Abstract
To investigate the role of adsorption and the subsequent biodegradation of α-olefin sulfonate (AOS) in a sewage treatment system, the adsorption of AOS onto three cultures was observed at three pH conditions of 3.5, 7.2 and 8.5. The tested microorganisms were Pseudomonas surfactassimilas, gram-negative Escherichia coli (F-1) and gram-positive Bacillus subtilis (PCI). Out of those three, only Pseudomonas surfactassimilas has the surfactant degrading ability.
The adsorption tests showed no significant difference in terms of adsorbing behavior between surfactant degrading and non-degrading bacteria as well as between gram-positive and gram-negative bacteria. In all cases of three bacteria, the adsorption took place according to a Freundlich adsorption isotherm and higher adsorption was observed at low pH of 3.5.
Only in the case of surfactant degrading Pseudomonas surfactassimilas, the initial reduction of AOS by physical adsorption was followed by the successive reduction due to the biodegradation; and re-added AOS was subject to the similar adsorption and subsequent biodegradation again.
These phenomena indicate that the removal of surfactant in a sewage treatment process is made not by a single step, but by the combination of two successive steps of the adsorption and the subsequent biodegradation.
