EBT SLIDES
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This document discusses bioremediation of BTEX (benzene, toluene, ethylbenzene, and xylenes) compounds. It provides background on what BTEX are, how they enter the environment, their health effects, and what bioremediation is. It then describes different bioremediation techniques for BTEX including in situ bioremediation approaches like intrinsic and engineered bioremediation. Key factors that affect bioremediation success like nutrients, moisture, temperature, and electron acceptors are explained. Advantages and disadvantages of in situ bioremediation are summarized. The role of different microbes and electron acceptors in the biodegradation process is also outlined.
EBT SLIDES
- 2. What Is BTEX?Benzene, toluene, ethylbenzene, xylenes.Naturally occurring components of petroleum end up largely in gasoline as a result of the refining process.
- 3. Benzenevolatile organic compound. Used in the production of synthetic materials and consumer products.Such as synthetic rubber, plastics, nylon, insecticides, paints, dyes, resins, and cosmetics.
- 4. Toluene & EthylbenzeneToluene Occurs naturally as a component of many petroleum products. Used as a solvent for paints, coatings, gums, oils, and resins.Ethylbenzene is used mostly as a gasoline and aviation fuel additive. It may also be present in consumer products such as paints, inks, plastics, and pesticides.
- 5. XyleneThree forms: ortho-, meta-, and para-.Ortho-xylene is the only naturally occurring form, the other two being man-made.Xylenes are used in gasoline and as a solvent in printing, rubber, and leather industries.
- 6. How Does BTEX Enter The Environment?With improper storage, chemicals leach into the groundwater and contaminate public and private water systems. Large bulk facilities, surface spills, and pipeline leaks. BTEX components may become attached to soil and rock particlesFind their way into groundwater. In groundwater, persist longer than if they were exposed to airTherefore affecting water supplies for months or even years
- 7. What Health Effects Are Expected From Exposure To BTEX?Associated with skin and sensory irritation, central nervous system depression, and effects on the respiratory system. Affect organs like kidney, liver & also blood systems.Human carcinogenWorkers exposed to high levels of benzene, found to have an increase in leukemia.
- 8. What is Bioremediation?Use of biological processes to degrade,break down, change, and/or essentially remove contaminants or impairments of quality from soil and water.a natural process which relies on bacteria, fungi, and plants to alter contaminants Metabolic processes of these organisms are capable of using chemical contaminants as an energy source, rendering the contaminants harmless or less toxic products in most cases.
- 9. Why do we need Bioremediation?Conventional methods include pump and treat systems, soil vapour extraction, incineration, and containment.Suffers drawbacks and may involve some level of risk.Bioremediation offers an alternative method to detoxify contaminants.
- 10. Factors Affecting BioremediationNutrient availabilityMoisture contentpHTemperature
- 11. Advantages And Disadvantages Of Bioremediation1) Bioremediation is a natural process.2) It is cost effective.3) Toxic chemicals are destroyed or removed from environment and not just merely separated.4) Low capital expenditure.5) Less energy is required as compared to other technologies6) Less manual supervision.
- 12. Disadvantages1) Slow. Time required is in day to months.2) Heavy metals are not removed.3) For insitu bioremediation site must have soil with high permeability.4) It does not remove all quantities of contaminants.5) Substantial gaps exist in the understanding of microbial ecology, physiology and genetic expression and site expression and site engineering. A stronger scientific base is required for rational designing of process and success.
- 13. Bioremediation of BTEX In situ bioremediationinvolves a direct approach for the microbial degradation of xenobiotics at the site of pollution e.g. soilnutrients is supplied at the site which promotes the microbial growth at the site itself.generally used for cleanup of oil spillages, beaches etc.
- 14. Bioremediation of BTEX In situ bioremediationIntrinsic bioremediationEngineered in situ bioremediation
- 15. Bioremediation of BTEX Intrinsic bioremediationThe inherent metabolic ability of the microorganisms to degrade certain pollutants.Dependent on the type and concentration of compounds, electron acceptor and the duration of bacteria exposed to contamination.
- 16. Bioremediation of BTEX Engineered in situ bioremediationbioremediation process is engineered to increase the metabolic degradation efficiency.done by supplying sufficient amount of nutrients and oxygen supply, adding electron acceptors and maintaining optimal temperature and pH.done to overcome the slow and limited bioremediation capability of microorganisms.
- 17. Bioremediation of BTEXAdvantages of in situ bioremediationThe method ensures minimal exposure to public or site personnels.There is limited or minimal disruption to the site of bioremediation.Due to these factors it is cost effective.The simultaneous treatment of contaminated soil and water is possible.
- 18. Bioremediation of BTEXsites are directly exposed to environmental factors like temperature, oxygen supply etc.The seasonal variation of microbial activity exists.Problematic application of treatment additives like nutrients, surfactants, oxygen etc.It is a very tedious and time consuming process.
- 19. Bioremediation of BTEX Electron acceptors and electron tower theoryThe rate of naturally occurring bioremediation of BTEX compounds is often limited by either the concentration of an electron acceptor or a nutrient needed during degradation.Typical electron acceptors utilized by microorganisms are oxygen, nitrate, iron (III), sulfate, and carbon dioxide
- 21. Electron acceptors and electron tower theory Depending on the mode of respiration, microbes can be classified into three categories: Aerobic Anaerobic Facultative
- 22. Electron acceptors and electron tower theoryAerobicAerobes thrive only in oxygenated environments.Dissolved oxygen is used as an electron acceptor.
- 23. Electron acceptors and electron tower theory AnaerobicStrict anaerobes grow only under highly reduced conditions, where oxygen is effectively absent. Strict anaerobes use electron acceptors such as sulfate or carbon dioxide.
- 24. Electron acceptors and electron tower theory FacultativeMicroorganisms that are able to adapt to both aerobic and anaerobic conditions, but are typically more active in the presence of oxygen.Most microbes utilizing nitrate as an electron acceptor tend to be facultative.
- 25. Electron acceptors and electron tower theoryThe following figure adapted from Jorgensen (1989) illustrates the sequence and products of electron acceptor utilization for oxidation of organic carbon.
- 26. Electron acceptors and electron tower theory Field evidence also seems to suggest that natural in situ bioremediation may employ different electron acceptors at various locations throughout a given site.
- 27. Electron acceptors and electron tower theoryPetroleum aromatic compounds have been shown to degrade by cleavage of the aromatic carbon ring as shown here for benzene:Figure courtesy of the Department of Chemistry, VPI&SU.
- 28. Electron acceptors and electron tower theory Although natural or artificial recharge may stimulate aerobic biodegradation by reintroducing oxygen to anaerobic regions, the low solubility of oxygen and the rapid reaction rates typical of aerobic environments can severely limit the aerobic biodegradation of petroleum hydrocarbons
- 29. Electron acceptors and electron tower theory Therefore for a more efficient degradation we should either use all three types of microbes or use enhanced in situ bioremediation
- 30. Casestudy 1Casestudy 1Examples of Bioremediation Description 18: U.S. Army Contracting Command Overseas Remediation.An overseas U.S. Army Military Base. This base has been active since the Korean War. A Lieutenant with the Army Corps of Engineers contacted Alabaster Corp. about a bioremediation project he was conducting. For many years large volumes of military equipment had been utilized at the subject location. The location had many UST or underground fuel storage tanks as well as AST or above ground fuel storage tanks. The facility operates and maintains a large amount of equipment ranging from typical tractors, cranes, bulldozers, and other earth moving apparatus to heavy military items such as tanks and other combat designed vehicles. The concrete slab throughout most of the very large subject area was heavy and thick to withstand the tremendous weight of the equipment. Large amounts of hydrocarbons had accumulated around and underneath various large cemented areas as well as within soil or non-cemented areas.Various Army Engineering experiments with bioremediation had showed only typical to minimal results. The current options being considered were destroying the concrete slab, excavating the contaminated earth and re-filling this with clean fill dirt before relaying the new concrete slab. This included several huge area around a large military base. The officers in charge were making a last attempt to keep this project within a budget. Many details must be left confidential.
- 31. CasestudyPollution: Hydrocarbons Accumulated From Years of Operation.Large volumes of hydrocarbon contamination. Total TPH ranged from minimal detection levels to as high as well over 100,000 mg/kg. The concrete itself had a saturated amount of hydrocarbons accumulated within. The drinking water supply was effected. Ground water contamination had detectable amounts of BTEX components and other GRO or gasoline range organics. Many details must be left confidential.Solution: Alabaster Corp. Bioremediation Products. Slab Injection, etc.A very large volume of Alabaster Corp. Bioremediation products were supplied to the U.S. Army Contracting Command for this overseas base. These included products like our BCC#1 Concentrate (Sold as CS2 or Super Concentrate) and microbial blend AB with Booster.
- 32. Case Studies in Bioremediation Results: The Project was Successful.The Army engineers involved were well acquainted with the process of bioremediation and utilizing the products. They were more than typically equipped and knowledgeable about various techniques involved with applying the products. They had several flexible and creative solutions to contracting dilemmas which would have made this project difficult and more expensive for most. Many details must be left confidential. However, we were verbally assured that they remediated “the substances” they intended. Over the next few months they tripled the original order.THANK YOU