological approach) - Biostimulation involves the “Modification of the environment” to stimulate existing bacteria capable of Bioremediation. This can be done by addition of various forms of rate limiting nutrients and electron acceptors, such as phosphorus, nitrogen, oxygen or carbon.

Bioremediation Methods

• Bioremediation may be done as In situ Bioremediation (at the site of the contamination) or Ex situ Bioremediation (away from the site).

1) On site or In situ Bioremediation (at the site of the contamination)

a) Bioventing: Method of treating contaminated soils by drawing oxygen through the soil to stimulate microbial activity.

b) Biofilters: Use of microbial stripping columns to treat air emissions.

c) Bioaugmentation: Addition of bacterial cultures to a contaminated medium. Frequently used in both In situ and Ex situ systems.

d) Biostimulation: Stimulation of indigenous microbial populations in soils or ground water by providing necessary nutrients.

e) Intrinsic bioremediation: Unassisted bioremediation of contaminant, only regular monitoring is done.

f)   Pump and treat: Pumping ground water to the surface, treating, and reinjection.

2) Off site or Ex situ Bioremediation (away from the site)

a)   Land farming: Solid-phase treatment system for contaminated soils, may be done In situ or Ex situ.

b)  Composting: Aerobic, thermophilic treatment process in which contaminated material is mixed with a bulking agent; can be done using static piles or aerated piles.

c)  Bioreactors: Biodegradation in a container or reactor; may be used to treat liquids or slurries.

f) Biopiles: It is a full-scale technology in which excavated soils are piled and typically constructed in a treatment area that consists of a leachate collection and aeration system. It is commonly applied to reduce concentrations of petroleum components in soils through utilizing the process of biodegradation.

Advantage of Bioremediation

• Bioremediation is a natural process, takes a slight time and suitable waste treatment process for contaminated materials.
• The residues for the treatment are usually harmless product including water, carbon-di-oxide and cell biomass.
• Helps in complete destruction of the pollutants. Many of the hazardous compounds can be converted to harmless products.
• Bioremediation does not use any dangerous chemicals. Bioremediation change dangerous chemicals into water and harmless gases.
• Simple, less labor intensive and less expensive due to their natural role in the environment.
• Eco-friendly and sustainable.
• Contaminants are destroyed, not simply transferred to different environmental media.
• Non interfering, potentially allowing for continued site use.
• Relative ease of execution.
• Effective way of remediating natural ecosystem from a number of contaminant and act as environment friendly options.

Disadvantage of Bioremediation

• Bioremediation is limited to those compounds that are biodegradable. Not all compounds are vulnerable to rapid and complete degradation.
• Sometimes, the products of biodegradation may be more stubborn or toxic than the parent compound.
• Biological processes are often highly specific. Important site influences essential for success include the presence of metabolically capable microbial populations, suitable environmental growth conditions, and appropriate levels of nutrients and contaminants.
• More research is needed to perfect this Bioremediation technology.
• Bioremediation process takes long period of time than other traditional treatment options, such as excavation and removal of soil or incineration.
• Requires very skilled human power.