Anaerobic Biodegradation of Organic Compounds

Because the free energy released in respiration decreases as oxygen is depleted and the microbial community shifts to the use of less favorable oxidants such 

The dichloroethene isomers (compounds with the same formula but different structures) can be further degraded under reducing conditions into chloroeth-ene (vinyl chloride), and the oxidation state of the carbon is thereby reduced to (— I)  

---

IS ISO (1995) ISO 11734. Water Quality -Evaluation of the Ultimate" Anaerobic Biodegradability of Organic Compounds in Digested Sludge - Method by Measurement of the Biogas Production, International Organization for Standardization,... 

ISO 11734 (1995). Water quality - Evaluation of the ultimate anaerobic biodegradability of organic compounds in digested sludge - Method by measurement of the biogas production... 

ISO 11734, Water Quality - Evaluation Of The Ultimate Anaerobic Biodegradability Of Organic Compounds In Digested Sludge - Method By Measurement Of The Biogas Production, 1998. 

Kameya T, Murayama T, Kitano M, et al. 1995. Testing and classification methods for the biodegradabilities of organic compounds under anaerobic conditions. Sci Total Environ 170 31-41. 

Microbial activity, which is often stimulated during bioremediation projects, can alter the external pH. For instance, the anaerobic degradation of chlorinated compounds produces organic acids and HC1 and the pH may drop to acidic values if the soil has a low buffering capacity. In this case, control of the external pH will be required in order to maintain biodegradation activity at... 

Battersby, N.S. and Wilson, V. Survey of the anaerobic biodegradation potential of organic compounds in digesting sludge, Appl. Environ. Microbiol, 55(2) 433-439, 1989. 

The empirically defined terms "humic acids" and "fulvic acids" have been used to denote important macromolecular constituents of aquatic systems. Even though their structures are incompletely resolved (Section 3.2.3 and 4.5.3), their association with low-molecular-mass organic compounds — and with metal cations — is important in determining the bioavailability and hence biodegradability and toxicity of organic compounds. Their role in the generation of OH radicals under anaerobic conditions is noted in Section 4.1.1, and as intermediates in electron-transfer reactions under anaerobic conditions in Section 5.5.5. 

FIGURE 2.32 Several examples of organic compounds that may be biodegraded in reducing, anaerobic environments. Note that most of these biodegradation reactions involve the reduction of the organic compoimd. 

The following example illustrates anaerobic biodegradation of a chlorinated organic compound that, because of its density, sinks to the bottom of a lake and dissolves in sediment pore water. 

---