Surfactant-Enhanced Insitu Biodegradation of Strongly Sorbing Organic Substances in Soil Environments PDF Download
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Category :
Languages : en
Pages : 42
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Book Description
Slightly soluble, high molecular weight chemicals and Polycyclic Aromatic Hydrocarbons (PAH), are common pollutants of concern in the remediation of oil spill sites. Low volatility, coupled with hydrophobic characteristics, make them more persistent in nature. In-place biological transformation is believed to be the most effective process for their removal. The hydrophobic nature of the contaminants results in a partition onto the soil matrix. In most cases this can account for 95-99% of the total contaminant mass. This limits the biological transformation by reducing the soluble concentration, therby, making them unavailable on the microbial population. Thus a well-designed bioremodiation process should consider a way of mobilizing the contaminants from the soil surface to make them available to the microbial population. Surfactants have been found to be effective in mobilizing hydrophobic contaminants from soil surface. Mobilization of contaminants by surfactants depends on the surfactant- soil-contaminant interactions. Edwards et al., (1991) developed a model for the prediction of the mobilization of low solubility organic contaminants by surfactants in soils.
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Category :
Languages : en
Pages : 42
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Book Description
Slightly soluble, high molecular weight chemicals and Polycyclic Aromatic Hydrocarbons (PAH), are common pollutants of concern in the remediation of oil spill sites. Low volatility, coupled with hydrophobic characteristics, make them more persistent in nature. In-place biological transformation is believed to be the most effective process for their removal. The hydrophobic nature of the contaminants results in a partition onto the soil matrix. In most cases this can account for 95-99% of the total contaminant mass. This limits the biological transformation by reducing the soluble concentration, therby, making them unavailable on the microbial population. Thus a well-designed bioremodiation process should consider a way of mobilizing the contaminants from the soil surface to make them available to the microbial population. Surfactants have been found to be effective in mobilizing hydrophobic contaminants from soil surface. Mobilization of contaminants by surfactants depends on the surfactant- soil-contaminant interactions. Edwards et al., (1991) developed a model for the prediction of the mobilization of low solubility organic contaminants by surfactants in soils.
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Languages : en
Pages : 62
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Book Description
Low-solubility Polycyclic Aromatic Hydrocarbons such as phenanthrene are easily biodegradable but due to sorption onto soil or/or their presence in a non-aqueous phase, their bioavailability is greatly reduced. In an aqueous environment where surfactants exist above their critical micelle concentration hydrophobic contaminant will partitioning into the hydrophobic core of the micelle. This enhances the apparent solubility of these hydrocarbons and therefore also their desorption from soils. Conceivably, in the absence of any inhibitory effects, such surfactants may enhance the biodegradation of the hydrocarbon. Through a set of screening experiments a group of non-ionic surfactants were identified which do not inhibit the bacterial degradation of the phenanthrene. A mathematical model was formulated to describe the interaction of the biomass-contaminant-water-surfactant system. The model assumes that the surfactant affects the solubility of phenanthrene and does not affect the biochemical characteristics of the biomass. An effective bioavailable concentration was defined. The model predicts experimental data well indicating that a part of the phenanthrene in the micelle phase can be degraded simultaneously with the phenanthrene in the aqueous phase. (jg) p.2.
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Category : Aeronautics
Languages : en
Pages : 548
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Category : Aeronautics
Languages : en
Pages : 456
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Category :
Languages : en
Pages : 0
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Book Description
Biodegradation of phenanthrene was studied in soil slurry reactors in the presence and absence of a surfactant solution. Results showed that the presence of surfactants slowed the initial biodegradation rate of phenanthrene, but increased the total mass of phenanthrene degraded over a four day period by 30%. A mathematical model was developed to simulate the dynamics of the biodegradation of low solubility hydrocarbons in the presence of soils and surfactants. Processes such as the desorption kinetics of the hydrocarbon from soil, the sorption of the surfactant onto soil and its effect on the sorption of the hydrocarbon, and the bioavailability of the hydrocarbon in different phases of the system are included in the model formulation. The experimental results were measured independently. The model was used to investigate the effect on the overall biodegradation of phenanthrene due to different operating conditions. simulation results showed that there is a system-specific optimum surfactant concentration, above which bioremediation is hindered.
Author: Robert D. Norris
Publisher: DIANE Publishing
ISBN: 9780788122507
Category :
Languages : en
Pages : 264
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Book Description
Provides a detailed background of the technologies available for the bioremediation of contaminated soil & ground water. Prepared for scientists, consultants, regulatory personnel, & others who are associated in some way with the restoration of soil & ground water at hazardous waste sites. Also provides insights to emerging technologies which are at the research level of formation, ranging from theoretical concepts, through bench scale inquiries, to limited field-scale investigations. 95 tables & figures.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309048966
Category : Science
Languages : en
Pages : 225
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Book Description
In situ bioremediationâ€"the use of microorganisms for on-site removal of contaminantsâ€"is potentially cheaper, faster, and safer than conventional cleanup methods. But in situ bioremediation is also clouded in uncertainty, controversy, and mistrust. This volume from the National Research Council provides direction for decisionmakers and offers detailed and readable explanations of: the processes involved in in situ bioremediation, circumstances in which it is best used, and methods of measurement, field testing, and modeling to evaluate the results of bioremediation projects. Bioremediation experts representing academic research, field practice, regulation, and industry provide accessible information and case examples; they explore how in situ bioremediation works, how it has developed since its first commercial use in 1972, and what research and education efforts are recommended for the future. The volume includes a series of perspective papers. The book will be immediately useful to policymakers, regulators, bioremediation practitioners and purchasers, environmental groups, concerned citizens, faculty, and students.
Author: Ajay Singh
Publisher: Springer Science & Business Media
ISBN: 3662060663
Category : Nature
Languages : en
Pages : 332
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Book Description
In this volume, experts from universities, government labs and industry share their findings on the microbiological, biochemical and molecular aspects of biodegradation and bioremediation. The text covers numerous topics, including: bioavailability, biodegradation of various pollutants, microbial community dynamics, properties and engineering of important biocatalysts, and methods for monitoring bioremediation processes. Microbial processes are environmentally compatible and can be integrated with non-biological processes to detoxify, degrade and immobilize environmental contaminants.
Author: D.R. Karsa
Publisher: Springer Science & Business Media
ISBN: 9401113483
Category : Technology & Engineering
Languages : en
Pages : 269
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Book Description
The awareness and development of 'biodegradable' surfactants pre-dates current pressures by the environmental movement by nearly three decades, wherein a responsible industry mutually agreed to replace 'hard', non-biodegradable com ponents of household detergents by 'soft', biodegradable alternatives, without course to legislation. The only requirement at that time was for surfactants used in detergents to exhibit a 'primary biodegradability' in excess of 80%; this referring to the disap pearance or removal from solution of the intact surface active material as de tected by specified analytical techniques. This proved useful, as observed environmental impacts of surfactants, e.g. visible foam on rivers, are associated with the intact molecule. Test methods for 'primary biodegradability' were eventually enshrined in EU legislation for nonionic surfactants (Directive 821242/EEC, amended 73/404IEEC) and for anionic surfactants (Directive 8212431EEC, amended 73/405IEEC). No approved test methods and resultant legislation have been developed for cationic and amphoteric surfactants to date. The environmental classification of chemical substances, which of course includes surfactants, and associated risk assessment utilises a second criterion 'ready biodegradability'. This may be assessed by a number of methods which monitor oxygen uptake (BOD), carbon dioxide production or removal of dis solved organic carbon (DOC). Some surfactants which comply with the above Detergents Directive are borderline when it comes to 'ready biodegradability'.
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ISBN:
Category :
Languages : en
Pages : 5
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Book Description
Nonionic surfactants may strongly interact with hydrophobic organic compounds (HOCs), soil, and microorganisms in soil/aqueous systems. These interactions affect the potential for surfactant-facilitated HOC transport in soil and groundwater systems, and the feasibility of engineered surfactant cleanup of contaminated sites (McCarthy and Wober, 1991). At sufficiently high bulk liquid concentrations at 25 C, most nonionic surfactants form regular micelles in single-phase solutions, whereas certain surfactants, such as C12E4, may form bilayer lamellae or other types of aggregates in more complex two-phase solutions. The critical concentrations for the onset of micelle and aggregate formation are termed the critical micelle concentration (CMC) and the critical aggregation concentration (CAC), respectively. Important changes occur in surfactant sorption, surfactant solubilization of HOCs, and microbial mineralization of HOCs in the presence of nonionic surfactants at or near these critical surfactant concentrations.
