BTEX hydrocarbons anaerobic degradation

The vast amount of data from natural attenuation studies of petroleum hydrocarbon plumes generally supports anaerobic degradation, especially for benzene, toluene, ethylbenzene, xylenes (BTEX) under field conditions. The first-order degradation rates observed under unspecified anaerobic conditions (Suarez and Rifai, 1999) are typically one or two orders of magnitude lower than rates reported under aerobic conditions (Nielsen et al, 1996). 

Benzene is one of a group of related aromatic monocyclic hydrocarbons (BTEX—benzene, toluene, ethylbenzene, and xylene), and since these are water soluble, there has been concern for their dissipation and persistence in groundwater under both aerobic and anaerobic conditions. Although aerobic growth at the expense of benzene was established many years ago, the pathway for its degradation was established only much later. The aerobic degradation of benzene by bacteria is... 

Hydrocarbons — Up until now, degradation of aromatic hydrocarbons has been limited to monocyclic representatives — particularly toluene, and there is only circumstantial evidence so far for the degradation of naphthalene and phenanthrene coupled to sulfate reduction under anaerobic conditions (Coates et al. 1996a) and the degradation of naphthalene, phenanthrene, and pyrene under denitrifying conditions (McNally et bal. 1998). This issue has been discussed more fully in Chapter 6, Section 6.7.3.2, and in the context of BTEX remediation in Section 8.2.6.I. 

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