Bioremediation refers to the process of using microorganisms to remove the environmental pollutants i.e. the toxic wastes found in soil, water, air etc. The microbes serve as scavengers in bioremediation. The removal of organic wastes by microbes for environmental clean-up is the essence of bioremediation. The other names used (by some authors) for bioremediation are bio-treatment, bio-reclamation and bio-restoration. Bioremediation of soil: A soil sample ((desert soil/soil with oil spills) ) was saturated with crude oil (17.3%, w/w) and aliquots were diluted to different extents with either pristine desert or petrol pump’s soils. Heaps of all samples were exposed to outdoor conditions through six months, and were repeatedly irrigated with water and mixed thoroughly. Quantitative determination of the residual oil in the samples revealed that oil-bioremediation in the undiluted heaps was nearly as equally effective as in the diluted ones. One month after starting the experiment. 53 to 63% of oil was removed. During the subsequent five months, 14 to 24% of the oil continued to be consumed by the microbes. The dynamics of the hydrocarbonoclastic bacterial communities in the heaps was monitored. The highest numbers of those organisms coordinated chronologically with the maximum oil-removal. Out of the identified bacterial species, those affiliated with the genera Nocardioides (especially N. deserti), Dietzia (especially D. papillomatosis), Microbacterium, Micrococcus, Arthrobacter, Pseudomonas, Cellulomonas, Gordonia and others were main contributors to the oil-consumption. Some species, e.g. D. papillomatosis showed the maximum tolerance compared with all the other studied isolates. It was concluded that even in oil-saturated soil, self-cleaning proceeds at a normal rate.

1. Bioremediation of Soil and Water (Contaminated with oil spills)
Dr. Naveen Gaurav
Associate Professor and Head
Department of Biotechnology
Shri Guru Ram Rai University
Dehradun

2. Bioremediation of soil and water (Contaminated with oil spills)
Bioremediation refers to the process of using microorganisms to remove the environmental
pollutants i.e. the toxic wastes found in soil, water, air etc. The microbes serve as
scavengers in bioremediation. The removal of organic wastes by microbes for
environmental clean-up is the essence of bioremediation. The other names used (by some
authors) for bioremediation are bio-treatment, bio-reclamation and bio-restoration.
Bioremediation of soil: A soil sample ((desert soil/soil with oil spills) ) was saturated with
crude oil (17.3%, w/w) and aliquots were diluted to different extents with either pristine
desert or petrol pump’s soils. Heaps of all samples were exposed to outdoor conditions
through six months, and were repeatedly irrigated with water and mixed thoroughly.
Quantitative determination of the residual oil in the samples revealed that oil-
bioremediation in the undiluted heaps was nearly as equally effective as in the diluted
ones. One month after starting the experiment. 53 to 63% of oil was removed. During the
subsequent five months, 14 to 24% of the oil continued to be consumed by the microbes.
The dynamics of the hydrocarbonoclastic bacterial communities in the heaps was
monitored. The highest numbers of those organisms coordinated chronologically with the
maximum oil-removal. Out of the identified bacterial species, those affiliated with the
genera Nocardioides (especially N. deserti), Dietzia (especially D. papillomatosis), Microbact
erium, Micrococcus, Arthrobacter, Pseudomonas, Cellulomonas, Gordonia and others were
main contributors to the oil-consumption. Some species, e.g. D. papillomatosis showed the
maximum tolerance compared with all the other studied isolates. It was concluded that
even in oil-saturated soil, self-cleaning proceeds at a normal rate.

4. Bioremediation of water (Contaminated with oil spills)
Oil is used in many processes, but not all oil is the same. Oil types can differ in viscosity (it’s
resistance to flow; molasses is highly viscous), volatility (how quickly it evaporates) and
toxicity (how poisonous it is to humans and the environment). These three characteristics
are very important when oil spills are being cleaned up, because the characteristics can
influence the method of clean-up that will be used. The following chart summarizes the
different types of oil and their characteristics.

5. Bioremediation is any process that uses decomposers and green plants, or their enzymes,
to improve the condition of contaminated environments. Bacteria can be used to clean up
oil spills in the ocean through bioremediation. Specific bacteria can be used to
bioremediate specific contaminants, such as hydrocarbons, which are present in oil and
gasoline.
Oil spills in the ocean have a severely negative effect on marine life, especially seabirds
and filter-feeders. Seabirds, such as seagulls and ducks, spend most of their life on water
and go to land only during their nesting period. The feathers of many seabirds are wettable
and must be carefully preened (or dried) for flight. If feathers come into contact with oil,
the seabird ingests the oil while trying to preen. Filter-feeders, such as clams and oysters,
take in surface water through their gills and filter it to take out any microscopic food. If
there is oil on the water, it gets concentrated within these shellfish and then accumulates
in their predators in a higher concentration.

7. Bioremediation of petroleum: Due to their ubiquity across environments, many organisms
have evolved to use the hydrocarbons and organic compounds in petroleum as energy while
simultaneously denaturing toxins through molecular transfer mechanisms.
Microbial bioremediation uses aerobic and anaerobic properties of various microbes
to respire and ferment compounds transforming toxins into innocuous compounds. These
resulting compounds exhibit more neutral pH levels, increased solubility in water, and are
less reactive molecularly. Baseline populations of oil-degrading microorganisms typically
account for less than 1% of microbiomes associated with marine ecosystems. Remediation
techniques which remove reaction limiting factors through the addition of substrate, can
boots microbe population towards 10% of the ecosystems microbiome. Dependent on
physical and chemical properties, petroleum-degenerative microorganisms take longer to
degrade compounds with high-molecular-weight, such as polycyclic aromatic
hydrocarbons (PAH's). These microbes require a wide array of enzymes for the breakdown
of petroleum, and very specific nutrient compositions to work at an efficient rate.
Microbes work in a step-wise fashion to breakdown and metabolize the components of
petroleum.
Linear Alkanes
Branched Alkanes
Small aromatic compounds
Cyclic Alkanes
Note: Treatments that use these breakdown processes most commonly use heat and
chemicals to extend the efficacy

8. Process

9. Some other Bioremediation methods to remove oil spills from water:
Phytoremediation is a process in which plants are used to sequester toxins and hydrocarbons into
plant tissue from contaminated soils. The main mechanisms for phytoremediation stem from
complex relationships between roots and rhizobia. Plants secrete sugars, enzymes, and oxygen
from roots which provide necessary substrates for rhizobia and associated rhizosphere microbes
to stimulate degradation of organic pollutants.
Studies have demonstrated the bioaccumulation abilities of various plants
with rhizobial associations, in particular Chromolaena odorata were able to remove 80% of
petroleum and heavy metal toxins from soils. While more commonly used on terrestrial
environments, contaminated marine environments also benefit from plants
based bioremediation through the use of various algae and macrophytes.
Phytoremediation is most effective when used in conjunction with microbial remediation
and Mycoremediation.
Mycoremediation techniques make use of pollutant tolerant fungi which sequester
or denature environmental toxins particularly heavy metals. Toxins are sequestered into highly
absorbent molecules such chitin and glucan which are found in fungal cell walls. Saccharomyces
cerevisiae (baker's yeast) can be used to remediate heavy metal contaminated marine
ecosystems, with 80% to 90% success in the case of arsenic. Polycyclic aromatic
hydrocarbons (PAH) concentrations of soil samples taken from contaminated oil drilling cuttings
in Nigeria have been decreased by 7% to 19% using white rot fungi under experimental
conditions. Soil contaminated with crude oil displays toxic levels of various heavy metals such
as lead, zinc and magnesium. Application of mycoremediation techniques to crude contaminated
soils have shown significant reductions of heavy metal concentrations.

10. Thank you
References: Online notes, notes from research papers and
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