Biodegradation

Degradation rates are drastically different depending on where breakdown occurs, and by what means. Aerobic degradation of linear alkanes generally involves the oxidation of terminal methyl groups to carboxylates, which are subsequently oxidized to CO₂ plus water. Biodegradation of organic contaminants is a complex process, and the finer points of the specific pathways are still being worked out. Biodegradation of poorly-sorbed molecules is faster than degradation of strongly sorbed organics. Degradation is generally faster and more complete when oxygen is the electron acceptor. Also, chlorinated hydrocarbons generally degrade slower than non-chlorinated hydrocarbons. Biodegradation of poorly-sorbed molecules is faster than degradation of strongly sorbed organics. Degradation rates of xenobiotic contaminants depend largely on the electron acceptor identity and availability and the inherent reactivity of the organic molecule, and/or substrate availability. Anaerobic degradation of many aromatic contaminants occurs by oxidation to phenols or organic acids, then long-chain volatile fatty acids, which are then transformed to methane and carbon dioxide.