Abstract
The biodegradation of sodium dodecyl sulfate (SDS), dodecane-1-derived linear alkyl benzene sulfonate (LAS) and sodium laurate (soap) was observed with the river die-away tests using Tama and Nogawa river water.
The course of biodegradation was followed by the measurements of the loss of organic carbon (total organic carbon : TOC) and the ferro in reagent active substances (FRAS), and the dissolved oxygen (DO) was also measured simultaneously to observe the progress of the self-purification process by biodegradation.
In the cases of SDS and soap, FRAS rapidly disappeared, whereas TOC disappeared rather slowly. On the other hand LAS was bio-degraded very slowly. All of the surfactants used in this test were almost completely decomposed into inorganic compounds during about 30 days.
The concentration of dissolved oxygen rapidly decreased at first with disappearance of FRAS, and then increased with progress of biodegradation until TOC completely disappeared.
Nearly the same results were obtained in the tests with both Tama and Nogawa river water.
