Bioremediation.

Use of microorganisms to degrade contaminants and alter environmental conditions.

1. DAVANGERE UNIVERSITY DEPt. OF MICROBIOLOGY SEMINAR ON – “BIOREMEDIATION”

2. CONTENTS Introduction. Types of bioremediation. Microorganisms in Bioremediation. Factors affecting Bioremediation. Advantages and Disadvantages of Bioremediation. Summary. Conclusion. References.

3. Bioremediation refers to the process of using living microorganisms to remove the environmental pollutants or prevent pollution. The removal of organic wastes by microbes for environmental clean-up the essence of bioremediation. Bioremediation is a combination of two words “ bio” means living and “ remediate” means to solve a problem or to bring the sites and affairs into the original state. Bioremediation technology using microorganisms was reportedly invented by George M. Robinson INTRODUCTION

4. Types of Bioremediation 1. In situ Bioremediation : In situ bioremediation means there is no need to excavate or remove soils or water in order to accomplish remediation. It is superior method to cleaning contaminated environments since it is cheaper and uses harmless microbial organisms to degrade the chemicals. It involves the supplying oxygen and nutrition by circulating aqueous solution through naturally occurring bacteria to degrade organic compounds. In situ bioremediation is applied to the degradation of contaminants in saturated soils and ground water.

5. Types of In situ Bioremediation There are two types of in situ bioremediation. 1. Intrinsic In situ Bioremediation : Conversion of environmental pollutants into the harmless forms through the innate capabilities of naturally occurring microbial population is called Intrinsic In situ Bioremediation. 2. Engineered In situ bioremediation : Its accelerates the degradation process by enhancing the physicochemical conditions to encourage the growth of microorganisms.

6. Advantages of In situ Bioremediation: Don’t require excavation of contaminated soils. Less expensive, less chance of contaminated other sites. Possible to treat a large volume of soil at once. Disadvantages of In situ Bioremediation: it is slow process and difficult to manage. Require uncompacted soil.

7. Ex situ Bioremediation Ex situ Bioremediation involves the removal of waste water material and their collection at a place to facilitate microbial degradation. The average time frame for ex situ Bioremediation is 60 – 90 days hence faster compared to In situ Bioremediation. Better control area, depth, nutrients, oxygen, moisture, temperature etc. On the basis of contaminated under treatment ex situ bioremediation is classified into two types solid phase system and slurry phase systems.

8. SOLID PHASE SYSTEM Land farming : Land farming is a simple technique in which contaminated soil is excavated( dig up) and spread over a prepared bed and periodically tilled until pollutants are degraded. Composting : Involves the combining contaminated soil with nonhazardous organic amendants such as manure and agricultural wastes. Biopiles : Typically used for treatment of surface contamination with petroleum hydrocarbons they are a refined version of land farming that tend to control physical losses of the contaminants by leaching and volatilization.

9. Slurry Phase system Slurry phase bioremediation is are relatively more rapid process compared to the other treatment process. Contaminated soil is combined with water and other additives in a large tank called a “Bioreactor “ Nutrients and oxygen are added and conditions in the bioreactor controlled to create the optimum environment for the microorganisms to degrade the contaminants. Slurry phase system include Bioreactors, Bioventing , Biosparging and Bioagumentation .

10. Bioreactors : Soil and water pumped up from a contaminated plume and processed through an engineered containment system. Degradation in a bioreactor is generally greater than in situ because the contained environment is more controllable and predictable. Bioventing : Bioventing employs low air flow rates. involves the amount of oxygen necessary for the degradation and nutrients through wells to contaminated soil to stimulate the indigenous bacteria.

11. Biosparging : Involves the injection of air under pressure below the water table to increase groundwater oxygen concentrations and enhance the rate of biological degradation of contaminants by naturally occurring bacteria. Bioagumentation : Bioremediation frequently involves the adding microbes and organisms to strengthen the same in waste to allow them take over and decontaminate the area.

12. Microorganisms in Bioremediation Living microorganisms are used in Bioremediation, to convert the complex toxic compounds into harmless by products of cellular metabolism such as CO2 and H2O. The successful use of microorganisms in Bioremediation depends on the development of a basic understanding of the genetics of a broad spectrum of microorganisms and Biotechnological innovation. Pure, mixed, enriched, and genetically engineered microorganisms have been used for degradation of the complex compounds. We can subdivide these microorganisms into the following groups: Aerobic : Alcaligenes , Sphingomonas , Rhodococcus , and Mycobacterium. Anaerobic : Anaerobic bacteria are used for bioremediation of polychlorinated biphenyls(PCBs) in river sediments, dechlorination of the solvent trichloroethylene(TCE) and chloroform. Ligninolytic fungi : Phanaerochaete chrysosporium

13. Factors affecting Bioremediation Nutrient availability : Inorganic nutrient such as nitrogen and phosphorus are necessary for microbial activity and cell growth. It has been shown that “treating petroleum-contaminated soil with nitrogen can increase cell growth rate, decrease the microbial lag phase, help to maintain microbial populations at high activity levels, and increase the rate of hydrocarbons degradation”. Moisture content : All soil microorganisms require moisture for cell growth and function. Availability of water affects circulation of water and soluble nutrients into and out of microorganisms cells. However, excess moisture, such as in saturated soil, is undesirable because it reduces the amount of available oxygen for aerobic respiration.

14. pH : pH of soil is important because survival of most microbial species are limited to a certain pH range. In addition, soil pH can affect availability of nutrients Temperature : Temperature influence rate of biodegradation by controlling rate of enzymatic reactions within microorganisms. Generally , “speed of enzymatic reactions in the cell approximately doubles for each 10 c rise in temperature”. Most of bacteria found in soil, including many bacteria that degrade petroleum hydrocarbons , are mesophiles which have an optimum temperature ranging from 25 c to 45 c.

15. Advantages of Bioremediation Bioremediation is a natural process and is therefore perceived by the public. Bioremediation is useful for the complete destruction of a wide variety of contaminants. Instead of transferring contaminants from one environmental medium to another, for example, from land to water or air, the complete destruction of target pollutants is possible. Bioremediation can often be carried out on site, often without causing a major disruption of normal activities. Bioremediation can prove less expensive than other technologies that are used for cleanup of hazardous waste.

16. REFERENCES Bhattacharya B.C., Banerjee . 2007. Environmental Biotechnology. Oxford university press. Pp 338. Dubey R.C. 1993. Biotechnology. S. Chand and company ltd. New Delhi. Pp 702. Mohanty M.K. 2008. Environmental Biotechnology. Adhyayan publishers and Distributors. New Delhi. Pp 257. Thakur I.S. Environmental Biotechnology. 2 nd edition. I.K. International publishing house pvt.ltd. New Delhi. Pp 516. Www. Iupac.org> publications > pac > pdf .

17. Disadvantages of Bioremediation Bioremediation is limited to those compounds that are biodegradable. Not all compounds are susceptible to rapid and complete degradation. There are some concerns that the products of biodegradation may be more persistent or toxic than the parent compound. Biological process are often highly specific. Microbial populations, suitable environmental growth conditions, and appropriate levels of nutrients and contaminants. It is difficult to deduce from bench and pilot-scale studies to full scale field operations. Bioremediation often takes longer than other treatments options.

18. SUMMARY Bioremediation is a waste management technique which involves the use of biological organisms to remove or neutralize pollutants from the contaminated site. Bioremediation is a treatment that uses naturally occurring organisms to breakdown hazardous substance into less toxic or non toxic substance. Technology generally classified as in situ and ex situ Bioremediation. In situ Bioremediation involves removal contaminated material at the site. And Ex situ bioremediation involves the removal of the contaminated material to be treated elsewhere.

19. CONCLUSION Bioremediation is a eco – friendly technology. It is effective process. Recovery of a contaminated medium by using living microorganisms. Approach to enhance the degrading capability. Application in all types of contaminated fields.