Comparison of diethylene glycol and phenol biodegradability by different test methods.

Biodegradation is generally recognised as an important removal mechanism for pollutants in natural ecosystems. It determines the concentration of substances in the environment. According to the legislation of the European Union, there are three levels for biodegradability testing protocols for chemicals which cover different test conditions. This paper describes one such multilevel approach to biodegradation testing. Four different tests were performed on diethylene glycol and phenol. Diethylene glycol did not fulfill the requirements for ready biodegradable substances, while it degraded well in wastewater treatment plant simulation test. Phenol in turn, resulted ready biodegradable, and its biodegradability depended less on experimental conditions than the biodegradability of diethylene glycol. This corroborates the importance of combining different test methods to obtain relevant biodegradability data.