Biodegradability
Biodegradation is the breakdown of chemical substances by living micro-organisms, and can occur under both aerobic and anaerobic conditions. In the natural environment, the former occurs in soil or water where oxygen is present, whereas anaerobic degradation occurs in sediments or ground water where oxygen is normally absent. Biodegradation is important in wastewater treatment plants where both aerobic and anaerobic processes may be involved.
In contrast to other environmental fate processes, such as hydrolysis or photochemical reactions, biodegradation is unique in that the outcome is usually the complete conversion of the organic substance to inorganic products. Biodegradation is an important natural process, which converts chemicals released into the environment into other chemicals and, eventually, into carbon dioxide.
Most hydrocarbon and oxygenated solvents are biodegradable, and degrade very rapidly in the air, in the soil, and in water. They do not bio-accumulate nor persist in the environment. They also have very low eco-toxicity. Emissions of organic solvents into the air degrade typically within a couple of days, after which they have broken down into carbon dioxide and water.
