Bioremediation of soil and water

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 ),  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.

3. 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. 

4. 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.

5. 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

6. Process

7. 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.

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