Environmental Engineering Reference
In-Depth Information
Contents
22.1 Introduction ...........................................
980
22.1.1 Principles .......................................
980
22.1.2 History .........................................
981
22.1.3 Definition .......................................
982
22.1.4 Political and Practical Acceptance ........................
983
22.2 Principles of Natural Attenuation ..............................
984
22.2.1 Plume Development and Transport Processes ..................
984
22.2.2 Proving Natural Attenuation and Implementing Monitored
Natural Attenuation .................................
986
22.2.3 Methods to Prove Monitored Natural Attenuation ...............
988
22.3 Natural Attenuation at Petroleum Hydrocarbon Contaminated Sites .........
992
22.3.1 Characteristics of Petroleum Hydrocarbon Mixtures ..............
992
22.3.2 Natural Attenuation Potential and Challenges at Petroleum
Hydrocarbon Contaminated Sites .........................
994
22.4 Natural Attenuation at Chlorinated Hydrocarbon Contaminated Sites ........
996
22.4.1 Characteristics of Chlorinated Hydrocarbons ..................
996
22.4.2 Evaluation of Natural Attenuation Potential and Challenges
at Chlorinated Hydrocarbon Contaminated Sites ................
998
22.4.3 Enhanced Natural Attenuation ...........................
1000
22.5 Natural Attenuation at Tar Oil Contaminated Sites ...................
1000
22.5.1 Introduction ......................................
1000
22.5.2 Characteristics of Tar Oil ..............................
1001
22.5.3 Natural Attenuation Potential of Tar Oil .....................
1007
22.5.4 Summary ........................................
1008
22.6 Conclusions and Outlook ...................................
1009
References ................................................
1011
22.1 Introduction
22.1.1 Principles
Natural Attenuation (NA) signifies the reduction of mass, toxicity, mobility, vol-
ume, and/or concentration of contaminants in soil or groundwater using naturally
occurring processes in soil. These processes can be classified as destructive and
non-destructive . Biodegradation, a process in which microorganisms break down
contaminants, is the most well-known and prevalent destructive mechanism. These
microorganisms use organic material, like organic contaminants, as a source for
growth and metabolism (i.e., as a carbon and energy source). Also abiotic degra-
dation processes like hydrolyses may occur. Non-destructive Natural Attenuation
processes include diffusion, dispersion, and volatilization, resulting in dilution and
spreading of contaminants, while sorption leads to a reversible or irreversible immo-
bilisation of contaminants. By its nature, Natural Attenuation is rather a series of
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