means without oxygen. More specifically, it refers to occurring or living
without oxygen present; therefore, the chemistry of the system, environment, or
organism is characterized by reductive conditions. Many organic contaminants are
degraded under anaerobic conditions by anaerobic bacteria called anaerobes. This
process is known as anaerobic biodegradation. Anerobes use nitrate, sulfate,
iron, manganese, and carbon dioxide as their electron acceptors. A related /term
Biodegradation is the breakdown of organic contaminants by microorganisms when
oxygen is not present. Some anaerobic bacteria use nitrate, sulfate, iron,
manganese, and carbon dioxide as their electron
acceptors, and break down organic chemicals into smaller compounds, often
producing carbon dioxide and methane as the final products. This general
mechanism of anaerobic biodegradation
is an example of anaerobic respiration. Alternatively some anaerobic
microorganisms can break down organic contaminants by fermentation. Fermentation
is where the organic chemical acts as an electron acceptor. Anaerobic
biodegradation is an important component of the natural
attenuation of contaminants at many hazardous waste sites.
is an adjective that means without oxygen. For example, anoxic ground water is
ground water that contains no dissolved oxygen. Anoxic ground-water conditions
at hazardous waste sites are common because biodegradation processes often use
up all the available oxygen. A related term is anaerobic.
is the breakdown of organic contaminants by microbial organisms into smaller
compounds. The microbial organisms transform the contaminants through metabolic
or enzymatic processes. Biodegradation processes vary greatly, but frequently
the final product of the degradation is carbon dioxide or methane.
Biodegradation is a key processes in the natural attenuation of contaminants at
hazardous waste sites. A related term is biotransformation.
Electron Acceptor Microorganisms such as bacteria obtain energy to grow by transferring electrons from an electron donor to an electron acceptor. An electron acceptor is a compound that receives or accepts an electron during cellular respiration. The microorganism through its cellular machinery collects the energy for its use. The process starts with the transfer of an electron from an electron donor. During this process (electron transport chain) the electron acceptor is reduced and the electron donor is oxidized. Examples of acceptors include oxygen, nitrate, iron (III), manganese (IV), sulfate, carbon dioxide, or in some cases the chlorinated solvents such as tetrachloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE), and vinyl chloride (VC). These reactions are of interest not only because they allow organisms to obtain energy, but also because they are involved in the natural